WO1999031716A1

WO1999031716A1 - Aligner, exposure method and method of manufacturing device

Info

Publication number: WO1999031716A1
Application number: PCT/JP1998/005567
Authority: WO
Inventors: Kousuke Suzuki
Original assignee: Nikon Corporation
Priority date: 1997-12-16
Filing date: 1998-12-09
Publication date: 1999-06-24
Also published as: AU1504799A

Abstract

In an aligner (100), the heat deformation of a mask (R) which is caused by the exposure beam application is measured while a plurality of photosensitive wafers (W) are exposed with the pattern of the mask (R) and, if the heat deformation exceeds a predetermined value, the exposure of the next wafers is suspended or stopped. After the mask (R) is cooled during the suspension or stop of the exposure and the heat deformation of the mask is lowered, the exposure is resumed. The suspension or stop of the exposure is controlled by a controller (21). In the case of scanning exposure, the difference in heat deformation between the central part and edge part in a non-scanning direction of the mask is measured and the exposure is controlled so that the difference may not exceed a predetermined value. Thus the distortion of the mask pattern image formed on the wafer (W) is prevented. The decline of the exposure precision which is caused by the heat deformation of the mask can be avoided.

Description

Description Exposure apparatus, exposure method, and device manufacturing method

The present invention relates to an exposure apparatus, an exposure method, and a device manufacturing method. More specifically, the present invention relates to an exposure apparatus and an exposure method for irradiating a mask with an exposure beam and transferring a pattern formed on the mask onto a substrate. And a device manufacturing method using the exposure apparatus or the exposure method. Background art

2. Description of the Related Art Conventionally, various exposure apparatuses have been used to manufacture semiconductor elements or liquid crystal display elements by photolithography, and at present, photomasks or reticle (hereinafter collectively referred to as “reticle”) are used. Projection exposure apparatus for transferring the above pattern onto a substrate such as a wafer or a glass plate having a surface coated with a photosensitive agent such as a thin resist through a projection optical system, for example, a so-called step-and-repeat method. A small projection exposure system (so-called stepper) is used. This stepper is also called a static exposure apparatus because the exposure of each shot area is performed with the reticle and the substrate stationary. When a semiconductor device or the like is manufactured by using such an exposure apparatus, it is necessary to form different circuit patterns on the substrate in a number of layers, so that the reticle on which the circuit pattern is drawn and the reticle on the substrate are used. It is important to accurately overlap the pattern already formed in each shot area. For this reason, the projection optical system used in the projection exposure apparatus is required to have good aberrations (imaging performance) such as magnification and distortion. Furthermore, integrated circuits and the like are becoming more and more highly integrated year by year, and accordingly, the minimum line width (device rule) of a circuit pattern is becoming increasingly finer year by year. The demand for exposure accuracy including overlay accuracy has also become strict. Under such a background, the reticle is illuminated with rectangular or arc-shaped illumination light, and the reticle and the substrate are synchronously scanned in a one-dimensional direction with respect to the projection optical system, so that the reticle pattern is projected on the substrate via the projection optical system. Scanning exposure apparatuses, such as a so-called slit-scan method for sequentially transferring images onto the top or a so-called step-and-scan method, have been developed. According to such a scanning type exposure apparatus, the reticle pattern can be transferred using only a part (central part) of the effective exposure field of the projection optical system having the least aberration. Fine patterns can be exposed with higher precision. Further, according to the scanning type exposure apparatus, the exposure field can be expanded in the scanning direction without being restricted by the projection optical system, so that a large area exposure is possible. On the other hand, relative scanning of the reticle and wafer has an averaging effect, and has the advantage that distortion and depth of focus can be expected. By the way, the projection magnification of the projection optical system used in the projection exposure apparatus is subject to slight temperature changes in the apparatus, slight pressure fluctuations in the atmosphere in the clean room where the projection exposure apparatus is placed, temperature changes, and changes in the projection optical system. It fluctuates near a predetermined magnification due to the irradiation history of the irradiation energy by the exposure light and the like. In addition, due to thermal expansion of a reticle or the like, a portion may be generated. For this reason, recent projection exposure apparatuses are provided with an imaging characteristic correction mechanism for finely adjusting the imaging characteristics of the projection optical system in order to maintain desired imaging characteristics. Examples of the imaging characteristic correction mechanism include a mechanism that changes the distance between the reticle and the projection optical system, a mechanism that drives a specific lens element that forms the projection optical system in the optical axis direction, and a mechanism that drives the lens element in the tilt direction. Or a mechanism for adjusting the pressure in a predetermined closed chamber provided in the projection optical system. In order to correct thermal deformation (also referred to as irradiation variation) of the reticle, for example, as disclosed in Japanese Patent Application Laid-Open No. HEI 4-192173, the temperature distribution in the reticle plane and the reticle It is known to calculate thermal deformation and drive or tilt some of the lens groups in the projection lens in the optical axis direction. However, the correction method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-192317 is sufficient in a static exposure apparatus (collective exposure apparatus) such as the above-described stepper to obtain a correction effect. For the reasons described in (1), there is an inconvenience that a sufficient correction effect cannot be obtained even when employed directly in a scanning exposure apparatus. The reticle is thermally deformed by the exposure light exposure, and this deformation depends on the in-plane temperature distribution of the reticle, and this in-plane temperature is higher in the central part than in the peripheral part. The amount of deformation between the center position and the end position is different, and a so-called barrel-shaped distortion occurs. In such a case, if a batch exposure apparatus such as a stepper is used, the lens group is driven in the optical axis direction by using the above-described imaging characteristic correction mechanism, thereby distorting the pattern image due to the reticle thermal deformation. One shot can be corrected. However, in a scanning exposure apparatus, the exposure light and the reticle move in phase, and more specifically, the reticle is scanned in an elongated illumination area (illumination spot) formed by illuminating the reticle with the exposure light. Therefore, the deformed shape or the degree of deformation of the reticle existing in the illumination area during scanning differs depending on the position in the scanning direction. In particular, when the illumination area is located at the center in the scanning direction of the reticle and when the illumination area is located at the end in the scanning direction of the reticle (the latter is the scanning start position or scanning end position), The deformed shape or degree of deformation of the reticle is large <different. As described above, when the reticle is greatly deformed into a barrel shape, the distortion of the pattern image due to the thermal deformation of the reticle is corrected to some extent in the non-scanning direction by correcting the magnification by the correction mechanism described above. It is possible to do. However, in the scanning direction, as described above, the amount of reticle deformation differs for each scanning position, and the amount of reticle deformation at the center of the reticle in the illumination area is large. It is difficult to correct the distortion of the pattern image no matter how they are combined. In addition, the above-described distortion of the pattern image is a factor of exposure failure, and has been a factor of lowering the yield of the product when manufacturing a micro-port device such as an integrated circuit. The present invention has been made under such circumstances, and a first object of the present invention is to provide an exposure apparatus capable of preventing a decrease in exposure accuracy due to thermal deformation of a mask and a method of manufacturing the same. is there. A second object of the present invention is to provide an exposure method that can prevent a decrease in exposure accuracy due to thermal deformation of a mask. A third object of the present invention is to provide a device manufacturing method capable of improving the productivity of a highly integrated device. DISCLOSURE OF THE INVENTION According to a first aspect of the present invention, an exposure apparatus for irradiating a mask (R) with an exposure beam and transferring a pattern (PA) formed on the mask (R) onto a substrate (W). An exposure device comprising a control device (21) for monitoring a change in a physical quantity related to the deformation of the mask (R) and temporarily interrupting the exposure operation when the physical quantity becomes equal to or more than a first predetermined value. An apparatus is provided. According to this, the change in the physical quantity related to the deformation of the mask is monitored, and when the physical quantity becomes equal to or more than the first predetermined value, the exposure operation is temporarily stopped, the mask is naturally cooled for a predetermined time, and the physical quantity is reduced. After decreasing the value to less than the first predetermined value, the control device restarts the exposure operation. Therefore, if the physical quantity related to the deformation of the mask becomes large <the allowable limit value (first predetermined value), the exposure operation is automatically interrupted. The distortion of the image of the mask can be suppressed within an allowable range, thereby making it possible to prevent a decrease in exposure accuracy due to thermal deformation of the mask. The processes performed by an ordinary exposure apparatus include loading a substrate into an exposure device, aligning the substrate, exposing a substrate or a plurality of shot areas (areas that will later become chips) partitioned on the board, and exposing the shot. It includes various process steps such as stepping movement between process areas and unloading for substrate exchange.Before stepping movement or unloading for substrate exchange, the exposure operation must be completed. ing. As used herein, the term "interrupting the exposure operation" does not include interrupting the exposure operation when initiating a process step in which such exposure is not performed. In other words, the term “interruption of the exposure operation” means that the mask is actively stopped during the process steps included in the exposure process or between subsequent process steps to reduce thermal deformation due to mask irradiation. Or means to cool. However, as described below, this active mask pause or cooling time may overlap with process steps such as substrate replacement. In this case, the control device (21) may restart the exposure operation when the physical quantity becomes equal to or less than a second predetermined value or after a predetermined time has elapsed. In such a case, when the physical quantity related to the deformation of the mask reaches a second predetermined value (for example, a value suitable for restarting the exposure operation), the control device automatically restarts the exposure operation. The exposure operation is not interrupted for a longer time, and the distortion of the pattern image due to the thermal deformation of the mask is maintained at a constant value. The following can be controlled automatically. Therefore, it is possible to prevent a decrease in exposure accuracy due to the thermal deformation of the mask without significantly lowering the throughput. Alternatively, the control device (21) interrupts the exposure operation in synchronization with the exposure operation of the predetermined number of substrates (W), that is, every time the exposure operation of the predetermined number of substrates (W) ends. And restart may be performed. In such a case, when exposing a plurality of substrates sequentially, the time required for substrate replacement and the time required for natural cooling of the mask can be greatly overlapped, so that exposure caused by thermal deformation of the mask can be achieved. In addition to preventing a decrease in optical accuracy, it is possible to further suppress the deterioration of throughput.o In the above-described exposure apparatus, the physical quantity may be a measured value such as a temperature. 1 = g = based on the amount calculated based on the measured physical quantity. In the above exposure apparatus, various physical quantities can be considered as the physical quantity. For example, the physical quantity may be an amount related to energy absorption by irradiation of the mask (R) with the exposure beam. The exposure apparatus further includes an imaging characteristic correction device that corrects an imaging characteristic of a pattern image of the mask (R), wherein the control device (21) is configured such that the physical quantity is less than the first predetermined value. During this period, the imaging characteristic correction device (14) can be controlled so as to cancel the influence of the deformation of the mask (R). According to this, while the physical quantity is less than the first predetermined value, the control unit controls the imaging characteristic correction apparatus so as to cancel the influence of the mask deformation. Distortion of the image of the pattern due to the deformation of the mask during the exposure while it is less than the predetermined value Can be prevented. Various configurations are conceivable as the imaging characteristic correcting device. For example, a driving device (21, 41, 42) that synchronously moves the mask (R) and the substrate (W) in a predetermined scanning direction. ), The imaging characteristic correction device may adjust a speed ratio of synchronous movement between the mask and the substrate. In such a case, by adjusting the speed ratio of the synchronous movement between the mask and the substrate by the imaging characteristic correcting device, it is possible to correct a magnification error in the scanning direction of the pattern image of the mask in the scanning direction. Alternatively, in a case where the exposure apparatus further includes a projection optical system (PL) for projecting an image of the pattern of the mask (R) onto the substrate, the imaging characteristic correction apparatus (14) It may adjust the imaging characteristics of the projection optical system. The exposure apparatus further includes a driving device (21, 41, 42) that synchronously moves the mask (R) and the substrate (W) in a predetermined scanning direction, and the physical quantity of the monitored object includes the mask (R) a barrel-shaped distortion in the scanning direction may be included. According to this, in a scanning exposure apparatus including a driving device that synchronously moves a mask and a substrate in a predetermined scanning direction, a barrel-type distortion in a scanning direction of a mask, which is particularly difficult to correct, is a physical quantity to be monitored. Therefore, even in the case of a scanning exposure apparatus, it is possible to suppress the image distortion of the pattern due to the thermal deformation of the mask to a certain value or less. In the above exposure apparatus, a pattern in consideration of deformation due to absorption of the exposure beam is drawn on the mask (R), and the control device (21) causes the pattern of the mask (R) to have a predetermined shape. The dummy exposure operation can be performed until the change occurs. According to this, since the pattern has a predetermined shape at the end of the dummy exposure, when the dummy exposure is not performed on the predetermined shape, immediately before the interruption of the exposure (when the physical quantity is By setting the shape to a shape symmetric to the shape of the pattern (at the first predetermined value), the interval between the first predetermined value and the second predetermined value is set to be approximately double as compared with the case of the above embodiment. As a result, the ratio of the time during which the exposure is interrupted to the time during which the exposure is performed can be reduced, thereby substantially reducing the waiting time and minimizing the deterioration of throughput. It can be stopped (see Figures 5 and 6). According to a second aspect of the present invention, there is provided an exposure method for irradiating a mask (R) with an exposure beam (IL) and transferring a pattern formed on the mask (R) onto a substrate (W). An exposure apparatus comprising: a first step of temporarily stopping an exposure operation when a physical quantity related to the deformation of the mask (R) is equal to or more than a first predetermined value; and a second step of restarting exposure. . According to the exposure method of this aspect, the exposure operation is temporarily interrupted when the physical quantity related to the deformation of the mask becomes equal to or more than the first predetermined value, and after the interruption, preferably after the mask is naturally cooled for a predetermined time, Exposure is resumed. For this reason, if the physical quantity related to the deformation of the mask becomes large and reaches the allowable limit value (first predetermined value), the exposure operation is interrupted, and the image distortion of the pattern due to the thermal deformation of the mask is caused. Can be suppressed to within an allowable range, thereby making it possible to prevent a decrease in exposure accuracy due to thermal deformation of the mask. In this exposure method, the restart of the exposure operation in the second step may be performed when the physical quantity becomes equal to or less than a second predetermined value. In such a case, when the physical quantity related to the deformation of the mask reaches a second predetermined value (for example, a value suitable for restarting the exposure operation), the exposure operation can be automatically restarted, and the throughput is considerably reduced. Without this, it becomes possible to automatically control the distortion of the pattern image due to the thermal deformation of the mask within an allowable range. In the above-described exposure method, the physical quantity may be a measured value such as a temperature, but, for example, the physical quantity is calculated based on the measured predetermined physical quantity. In the above-described exposure method, various physical quantities can be considered as the physical quantity. For example, the physical quantity may be an amount related to energy absorption by irradiation of the mask (R) with the exposure beam (IL). . According to a third aspect of the present invention, there is provided an exposure method for irradiating a mask (R) with an exposure beam (IL) and transferring a pattern formed on the mask (R) onto a substrate (W). An exposure method is provided, wherein the exposure operation is interrupted (paused) and restarted every time the exposure operation of a predetermined number of substrates (W) is completed. According to this method, when exposing a plurality of substrates sequentially, the time required for substrate replacement and the time required for natural cooling of the mask can be substantially overlapped, so that exposure accuracy caused by thermal deformation of the mask can be achieved. In addition to preventing a decrease in the output, it is possible to improve the throughput. According to a fourth aspect of the present invention, in an exposure method for irradiating a mask (R) with an energy beam (IL) from a beam source and transferring a pattern formed on the mask onto a substrate (W), An exposure method comprising: detecting information on an energy absorption amount of the mask by the irradiation of the energy beam; and limiting irradiation of the energy beam to the mask based on the detected information on the energy absorption amount. Provided. According to this, information on the energy absorption amount of the mask due to the irradiation of the energy beam is detected, and the mask is detected based on the detected information on the energy absorption amount. The irradiation of the energy beam to the mask can be limited, for example, before the mask absorbs more than an acceptable level of energy, thereby reducing the image of the pattern due to thermal deformation of the mask. Distortion can be suppressed within an allowable range, and a decrease in exposure accuracy due to thermal deformation of the mask can be prevented. Here, limiting the irradiation of the energy beam includes not only adjusting the power of the energy beam, for example, the exposure beam, but also interrupting the irradiation of the exposure beam. When the irradiation of the energy beam is restricted, the exposure time and the like may be appropriately adjusted in order to maintain a desired amount of exposure to the substrate, particularly to a substrate coated with a photosensitive material such as a photo resist. . For example, when scanning exposure is performed, the moving speed of the substrate with respect to the energy beam may be appropriately adjusted according to the power of the exposure beam. In the fourth aspect, when exchanging the substrate (W) onto which the pattern of the mask (R) is transferred, the exposure operation may be interrupted. In such a case, the time required for substrate replacement and the time required for natural cooling of the mask can be overlapped, so that exposure accuracy can be prevented from lowering due to thermal deformation of the mask and throughput can be improved. become. In the above exposure method, various methods for limiting the irradiation of the energy beam can be considered. For example, the restriction may include stopping beam irradiation from the beam source, or may include blocking a beam path of the energy beam, or the mask (R) This may include reducing the intensity of the energy beam irradiated on the substrate. The beam irradiation can be stopped by stopping the laser oscillation of a beam source such as a laser light source, and the beam path can be blocked, for example, by shutting down a beam or a blind placed in the beam path. The intensity of the energy beam can be reduced by using a dimming filter, a light amount aperture, or the like. According to a fifth aspect of the present invention, there is provided a device manufacturing method for manufacturing a device using the exposure apparatus according to the first aspect. According to a sixth aspect of the present invention, there is provided a device manufacturing method including the exposure method according to the second aspect. According to a seventh aspect of the present invention, there is provided an exposure method for irradiating a mask (R) with an exposure beam (IL) from a light source (1) and transferring a pattern formed on the mask onto a substrate (W). An exposure method is provided that monitors a physical quantity related to the deformation of the mask and detects that the physical quantity has exceeded a predetermined value. According to this, since the physical quantity related to the deformation of the mask is monitored and it is detected that the physical quantity has exceeded a predetermined value, the deformation of the mask can be kept within an allowable value. Various means may be used for this purpose.For example, the exposure operation may be interrupted when the physical quantity has exceeded a predetermined value, or the mask has been cooled when the physical quantity has reached a predetermined value. You may. Here, the cooling of the mask includes both natural cooling and forced cooling by an appropriate cooling device. In the exposure method according to the seventh aspect, the irradiation of the exposure beam from the light source may be stopped when the physical quantity has reached a predetermined value or more, or the exposure may be performed when the physical quantity has reached a predetermined value or more. The intensity of the beam may be reduced, or the beam path of the exposure beam may be cut off when the physical quantity has reached a predetermined value or more. In the exposure method according to the seventh aspect, the physical quantity includes various ones, but the physical quantity may be an energy absorption amount of the mask, or may be a distortion amount of the pattern of the mask. good. According to the eighth aspect of the present invention, an exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam to expose a substrate or a region partitioned in the substrate with an image of the pattern is performed. An exposure apparatus that sequentially executes a plurality of substrates or a plurality of regions partitioned on the substrate,

A measuring device for measuring a thermal deformation amount of the mask or a factor causing the thermal deformation of the mask by irradiating the mask;

And a control device for interrupting the next exposure operation when the thermal deformation amount or the factor becomes equal to or larger than a first value set in advance. According to the exposure apparatus according to the eighth aspect of the present invention, since the exposure apparatus includes a measuring device for measuring the amount of thermal deformation of the mask or a factor causing the thermal deformation, the amount of thermal deformation of the mask or the factor is, for example, The exposure operation of the next substrate or the next shot region in the substrate can be temporarily interrupted before exceeding the first value corresponding to the allowable upper limit of thermal deformation. In the exposure operation, the exposure operation can be restarted when the mask is cooled and the amount of thermal deformation decreases to a preset second value. As a result, it is possible to prevent the mask pattern from being distorted due to thermal deformation and to maintain desired imaging characteristics. Factors that cause thermal deformation are, for example, the temperature of the mask and the thermal energy absorbed by the mask from the exposure beam. According to the present invention, the amount of thermal deformation of the mask or a factor causing the thermal deformation can be determined by the measuring instrument. For example, the amount of thermal deformation of the mask can be obtained by using a model calculation formula showing the amount of thermal deformation with respect to the elapsed time t from the start of irradiation of the mask as shown in the specific example of the present invention. For example, to effectively prevent (barrel-shaped) distortion of the projected image on the substrate due to the thermal deformation of the mask, the thermal deformation at the center and at the edge of the mask is obtained using a model calculation formula, and the difference between them is calculated. Seeking By doing so, the degree of distortion can be estimated. Alternatively, as a factor that causes thermal deformation, the temperature of the mask, for example, the temperature difference between the center and the end of the mask or the temperature distribution of the mask is measured with a temperature sensor or the like, and from the obtained temperature distribution, for example, The amount of thermal deformation of the mask can be obtained by using the calculation method disclosed in Japanese Patent Application Laid-Open No. 4-192173. That is, in the present invention, the amount of thermal deformation of the mask can be indirectly measured by measuring a factor or a parameter that causes thermal deformation of the mask, such as the mask temperature or the thermal energy absorbed by the mask. The measuring device may be a computing device that calculates thermal deformation based on the model calculation formula. When calculating the amount of thermal deformation from the temperature distribution of the mask, the measuring device may include not only a computing device but also a temperature sensor. The measuring device can also function as a timer that measures the elapsed time from the start of mask irradiation. The control device not only controls interruption and start of the exposure operation, but also functions as the computing unit. The exposure apparatus of this aspect can be a scanning type exposure apparatus that moves a mask and a substrate in synchronization in a scanning direction. In this case, the arithmetic unit as the measuring device calculates the thermal deformation amount M 1 (t) at the center of the mask in the non-scanning direction with respect to the elapsed time t from the start of irradiation on the mask based on the thermal deformation model calculation formula of the mask. And the thermal deformation amount M 2 (t) at the mask edge and their difference can be calculated. According to a ninth aspect of the present invention, an exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam and exposing a substrate or a region partitioned in the substrate with an image of the pattern is performed. An exposure method that is sequentially executed over a plurality of substrates or a plurality of partitioned regions in the substrate,

Determining the thermal deformation of the mask; An exposure method is provided in which, when the thermal deformation amount of the mask becomes equal to or larger than a preset value, the exposure operation for the next substrate or area is interrupted. According to the exposure method according to the ninth aspect of the present invention, since the thermal deformation of the mask from the start of irradiation of the mask is known, when the thermal deformation exceeds a reference value, the thermal deformation returns to a predetermined value. The exposure of the next substrate to be exposed or the next shot area defined in the substrate can be temporarily stopped. As a result, it is possible to prevent a mask pattern image from being distorted due to mask distortion, and to maintain good imaging characteristics. In the exposure method according to this aspect, the amount of thermal deformation of the mask can be calculated from the start of irradiation of the mask, based on a model formula relating to the thermal deformation of the mask with respect to the elapsed time t from the start of irradiation of the mask. In this case, before the start of exposure, a time schedule for a change in the amount of thermal deformation of the mask with respect to an elapsed time from the start of irradiation of the mask is obtained based on a model formula for thermal deformation of the mask. The exposure operation for the next substrate or area can be interrupted at a time when the value reaches or exceeds the set value. Such a time schedule may be stored in the control device or a separately provided memory in advance. The model equation may include a thermal deformation time constant and a thermal deformation saturation value as parameters. According to a tenth aspect of the present invention, an exposure operation of irradiating a mask on which a predetermined pattern is formed and exposing a substrate or a region partitioned in the substrate with an image of the pattern is performed by a plurality of substrates. Alternatively, in the exposure method, which is sequentially performed over a plurality of partitioned areas in the substrate,

Measuring the temperature distribution of the mask;

Determining the amount of thermal deformation based on the temperature distribution of the mask;

When the amount of thermal deformation exceeds a preset value, the next substrate or area The exposure operation is interrupted. According to the exposure method of this aspect, the amount of thermal deformation is indirectly obtained from the temperature distribution of the mask, so that deterioration of the imaging characteristics due to thermal expansion of the mask can be prevented. In order to determine the amount of thermal deformation from the temperature distribution of the mask, for example, a calculation method disclosed in Japanese Patent Application Laid-Open No. 4-192173 may be used. The exposure apparatus according to the present invention can be manufactured by the following manufacturing method. According to a eleventh aspect of the present invention, there is provided a method for manufacturing an exposure apparatus for irradiating a mask with an exposure beam and transferring a pattern formed on the mask onto a substrate,

Providing an irradiation system for irradiating the mask with an exposure beam;

There is provided a method of manufacturing an exposure apparatus, comprising: monitoring a change in a physical quantity associated with the deformation of the mask, and providing a control device for temporarily stopping the exposure operation when the physical quantity becomes equal to or more than a first predetermined value. The method further comprises providing a projection optical system between the mask and the substrate for projecting a pattern formed on the mask onto the substrate at a predetermined projection magnification; and synchronizing the mask, the substrate, and the exposure beam. And providing a stage system for moving. Further, according to the 12th aspect of the present invention, the exposure operation of irradiating a mask on which a predetermined pattern is formed and exposing a substrate or a region partitioned in the substrate with an image of the pattern includes a plurality of exposure operations. A method of manufacturing an exposure apparatus that sequentially executes over a substrate or a plurality of partitioned areas in the substrate,

Providing an irradiation system for irradiating the mask with an exposure beam;

A measuring device for measuring an amount of thermal deformation of the mask due to irradiation of the mask or a factor causing thermal deformation of the mask;

Providing a control device for interrupting the next exposure operation when the thermal deformation amount or the factor becomes equal to or more than a preset value; and a method of manufacturing an exposure device. The method may further include the step of providing a memory storing a thermal deformation model calculation formula for calculating a thermal deformation amount of the mask. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to one embodiment.

FIG. 2 is a diagram showing the projection optical system partially cut away for explaining the configuration of the imaging performance correcting mechanism of FIG.

FIG. 3 is a plan view showing the points used to determine the amount of deformation of the reticle.

FIG. 4 is a diagram showing how the thermal deformation of the reticle changes over time.

FIG. 5 is a diagram showing how the physical quantity changes when the exposure method according to the present invention in which the exposure operation is interrupted and resumed according to the physical quantity corresponding to the corrected residual error is adopted.

FIG. 6 is a diagram showing how the physical quantity changes when the exposure method according to the present invention in which a pattern that cancels the thermal deformation of the reticle is drawn on the reticle and dummy heating is performed in advance is employed.

FIG. 7 is a flowchart for explaining an embodiment of the device manufacturing method according to the present invention.

FIG. 8 is a flowchart showing the processing in step 204 of FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to one embodiment. The exposure apparatus 100 is a so-called step-and-scan type scanning exposure apparatus. The exposure apparatus 100 includes an illumination system including a light source 1 and an illumination optical system (2 to 9). A reticle stage RST that holds a reticle R as a disc, a projection optical system P, and an imaging performance correction mechanism that is provided in the projection optical system PL and corrects imaging performance such as magnification 1

4.The lens controller 15 that controls the imaging performance correction mechanism 14, the wafer stage WST that holds the wafer W as a substrate, and moves two-dimensionally in the XY plane while holding the wafer W, and the control system for these. Have. The illumination system includes a light source 1, a first fly-eye lens 2, a vibration mirror _3, a second fly-eye lens 4, a half mirror 5, an integrator lens sensor 6, a reticle blind 7, a bending mirror 8, and a condenser single lens system 9. And so on. Here, the components of the illumination system will be described together with the operation. Illumination light IL as exposure light generated by the light source 1 passes through a shutter (not shown), and is then illuminated by a first fly-eye lens 2 (intensity distribution). ) Is converted to a nearly uniform light flux. As illumination light IL, for example K r F excimer one laser light (wavelength 248 eta m) and A r F excimer laser beam (wavelength 1 93 nm), or F ₂ excimer Ichizako (Wavelength 1 57 nm) or the like is used Can be An example of an exposure apparatus using an excimer laser as a light source is disclosed in Japanese Patent Application Laid-Open No. 57-198631 (corresponding US Pat.

58, 994), and JP-A-1-259533 (corresponding U.S. Pat. No. 5,307,207). Examples of an exposure apparatus using an excimer laser light source for step-and-scan exposure include: Disclosed in JP-A-6-132195 (corresponding U.S. Patent No. 5,477,304), JP-A-7-142354 (corresponding U.S. Patent No. 5,534,970), etc. Have been. Therefore, also in the exposure apparatus of FIG. 1, it is possible to apply the technology relating to the excimer laser and the exposure apparatus disclosed in each of the above-mentioned patent publications as they are, or to partially modify them. To the extent permitted by the national laws of the designated country or selected elected country in this international application, the above publications and US patents will be incorporated by reference. The light beam emitted from the first fly-eye lens 2 is bent in a horizontal direction via a vibration mirror 13 for smoothing interference fringes and weak speckles generated on the irradiated surface (reticle surface or wafer surface). The illuminance distribution is further made uniform by the second fly-eye lens 4 and reaches the half mirror 15. Most of this light flux (pulse illumination light) IL (about 97%) passes through the half mirror 15 to illuminate the reticle blind 7 with uniform illuminance. Here, the reticle blind 7 is composed of two movable blinds and a fixed blind disposed near the movable blind and having a fixed opening shape. The arrangement surface of the movable blind is conjugate to the reticle R pattern surface. The fixed blind is, for example, a field stop in which a rectangular aperture is surrounded by four knife edges, and the vertical width of the rectangular aperture is defined by a movable blind, thereby illuminating the reticle R. The width of the slit-shaped illumination area I can be set to a desired size. The movable blind is driven in the opening and closing direction by a movable blind drive mechanism (not shown) so that its operation is controlled by the main controller 21 in accordance with masking information called a process program. Has become. The luminous flux that has passed through the reticle blind 7 reaches the bending mirror 8, where it is bent vertically downward, and illuminates the illumination area IAR of the reticle R on which the circuit butter, etc., is drawn via the condenser lens system 9. .

On the other hand, the remaining pulse illumination light IL (about 3%) is reflected by the half mirror 5 and received by the integrator sensor 6. The amount of illumination light on the reticle R can be detected by the integer sensor 6. The light amount signal from the integrator sensor 6 is transmitted to the main controller 2 1 Is supplied to A reticle R force is fixed on the reticle stage RST by, for example, vacuum suction. The material used for the reticle R must be properly used depending on the light source used. That is, when a light source K r F excimer one laser light and A r F excimer one The light can be used synthetic quartz, F ₂ excimer - When using a laser light, must be formed of fluorite There is. The reticle stage RST is driven on a reticle base (not shown) by a reticle driving unit 41 composed of a linear motor or the like, and is perpendicular to an optical axis IX of an illumination optical system (coincides with an optical axis AX of a projection optical system PL described later). It is movable in a predetermined scanning direction (here, the Y-axis direction) within a predetermined stroke within a predetermined plane. The reticle stage RST has a movement stroke that allows the entire surface of the reticle R to cross at least the optical axis IX of the illumination optical system. Further, reticle stage RST is configured to be finely driven in the X-axis direction and the rotation direction around the Z-axis orthogonal to the XY plane in order to position reticle R. The position of the reticle stage RST is constantly measured at a resolution of, for example, several nm to 1 nm or less by a reticle laser interferometer system (not shown). The position information of the reticle stage RST from the interferometer system is transmitted to the main controller 2. The main controller 21 controls the reticle stage RST via the reticle drive system 41 based on the positional information of the reticle stage RS. ₍ Note that the measuring axis of the reticle laser interferometer system is, for example, Two axes are provided in the scanning direction, and one axis is provided in the non-scanning direction.In this case, the reticle stage is positioned by a reticle alignment system (not shown) so that the reticle R is accurately positioned at a predetermined reference position. Early RST Since the position is determined, the position of the reticle R is measured with sufficiently high accuracy only by measuring the position of the reflection surface (not shown) provided on the reticle stage RST by the reticle interferometer system. The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX (coincident with the optical axis IX of the illumination optical system) is the Z-axis direction. As the projection optical system PL, here, a refraction optical system including a plurality of lens elements arranged at predetermined intervals along the optical axis AX direction so as to have a telecentric optical arrangement on both sides is used. This projection optical system PL is a reduction optical system having a predetermined projection magnification, for example, 1/4 (or 1/5). Therefore, when the illumination area IAR of the reticle R is illuminated by the illumination light IL from the illumination optical system, a part of the circuit pattern of the reticle R is transmitted through the projection optical system PL by the illumination light IL passing through the reticle R. Is reduced and projected on a wafer W coated with a photo resist on the surface. Further, the imaging performance correcting mechanism 14 is provided inside the projection optical system P as described above. In the present embodiment, as shown in FIG. 2, a specific plural (here, five) lenses of the plural lens elements constituting the projection optical system PL are used as the imaging performance correcting mechanism 14. Each of groups 2, 2, 3, 24, 25, and 26 is independently moved in the optical axis AX direction using piezoelectric elements 27, 28, 29, 30, and 31 such as piezo elements. (Z direction) and a mechanism that can be driven in the tilt direction with respect to the XY plane are used. The lens groups 22, 23, 24, 25, and 26 are respectively connected to the lens barrel PP by three piezo elements 27, 28, 29, 30, and 31 via respective holders. It is supported by three points. Therefore, by independently driving each of the three piezo elements 27, 28, 29, 30 and 31, each lens group 22 23 23 24 24 25 26 Can be driven in the optical axis AX direction (Z direction) and the tilt direction with respect to the XY plane. The imaging performance correction mechanism is, for example, Kaihei No. 4-127515 and No. 4-134813 and their corresponding U.S. Patent Nos. 5,117,255, which are designated in this international application. To the extent permitted by the laws of the designated designated country or the selected elected country, their disclosure shall be incorporated as a part of the text. In the present embodiment, as will be described later, the imaging performance correcting mechanism 14 corrects five aberrations, specifically, curvature of field, magnification, distortion, coma, and spherical aberration. The imaging performance correction mechanism 14 and the lens controller 15 constitute an imaging characteristic correction device that corrects the imaging characteristics of the pattern image of the reticle R. The specific contents of the imaging characteristic correction by the imaging characteristic correction device will be described later in detail. When KrF excimer laser light or ArF excimer laser light is used as the illumination light IL, synthetic quartz or the like can be used as each lens element constituting the projection optical system PL. When using F ₂ excimer laser light, fluorite is used as the material of the lenses used in the projection optical system PL. Returning to FIG. 1, the wafer stage WST moves on a base (not shown) in the Y-axis direction (left-right direction in FIG. 1), which is the scanning direction, and in the X-axis direction (perpendicular to the paper plane in FIG. 1). A possible XY stage 18 and a Z stage 17 provided on the XY stage 18 are provided.

The XY stage 18 is actually driven in the XY two-dimensional direction on the base by a two-dimensional planar motor or the like, and the Z stage 17 is moved in the Z direction by a driving mechanism (not shown). In FIG. 1, these two-dimensional planar motors, drive mechanisms, and the like are represented as a wafer drive unit 42 as a representative example, while being driven within a predetermined range (for example, a range of 100 m). . A wafer W is suction-held on a Z stage 17 via a wafer holder (not shown). Further, on the Z stage 17, there is provided an irradiation amount sensor 20 for detecting an irradiation amount that passes through the reticle R and the projection optical system PL and reaches the wafer surface. The detection value of the irradiation amount sensor 20 is supplied to the main controller 21. The position of the Z stage 17 (i.e., wafer W) in the XY plane is constantly measured, for example, with a resolution of several nm to 1 nm or less by a wafer laser interferometer system (not shown). The Z stage RST position information is sent to the main controller 21, and the main controller 21 sends the wafer W in the XY plane via the wafer driving device 42 based on the Z stage 17 position information. To control the position. Note that the wafer laser interferometer system has, for example, one axis in the scanning direction and two axes in the non-scanning direction. Further, in the exposure apparatus 100 of the present embodiment, the two focus detection systems, ie, reticle sensors, which are integrally attached to the projection optical system PL via a holding member (not shown), are provided. A focus detection system (hereinafter, referred to as “reticle AF system”) 12 and a wafer focus detection system (hereinafter, referred to as “wafer AF system”) 19 are provided. The wafer AF system 19 includes an irradiation optical system 19a that irradiates the wafer W with a detection beam obliquely, and a light-receiving optical system 19b that receives the reflected light of this detection beam from the wafer W surface. An oblique incident light type focus position detection system that detects the position of the wafer W in the Z direction is used. For example, this wafer AF system 1 9 Japanese Patent Publication No. 215303 and U.S. Pat. No. 4,801,977 corresponding thereto, and Japanese Patent Application Laid-Open Nos. 5-2755313 and 5-190423 And the corresponding focus position detection systems disclosed in US Pat. Nos. 5,502,311. The above US patents are hereby incorporated by reference, with the disclosure incorporated by reference, to the extent allowed by the national laws of the designated or elected country of this international application. The reticle AF system 12 includes an irradiation optical system 12a for irradiating the pattern surface of the reticle R with a detection beam obliquely, and a light receiving optical system 12b for receiving the reflected light of the detection beam from the reticle surface. An oblique incident light type focus position detection system having the following is used. The reticle AF system 12 is for detecting the optical axis IX of the pattern surface of the reticle R and the position in the Z direction of a region near the optical axis IX. The reticle AF system 12 may have the same configuration as that disclosed in Japanese Patent Publication No. 8-21531 and the corresponding US patent. The AF system is not limited to the obliquely incident light type. For example, an interferometer that measures the Z position of the wafer surface or reticle surface, or a direct focus that directly measures the distance between the projection optical system and the wafer or reticle. A sensor may be employed. In addition, the exposure apparatus 100 of the present embodiment is provided with an off-axis type alignment system for detecting alignment marks (not shown) attached to each shot area on the wafer W. The main controller 21 detects the position of the alignment mark on the wafer W using an alignment system prior to the scanning exposure described below, and based on the detection result, the reticle driving system 41 and The wafer driving device 42 aligns the reticle R with the wafer W (alignment). Next, the principle of scanning exposure in the exposure apparatus 100 of the present embodiment will be briefly described. explain. The reticle R is illuminated by a rectangular (slit-shaped) illumination area IAR having a longitudinal direction perpendicular to the scanning direction of the reticle R (Y-axis direction). Is scanned with. The illumination area IAR (the center is substantially coincident with the optical axis AX) is projected onto the wafer W via the projection optical system PL, and a slit-shaped projection area conjugate to the illumination area IAR, that is, an exposure area IA is formed. Since the wafer W has an inverted image relationship with the reticle R, the wafer W is scanned at the speed VW in the direction opposite to the direction of the speed VR (+ Y direction) in synchronization with the reticle R, and The entire shot area can be exposed. At the time of this scanning exposure, the reticle R and the wafer W, that is, the reticle stage RST and the wafer stage WST are accurately adjusted by the reticle drive unit 41, the drive unit 42, and the main controller 21 to the reduction magnification of the projection optical system PL. Synchronous movement is performed at the corresponding speed ratio VW / VR, and the pattern in the butter area of the reticle R is accurately reduced and transferred onto the shot area on the wafer W. Further, the entire area of the pattern area on the reticle R is illuminated by scanning, and the entire area of the pattern area of the reticle R is sequentially transferred onto the wafer W. As is apparent from the above description, in the present embodiment, the reticle driving system 41, the wafer driving device 42, and the main controller 21 constitute a driving device for synchronously moving the reticle R and the wafer W. In addition, during the above scanning exposure, the main controller based on the detection signals of the wafer AF system 19 and the reticle AF system 12 so that the pattern surface of the reticle R and the surface of the wafer W become conjugate with respect to the projection optical system PL. The Z stage 17 is driven and controlled in the Z-axis direction by the controller 21 via the wafer driving device 42 to perform focus correction. The focus correction will be further described later. In the exposure apparatus 100 of the present embodiment, the transfer of the reticle pattern by the scanning exposure to the shot area on the wafer W as described above and the stepping operation to the scanning start position of the next shot area are repeatedly performed. Accordingly, step-and-scan exposure is performed, and a reticle pattern is transferred to all shot areas on the wafer W. As described above, the illumination optical system composed of multiple optical members, the projection optical system, and the reticle stage and wafer stage composed of many mechanical parts were assembled electrically, mechanically and optically, and assembled. The exposure apparatus 100 of the present embodiment can be manufactured by comprehensively adjusting the exposure apparatus (adjustment of the optical path, stage speed, synchronization timing, operation confirmation, etc.). Next, six types of imaging performance in the exposure apparatus 100, specifically, methods of correcting focus, curvature of field, magnification, distortion, coma, and spherical aberration will be described. First, in the initial adjustment stage, while driving the five lens groups 22 to 26 constituting the imaging performance correction mechanism 14 one by one, focus, field curvature, magnification, distortion, coma, We measured six types of imaging performance of spherical aberration, and obtained the above-mentioned six types of imaging performance change coefficients in each lens group 22-26. The imaging performance change coefficient may be an optically calculated value. Of the above-mentioned imaging performance change coefficients, a five-element simultaneous linear equation can be established using the five types of imaging performance change coefficients excluding focus and the movement amounts (drive amounts) of the five lens groups. it can. Here, the focus is removed because when the lens group is driven to correct other imaging performance such as magnification, the focus fluctuates accordingly, so the focus must be corrected by another device. Because there is. This This will be described later. Then, by using the five-way simultaneous linear equation established above, for example, when it is desired to change the magnification to a predetermined magnification, a certain amount is put in the imaging performance change coefficient of the magnification of the above simultaneous equation, and the other four types are set. By establishing a new simultaneous equation with the imaging performance change coefficient of `` 0 '' added, solving this simultaneous equation to obtain the drive amount of each lens group, and driving each lens group according to this drive amount It is possible to control only the magnification to a predetermined value without affecting the field curvature, the distortion, the coma, and the spherical aberration. Here, the case where the magnification is changed has been described, but the curvature of field, distortion, coma aberration, and spherical aberration are the same as above, and the values can be individually changed without affecting other factors. it can. Next, a focus correction method will be described. First, in order to obtain the conjugate relationship between the reticle R and the wafer W, the position of the reference Z stage 17 is obtained. Specifically, a measurement reticle on which a predetermined measurement mark is drawn is mounted on a predetermined position of the reticle stage RST, and the photosensitive mark is applied to the measurement mark while step-moving the Z stage 17 in the Z direction. After being transferred (baked) onto the coated wafer W, the wafer W is developed by a developing device. Next, the wafer W is observed with an optical microscope to find the position of the Z stage 17 having the best burned mark shape. The Z position of Z stage 17 at this time is set as the reference position, and the outputs of reticle AF system 12 and wafer A `` system 19 '' when Z stage 17 is at that reference position are stored in memory as the respective AF reference positions. The following focus fluctuation correction is managed by the displacement from this reference position, that is, the main controller 21 outputs the outputs of the reticle AF system 12 and the wafer AF 19 as described above. Make sure that it does not fluctuate from each AF reference position. That is, the Z stage 17 is driven and controlled in the optical axis direction so that the optical distance between the reticle R and the wafer W is kept constant. The focus correction is performed in this manner. More specifically, assuming that the displacement on the reticle R and the wafer W side detected from the AF reference position are Rz and Wz, respectively, and the projection magnification is ML, the focus displacement △ F is

△ F2 R z xM L ² — Wz

It is expressed as By moving the Z stage 17 in the Z-axis direction such that the value becomes 0, the conjugate relationship between the reticle R and the wafer W is maintained. As a specific example, if the reticle R is displaced by 1 m in the Z-axis direction during scanning, (1/4) ² = 0 on the wafer W surface when the projection magnification is 0.25 times (1/4 times). 06 25> um. At this time, the AF can be set to 0 by intentionally displacing the wafer W by 0.625 xm in the Z-axis direction, that is, by setting Wz = 0.625yum in the above equation, The optical distance between the reticle R and the wafer W can be maintained. Of course, the projection magnification of the projection optical system PL is not limited to 1/4, but it can be handled by multiplying the square of the projection magnification by the displacement amount on the reticle side. When the lens groups 22 to 26 are driven in order to correct other imaging performance such as the above-mentioned magnification, the amount of focus change that occurs as a side effect due to this is changed by the above-described imaging performance change coefficient and each lens. The calculation is made based on the drive amounts of groups 22 to 26. The calculated focus change amount is added to the output of the wafer AF system 19 as an offset at the time of the above-described focus correction, so that the optical distance between the reticle R and the wafer W becomes a predetermined value. Can be kept. Next, a method for calculating the thermal deformation of the reticle R, and the magnification (or the magnification) of the projected image of the reticle pattern onto the wafer W by the projection optical system PL caused by this thermal deformation The method for correcting the (stiction) will be described in detail. First, a point for calculating the thermal deformation of reticle R is selected. FIG. 3 shows a plan view of the reticle R. As shown in FIG. 3, at least two points M 1 (the center of the reticle) and M 2 (the end of the reticle R) for which magnification is to be determined along the scanning direction of the reticle R are selected. The position and number of selected points are not limited to those shown in Fig. 3, but may be those that require the distortion of the side of the reticle R in the non-scanning direction (distribution of displacement in the reticle plane in the scanning direction). Good. Next, a method of obtaining the reticle transmittance, which is a premise of the thermal deformation calculation, will be described. First, in a state where the reticle R is not placed on the reticle stage RST, the main controller 21 drives the wafer stage 18 via the wafer driving device 42 to move the irradiation amount sensor 20 directly below the projection optical system PL. Go to Next, the main controller 21 turns on the light source 1, illuminates the illuminance sensor 20 with the illumination light IL via the projection optical system PL, and outputs the output of the illuminance sensor 20 at that time. It is stored in memory (not shown). At this time, the main controller 21 measures the output of the irradiation amount sensor 20 over the entire scanning range while scanning the reticle stage RST via the reticle driving system 41 so that the same conditions as the actual exposure are obtained. Then, the total is stored in the memory. Next, the reticle R is set on the reticle stage RST by a reticle loader (not shown), and in this state, the main controller 21 scans the reticle stage RST in the same manner as described above while scanning the irradiation amount sensor 20 over the entire scanning range. The outputs are measured and summed, and the reticle R is calculated by calculating the ratio of the total value of the outputs of the dose sensors 20 to the total value of the outputs of the dose sensors 20 stored in the memory above. Can be determined. In each of the above two dose measurements, it is desirable to measure the output of the integrator sensor 6 and normalize the output of the dose sensor 20. In such a case, even if the power of the light source 1 fluctuates, the transmittance of the reticle R can be accurately obtained without being affected by the fluctuation. Further, in the above description, the irradiation amount is measured while scanning the reticle stage RST. However, the measurement may be performed while repeating the step movement of the reticle R for each range in which the illumination area covers. Alternatively, the output of the irradiation amount sensor 20 may be represented as a function corresponding to the scanning coordinates of the reticle R, and the function may be stored in the memory. Next, a method of calculating the thermal deformations M 1 (t) and M 2 (t) of the points M 1 and M 2 of the reticle R will be described. First, a model equation for the thermal deformation of the reticle R as shown in the following equation (1) is established.

M (t) = M (t -Δ t) X e ρ ρ (-Δ t / T) + K xWx (1−7?) X (1-r) x [1 -exp (-Δ t / T) ] · · · (1)

In the above equation, T is the time constant of thermal deformation at the measurement point, Κ is the thermal deformation saturation value at the measurement point, At is the measurement interval, W is the irradiation power of reticle R, 7 is the transmittance of reticle R, and r is the reticle The reflectance of R. Among them, the value obtained above is used for the transmittance 7? Of the reticle R. In addition, the reflectance r of the reticle R is obtained in advance. Then, a predetermined experiment is performed, and the relationship between the illumination energy and the irradiation expansion of the reticle R is obtained at points Μ1 and Μ2 at the measurement interval Δΐ. The reticle irradiation power W during this experiment is calculated based on the output of the integrator sensor 6 at that time. Relationship between integre overnight sensor 6 and reticle irradiation power W Are proportional to each other, the ratio α between the two is determined in advance by experiment, this is stored in memory, and the ratio is multiplied by the output I of the integrator sensor 6 to calculate the reticle irradiation power W described above. I do. By applying force fitting to the data at each point obtained from the experimental results, the time constants of thermal deformation at points Μ1 and Μ2, Τ1, Τ2, and points Μ1, Μ2 Equations (2) and (3) can be obtained by finding the thermal deformation saturation values Κ 1 and Κ 2 of, and substituting them into D and の in the above equation.

Μ 1 (t) = Μ 1 (t -Δ t) xe ρ ρ (-Δ t / T 1) + K 1 xWx (1−7?) X (1-r) x [1 -exp (-Δΐ / Τ 1)] · · · (2)

M2 (t) = M2 (t -Δ t) X exp (-Δ t / T 2) + K 2 XWx (1-77) x (1-r) x [1 -exp (-ΔΪ / Τ 2)] (3) Then, at the time of exposure, the output of the integrator sensor 6 at that time is multiplied by the above ratio α to calculate the reticle irradiation power W. Then, the thermal deformation amounts 1 ^ 11 (t) and M 2 (t) of M 1 and 2 at time t are calculated. The calculation interval At may be determined based on the amount of change in the points M1 and M2 per unit time and the required accuracy. In practice, a value of 10 msec or less is often selected. In this case, since the reticle irradiation power W is calculated based on the output of the integrator sensor 6 at the time of exposure, even when the power of the light source 1 fluctuates or the amount of illumination light is intentionally reduced, It is possible to calculate the reticle irradiation power W accurately. In order to obtain the time constants T 1 and T 2 for thermal deformation of M 1 and M 2 and the saturation values K 1 and Κ 2 for thermal deformation of M 1 and M 2, the linear expansion of the material of reticle R Energy from coefficient The amount of thermal deformation for lugi absorption may be determined from thermal simulation. It is sufficient that the reticle reflectivity is obtained in advance and stored in a memory.However, there is a variation in the reflectivity among a plurality of reticles, and a calculation error can be ignored by using a uniform reflectivity. If it disappears, the reticle reflectivity may be registered with a resolution that can be neglected so that the calculation error can be ignored, and the reticle reflectance may be selected according to the reticle R to be used. In the model formulas (2) and (3), a first-order lag system (= first-order differential equation) is assumed, but multiple time-constant components may be used for more accurate calculations. If two time constant models are applied only to M1, the following equations (4) and (5) are obtained: In equations (4) and (5), the time constant of thermal deformation and Each component is indicated by suffixes A and B added to the thermal deformation saturation value.

M 1 _A (t) = M 1 _A (t -Δ t) xexp (-Δ t / T _A ) + K _A x Wx (1-7?) X (-r) x [1 -ex p (-At / T _A )] · · · (4)

M 1 _B (t) = M 1 B (t -Δ t) xexp (-Δ t / T _B ) + K _B x Wx (1-7?) X (1— r) x [1—exp (— t / T _B )] · · ■ (5)

M 1 (t) = M 1 _A (t) + M 1 _B (t

Of course, the time constant is not limited to the above two, but can be easily extended to three time constants, and furthermore, there is a time delay between irradiation and appearance of a change in magnification (in terms of control). If there is so-called "dead time", It is not limited to the above calculation model. Next, a magnification correction method in the non-scanning direction will be described. The above M1 (t) and M2 (t) are thermal deformations of the reticle in the scanning direction of each point, however, it is usually safe to assume that the reticle fluctuates by the same amount in the non-scanning direction. t) and M 2 (t) are corrected by giving an offset to the magnification correction. That is, by changing the projection magnification of the projection optical system PL consciously according to the coordinates of the reticle in the scanning direction, a change in magnification in the non-scanning direction due to thermal deformation of the reticle is corrected. (1) When the end of the reticle R in the scanning direction is in the illumination area IAR, M2 (t) is the offset value of the magnification, and when the center of the reticle R is in the illumination area IAR, M1 (t) is the offset value of the magnification. . In the intermediate state between ① and ② above, the offset value of the magnification according to the coordinates is approximated by, for example, approximation with a quadratic function so that the magnification changes smoothly from M 1 (t) and M 2 (t). Find and correct. When the thermal deformation of the reticle R is different between the scanning direction and the non-scanning direction, the magnification change in the non-scanning direction is separately calculated in the same manner as in the above M 1 (t) and M 2 (t). May be. As a simple correction method to reduce the calculation time, an average of M1 (t) and M2 (t) is calculated as an offset value of the magnification, and a constant value is obtained without depending on the coordinates of reticle R. Magnification correction may be performed. Next, a method of correcting the magnification in the scanning direction will be described. The magnification in the scanning direction can be corrected by calculating the average value of M1 (t) and M2 (t) as a magnification error and changing the relative speed ratio between the reticle R and the wafer W accordingly. Unlike the magnification correction in the non-scanning direction, the magnification correction in the scanning direction has no choice but to correct the intermediate value between M1 (t) and M2 (t) as a magnification error. In the main controller 21 of the exposure apparatus 100 of this embodiment, the above-described step 'and' scan exposure is sequentially repeated for a plurality of wafers. At this time, the pattern of the reticle R is transferred to the wafer W. During exposure, the thermal deformation amounts M 1 (t) and M 2 (t) of the reticle R bottles M 1 and M 2 are constantly calculated using the above equations (2) and (3). Calculated at intervals of t. While these amounts of thermal deformation are small, as described above, other imaging performances of the projection optical system PL, such as curvature of field, coma, Without affecting aberrations, etc., the magnification and distortion of the projected image of the reticle pattern due to the thermal deformation of the reticle are corrected, and the Z stage 17 is driven and controlled in consideration of the effects of these corrections to focus. Correction has been performed. When the exposure operation is repeatedly performed using the same reticle R while correcting various imaging performances as described above, the irradiation energy of the illumination light IL is accumulated in the reticle R, and the thermal deformation amount of the reticle R gradually decreases. However, the situation of this change in thermal deformation differs for each point of reticle R. As a result, as shown in Fig. 4, as the irradiation energy accumulates (time elapses), the difference {M1 (t) between the thermal deformation amounts M1 (t) and M2 (t) of points M1 and M2 of reticle R t) — M2 (t)} gradually increases, and barrel distortion occurs in the projected image (transfer image) of the reticle pattern. However, as described above, the magnification correction in the scanning direction is performed using the average value of M1 (t) and M2 (t) as a magnification error. (t) -M2 (t)}, and if left unchecked, at some point it will be unacceptable. Thus, in the exposure apparatus 100 of the present embodiment, the main controller 21 calculates the difference (M1 (t) -M 2 ( t)} and monitor this change. In this case, we can easily think of As can be seen, since the rectangular pattern changes into a barrel-shaped distortion shape due to the thermal deformation of the reticle R, monitoring the change of the above difference {M 1 (t) -M 2 (t)} as a physical quantity is This is nothing less than monitoring the barrel type physical quantity as a physical quantity. Further, the above difference is a difference between thermal deformation amounts at different points on the reticle, and thus is a kind of information regarding an energy absorption amount of the reticle R due to irradiation of the illumination light (energy beam) IL. Then, when the difference {M1 (t) -M2 (t)} reaches the first predetermined value LH, the main controller 21 suspends the exposure operation once, the reticle R is naturally cooled, and reaches the second predetermined value LL. Wait until it becomes. Thereafter, when the difference {M1 (t) -M2 (t)} becomes smaller than the second predetermined value LL, the main controller 21 resumes the exposure operation, and again executes the difference {M1 (t) —M2 (t)} until the first predetermined value LH is reached. Thereafter, by repeating this operation, it is possible to prevent the correction residual error of the magnification in the scanning direction determined according to the difference {M 1 (t) -M2 (t)} from exceeding the allowable value. Fig. 5 shows how the difference {M 1 (t)-M2 (t)} changes with time when the exposure operation is repeatedly performed in this manner. . In FIG. 5, the dotted line shows how the difference {M 1 (t) -M2 (t)} changes with time when the exposure is not interrupted. The first predetermined value LH may be determined based on required accuracy (exposure accuracy, overlay accuracy, etc.). When the required accuracy differs for each lot, a different first predetermined value is set for each lot, so that the exposure interruption time (waiting time) can be set for a lot with relatively low required accuracy. Time) can be reduced, so that the throughput can be improved as a result. Also, the time during which the difference {M 1 (t) -M 2 (t)} changes from the second predetermined value LL to the first predetermined value LH is set to the exposure time for one wafer W. As a result, the exchange time after the exposure of one wafer W is completed for cooling the reticle. It may be used as a waiting time (Saiichi Burlap). Specifically, from the number of shots in one wafer W and the exposure time of one shot, it is possible to predict M 1 (t) and M 2 (t) during the exposure of one wafer from the above equation to some extent. It is possible. By doing so, the pure waiting time is reduced, and the deterioration of the throughput can be further suppressed. Of course, the time required for the difference {M1 (t) -M2 (t)} to change from the second predetermined value LL to the first predetermined value LH is exactly the time required for exposure of a plurality of wafers W ( (Including an exchange time on the way), and in such a case, the pure waiting time is reduced for the same reason, and the deterioration of the throughput can be suppressed accordingly. As another form, there is a method in which thermal deformation of the reticle is canceled beforehand when drawing a pattern. In this case, as can be easily imagined from FIG. 4, the rectangular pattern changes into a barrel-shaped disposition shape due to the thermal deformation of the reticle R. In consideration of this, a thread-wound distortion shape is preliminarily provided on the reticle. Should be drawn. Hereinafter, the reticle on which the pin-shaped distortion-shaped pattern is drawn is referred to as a reticle R 'for convenience. The reticle R ′ is thermally deformed by the irradiation of the illumination light, and gradually changes into a barrel-shaped dissection shape as the irradiation energy is absorbed. In other words, the reticle R 'gradually decreases in the degree of the pincushion shape, cancels the pincushion-type distortion on the way, and has an appropriate rectangular pattern shape. It changes so that the barrel shape gradually becomes stronger. Therefore, when a predetermined number of wafers W are continuously exposed using the reticle R ′, the main controller 21 executes the patterning of the reticle R ′ prior to starting the exposure on the actual wafer. Dummy exposure until To irradiate the reticle R with illumination light. Since the reticle R is heated by the irradiation of the illumination light by the dummy exposure, it is hereinafter referred to as a dummy heat. The above-mentioned predetermined shape is, for example, a shape (the barrel at that time) symmetric to the shape of the pattern immediately before the interruption of the exposure when the above-described dummy exposure is not performed (when the physical quantity is the first predetermined value LH). The shape of a thread-wound distortion that cancels the mold distortion). In this case, the value of the difference {M 1 (t) −M 2 (t)} at which the pattern of the reticle R, has the above-mentioned predetermined shape is set as a second predetermined value LL ′. Then, the main controller 21 starts exposure of the actual wafer when the difference {M 1 (t) −M 2 (t)} reaches the second predetermined value LL ′. As in the case of FIG. 5, the exposure operation is performed such that the difference {M 1 (t) —M 2 (t)} is maintained between the first predetermined value LH, and the second predetermined value LL, Is repeated alternately. This is shown in Figure 6. In this way, the corrected residual error determined according to the physical quantity {M 1 (t) — M 2 (t)} within the allowable range becomes positive or negative, so comparing Fig. 5 and Fig. 6 As is apparent, the width between the first predetermined value LH 'and the second predetermined value LL' can be set to almost twice the width between LH and LL in FIG. 5, and the exposure is interrupted. The ratio of time to the exposure time can be reduced, the waiting time for cooling the reticle R 'can be substantially reduced, and the deterioration of the throughput can be minimized. . As described above, according to the exposure apparatus 100 of the present embodiment, the main controller 21 uses the physical quantity (M 1 (t) described above as the physical quantity related to the deformation of the reticle R (or R ′). -M 2 (t)}, and when the physical quantity exceeds the first predetermined value LH, the exposure operation is temporarily stopped, the reticle is naturally cooled for a predetermined time, and the physical quantity resumes the exposure operation. When the value reaches the second predetermined value LL, which is a value suitable for performing exposure, the exposure operation is automatically restarted, so that the interruption time is prevented from becoming unnecessarily long, and the pattern caused by thermal deformation of the reticle R is prevented. Constant image distortion It can be controlled automatically below the value. Therefore, it is possible to prevent a decrease in exposure accuracy due to thermal deformation of the reticle R without significantly lowering the throughput. This is particularly effective when the reticle R is made of a material that is easily affected by heat, such as fluorite. In the above embodiment, the thermal deformation of the reticle R has been described, but the thermal deformation of the projection optical system (projection lens) PL is also calculated at the same time, and these are combined so as to be reflected in the magnification correction in the scanning direction and the non-scanning direction. But of course it is good. In such a case, it is possible to correct the imaging performance with higher accuracy. Many examples of the calculation and correction of the thermal deformation of the projection optical system (projection lens) PL are already known, and those methods can be adopted. Such calculations and corrections are disclosed, for example, in Japanese Patent Application Laid-Open No. 7-94339 and corresponding US Patent Nos. 5,661,546, and Or, to the extent permitted by the national laws of the selected country, these disclosures may be incorporated and incorporated as part of the text. In addition, the calculation of the change in the imaging performance of the projection optical system (projection lens) PL due to environmental fluctuations (changes in atmospheric pressure, temperature, and humidity) is performed. Accuracy can be improved. Further, in the above embodiment, the configuration is such that six types of imaging performance are calculated and corrected by six types of correction means (five lens groups 22 to 26 and a Z stage 17). Of course, if n is negligible, the imaging performance to be corrected may be reduced for implementation. Conversely, in order to further increase the exposure accuracy, the number of types of imaging performance to be corrected may be increased as compared with the case of the present embodiment. In other words, the magnification correction mechanism is indispensable, but it is only necessary to judge whether or not to adopt other corrections of imaging performance based on the required accuracy. In the above-described embodiment, the case where the barrel-shaped distortion has occurred in the reticle has been described. However, even when other distortions have occurred, the same processing can be performed to effectively cope with the distortion. In the above embodiment, the reticle is deformed by thermal deformation due to the exposure light, and the physical quantity {M 1 (t) —M 2 (t)} corresponding to the corrected residual error that cannot be corrected is equal to the first predetermined value LH When the exposure time exceeds the limit, the exposure operation is interrupted to start cooling the reticle, and the exposure operation is restarted when the value falls below the second predetermined value LL. Of course, the exposure operation may be restarted after a certain period of time required for natural cooling has elapsed without checking whether or not the exposure operation has been performed. In addition, when a cooling device for reticle R is separately provided, thermal deformation of the reticle may be obtained in consideration of the cooling function. What is important is to monitor the physical quantity related to the deformation of the reticle R and detect that the value has exceeded a predetermined value. This makes it possible to keep the deformation of reticle R within an allowable value. When the physical quantity becomes equal to or more than a predetermined value, for example, the reticle R may be forcibly cooled using a cooling device such as a water-cooled cooling device, a Peltier device, or a heat pipe. Alternatively, a light-reducing filter such as an ND filter or a light-amount stop is arranged at a position in the illumination optical system conjugate with the pupil of the projection optical system PL, for example, at the exit end face of the second fly-eye lens 4, and irradiates the reticle R with these. The intensity of the pulsed illumination light IL may be reduced. In the above embodiment, the case where the physical quantity to be monitored is a calculated value has been described, but the present invention is not limited to this. For example, two or three or more points having different reticle R as the physical quantity are used. These temperatures may be selected, and these temperatures may be measured at predetermined time intervals using a temperature sensor. From the relationship between the temperatures of two or more points of the mask, that is, the temperature distribution of the mask, for example, refer to The amount of thermal deformation can be determined using the calculation method disclosed in No. 17. The exposure operation can be interrupted when the amount of thermal deformation is equal to or more than a predetermined value, using the amount of thermal deformation obtained in this manner, as in the above-described embodiment. Alternatively, the relationship between the temperature distribution of the mask and the amount of thermal deformation can be determined in advance, and the exposure operation can be interrupted when the temperature distribution becomes a predetermined distribution based on the relationship. In the latter case, the mask pattern distortion is monitored indirectly through the measured temperature. As far as the national laws of the designated country designated in this international application or the selected elected country permit, the disclosure of the aforementioned Japanese Patent Application Laid-Open No. 4-192173 is incorporated herein by reference. In the above embodiment, the physical quantity {M 1 (t) —M 2 (t)} corresponding to the thermal deformation of the reticle R due to the exposure light is monitored as the physical quantity related to the deformation of the reticle R. The case where the exposure operation is interrupted when the predetermined value LH exceeds 1 has been described, but the present invention is not limited to this. For example, information on the amount of energy absorbed by the reticle R due to irradiation of the illumination light (energy beam) IL from the light source (beam source) 1 (for example, the time integrated value of the output of the integrate sensor 6 or the time integrated value and the ratio It is also possible to limit the irradiation of the reticle R with the energy beam based on the detected information on the energy absorption. In this way, for example, it is possible to limit the irradiation of the reticle R with the energy beam IL before the reticle R absorbs an energy exceeding an allowable level, thereby forming an image of a pattern caused by thermal deformation of the reticle R. The distortion can be suppressed within an allowable range, and it becomes possible to prevent a decrease in exposure accuracy due to thermal deformation of the reticle R. Here, as a method of limiting the irradiation of the energy beam, the laser oscillation of the light source (excimer laser) 1 as a beam source is stopped to stop the irradiation of the pulse illumination light (energy beam) IL. Not shown shirt or reticle in the system The beam path (optical path) of the pulsed illumination light IL may be blocked by the movable blind, or the voltage applied to the light source (charging current) may be adjusted, or the position in the illumination optical system conjugate with the pupil of the projection optical system PL. For example, a light-reducing filter such as an ND filter, a light-amount aperture, or the like may be arranged on the exit end face of the second fly-eye lens 4 to reduce the intensity of the pulse illumination light IL applied to the reticle R. When adjusting the amount of illumination on the reticle R, the amount of light irradiation (integrated exposure) on a photosensitive material such as a photoresist applied on the substrate is adjusted to a desired value. The movement speed of the mask and the substrate at the time of scanning exposure may be adjusted according to the amount of illumination light that has been set. Further, the width of the projection area IA in the scanning direction may be changed, or the oscillation cycle of the pulsed illumination light may be changed. A shirt, a reticle movable blind, a dimming filter, a light amount aperture, and a control method thereof for restricting the irradiation of the energy beam are disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 2-169917. To the extent permitted by the designated or designated elected States in the application, these disclosures are incorporated by reference and are incorporated herein by reference. Further, in the above embodiment, the amount of thermal deformation represented by M 1 (t) —M 2 (t) is calculated in real time based on the model formulas (1) to (3) using the output data from the integrator sensor. However, by substituting the illumination light pattern preset for use in actual exposure into the model formula, M 1 (t) —M 2 (t) with respect to the elapsed time t from the start of mask illumination, that is, heat A time schedule of the deformation amount may be obtained in advance. In this case, the obtained time schedule is stored in the control device or a memory provided separately, and only the time from the start of illumination is measured at the time of actual exposure, and M 1 (t) —M 2 (t ) Can be controlled to interrupt the exposure operation when a time has been reached that is greater than or equal to a first predetermined value. This makes it easy to manage the operation time of the exposure apparatus when continuously exposing a plurality of substrates. Becomes In particular, when the exposure apparatus is incorporated in a manufacturing line for mass-producing devices such as semiconductor circuit chips using a device manufacturing process described later, control and management of the manufacturing line are facilitated. Further, in the above embodiment, the exposure operation for cooling the mask was interrupted for each substrate or each time a predetermined number of substrates were exposed. However, a plurality of shots may be included in one substrate. When an area (a unit in which a chip is formed) is partitioned, the exposure operation may be temporarily interrupted each time one or more shot exposure operations are completed. In the above embodiment, the case where excimer laser light is used as the illumination light for exposure has been described. However, the present invention is not limited to this. Illumination light for exposure is, for example, 5 to 15 nm. EUV (Extreme Ultra violet) light (eg, = 13.4 nm) having an oscillation spectrum in the (soft X-ray region) may be used. Furthermore, ultra-high pressure mercury lamp, instead of such as an excimer laser, or F ₂ laser, infrared region oscillated from the DFB semiconductor laser or fiber one laser, or a single wavelength laser in the visible range, for example, erbium (or erbium and Germany Toribiumu Both may be amplified by a doped fiber amplifier, and a harmonic converted to ultraviolet light using a nonlinear optical crystal may be used. For example, if the oscillation wavelength of a single-wavelength laser is in the range of 1.51 to 1.59 μΓτι, the 8th harmonic whose generation wavelength is in the range of 189 to 199 nm, or the generated wavelength is The 10th harmonic within the range of 151-159 nm is output. In particular, if the oscillation wavelength is in the range of 1.544 to 1.553 yum, the 8th harmonic in the range of 193 to 194 nm, that is, ultraviolet light having almost the same wavelength as the ArF excimer laser, Assuming that the oscillation wavelength is in the range of 1.57 to 1.58 xm, the 10th harmonic within the range of 157 to 158 门 [^, that is, almost the same wavelength as the F ₂ laser Ultraviolet light is obtained. If the oscillation wavelength is in the range of 1.03 to 1.12 μπι, the 7th harmonic whose emission wavelength is in the range of 147 to 160 nm will be output, and Assuming that the wavelength is in the range of 0.909 to 1.106 / m, the generated wavelength is the seventh harmonic within the range of 157 to 158 μηη, that is, the wavelength is almost the same as that of the F ₂ laser. Is obtained. It should be noted that, as the single-wavelength oscillation laser, a laser made of yttrium-doped fiber is used. In the above-described projection exposure apparatus using EUV light, a reflective reticle is used, and the optical path from the laser light source to the wafer is usually kept in a vacuum, so that heat of the reticle is not released to the outside. Therefore, even in a projection exposure apparatus using EUV light, a decrease in exposure accuracy can be prevented by monitoring information on reticle deformation and information on heat (energy) absorption of the reticle as in the present invention. When a mold reticle is used, a beam splitter is arranged between the reticle and the projection optical system, and the reticle is irradiated with illumination light for exposure through the beam splitter, so that the illumination optical system Can be arranged on the same side of the reticle as the projection optical system. The EUV light can be adjusted so that its principal ray is inclined with respect to the direction orthogonal to the reticle and enters the reticle. Incidentally, the projection optical system may be constituted by only a plurality of reflection optical elements, and the reticle side may be a non-telecentric optical system. In the present invention, the exposure beam is not limited to ultraviolet light including EUV light, visible light, and infrared light, and may be radiation such as X-rays or particle beams such as electron beams.

[Device manufacturing method]

Next, a device using the above-described exposure apparatus and exposure method in a lithographic process. An embodiment of a method for manufacturing a metal will be described. Fig. 7 shows a flowchart of an example of manufacturing devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.). As shown in FIG. 7, first, in step 201 (design step), a device function / performance design (for example, a circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. . Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon. Next, in step 204 (wafer processing step), using the mask and wafer prepared in steps 201 to 203, an actual circuit is formed on the wafer by lithography technology or the like as described later. Etc. are formed. Next, in step 205 (device assembling step), device assembly is performed using the wafer processed in step 204. Step 205 includes, as necessary, processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation). Finally, in step 206 (inspection step), an operation check test, a durability test, and the like of the device manufactured in step 205 are performed. After these steps, the device is completed and shipped. FIG. 8 shows a detailed example of the step 204 in the case of a semiconductor device. In FIG. 8, in step 211 (oxidation step), the surface of the wafer is oxidized. In step 2 1 (CVD step), an insulating film is formed on the wafer surface. Step 2 1 3 (Electrode formation step) In this case, electrodes are formed on the wafer by vapor deposition. In step 2 14 (ion implantation step), ions are implanted into the wafer. Each of the above-mentioned steps 211 to 214 constitutes a pre-processing step of each stage of wafer processing, and is selected and executed according to a necessary process in each stage. In each stage of the wafer process, when the above-mentioned pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, in step 2 15 (register forming step), a photosensitive agent is applied to the wafer. Subsequently, in step 211 (exposure step), the circuit pattern of the mask is transferred to the wafer by the above-described exposure apparatus and exposure method. Next, in Step 217 (development step), the exposed wafer is developed, and in Step 218 (etching step), the exposed members other than the portion where the resist remains are removed by etching. Then, in step 219 (registry removal step), unnecessary resists after etching are removed. By repeating these pre-processing and post-processing steps, multiple circuit patterns are formed on the wafer. If the device manufacturing method of the present embodiment described above is used, the above-described exposure apparatus 100 and its exposure method are used in the exposure step (step 2 16), so that exposure defects due to thermal deformation of the reticle can be prevented. Generation can be prevented, the device yield can be improved, and the productivity of highly integrated devices can be improved. In the above embodiments, the exposure process, the exposure apparatus, and the device manufacturing method used in the semiconductor device manufacturing process have been described as examples. Exposure apparatus and method for transferring onto a plate, device used for manufacturing thin-film magnetic head The present invention can also be applied to an exposure apparatus and method for transferring a semiconductor pattern onto a ceramic wafer, and an exposure apparatus and method used for manufacturing an imaging device (such as a CCD). In addition to micro devices such as semiconductor devices, glass substrates or silicon wafers are used to manufacture reticles or masks used in optical exposure equipment, EUV exposure equipment, X-ray exposure equipment, electron beam exposure equipment, etc. The present invention can also be applied to an exposure apparatus and a method for transferring a circuit pattern to the same. Industrial applicability

According to the exposure apparatus and the exposure method of the present invention, it is possible to prevent a decrease in exposure accuracy due to thermal deformation of a mask during exposure, and to achieve high accuracy even for a highly integrated pattern of an integrated circuit. Exposure becomes possible. Further, according to the device manufacturing method of the present invention, a highly integrated and highly reliable device such as a semiconductor chip can be obtained.

Claims

The scope of the claims

1. An exposure apparatus that irradiates a mask with an exposure beam and transfers a pattern formed on the mask onto a substrate,

A control device for monitoring a change in a physical quantity associated with the deformation of the mask and temporarily interrupting an exposure operation when the physical quantity becomes equal to or more than a first predetermined value.

2. The exposure apparatus according to claim 1, wherein the control device restarts the exposure after a predetermined time has elapsed after the interruption of the exposure operation.

3. The exposure apparatus according to claim 1, wherein the control device restarts the exposure operation when the physical quantity becomes equal to or less than a second predetermined value.

4. The exposure apparatus according to claim 1, wherein the control device interrupts the exposure operation each time the exposure operation of a predetermined number of substrates is completed.

5. The exposure apparatus according to claim 1, wherein the physical quantity is a quantity calculated based on a measured predetermined physical quantity.

6. The exposure apparatus according to claim 1, wherein the physical quantity is a quantity related to energy absorption by irradiation of the mask with the exposure beam.

7. The exposure apparatus according to claim 6, wherein the physical quantity is a quantity based on a difference in energy absorption between the center and the end of the mask due to exposure of the exposure beam.

8. The physical quantity is a temperature distribution of the mask. 3. The exposure apparatus according to claim 1.

9. The exposure apparatus according to claim 1, further comprising a detector for directly or indirectly detecting the physical quantity.

10. An imaging characteristic correction device for correcting the imaging characteristic of the pattern image of the mask is further provided,

The control device controls the imaging characteristic correction device so as to cancel the influence of the deformation of the mask while the physical quantity is less than the first predetermined value. 9. The exposure apparatus according to claim 8.

11. A drive device for synchronously moving the mask and the substrate in a predetermined scanning direction,

10. The exposure apparatus according to claim 10, wherein the imaging characteristic correction device adjusts a speed ratio of a synchronous movement between the mask and the substrate.

12. A projection optical system for projecting an image of the pattern of the mask onto the substrate is further provided.

The exposure apparatus according to claim 10, wherein the imaging characteristic correction device adjusts an imaging characteristic of the projection optical system.

13. A drive device for synchronously moving the mask and the substrate in a predetermined scanning direction,

9. The exposure apparatus according to claim 1, wherein the physical quantity includes a barrel-shaped region of the mask in the scanning direction. 10.

14. The physical quantity is at the center and the end in the non-scanning direction of the mask. 14. The exposure apparatus according to claim 13, wherein the exposure apparatus is a physical quantity related to deformation of the mask.

15. A pattern is drawn on the mask in consideration of the deformation due to the absorption of the exposure beam,

4. The exposure apparatus according to claim 3, wherein the control device performs a dummy exposure operation until the pattern of the mask changes to a predetermined shape.

16. An exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam to expose a substrate or a region partitioned in the substrate with an image of the pattern is performed on a plurality of substrates or the substrate. An exposure apparatus for sequentially executing a plurality of partitioned areas,

A measuring instrument for measuring an amount of thermal deformation of the mask or a factor causing thermal deformation of the mask by irradiating the mask with an exposure beam;

And a control device for interrupting the next exposure operation when the thermal deformation amount or the factor becomes equal to or greater than a first value set in advance.

17. The exposure apparatus according to claim 16, wherein the exposure apparatus is a scanning exposure apparatus that synchronously moves a mask and a substrate in a scanning direction.

18. The measuring instrument calculates the thermal deformation amount M 1 (t) and the thermal deformation amount M 1 (t) at the center of the mask in the non-scanning direction with respect to the elapsed time t from the start of irradiation on the mask, based on the mask thermal deformation model calculation formula A computing unit that computes the thermal deformation amount M 2 (t) at the end of the mask and a difference between them, and when the difference becomes equal to or greater than a first value set in advance, the control device performs the next exposure operation. The exposure apparatus according to claim 17, wherein the exposure is interrupted.

1 9. Further, a memory for storing a thermal deformation model calculation formula of the mask is provided. 19. The exposure apparatus according to claim 18, wherein:

20. The factor is temperature, and the measuring device includes a temperature sensor, and is thermally deformed based on a difference between a temperature at a mask central portion and a temperature at a mask edge in a non-scanning direction measured by the temperature sensor. The sl ^ t device lAo according to claim 17, wherein the amount is obtained.

21. The exposure device according to claim 16, wherein the control device restarts the exposure operation when the amount of thermal deformation falls below a set second value after the interruption of the exposure operation. apparatus.

22. An exposure method for irradiating a mask with an exposure beam and transferring a pattern formed on the mask onto a substrate,

A first step of temporarily suspending the exposure operation when a physical quantity related to the deformation of the mask becomes equal to or more than a first predetermined value;

A second step of restarting the exposure.

23. The exposure method according to claim 22, wherein the restart of the exposure operation in the second step is performed when the physical quantity becomes equal to or less than a second predetermined value.

24. The exposure method according to claim 22, wherein the physical quantity is a predetermined calculated value.

25. The exposure method according to claim 22, wherein the physical quantity is a quantity related to energy absorption by irradiation of the mask with the exposure beam.

26. The mask is irradiated with the exposure beam, and the pattern formed on the mask is An exposure method for transferring

An exposure method, wherein the exposure operation is temporarily stopped and restarted each time the exposure operation of a predetermined number of substrates is completed.

27. An exposure method for irradiating a mask with an energy beam from a beam source and transferring a pattern formed on the mask onto a substrate,

Detecting information on the amount of energy absorption of the mask by the irradiation of the energy beam;

An exposure method, comprising: limiting irradiation of an energy beam to the mask based on information on the detected amount of energy absorption.

28. When the information on the amount of energy absorption exceeds a predetermined value, the irradiation of the energy beam to the mask is interrupted, and the timing of the interruption and the timing of replacing the substrate are matched. 27. The exposure method according to 27.

29. The exposure method according to claim 27, wherein limiting the irradiation of the energy beam includes stopping beam irradiation from the beam source.

30. The exposure method according to claim 27, wherein limiting the irradiation of the energy beam includes blocking a beam path of the energy beam.

31. The exposure method according to claim 27, wherein limiting the irradiation of the energy beam includes reducing the intensity of the energy beam applied to the mask.

32. A device manufacturing method for manufacturing a device using the exposure apparatus according to any one of claims 1 to 9 and 16.

33. A device manufacturing method comprising the exposure method according to any one of claims 22, 26 and 27.

34. An exposure method for irradiating a mask with an exposure beam from a light source and transferring a pattern formed on the mask onto a substrate,

An exposure method comprising: monitoring a physical quantity related to the deformation of the mask, and detecting that the physical quantity has exceeded a predetermined value.

35. The exposure method according to claim 34, further comprising interrupting the exposure operation when the physical quantity becomes equal to or more than a predetermined value.

36. The exposure method according to claim 34, further comprising cooling the mask when the physical quantity becomes equal to or more than a predetermined value.

37. The exposure method according to claim 34, further comprising: stopping irradiation of an exposure beam from the light source when the physical quantity becomes equal to or more than a predetermined value.

38. The exposure method according to claim 34, further comprising: decreasing the intensity of the exposure beam when the physical quantity becomes equal to or more than a predetermined value.

39. The exposure method according to claim 34, comprising blocking a beam path of the exposure beam when the physical quantity becomes equal to or more than a predetermined value.

40. The method according to claim 34, wherein the physical quantity includes an energy absorption amount of the mask.

41. The physical quantity according to claim 34, wherein the physical quantity includes a distortion quantity of the mask pattern. Exposure method.

42. Exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam and exposing a substrate or a region partitioned in the substrate by an image of the pattern is performed by a plurality of substrates or a plurality of substrates. An exposure method that sequentially executes over a plurality of partitioned areas,

Determining the thermal deformation of the mask;

An exposure method, wherein the exposure operation for the next substrate or area is interrupted when the amount of thermal deformation of the mask becomes equal to or greater than a preset value.

43. The exposure according to claim 42, wherein the amount of thermal deformation of the mask is calculated from the start of irradiation of the mask, based on a model formula relating to the thermal deformation of the mask with respect to an elapsed time t from the start of irradiation of the mask. Method.

4 4. Before the start of exposure, a time schedule for the change in the amount of thermal deformation of the mask with respect to the elapsed time from the start of irradiation of the mask is obtained based on a model formula for the thermal deformation of the mask. 43. The exposure method according to claim 42, wherein the exposure operation for the next substrate or region is interrupted at a time when the predetermined value or more is reached.

45. The exposure method according to claim 43, wherein the exposure operation is performed while moving the mask and the substrate synchronously in the scanning direction.

46. Based on the thermal deformation model calculation formula of the mask, the change M 1 (t) of the thermal deformation amount at the center of the mask in the non-scanning direction with respect to the elapsed time t from the start of irradiation on the mask and the thermal deformation at the end of the mask The amount change M 2 (t) and their difference are calculated, and when the difference exceeds a preset value, the next exposure operation The exposure method according to claim 45, wherein the step is interrupted.

47. The exposure method according to claim 43, wherein the model formula includes a thermal deformation time constant and a thermal deformation saturation value as parameters.

48. An exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam and exposing a substrate or a region partitioned in the substrate by an image of the pattern is performed on a plurality of substrates or a plurality of substrates in the substrate. An exposure method that sequentially executes over a plurality of partitioned areas,

Measuring the temperature distribution of the mask;

An exposure method, wherein the exposure operation for the next substrate or region is interrupted when the amount of thermal deformation becomes equal to or greater than a preset first value.

49. The exposure method according to claim 42, wherein after the exposure operation is interrupted, the exposure operation is restarted when the amount of thermal deformation becomes equal to or less than the set second value.

50. A method for manufacturing an exposure apparatus that irradiates a mask with an exposure beam and transfers a pattern formed on the mask onto a substrate,

Providing an irradiation system for irradiating the mask with an exposure beam;

A method for manufacturing an exposure apparatus, comprising: monitoring a change in a physical quantity associated with the deformation of the mask, and providing a control device for temporarily stopping the exposure operation when the physical quantity becomes equal to or more than a first predetermined value.

51. Further, a projection optical system for projecting a pattern formed on the mask onto the substrate at a predetermined projection magnification is provided between the mask and the substrate;

A stage system for moving the mask, substrate and exposure beam in synchronization The method for manufacturing an exposure apparatus according to claim 50, further comprising:

52. Exposure operation of irradiating a mask on which a predetermined pattern is formed with an exposure beam and exposing a substrate or a region partitioned in the substrate with an image of the pattern is performed on a plurality of substrates or the substrate. Manufacturing of an exposure apparatus which is sequentially executed over a plurality of divided areas,

Providing an irradiation system for irradiating the mask with an exposure beam;

Providing a control device for interrupting the next exposure operation when the amount of thermal deformation or the factor exceeds a preset value.

5 3. Based on the thermal deformation model calculation formula for the mask, the measuring device calculates the change in the thermal deformation amount M 1 (t in the non-scanning direction with respect to the elapsed time t from the start of irradiation on the mask in the non-scanning direction. 53. The method of manufacturing an exposure apparatus according to claim 52, wherein the calculator is a computing unit that computes a change M 2 (t) in the amount of thermal deformation at the end of the mask and a difference therebetween.

54. The method of manufacturing an exposure apparatus according to claim 53, further comprising: providing a memory storing a thermal deformation model calculation formula of the mask.