WO2001035451A1 - Illuminator, aligner, and method for fabricating device - Google Patents

Abstract

An illuminator comprises a unit (18) for splitting an incident energy beam (57) from a laser light source reflected from reflectors (48a, 48b, 48c) into a plurality of light beams, making mutually different the optical path lengths of the split light beams from the laser light source to the illuminated face and imparting differences of optical path length (difference of optical path) longer than the temporal coherence length. Consequently, generation of speckles (interference fringes) deteriorating the uniformity of illuminance on the illuminated face can be suppressed. Since reflectors having reflectance of 95% or above can be employed as the ones constituting the light beam splitting unit (18), the loss of the quantity of light is reduced and an abundant quantity of illumination light can be supplied to the illuminated face. Such suppression of speckles is especially advantageous when laser light having high spatial coherence is employed.

Description

 Specification

 Illumination apparatus, exposure apparatus, and device manufacturing method

 The present invention relates to an illumination device, an exposure device, and a device manufacturing method, and more particularly, to an illumination device that illuminates a surface to be irradiated with laser light, a semiconductor device (integrated circuit), a liquid crystal display, and the like including the illumination device. The present invention relates to an S-optical device used in a lithographic process when manufacturing an electronic device, and a device manufacturing method using the exposure device. Background art

 2. Description of the Related Art Various exposure apparatuses have been used for forming fine patterns of electronic devices such as semiconductor elements (integrated circuits) and liquid crystal displays. In recent years, with the increasing integration of semiconductor devices, etc., a mask or reticle (hereinafter, collectively referred to as a “reticle”) in which a pattern to be formed has been formed in proportion to a factor of about 4 to 5 is formed. ), And the reticle pattern is reduced and transferred onto a substrate such as a wafer or a glass plate (hereinafter collectively referred to as a “wafer”) via a projection optical system. A projection exposure apparatus such as an apparatus (a so-called stepper) or a step-and-scan type scanning exposure apparatus (a so-called scanning stepper) with an improved version of this stepper is mainly used.

In this type of projection exposure apparatus, the exposure wavelength has been shifted to shorter wavelengths in order to cope with miniaturization of patterns of integrated circuits and the like. At present, the wavelength is mainly 2848 nm of KrF excimer laser, but the shorter wavelength of 19.3 nm of ArF excimer laser is entering the stage of practical use. And even short waves There are also proposals for projection exposure systems that use a light source in the so-called vacuum ultraviolet range, such as a long-wavelength F.157 nm laser and an A-laser with a wavelength of 126 nm. .

 In addition, in order to operate electronic devices as final products at high speed, it is necessary to make the line width of a pattern transferred onto a wafer uniform in each shot area (in each device chip). For that purpose, it is necessary to equalize the exposure amount in each shot area, and an illumination optical system for illuminating the illuminated surface (reticle) with uniform illuminance is required.

 By the way, in recent exposure apparatuses that use an ultraviolet laser light source, it is difficult to sufficiently correct the chromatic aberration of the projection optical system because only one or two types of glass materials have good transmittance for ultraviolet light. It has become. Therefore, by narrowing the wavelength width (spectral half width) of the laser light emitted (output) from the laser light source to, for example, the natural oscillation wavelength width of about 1Z100 to 1300, it is possible to reduce the bandwidth. It is widely practiced to substantially eliminate the adverse effects of chromatic aberration.

However, narrowing the bandwidth of the laser light source described above not only narrows the spectral half width, but also limits the number of oscillation modes of the laser light source. As a result, the spatial coherence (coherence) of the laser light Gender). And, due to the improved spatial coherence, uneven illuminance due to interference fringes (speckles) occurs on the reticle surface and the wafer surface, deteriorating the illuminance uniformity of the illumination light, and consequently the line width of the transfer pattern. In some cases, the uniformity was deteriorated. The present invention has been made under such circumstances, and a first object of the present invention is to provide an illuminating device capable of improving illuminance uniformity on a surface to be illuminated. It is a second object of the present invention to provide an exposure apparatus capable of realizing high-precision exposure with improved uniformity of a pattern line width transferred onto a substrate. A third object is to provide a device manufacturing method capable of improving the productivity of highly integrated microdevices. Disclosure of the invention

 According to a first aspect of the present invention, there is provided an illumination device for illuminating a surface to be illuminated, comprising: a light source; a light beam from the light source being divided into a plurality of light beams; And a light splitting unit having a plurality of reflecting surfaces for making optical path lengths reaching the surfaces different.

 According to this, when light is output from the light source, the light enters the light splitting unit, and is reflected by a plurality of reflecting surfaces in the unit to form a plurality of split luminous fluxes to form an illuminated surface. Respectively. In this case, when each of the plurality of divided light beams is reflected by each reflecting surface, the optical path length from the light source to the irradiated surface is made different, and an optical path length difference (optical path difference) is given. Therefore, the occurrence of speckles (interference fringes) that may deteriorate the illuminance uniformity on the irradiated surface is suppressed, so that the illuminated surface can be illuminated with uniform illuminance. In particular, when light having high spatial coherence is used, the advantage of suppressing the above-described speckle generation is great.

 In this case, the plurality of reflecting surfaces are arranged in multiple stages in the predetermined one direction so that the light beam can be divided into a plurality of portions in a predetermined direction in a cross section perpendicular to the optical axis of the light beam from the light source. And may be arranged so as to be shifted by a predetermined distance in the optical axis direction. In such a case, with a simple configuration, the light beam from the light source can be divided into a plurality of light beams, and a difference in the optical path length can be generated between each of the divided light beams. Can be suppressed.

In this case, the predetermined one direction may be a direction in which the light output from the light source has high interference. In such a case, the light beam is divided into a plurality of light beams in a predetermined direction having high coherence, and a difference in the optical path length occurs between the divided light beams. Generation can be suppressed efficiently. In the first lighting device of the present invention, the plurality of reflection surfaces may be reflection surfaces of different reflection mirrors.

 In this case, of the plurality of reflecting mirrors, a reflecting mirror satisfying a condition that another reflecting mirror adjacent to the rear side of the light beam in the optical axis direction exists, the reflecting mirror maintains the optical axis while maintaining its posture. The cross-sectional shape of the side surface is set so that when the mirror is translated rearward by a predetermined distance along the reflecting surface, the reflecting surface of the other reflecting mirror and its own reflecting surface form a single reflecting surface without any gap. It can be said that it has been done.

 In the first lighting device of the present invention, the plurality of reflection surfaces may be formed at different locations of the same member.

 In the first lighting device of the present invention, each of the plurality of reflecting surfaces may have a reflectance of about 95% or more. In such a case, a large amount of illumination light can be supplied to the illuminated surface with little loss of light intensity.

 In the first lighting device of the present invention, the light splitting units are arranged as the plurality of reflection surfaces in multiple stages in a predetermined first direction in a cross section perpendicular to an optical axis of the light flux from the light source. A first reflecting surface group that is divided by a predetermined distance in the optical axis direction and divides the light beam into a plurality of light beams and folds the optical axis of each of the divided light beams in the second direction; and the second direction. Are arranged in multiple stages with respect to a predetermined third direction in a cross section perpendicular to the plane, and are arranged to be shifted by a predetermined distance in the second direction, divide each of the divided light beams into a plurality of light beams and separate the light beams And a second reflection surface group that is bent in four directions.

In the first illuminating device of the present invention, the light splitting unit may generate a difference in the optical path length between the split light beams reflected by the plurality of reflecting surfaces, which is equal to or longer than a temporal coherence length of the light. Is desirable. In such a case, there is no coherence between the divided light beams, so that it is possible to almost certainly avoid the occurrence of interference fringes on the irradiated surface, and to further improve the illuminance uniformity on the irradiated surface. In Monkey

 In the first illuminating device of the present invention, each of the divided luminous fluxes arranged on the optical path of the light between the light splitting unit and the surface to be illuminated and split by the light splitting unit is irradiated. An illumination uniforming optical system including an optical integrator may be further provided. In such a case, it is possible to further improve the illuminance uniformity on the surface to be illuminated by the synergistic action of the division of the luminous flux by the light dividing unit and the illuminance uniforming optical system including the optical integrator.

 In this case, the optical integrator may be any one of a fly-eye lens, an aperture lens, and a diffractive optical element. In the first lighting device of the present invention, when an optical integrator is provided on an optical path between the light splitting unit and the irradiated surface, the optical integrator has a plurality of elements; Each of the split light beams split by the unit may be applied to a different element set having at least one of the elements as an element. In such a case, each divided light beam is irradiated to a different element set having at least one element as an element, so that a plurality of light beams should overlap each other on the element. Deterioration of uniformity of illuminance due to irradiance can be prevented or suppressed, and as a result, uniformity of illuminance on the irradiated surface can be reliably ensured.

 In this case, it is possible that each of the element groups irradiated with the different divided light beams is partitioned by a light shielding member.

In this case, the optical integrator can be any one of a fly-eye lens and a diffractive optical element (diffractive optical element). In the first lighting device of the present invention, when an optical integrator is provided on an optical path between the light splitting unit and the surface to be irradiated, the light splitting unit includes: The incident angles of the split light beams with respect to the optical integrator are different so that the split light beams enter the entire surface. Can be made.

 In the first lighting device of the present invention, the light source may be a laser light source.

 According to a second aspect of the present invention, there is provided an illuminating device for illuminating a surface to be illuminated, comprising: a light source; A reflecting unit having a plurality of reflecting surfaces arranged in multiple stages with respect to the predetermined direction so as to be dividable in the optical axis direction and displaced by a predetermined distance in the optical axis direction. It is.

 According to this, when a light beam is output from the light source, the light beam enters the reflection unit, is reflected by a plurality of reflection surfaces in the unit, becomes a plurality of divided light beams, and reaches the irradiated surface. Irradiated respectively. In this case, when each of the plurality of divided luminous fluxes is reflected by each reflecting surface, the optical path length from the light source to the irradiated surface is made different according to the arrangement of each reflecting surface, and the optical path length difference (optical path difference) Is given. Therefore, the generation of speckles (interference fringes) which may deteriorate the illuminance uniformity on the illuminated surface is suppressed, so that the illuminated surface can be illuminated with uniform illuminance. In particular, when light having high spatial coherence is used, the advantage of suppressing the above-described speckle generation is great.

 In this case, a shaping optical system is provided between the light source and the reflection unit to shape a cross-sectional shape of a light beam from the light source, and the reflection unit is shaped by the shaping optical system. The later light beam can be divided into a plurality of light beams.

 In the second illumination device of the present invention, the plurality of reflecting surfaces divide the light beam from the light source into a plurality of light beams and vary the optical path length from the light source to the irradiated surface between the divided light beams. It can be.

According to a third aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a pattern surface of a mask to a substrate, comprising: a light source; and a plurality of light beams from the light source. And a light splitting unit having a plurality of reflective surfaces for splitting and making the optical path length from the light source to the pattern surface between the split light beams different from each other.

 According to this, when light is output from a light source, the light enters a light splitting unit, and is reflected by a plurality of reflecting surfaces in the unit to form a plurality of split light fluxes to form a mask pattern. The surface is respectively illuminated. In this case, when each of the plurality of split light beams is reflected by each reflecting surface, the optical path length from the light source to the pattern surface is made different, and an optical path length difference (optical path difference) is given. Therefore, the occurrence of speckles (interference fringes), which may deteriorate the uniformity of illuminance on the pattern surface, is suppressed, so that the pattern surface of the mask can be illuminated with uniform illuminance. Therefore, the uniformity of the illuminance on the substrate to which the pattern formed on the pattern surface of the mask is transferred can be ensured, and the uniformity of the pattern line width formed on the substrate can be improved. The pattern can be transferred with high precision.

 In this case, the illuminance equalizing optics including an optical integrator disposed on the optical path of the light between the light splitting unit and the pattern surface, and irradiated with each split light beam split by the light splitting unit. The system can be further provided.

 In this case, the optical integrator has a plurality of elements, and each of the split light beams split by the light splitting unit is applied to a different element set having at least one of the elements as an element. It can be.

The first exposure apparatus of the present invention may further include a projection optical system for projecting the light emitted from the mask onto the substrate. In such a case, as described above, the generation of interference fringes on the pattern surface of the mask can be reduced and the pattern can be illuminated with high illuminance uniformity by the light division unit. Therefore, for example, by using a light source that outputs light with high spatial coherence as the light source, In addition to substantially eliminating the adverse effects of chromatic aberration of the projection optical system, the projection optical system achieves improved illuminance uniformity of light projected on the substrate surface and, as a result, highly accurate exposure with improved pattern line width uniformity. It is possible to do.

 In the first exposure apparatus of the present invention, the light source may be a laser light source.

 According to a fourth aspect of the present invention, there is provided an exposure apparatus for transferring a pattern formed on a pattern surface of a mask to a substrate, comprising: a light source; and a light source of a light beam from the light source in a cross section perpendicular to the light passage. A reflection unit having a plurality of reflection surfaces arranged in multiple stages in the predetermined one direction so as to be able to divide the light beam into a plurality of parts in a predetermined one direction, and displaced by a predetermined distance in the optical axis direction; A second exposure apparatus comprising:

 According to this, when a light beam is output from the light source, this light beam enters the reflection unit, and is reflected by a plurality of reflection surfaces in the unit to form a plurality of divided light beams to form a pattern surface of a mask. Respectively. In this case, when each of the plurality of divided light beams is reflected by each reflecting surface, the optical path length from the light source to the pattern surface is made different according to the arrangement of each reflecting surface, and the optical path length difference (optical path difference) is reduced. Granted. Therefore, the occurrence of speckles (interference fringes) that may deteriorate the illuminance uniformity on the turn surface is suppressed, so that the pattern surface of the mask can be illuminated with uniform illuminance. Therefore, uniformity of the illuminance on the substrate on which the pattern formed on the pattern surface of the mask is transferred can be ensured, whereby the uniformity of the pattern line width formed on the substrate can be improved, and the fineness of the pattern on the substrate can be improved. The pattern can be transferred with high precision.

 In this case, the plurality of reflecting surfaces can divide the light beam from the light source into a plurality of light beams and make the optical path length from the light source to the irradiated surface between the divided light beams different from each other. .

In the lithographic process, the first and second exposure apparatuses of the present invention are used. By performing the exposure, the line width control accuracy is improved by improving the illuminance uniformity of the illuminating light on the substrate surface, so that a pattern of a plurality of layers can be formed on the substrate with high accuracy. Therefore, a highly integrated microdevice can be manufactured with a high yield, and the productivity can be improved. Therefore, from another viewpoint, the present invention is a device manufacturing method using the exposure apparatus of the present invention.

 FIG. 1 is a diagram schematically showing an overall configuration of an exposure apparatus according to a first embodiment of the present invention.

 FIG. 2 is a diagram showing a specific configuration of the light dividing unit and the first fly-eye lens of FIG.

 FIG. 3 is a diagram showing a modification of the light splitting unit of FIG.

 FIG. 4 is a side view showing a light splitting unit according to a second embodiment of the present invention together with a first fly eye lens.

 FIG. 5 is a flowchart for explaining an embodiment of the device manufacturing method according to the present invention.

 FIG. 6 is a flowchart showing the processing in step 204 of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

 << 1st Embodiment >>

 Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 schematically shows a configuration of an exposure apparatus 10 according to a first embodiment including an illumination apparatus according to the present invention as an illumination system for illuminating a reticle R as a mask. The exposure apparatus # 0 is a step-and-scan type scanning projection exposure apparatus that uses pulsed ultraviolet light in the ultraviolet or vacuum ultraviolet region as illumination light for exposure, In other words, it is a so-called scanning stepper.

 The exposure apparatus 10 includes an illumination system including a laser light source (hereinafter, appropriately referred to as a “light source”) 11 and an illumination optical system 40, and a reticle as a mask illuminated by pulsed ultraviolet light EL from the illumination system. A reticle stage RST that holds R, a projection optical system that projects the pulsed ultraviolet light EL emitted from the reticle R onto a wafer W as a substrate, and a substrate stage on which a tilt stage 58 is mounted. -It is equipped with a wafer stage WS and a control system for them. Examples of the light source 11 include an ArF excimer laser light source (oscillation wavelength: 193 nm) having a band-narrowing module (not shown) including a spectral optical element such as a grating, a prism, and an etalon element. A narrow-band laser light source (e.g., an oscillation wavelength of 157 nm) is used. In addition, as the light source 11, not only a narrow band KrF excimer laser light source but also a laser light source including a so-called injection seed type laser using a narrow band laser beam as a seed may be used.

 In the present embodiment, the light source 1 が includes an illumination optical system 40, a reticle stage RST, a projection optical system P, a wafer stage WST, and an exposure apparatus main body including a main body column (not shown) holding these components. It is placed separately from the stored chamber (not shown). That is, the light source 11 is installed in a low-clean service room separate from the clean room in which the chamber is installed, or in a utility space provided under the floor of the clean room, and the beam matching unit is installed in the chamber. It is connected via a drawing optical system (light transmitting optical system) (not shown) that includes at least a part of an optical axis adjusting optical system called a lens.

 The illumination optical system 40 makes the inside airtight to the outside air,

Illumination system housing (not shown) filled with clean dry nitrogen gas (N ₂ ) or helium gas (H e) with a (oxygen) content of several percent or less, preferably less than 1% (several PP m or less) And mirrors 13, 14, and a beam shaping, which are sequentially arranged along the optical path of the laser beam LB output from the light source 1 in the illumination system housing. Optical system 3 3, light splitting unit (reflection unit) 18, 1st fly-eye lens 20 as optical integrator (homogenizer), relay lens 21, mirror 22, relay lens 23, optical integrator ( 2nd fly-eye lens 24 as a homogenizer), illumination system aperture stop plate 25, relay lenses 26, 27, fixed reticle blind 28 A, movable reticle blind 28, condenser lenses 29, 30 A mirror 31 and a main condenser lens 32 are provided.

 Here, each component of the illumination optical system 40 will be described together with its operation. The beam shaping optical system 33 is composed of a combination of optical elements. The beam shaping optical system 33 changes the cross-sectional shape of the laser beam LB pulsed from the light source 11 into a light splitting unit 18 provided behind the optical path of the laser beam LB. It is shaped so as to efficiently enter the first fly-eye lens 20, and is composed of, for example, a cylinder lens and a beam expander.

 The light splitting unit 18 splits the laser beam LB after the cross-sectional shape shaping from the beam shaping optical system 33 into a plurality of light fluxes, and imparts an optical path length difference between the split light fluxes. The first fly-eye lens 20 at the subsequent stage is irradiated. The combination of the light splitting unit 18 and the first fly-eye lens 2 ° will be described later in further detail.

 On the optical path of the laser light behind the first fly-eye lens 20, a relay optical system including relay lenses 21 and 23 is disposed with a mirror 22 interposed therebetween, and the optical path of the rear relay lens 23. A second fly's eye lens 24 is arranged behind. In this embodiment, the first fly-eye lens 20 and the second fly-eye lens 24 constitute a double fly-eye lens system, and the double fly-eye lens system and the lenses 21 and 23 provide illuminance. A homogenizing optical system is configured.

As the second fly-eye lens 24, two lens bundles 24 A and 24 B each having a flat surface on one side, on which lens elements are arranged in close contact with each other in a mosaic shape A so-called mosaic fly-eye lens, which is arranged close to each other along the optical axis IX of the illumination optical system (corresponding to the optical axis AX of the projection optical system PL described later) so as to face each other, Used. Such a mosaic fly-eye lens is disclosed, for example, in Japanese Patent Application Laid-Open Nos. Hei 9-265554, Hei 8-3161623, and US Patent Nos. 5,739,89 corresponding thereto. It is disclosed in detail in No. 9, etc. In this case, the lens bundles 24 A and 24 B function as one fly-eye lens only when the two are combined. In addition, as far as the national laws of the designated country designated in this international application or the selected elected country allow, the disclosure in the above-mentioned public notice and the corresponding US patent shall be incorporated herein by reference. Note that the laser beam emitted from the second fly-eye lens 24 will be appropriately referred to as “exposure light EL” below.

 Note that a vibration mirror for smoothing interference fringes and weak speckles generated on the irradiated surface (the pattern surface of the reticle R and the wafer W surface) can be used as the mirror 22. In this case, the vibration (deflection angle) of the vibrating mirror can be controlled by the main controller 50 via a drive system (not shown). Incidentally, a configuration in which such a vibrating mirror and a double fly-eye lens system are combined is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 1-259533 and US Pat. No. 5,307,20 corresponding thereto. No. 7, and as far as the national laws of the designated country designated in this international application or the selected elected country allow, the disclosure in the above-mentioned gazettes and U.S. patents is partially incorporated herein by reference. And

The illumination system aperture stop plate 25 made of a disc-shaped member is disposed near the exit surface of the second fly-eye lens 24. The illumination system aperture stop plate 25 is provided at substantially equal angular intervals, for example, an aperture stop composed of a normal circular aperture, an aperture stop composed of a small circular aperture, for reducing a threshold value which is a coherence factor, and a ring illumination. Annular aperture stop, and a modified aperture stop with multiple apertures eccentrically arranged for the modified light source method (only two of these are shown in FIG. 1). Etc.) are arranged. The illumination system aperture stop plate 25 is rotated by a drive device 34 such as a motor controlled by a main controller 50, whereby one of the aperture stops is placed on the optical path of the exposure light EL. The shape of the light source surface in the Keller illumination described later is limited to a ring, a small circle, a large circle, or a fourth shape.

 A fixed reticle blind 28 A and a movable reticle blind 28 B are arranged on the optical path of the exposure light EL behind the illumination system aperture stop plate 25 via relay lenses 26 and 27. The fixed reticle blind 28 A is arranged on a plane slightly defocused from a conjugate plane with respect to the pattern plane of the reticle R, and has a rectangular opening defining an illumination area I A R on the reticle R. A movable reticle blind 28B having an opening whose position and width in the direction corresponding to the scanning direction is variable is arranged near the fixed reticle blind 28A, and is movable at the start and end of scanning exposure. By further limiting the illuminated area IAR via the reticle blind 28 B, the exposure of unnecessary parts is prevented. Condenser lenses 29, 30 are sequentially arranged on the optical path of the exposure light E behind the movable reticle blind, and on the optical path further behind the condenser lens 30, ultraviolet light passing through the condenser lens 30 is provided. A mirror 31 for reflecting the pulsed light toward the reticle R is arranged, and a main condenser lens 32 is arranged on the optical path of the exposure light EL behind the mirror 31.

 In the above configuration, the entrance surface of the first fly-eye lens 20, the entrance surface of the second fly-eye lens 24, the arrangement surface of the blade of the movable reticle blind 28 B, and the pattern surface of the reticle R are optically The light source surface formed on the exit surface side of the first fly-eye lens 20, the light source surface formed on the exit surface side of the second fly-eye lens 24, and the Fourier transform surface of the projection optical system PL The exit pupil plane) is optically set to be conjugate to each other, forming a Koehler illumination system.

Next, the operation of the illumination optical system 40 configured as described above will be briefly described. The laser beam B pulsed from the laser light source 11 is sequentially reflected by the mirrors 13 and 14 and then enters the beam shaping optical system 33 where the rear light splitting unit 1 The cross-sectional shape is shaped so as to efficiently enter the eighth fly eye lens 20 and the first fly eye lens 20. Next, the laser beam LB is split into a plurality of light beams by the light splitting unit 18 and is incident on the first fly-eye lens 2 ° as a light beam group in which coherence is suppressed as described later. As a result, a surface light source, that is, a secondary light source including a large number of light source images (point light sources) is formed at the exit end of the first fly-eye lens 20. The pulsed ultraviolet light diverging from each of these many point light sources enters the second fly-eye lens 24 via the relay lens 21, the mirror 22 and the relay lens 23 in this order. As a result, a tertiary light source is formed at the exit end of the second fly-eye lens 24, which is composed of a large number of point light sources in which a large number of minute light source images are uniformly distributed in a predetermined shape area. The exposure light EL emitted from the tertiary light source passes through one of the aperture stops on the illumination system aperture stop plate 25, and then passes through the relay lens 26,

After passing through 27, the rectangular opening of the fixed reticle blind 28 A is illuminated with a uniform intensity distribution (illuminance distribution).

 The 11-light EL passed through the opening of the fixed reticle blind 28 A in this way passes through the movable reticle blind 28 B, and then passes through the condenser lenses 29, 30, and the optical path is vertically moved downward by the mirror 31. After being folded into the main capacitor lens 32, a predetermined illumination area on the reticle R held on the reticle stage RST (slit or rectangular illumination area extending linearly in the X-axis direction)

Illuminate I A R with uniform illumination distribution. Here, the rectangular slit-shaped illumination light applied to the reticle R is set to extend in the X-axis direction (non-scanning direction) in the center of the circular projection field of view of the projection optical system P in FIG. The width of the illumination light in the Y-axis direction (scan direction) is set almost constant.

A reticle R is mounted on the reticle stage RST, and is held by suction via an unshown electrostatic chuck (or vacuum chuck) or the like. Reticle The stage RST can be finely driven in a horizontal plane (XY plane), and can be scanned in a predetermined stroke range in a scanning direction (Υ-axis direction) by a reticle stage driving unit 56R. The position of reticle stage RS # during this scanning is measured by an external laser interferometer 54R via a moving mirror 52R fixed on reticle stage RS #, and this laser interferometer 54R Is supplied to the main controller 50.

 The material used for the reticle R needs to be properly used depending on the light source used. That is, when an A r F excimer laser or a K r F excimer laser is used as a light source, synthetic quartz can be used, but when a laser is used, fluorite or fluorine-top quartz or the like can be used. It is necessary to form with.

For the projection optical system PL, for example, a bilateral telecentric reduction system is used. The projection magnification 3 of the projection optical system PL is, for example, 14, 1/5 or 1/6. For this reason, as described above, when the illumination area IAR on the reticle R is illuminated by the exposure light EL, the diffracted light corresponding to the pattern formed on the reticle R is projected toward the projection optical system PL. The image reduced by a factor of 0 is condensed and imaged by the projection optical system PL to form a slit-shaped exposure area IA on the wafer W having a surface coated with a resist (photosensitive agent). Is projected and transferred. In the present embodiment, vacuum ultraviolet light (VUV light) having a wavelength of about 200 nm or less is used. Therefore, as the projection optical system PL, a catadioptric system having a reflective optical element and a refractive optical element is used. Toric). Examples of this reflective refraction type projection optical system include, for example, Japanese Patent Application Laid-Open No. Hei 8-171504 and US Patent Nos. 5,668,672 corresponding thereto and Japanese Patent Application Laid-Open No. — A catadioptric system having a beam splitter and a concave mirror as a reflective optical element, as disclosed in US Pat. No. 2,019,955 and corresponding US Pat. Nos. 5,835,275; Are Japanese Patent Application Laid-Open Nos. Hei 8-334649 and U.S. Pat. Nos. 5,689,377 corresponding thereto, and Japanese Patent Laid-Open No. 10-33939 and corresponding US Patent issued No. 873,605 (filing date: June 12, 1997), etc., use a catadioptric system with a concave mirror etc. instead of a beam splitter as a reflective optical element be able to. To the extent permitted by the national laws of the designated or designated elected country in this international application, the disclosures in the above publications and their corresponding U.S. patents and U.S. patent applications shall be incorporated by reference. Department.

 In addition, a plurality of refractive optics disclosed in U.S. Pat. Nos. 5,031,976, 5,488,229, and 5,717,518. The element and two mirrors (a primary mirror, which is a concave mirror, and a sub-mirror, which is a backside mirror with a reflective surface formed on the opposite side of the refraction element or parallel plane plate from the entrance surface) are arranged on the same axis. However, a catadioptric system that re-images the intermediate image of the reticle pattern formed by the plurality of refractive optical elements on the wafer by the primary mirror and the secondary mirror may be used. In this catadioptric system, a primary mirror and a secondary mirror are arranged following a plurality of refractive optical elements, and the illumination light passes through a part of the primary mirror and is reflected in the order of the secondary mirror and the primary mirror. It will pass through a portion and onto the wafer. To the extent permitted by the national laws of the designated State or selected elected States in this International Application, the disclosures in the above US patents will be incorporated by reference into this specification. Further, the catadioptric projection optical system has, for example, a circular image field, is telecentric on both the object side and the image side, and has a projection magnification of 14 or 1/5. May be used. In the case of a scanning exposure apparatus having a catadioptric projection optical system, the irradiation area of the illumination light has its optical axis substantially centered within the field of view of the projection optical system, and is almost perpendicular to the scanning direction of the reticle or wafer. It may be of a type defined in a rectangular slit shape extending along the orthogonal direction. According to the scanning exposure apparatus having such a catadioptric projection optical system, for example, even if a laser beam having a wavelength of 157 nm is used as illumination light for exposure, a fine pattern of about 100 nm LZS pattern can be formed on a wafer. It is possible to transfer on the top with high precision.

The exposure light EL is an A r F excimer laser light or a K r F excimer laser light. In the case of using F., both synthetic quartz and fluorite can be used as the lens elements constituting the projection optical system PL. All fluorite is used for the lens material used for PL. In the case where an ArF excimer laser beam and a KrF excimer laser beam are used as the exposure light EL, a refraction system including only a refraction optical element may be used. When a laser beam or an Ar laser beam is used, a reflection system including only a reflection optical element may be used, or an F "laser beam or a diffraction system may be used.

 The wafer stage WST is two-dimensionally driven by a wafer stage drive unit 56W in the Y-axis direction, which is the scanning direction, and the X-axis direction, which is orthogonal thereto. On the Z tilt stage 58 mounted on the wafer stage W ST, a wafer W is held by electrostatic suction (or vacuum suction) via a wafer holder (not shown). The Z tilt stage 58 has functions of adjusting the position of the wafer W in the Z direction (focus position) and adjusting the inclination angle of the wafer W with respect to the XY plane. The position of the wafer stage WST is measured by an external laser interferometer 54 W through a movable mirror 52 W fixed on the Z tilt stage 58, and the position of the laser interferometer 54 W is measured. The value is supplied to the main controller 50.

 The control system is mainly constituted by a main control device 50 as a control device in FIG. The main controller 50 includes a so-called microcomputer (or workstation) including a CPU (central processing unit), ROM (read, only memory), RAM (random access memory), and the like. For example, synchronous scanning of the reticle R and the wafer W, stebbing of the wafer W, exposure timing, and the like are collectively controlled so that the operation is appropriately performed.

Further, in the main controller 50, at the time of the above scanning exposure, for example, control based on a detection value of a light amount measuring device such as a photoelectric conversion element (not shown) provided in the illumination optical system 40 is performed. By supplying control information to the light source 11, the light emission timing of the light source 11, the light emission power, and the like are controlled to adjust the light amount of the exposure light EL applied to the reticle R. In addition, the main controller 50 drives the illumination system aperture stop plate 25

It controls the opening and closing operation of the movable reticle blind 28 B in synchronization with the operation information of the stage system.

 By the way, if the double fly-eye lens system as described above is adopted, it is possible to make the illuminance of the illuminating light flux on the irradiated surface of the reticle R and the wafer W uniform. However, when the laser light output from the light source 11 has a high spatial coherence, the light beams transmitted through the different lens elements of the fly-eye lenses 20 and 24 interfere with each other, and the illuminated surface May form interference fringes (speckles), which may degrade illuminance uniformity. In the case of the present embodiment, since the narrow band laser light LB having high spatial coherence is used, the spatial coherence of the light beam incident on the first fly-eye lens 20 is reduced, and the illuminance uniformity caused by the speckle is reduced. The light splitting unit 18 described above is provided in order to prevent the deterioration of the illumination, and a special fly-eye lens 20 is also used as the first fly-eye lens 20 from the viewpoint of more effectively preventing the deterioration of the illuminance uniformity. Things are used. Hereinafter, these points will be described in detail with reference to FIG. FIG. 2 is a perspective view showing a configuration example of the light splitting unit 18 and the first fly-eye lens 20 according to the present embodiment.

 As shown in FIG. 2, the light splitting unit 18 is composed of a pair of plate members 49 a and 49 b opposed to each other and arranged in parallel with the YZ plane, and these plate members 49 a ,

4 9b are connected to each other. A mounting frame 49 composed of four shafts 61a to 61d extending in the X-axis direction is connected to the mounting frame 49 via a mounting member (not shown). The plane mirrors 48a, 48b, and 48 are used as reflecting mirrors having a plurality of (three in Fig. 2) high-reflectance reflecting surfaces held at an inclination angle of 45 degrees parallel to Have. Each of the plane mirrors 48a to 48c has a reflecting surface with a reflectivity of about 95% formed by a metal thin film such as aluminum or a dielectric multilayer film with the X-axis direction as a longitudinal direction. The reflecting surface of each of these plane mirrors 48a to 48c is formed by a laser beam LB output from the light source 11 after shaping by the beam shaping optical system 33 (hereinafter referred to as “laser beam” for convenience). The laser beam 57 is arranged in multiple stages in the Z-axis direction so that the laser beam 57 can be divided into multiple parts in a given direction (Z-axis direction) in a section perpendicular to the optical axis (XZ section). And is shifted by a predetermined distance in the optical axis direction (丫 -axis direction).

 In this case, in the laser beam LB output from the light source 11, the direction corresponding to the Z-axis direction in FIG. 2 is the direction having high coherence, and the cross-sectional shape of this direction is determined by the beam shaping optical system 33. It has been expanded.

 The reflecting surfaces of the plane mirrors 48a to 48c are configured to reflect the laser beam 57 with almost no gap. That is, the shape of the plane mirrors 48a to 48c in the YZ section is tapered so that at least the lower end thereof is inclined in parallel to the X 丫 plane. When viewed in the + Y direction, the laser beam 57 has no gaps in the X-axis direction as well as in the Z-axis direction (with unnecessary shielding portions being almost zero), and the plane mirrors 48 a to 4 a 8c, respectively. That is, among the plane mirrors 48a to 48c, the plane mirrors 48a and 48b satisfying the condition that another plane mirror adjacent to the rear side in the optical axis direction of the laser beam exists. When the mirror is translated rearward by a predetermined distance along the optical axis while maintaining that posture, a gap is formed by the reflection surface of the other flat mirrors 48 b and 48 c and its reflection surface. The above-mentioned taper processing is performed so that the cross-sectional shape of the side surface forms a single reflecting surface. The flat mirror 48c is also taped, but this need not be the case.

In the light splitting unit 18, the plane mirrors 48 a to 48 c are Z-axis, Because the laser beam 57 is shifted in the Y-axis direction, when the laser beam 57 enters the light splitting unit 18 from the -Y direction, it enters the flat mirror 48a located at the most Y side (+ Z side). The first split beam 59a reflected in the + Z direction by the plane mirror 48a and the plane mirror 48b positioned at the center among the light beams not incident on the plane mirror 48a. Incident on the plane mirror 48b and reflected in the + Z direction by the plane mirror 48b, and the second divided light flux 59b and incident on the plane mirror 48c without being incident on the plane mirrors 48a and 48b, The light is split into three light beams, that is, a third light beam 59c reflected by the plane mirror 48c in the + Z direction.

 Then, the divided light beams 59a, 59b, 59c individually enter the different lens groups 20a, 20b, 20c constituting the first fly-eye lens 20. Here, the lens groups 20a and 20b.20c are each composed of a plurality of lens elements arranged without a gap in the X-axis direction, as shown in FIG. Are arranged in parallel with each other. That is, the first fly-eye lens 20 is constituted by lens groups 20a, 20b, and 20c arranged corresponding to the reflection surfaces of the plane mirrors 48a to 48c, respectively.

Here, each of the divided light beams 59 a to 59 c has an optical path difference (optical path length difference) corresponding to the S position of each plane mirror _ 48 a to 48 c (more precisely, these reflecting surfaces). Has occurred. That is, the distance between the plane mirror 48a and the plane mirror 48b (the sum of 3 in the axial direction and Z in the Z direction) is between the split beam 59a and the split beam 59b. The difference between the split beam 59b and the split beam 59c is caused by the distance between the plane mirror 48b and the plane mirror 48c (Ac in the 丫 -axis direction and Ac in the Z-axis direction). (The sum of A d). In the present embodiment, the plane mirrors 48a to 48c are arranged such that the optical path difference is longer than the temporal coherence length of the laser beam 57. As a result, there is no spatial coherence (coherence) between the divided light beams 59a to 59c, and interference fringes and weak specifications on the irradiated surface (reticle pattern surface and wafer W surface) are lost. Has been smoothed. Here, the arrangement of the plane mirrors 48a, 48b, and 48c will be described using a specific example. Now, in the case of an exposure apparatus using, for example, a narrow-band ArF excimer laser (wavelength: 193 nm) as the light source 11, in order to sufficiently suppress the influence of the chromatic aberration of the projection optical system PL, it is necessary to use a laser. The spectral half-width must be about 0.4 pm, and the temporal coherence length ((laser wavelength) / spectral half-width) of the laser beam (illumination beam) at this time is Π 9 3 (nm )}] /0.4 (pm) = 9 3 (mm), so between the split light flux 59 a and the split light flux 59 b, and between the split light flux 59 b and the split light flux 59 c By providing an optical path difference of more than 93 (mm), the spatial coherence (coherence) between the divided light beams can be eliminated. That is, the plane mirrors should be arranged so that (A a + A b ≥93 (mm)) and (A c + A d ≥93 (mm)).

 Further, in the case of an exposure apparatus using a laser (wavelength: 157 nm) having a half-width of a spectrum of 0.5 b! The plane mirrors may be arranged so as to provide an optical path difference of {155 (nm)} V0.5 (pm) = 49 (mm) between the light beams 59a to 59c.

 When attaching the flat mirrors 48a to 48c to the plate members 49a and 49b constituting the mounting frame 49, the positional relationship and the angular relationship of the flat mirrors 48a to 48c are required. It is desirable to provide a fine adjustment mechanism for the mounting position so that the mounting position can be set correctly. Similarly, when the mounting frame 49 is installed in the illumination optical system 40, the mounting position adjustment mechanism is also required. It is desirable to provide.

Further, in the present embodiment, as shown in FIG. 2, the shielding members 20 s are respectively arranged between the above-described lens groups 20 a to 20 c constituting the first fly-eye lens 20, and the adjacent lens groups The overlap between the divided luminous fluxes 59a and 59b and between the 59b and 59c is prevented. As a result, the uniformity of the illuminance on the lens groups 20a to 20c constituting the first fly-eye lens 20 is improved, and in this regard, the illuminance on the irradiated surface (reticle R and wafer W) is also improved. Illuminance uniformity is assured Is maintained.

 In order to further reduce the interference between the divided light beams 59 a to 59 c, the polarized light is placed in the optical path of the laser light beam 57 or near the entrance surface or the exit surface of the first fly-eye lens 20. It is also possible to provide polarization direction rotating elements having different rotation angles so that the polarization states of the divided light beams 59a to 59c are different from each other. As the polarization direction rotating element, a birefringent material having a tapered thickness (crystal, calcite, etc.) or a birefringent material having a different thickness for each of the divided light beams 59 a to 59 c may be used. .

 Next, the flow of the IS light operation by the exposure apparatus 10 of the present embodiment configured as described above will be briefly described with reference to FIG.

 First, a reticle loader and a wafer loader (not shown) perform reticle loading and wafer loading under the control of the main controller 50, and a reticle microscope, a reference mark plate on the wafer stage WST, and an off-axis alignment detection system. (Both not shown), etc., are used to carry out preparatory work such as reticle alignment and baseline measurement (measurement of the distance between the detection center of the alignment detection system and the optical axis of the projection optical system PL) in a predetermined procedure. Done.

 After that, the main controller 50 executes an alignment measurement such as EGA (enhanced global alignment) for the wafer W using an alignment detection system (not shown). If the movement of the wafer W is necessary in such an operation, the main controller 50 moves the wafer stage WST (wafer W) in a predetermined direction.

The above-mentioned preparation work for reticle alignment, baseline measurement, etc. is described in, for example, Japanese Patent Application Laid-Open No. Hei 4-324249 and the corresponding US Pat. No. 5,243,195. The EGA following this is described in detail in Japanese Patent Application Laid-Open No. 61-44429 and US Patent No. 4,780,617 corresponding thereto. The designated country or election chosen in this international application To the extent permitted by national laws and regulations of the country, the disclosures in the above publications and the corresponding US patents corresponding thereto are incorporated herein by reference.

 After the alignment measurement as described above, the step-and-scan exposure operation is performed as follows.

 In this exposure operation, first, the wafer stage WST is moved so that the XY position of the wafer W becomes the scanning start position for the exposure of the first shot area (first shot) on the wafer W. . At the same time, the reticle stage R ST is moved so that the XY position of the reticle R becomes the scanning start position. Then, based on the position information of wafer W measured by main controller 50 wafer force interferometer 54 W and the position information of reticle R measured by reticle interferometer 54 R, reticle R (reticle stage RST) and the wafer W (wafer stage WST), while illuminating the illuminated area IAR with the exposure light EL from the illumination optical system 40 while synchronizing the movement of the wafer W (wafer stage WST). Is performed.

 In this way, when the transfer of the reticle pattern to one shot area is completed, the wafer stage WST is stepped by one shot area, and scanning exposure is performed for the next shot area. In this way, the stepping and the scanning exposure are sequentially repeated, and the required number of shot patterns are transferred onto the wafer W.

 Here, in the above scanning exposure, the reticle R is illuminated by the exposure light EL with good illuminance uniformity as described above, and as a result, the illuminance uniformity on the image plane (wafer W surface) is improved, and the wafer W The line width uniformity of the pattern transferred to each of the above shot areas is also improved.

As described above, according to the illumination system (11, 40) according to the present embodiment, when the laser beam LB is output from the light source 11, this laser beam passes through the mirrors 13, 14 The beam shaping optical system 3 3 is reached, where its cross-sectional shape is shaped. And enters the beam splitting unit 18 as a laser beam 57, and is reflected by a plurality of plane mirrors 48 a to 48 b constituting the unit 18 to be split beam 59 a, 59 b, 59 c, the light is incident on the first fly-eye lens 20, respectively, and is exposed through the optical element group to the pattern surface of the reticle R, which is the illuminated surface conjugate with the incident surface of the first fly-eye lens 20. Irradiated as EL. In this case, when each of the plurality of divided light beams is reflected by the plane mirrors 48a to 48b, the optical path length from the light source 11 to the irradiated surface is made different, and an optical path length difference (optical path difference) is given. It has been done. Therefore, the generation of speckles (interference fringes) which may deteriorate the illuminance uniformity on the irradiated surface is suppressed, so that the irradiated surface can be illuminated with uniform illuminance. In the light splitting unit 18, as the plane mirrors 48 a to 48 b, those having a reflection surface with a reflectivity of about 95% or more are adopted. Since the laser beam is only reflected once, there is a merit that the light amount loss is small and abundant illumination light amount can be provided on the irradiated surface. Therefore, adoption of an illumination system including the light splitting unit 18 in an exposure apparatus makes it possible to increase the exposure power and further improve the throughput (processing capacity). Further, when a narrow-band laser beam having high spatial coherence is used as in the present embodiment, the advantage of suppressing the generation of speckle is particularly great.

In the light splitting unit 18, the laser light beam 57 is divided into a plurality of beams in the first direction where the coherence is high, and there is an optical path length difference between each of the split light beams. The generation of speckles can be suppressed efficiently. Further, according to the exposure apparatus 10 of the present embodiment, the illumination system (11, 40) reduces the generation of interference fringes on the reticle pattern surface (the surface to be irradiated) and achieves high illuminance uniformity of the reticle. By illuminating R, it is possible to improve the uniformity of the illuminance of the laser beam projected on the wafer W surface by the projection optical system PL, and to achieve high-precision exposure with improved uniformity of the pattern line width. Become. Light source 1 1 As a result, it is possible to use a narrow-band laser light source having a high spatial coherence, thereby substantially eliminating the adverse effect of chromatic aberration of the projection optical system PL.

 In the above embodiment, the case where the laser beam is divided in the direction of high coherence and the light dividing unit 18 that reflects only once is used has been described. However, the present invention is not limited to this. Instead, for example, as shown in FIG. 3, the light division unit 118 that performs the two-way reflection of the laser beam 57 may be used instead of the light division unit 18. Here, the operation of the light splitting unit 118 of FIG. 3 will be described. In the light splitting unit 118, the laser beam 57 traveling in the + Y direction is inclined at an angle of 45 degrees with respect to the X and Y axes, and the flat mirrors 48a to 4 As in 8c, X-axis direction (first direction) and Y-axis direction

The three plane mirrors 48 a! To 48 composing the first reflecting surface group which are displaced by a predetermined distance (in the optical axis direction) are directed in the + X direction (second direction), respectively. The light is reflected and divided into three parts (divided into three equal parts) in the X-axis direction. In the present embodiment, the first direction in which the light beam is split is the same as the second direction in which each split light beam is bent, but this is not necessarily required. That is, the plane mirrors 48a to 48c need not necessarily be inclined at an angle of 45 degrees with respect to X and Y 铀. It is only necessary that the light beam 57 be divided into three parts on a plane parallel to the YZ plane when viewed in a plane perpendicular to the optical axis.

Next, each of the three divided light beams 59, 59, 59 _; traveling in the + X direction is inclined at an angle of 45 degrees with respect to the X and Z axes, and the above-described plane mirror 48 a ~

Similarly to 48 c, three plane mirrors 48 a to 48 forming a second reflecting surface group arranged at a predetermined distance in the X-axis direction and the Z 铀 direction (third direction).

(By ^, each is reflected in the + Z direction (fourth direction) and is divided into three parts (divided into three parts) in the Z-axis direction. As a result, the laser beam 57 is divided into nine parts in the XZ two-dimensional direction. is, nine split beam _{5 9 Μ ~ 5 9:.} i3 become in this embodiment, the four-way that the third direction and the divided light fluxes each split light beams are split is folded Although the direction is the same, it is not always necessary to do so. That is, it is not necessary to tilt the plane mirrors 48a to 48c at an angle of 45 degrees with respect to the X and Z axes. It is only necessary that each of the divided light beams 5959, 59 _{: i} be divided into three parts on a plane parallel to the XY plane as viewed in a plane perpendicular to the optical axis.

. In this case, first reflected in divided split light beams 5 9, 5 9, "and between 5 9 _t is cause optical path difference as described above, the divided light fluxes 5 _9: is the second time also between the reflection occurs is further divided by the split light beams 5 9 _u, 5 9 5 9 optical path difference occurs. Similarly, there is an optical path difference between the split light beams generated from the split light beams 59 ", 59, and so on generated by the first reflection. Therefore, an optical path difference can be generated between all of the nine divided light beams, and the plane mirrors 48 and 48 are so arranged that each optical path difference is longer than the temporal coherence length of the laser light beam 57 as described above. _a: ~ 4 8 c:, plane mirror one 4 8 a, by arranging the ~ 4 8 c ", nine split beam _{5 9 μ ~ 5 9: 1} :! the mutual spatial Kohi one Reference (Coherence) is eliminated, and the generation of interference fringes on the irradiated surface (reticle pattern surface and wafer W surface) can be further reduced. In this case, as the nine split beam 5 9 _Micromax ~ 5 9 _u is incident on different that lens groups橫成the first fly-eye lens, a plane mirror one _{4 8 a: ~ 4 8 c} t, the plane mirror One 48 a, ~ 48 C, is arranged.

 By using the light splitting unit 1 18 that can perform two-fold bending reflection as described above, it is possible to shape the cross section of the laser beam in the beam shaping optical system 33 (enlarge the beam) in any direction. Therefore, the degree of freedom of arrangement of each optical element including the beam shaping optical system is improved. In addition, by adjusting the number of mirrors and the number of lens elements that compose the fly-eye lens, it is also possible to make a one-to-one split light beam incident on one lens element that composes the first fly-eye lens. As a result, the illuminance uniformity can be further improved.

 << 2nd Embodiment >>

Next, a second embodiment of the present invention will be described with reference to FIG. Where The same or equivalent components as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted. The exposure apparatus according to the second embodiment is different from the first embodiment only in the configuration of the light dividing unit and the first fly-eye lens. The configuration of the other parts is the same as that of the above-described first embodiment. Will be described centering on the different points described above.

 FIG. 4 is a side view showing the configuration of the light splitting unit 18 ′ and the first fly-eye lens 20 ′ according to the second embodiment.

 The light splitting unit 18 ′ is arranged on the optical path of the laser beam 57 from the beam shaping optical system 33 described above. As shown in FIG. 4, the light splitting unit 18 ′ includes a mounting frame 49 and plate members 49 a and 49 b facing each other, which constitute the mounting frame 49 (see FIG. 4). In the figure, the plate-like member on the far side of the paper is hidden), so that the inclination angles are (45 ° -α), 45 °, and (45 ° + α) The plane mirrors 48d, 48e and 48f are provided. These plane mirrors 48d, 48e, and 48f divide the laser beam 57 into a plurality in the first direction (Z-axis direction) in a cross section (XZ section) perpendicular to the optical axis of the laser beam 57. As far as possible, they are arranged in multiple stages in the Z-axis direction, and are arranged so as to be shifted by a predetermined distance in the optical axis direction (Y direction). Therefore, when the laser beam 57 traveling in the + Y direction enters these plane mirrors 48d to 48f, this laser beam 57 is located at the most Y side (+ Z side). The split beam 59 d that enters the plane mirror 48 d and is reflected by the plane mirror 48 d, enters the plane mirror 48 e without being incident on the plane mirror 48 d, and is reflected by the plane mirror 48 e The split light beam 59e is split into a split light beam 59e and a split light beam 59f which enters the plane mirror 48f without being incident on the plane mirrors 48d and 48e and is reflected by the plane mirror.

In this case, since the inclination angles of the plane mirrors 48 d to 48 f are set as described above, the split light fluxes 59 d to 59 f are reflected by the plane mirrors 48 d to 48 f, respectively, all of which are described above. The first fly eye provided in place of the first fly eye lens 20 Light is emitted toward the entire surface of the lie-eye lens 20 '. That is, the predetermined angle α is determined so that the split light fluxes 59 d to 59 f are emitted toward the entire surface of the first fly-eye lens 20 ′.

 The first fly-eye lens 20 ′ is not a special one like the first fly-eye lens 20 of the first embodiment, but a known fly-eye lens in which a large number of lenses are converged is used. .

 In the present embodiment, an optical path difference and an angle difference of an incident angle are generated between the divided luminous fluxes 59 d to 59 f according to the positional relationship between the plane mirrors 48 d to 48 f, and the first fly eye Since the spatial coherence of the light beam incident on the lens 20 ′ is reduced, the interference fringes on the illuminated surface are smoothed. Therefore, it is possible to improve the illuminance uniformity on the irradiated surface, and as a result, it is possible to improve the uniformity of the pattern line width transferred onto the wafer.

 In the second embodiment, since each light beam incident on the fly-eye lens 20 ′ has a different incident angle, the exit surface of the plurality of lens elements forming the fly-eye lens 20 ′ is formed. It is desirable that the surface shape be a convex surface (convex lens). This makes it possible to efficiently guide all of the divided light beams 59 d to 59 f having different incident angles to the reticle R.

In each of the above embodiments, the reflection mirrors constituting the light splitting unit are all flat mirrors. However, the present invention is not limited to this, and the shape of the reflection mirror may be a convex surface, a concave surface, It may have a shape such as a cylinder surface. Further, a plurality of reflecting surfaces may be formed in different places of the same member. If necessary, another optical element such as a lens and a mirror can be arranged between the light splitting unit and the first fly-eye lens. Further, the number of reflecting mirrors constituting the light splitting unit is not limited to three as in the above embodiments, and the coherence can be further reduced by using more mirrors. Needless to say, there is. Further, in each of the above embodiments, the illuminance uniforming optical system is configured by a double fly-eye lens. However, the present invention is not limited thereto, and a single fly-eye lens may be configured. Of course, it is also possible to use a rod lens (internal reflection type integrator). Further, a DOE (diffractive optical element) may be used instead of the first fly-eye lens, and an illuminance uniforming optical system may be configured in combination with an optical integrator (such as a fly-eye lens or a rod lens). For example, when using annular illumination, it is desirable to set the illuminance distribution on the light source surface in an annular shape from the viewpoint of reducing the light amount loss. In order to realize such an illumination distribution, in the case of a fly-eye lens, it is necessary to machine each lens element into an aspherical surface, but such a machining operation is impractical. In contrast, in the case of D〇E, a Fresnel lens having the same function as an aspherical lens can be produced relatively easily, which is convenient in such a case. When a DOE having the same function as the first fly-eye lens 20 of the first embodiment is created, an arrangement corresponding to each lens element of the first fly-eye lens 20 is made on the same transparent substrate. Then, a plurality of Fresnel lenses may be manufactured, and a shielding film (light shielding film) corresponding to the above-described shielding material 20 s may be provided between the Fresnel lens groups.

 When a DOE (diffractive optical element) is used instead of the first fly-eye lens, and the illuminance uniforming optical system is configured in combination with the fly-eye lens, the next light may be It is conceivable that a specific lens element of the lens, for example, a lens element located on the optical axis is intensively irradiated.In such a case, the illuminance distribution on the reticle pattern surface becomes non-uniform. From the viewpoint of preventing the above, it is desirable to use a dummy element for the 0th-order light cut as a specific lens element or to shield light emitted from the specific lens element.

Also, in each of the above embodiments, it is assumed that the spatial coherence of the laser light is increased by using a narrow band laser light source as the light source 11. However, the present invention is not limited to a laser light source as well as an illumination system and an exposure apparatus that use other light sources other than a laser light source, as long as the light source outputs light with high spatial coherence. Can be suitably applied.

 In each of the above embodiments, the reduction optical system is used as the projection optical system PL. However, the present invention is not limited to this, and any one of an equal magnification system and an enlargement optical system may be used.

 In addition, the illumination optical system and projection optical system composed of multiple lenses are incorporated into the exposure apparatus main body for optical adjustment, and a reticle stage and wafer stage consisting of many mechanical parts are attached to the exposure apparatus main body to connect wiring and piping. The exposure apparatus of each of the above embodiments can be manufactured by performing overall adjustment (electrical adjustment, operation check, etc.). It is desirable that the IS optical device be manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

 In the above embodiment, the case where the present invention is applied to the scanning stepper has been described. However, the present invention is not limited to this, and the mask pattern is transferred to the substrate while the mask and the substrate are kept stationary. Step-and-repeat type projection, in which the mask pattern is transferred to the substrate in a step-and-repeat manner, and the proximity of the mask to the substrate without using a projection optical system to transfer the mask pattern to the substrate. However, the present invention can be suitably applied. Even in the latter case, the mask can be illuminated with uniform illuminance by the illuminating device according to the present invention, so that the illuminance uniformity on the substrate onto which the pattern formed on the mask is transferred is ensured. As a result, the uniformity of the pattern line width formed on the substrate is improved, and the fine pattern can be transferred onto the substrate with high accuracy.

In each of the above embodiments, the present invention provides an exposure light EL as an ArF excimer laser light (wavelength: 193 nm), a KrF excimer laser light (wavelength: 248 nm), or an Fr excimer laser light (wavelength: 248 nm). Although the description has been given of the case where the present invention is applied to an exposure apparatus using ._, laser light (wavelength: 157 nm), etc., the present invention is not limited to this. Kr_, laser light, wavelength 1 The present invention is also suitable for an exposure apparatus using vacuum ultraviolet light such as 6 nm Ar and laser light. Can be used.

 In addition, a single-wavelength laser beam in the infrared or visible range oscillated from a DFB semiconductor laser or a fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium). It is also possible to use a harmonic whose wavelength has been converted to ultraviolet light using a nonlinear optical crystal.

 For example, if the oscillation wavelength of a single-wavelength laser is in the range of 1.51 to 1.59 im, the 8th harmonic whose generation wavelength is in the range of 189 to "! 99 nm, or The 10th harmonic whose output wavelength is in the range of 151 to 159 nm is output, especially when the oscillation wavelength is in the range of 1.544 to 1.553 im. An 8th harmonic within the range of 93 to 194 nm, that is, ultraviolet light having substantially the same wavelength as the ArF excimer laser light is obtained, and the oscillation wavelength is within the range of 1.57 to 1.58. Then, the 10th harmonic having a generated wavelength in the range of 157 to 158 nm, that is, ultraviolet light having substantially the same wavelength as the F laser light is obtained.

If the oscillation wavelength is in the range of 1.03 to 1.12 m, a 7th harmonic whose output wavelength is in the range of 147 to 160 nm is output, and especially the oscillation wavelength is 1.09. 9 to 1.1 0 when in the range of 6 / m, 7 harmonic in the range generation wavelength of 1 57~ 1 58 tim, i.e. the _c substantially the same wavelength as comprising ultraviolet light is obtained when the laser beam As the single-wavelength oscillation laser, for example, a ytterbium 'doped' fiber laser can be used.

 《Device manufacturing method》

 Next, an embodiment of a device manufacturing method using the above-described lithography system (exposure apparatus) and exposure method in a lithography step will be described.

Figure 5 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. 5, first, in step 201 (design step), a device function / performance design (for example, circuit design of a semiconductor device) is performed. A pattern is designed to realize the function. 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 the 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 assembling 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), inspections such as an operation confirmation test and a durability test of the device created in step 205 are performed. After these steps, the device is completed and shipped.

 FIG. 6 shows a detailed flow example of step 204 in the semiconductor device. In step 2 11 (oxidation step) in FIG. 6, the wafer surface is oxidized. In step 2 12 (CVD step), an insulating film is formed on the wafer surface. In steps 2-3 (electrode formation step), 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-described 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 2 16 (exposure step), the exposure apparatus and the exposure apparatus described above are used. The circuit pattern of the mask (reticle) is transferred to the wafer by an optical method. Next, in Step 218 (etching step), the exposed members other than the portion where the resist remains are removed by etching. Then, in step 219 (resist removing step), the unnecessary resist after etching is 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 exposure apparatus of each of the above embodiments is used in the exposure step (Step 2 16), so that the fine pattern is formed on the substrate by the exposure light with uniform illuminance. The transfer can be performed with high accuracy, and as a result, the productivity of a highly integrated microdevice can be improved. Industrial applicability

 As described above, the illumination device of the present invention is suitable for illuminating an irradiated surface with uniform illuminance. Further, the exposure apparatus of the present invention is suitable for forming a plurality of fine patterns on a substrate such as a wafer with high precision in a lithography process for manufacturing microdevices such as integrated circuits. Further, the device manufacturing method according to the present invention is suitable for manufacturing a device having a fine pattern.

Claims

The scope of the claims

1. A lighting device for illuminating an irradiated surface,

 Light source;

 A light splitting unit that splits a light beam from the light source into a plurality of light beams and has a plurality of reflective surfaces that make the optical path length from the light source to the irradiated surface between the split light beams different from each other.

2. The lighting device according to claim 1,

 The plurality of reflection surfaces are arranged in multiple stages in the predetermined one direction so that the light beam can be divided into a plurality of predetermined one directions in a cross section perpendicular to an optical axis of the light beam from the light source, and An illuminating device, wherein the illuminating device is displaced by a predetermined distance in an optical axis direction.

3. The lighting device according to claim 2,

 The lighting device according to claim 1, wherein the predetermined direction is a direction in which the light output from the light source has high coherence.

4. The lighting device according to claim 1,

 The plurality of reflecting surfaces are respectively reflecting surfaces of different reflecting mirrors.

5. The lighting device according to claim 4,

Among the plurality of reflecting mirrors, a reflecting mirror that satisfies the condition that there is another reflecting mirror adjacent to the rear side in the optical axis direction of the light beam is provided along the optical axis while maintaining its posture. When translated rearward by a predetermined distance, the other reflection mirror A lighting device, wherein a cross-sectional shape of a side surface is set so that a single reflecting surface having no gap is formed by one reflecting surface and its own reflecting surface.

6. The lighting device according to claim 1,

 The lighting device according to claim 1, wherein the plurality of reflection surfaces are formed at different portions of the same member.

7. The lighting device according to claim 1,

 The lighting device, wherein each of the plurality of reflection surfaces has a reflectance of about 95% or more.

8. The lighting device according to claim 1,

 The light splitting units are arranged in multiple stages with respect to a predetermined first direction in a cross section perpendicular to an optical axis of the light flux from the light source as the plurality of reflecting surfaces, and are arranged by being shifted by a predetermined distance in the optical axis direction. A first reflecting surface group that divides the light beam into a plurality of light beams and bends the optical axis of each of the divided light beams in a second direction, and is arranged in multiple stages with respect to a predetermined third direction in a cross section perpendicular to the second direction. And a second reflection surface group that is arranged so as to be shifted by a predetermined distance in the second direction and divides each of the divided light beams into a plurality of light beams and bends the optical axis of each of the divided light beams in the fourth direction. A lighting device, comprising:

9. The lighting device according to claim 1,

The lighting device according to claim 1, wherein the light splitting unit causes a difference in the optical path length equal to or longer than a temporal coherence length of the light between the split light beams respectively reflected by the plurality of reflecting surfaces.

10. The lighting device according to claim 1,

 An illuminance equalizing optical system including an optical integrator disposed on an optical path of the light between the light splitting unit and the irradiated surface and irradiated with each split light beam split by the light splitting unit. A lighting device, further comprising:

11. The lighting device according to claim 10, wherein

 The lighting device according to claim 1, wherein the optical integrator is one of a fly-eye lens, a rod lens, and a diffractive optical element.

12. The lighting device according to claim 10, wherein

 The optical lighting device has a plurality of elements,

 A lighting device, wherein each split light beam split by the light splitting unit is applied to a different element set having at least one of the elements as an element.

13. The lighting device according to claim 12,

 A lighting device characterized in that a space between element sets to which the different divided light beams are respectively irradiated is partitioned by a light shielding member.

1. The lighting device according to claim 13,

 The lighting device according to claim 1, wherein the optical integral is one of a fly-eye lens and a diffractive optical element.

15. The lighting device according to claim 10, wherein

The light splitting unit is arranged so that each of the split light beams is incident on the entire surface of the optical integrator. An illuminating device characterized in that the incident angle with respect to the tigray is different.

16. The lighting device according to claim 1,

 The lighting device, wherein the light source is a laser light source.

1 7. A lighting device for illuminating an irradiated surface,

 Light source;

 The light flux from the light source is arranged in multiple stages with respect to the predetermined one direction so that the light flux can be divided into a plurality of pieces in a predetermined direction in a cross section perpendicular to the optical axis of the light flux, and is shifted by a predetermined distance in the optical axis direction. A reflecting unit having a plurality of reflecting surfaces arranged in a horizontal direction.

18. The lighting device according to claim 17, wherein

 A shaping optical system arranged between the light source and the reflection unit, for shaping a cross-sectional shape of a light beam from the light source;

 The illumination unit, wherein the reflection unit divides the light beam after being shaped by the shaping optical system into a plurality of light beams.

19. The lighting device according to claim 17, wherein

 The illuminating device, wherein the plurality of reflection surfaces divides a light beam from the light source into a plurality of light beams, and changes a light path length from the light source to the irradiated surface between the divided light beams.

20. An exposure apparatus for transferring a pattern formed on a pattern surface of a mask to a substrate,

Light source; A light splitting unit having a plurality of reflecting surfaces for splitting a light beam from the light source into a plurality of light beams and having different optical path lengths from the light source to the pattern surface on which the pattern is formed between the split light beams; Exposure equipment provided.

21. In the exposure apparatus S according to claim 20,

 An illuminance uniforming optical system that is disposed on an optical path of the light between the light splitting unit and the pattern surface and includes a optical integrator that is irradiated with each split light beam split by the light splitting unit. An exposure apparatus, further comprising:

22. In the optical device ^ according to claim 21,

 The optical lighting device has a plurality of elements,

 An exposure apparatus, wherein each of the split light beams split by the light splitting unit is irradiated to mutually different element sets each including at least one of the elements.

23. The exposure apparatus according to claim 20, wherein

 The optical device according to claim 1, further comprising a projection optical system for projecting the light emitted from the mask onto the substrate.

24. The exposure apparatus according to claim 20, wherein

 An exposure apparatus, wherein the light source is a laser light source.

25. An exposure apparatus for transferring a pattern formed on a pattern surface of a mask onto a substrate,

 Light source;

The light beam in a predetermined direction in a cross section perpendicular to the optical axis of the light beam from the light source; A reflection unit having a plurality of reflection surfaces which are arranged in multiple stages with respect to the predetermined direction so as to be able to be divided into a plurality of parts, and which are displaced by a predetermined distance in the optical axis direction.

26. The exposure apparatus according to claim 25, wherein

 An exposure apparatus, wherein the plurality of reflecting surfaces divide a light beam from the light source into a plurality of light beams and vary the optical path length from the light source to the irradiated surface between the divided light beams.

27. A device manufacturing method including a lithographic process,

 27. A device manufacturing method, comprising performing exposure using the exposure apparatus according to claim 20 in the lithographic process.