DE102006028242A1 - Projection objective of micro-lithographic projection exposure equipment e.g. for fabrication of integrated circuits, has diffractive optical element arranged in pupil plane - Google Patents

Abstract

A projection objective (100) for displaying a mask positionable in an object plane (OP) on to a light-sensitive layer positionable in an image plane (IP) has a first pupil plane (PP1) which is the pupil plane lying nearest to the object plane of the projection objective, at least a second pupil plane (PP2) which is the pupil plane lying nearest to the image plane of the projection objective and at least one diffractive optical element (115a) arranged mainly in the first pupil plane. Independent claims are included for the following. (1) (A) A micro-lithographic projection exposure installation (2) (B) A method for micro-lithographic fabrication of micro-structured components (3) (C) A micro-structured component.

Description

The The invention relates to a projection objective of a microlithographic Projection exposure system.

microlithographic Projection exposure equipment is becoming more microstructured for fabrication Components, such as integrated circuits or LCD's applied. A Such projection exposure apparatus has a lighting system and a projection lens. In the microlithography process, the Image of a mask illuminated by the illumination system (= Retikel) by means of the projection lens on a with a photosensitive Layer (photoresist) coated and in the image plane of the projection lens arranged substrate (e.g., a silicon wafer) projected to the Mask structure on the photosensitive coating of the substrate transferred to. The maximum achievable resolution the projection exposure machine increases with decreasing wavelength of the Lighting system and with increasing image-side numerical Aperture of the projection lens.

One A major problem with projection lenses is that with increasing Numerical aperture, especially in immersion objectives with numerical Apertures larger than One, the lens diameters in the projection lens go up, which on the one hand on the required beam deflections and on the other to the required correction of the curvature of the image shell (so-called. Petzval curvature) is due.

to Correction of Petzval curvature is used in both refractive and catadioptric systems a combination of positive (collecting) lenses and (negative) dissipating lenses used, wherein at the positive lenses the height of Marginal rays relatively large and at the negative lenses the height the marginal rays is small. Further, the Petzval correction Concave mirror used, since these compared to positive refractive Lenses with the same sign of the refractive power an opposite Generate Petzval curvature, such that by suitable combination a compensation of the Petzval curvature is achieved can be.

For the correction of chromatic aberrations in the projection lens, eg off US 6,829,099 B2 , also the use of diffractive optical elements (DOE's) known. In contrast to refractive lenses, these have an opposite dispersion with the same sign of the refractive power, so that color errors can be corrected by the use of DOEs. However, DOEs do not contribute to the Petzval curvature.

task It is the object of the present invention to provide a projection objective of a to provide a microlithographic projection exposure apparatus, which without impairment the picture quality a reduction in the maximum diameter of the optical elements allows.

These Task becomes according to the characteristics the independent one claims solved.

According to one Aspect of the invention comprises a projection objective according to the invention microlithographic projection exposure machine for imaging a positionable in an object plane mask on one in an image plane positionable photosensitive layer has a first pupil plane, which closest to the object plane Pupil plane of the projection lens is, at least a second Pupil plane, which is the pupil plane closest to the image plane of the projection lens, and at least one diffractive optical Element on, which is essentially in the first pupil plane is arranged.

Under "pupil level" here is one for optical axis to understand vertical plane, which by a Point runs, at which a principal ray intersects the optical axis (also "real Pupil plane "). Under "marginal ray" is in the sense of The present application in each case to understand the outermost beam, the delimits the object center tuft emanating from an object point on the optical axis. Further, under an "optical Axis "one each straight line or a succession of straight line sections to be understood by the centers of curvature the respective optical components runs.

For the purposes of the present application, the wording "substantially in the first pupil plane" is to be understood as meaning that, according to the invention, even slight deviations from the exact positioning in the first pupil plane are possible and are encompassed by the present application For such a slight deviation, the principal ray height at the position concerned may be used. Taking into account that in the pupil plane itself the principal ray height is zero, according to the invention such a deviating position is encompassed by "substantially in the pupil plane", in which the main ray height reaches a maximum of ± 10% of half the optically effective diameter of the diffractive optical element this position is.

• (a) Infolge des erfindungsgemäßen Einsatzes des DOE in der ersten Pupillenebene wird eine Reduzierung der maximal auftretenden Durchmesser der refraktiven Linsen erreicht. Durch den Einsatz des DOE's wird positive Brechkraft eingeführt, die im Projektionsobjektiv an anderer Stelle in Form von refraktiver Brechkraft eingespart werden kann, so dass sich der Gesamtaufbau des Abbildungssystems hinsichtlich der Petzval-Korrektur ändert und insgesamt weniger negative Petzval-Krümmung korrigiert werden muss. Dies führt zu einer Verringerung der erforderlichen Linsendurchmesser und somit auch zu einer Materialeinsparung.
• (b) Da in einem Projektionsobjektiv mit zwei Pupillenebenen die erste, der Objektebene nächstliegende Pupillenebene einen wesentlich geringeren Durchmesser als die zweite, der Bildebene nächstliegende Pupillenebene aufweist, wird die Realisierung von DOE's mit signifikant verringertem Durchmesser ermöglicht, was fertigungstechnisch im Hinblick auf den zur Herstellung solcher DOE's angewandten Lithographieprozess von Vorteil ist.
• (c) Der erfindungsgemäße objektebenennahe Einsatz des DOE's hat den weiteren Vorteil, dass die Möglichkeiten zur Abblendung von Streulicht (welches von einem DOE üblicherweise in der Größenordnung von etwa 10% generiert wird) vermehrt werden. Dies ist deshalb von Bedeutung, weil regelmäßig nur ein begrenzter Anteil des Lichtes in die gewünschte Beugungsordnung gelangt und im übrigen Streulicht generiert wird, das abgeblockt werden muss oder zu einem Kontrastverlust führt.

Thus, according to the invention, at least one DOE is used essentially in the first pupil plane in a system having at least two pupil planes. This results in the following advantages:

• (a) As a result of the use according to the invention of the DOE in the first pupil plane, a reduction of the maximum occurring diameter of the refractive lenses is achieved. Through the use of the DOE's positive power is introduced, which can be saved in the projection lens elsewhere in the form of refractive power, so that the overall structure of the imaging system changes in Petzval correction and overall less negative Petzval curvature must be corrected. This leads to a reduction of the required lens diameter and thus also to a material saving.
• (b) Since in a projection objective with two pupil planes, the first pupil plane closest to the object plane has a substantially smaller diameter than the second pupil plane closest to the image plane, it is possible to realize DOEs with a significantly reduced diameter, which is production-wise with respect to production such DOE's applied lithography process is beneficial.
• (c) The object-level use of the DOE according to the invention has the further advantage that the possibilities for dimming scattered light (which is usually generated by a DOE on the order of about 10%) are increased. This is important because regularly only a limited proportion of the light gets into the desired diffraction order and the rest of the scattered light is generated, which must be blocked or leads to a loss of contrast.

As explained below, is to achieve the mentioned under (a), particularly desired according to the invention Effect aware of a possibly minor correction of chromatic aberrations in the design according to the invention put up for a particularly effective Petzval correction and thus a reduction in the maximum lens diameter in the projection lens to enable.

wobei h die Randstrahlhöhe am Ort dieses optischen Elements, K die Brechkraft und n_u die Abbé-Zahl angeben (wobei die Abbé-Zahl n_u für refraktive Linsen positiv ist, und wobei die Abbé-Zahl n_u für ein DOE proportional zu –λ und somit negativ ist). Aus der Beziehung (1) folgt, dass für eine optimale Korrektur von Farblängsfehlern eigentlich der Term K·h² bezüglich der Einsatzposition des DOE zu maximieren ist. Dabei ist zu berücksichtigen, dass für die Brechkraft K eines DOE's in Abhängigkeit von seiner Gitterkonstante g in erster Näherung die folgende Proportionalitätsbeziehung gilt: 1g ∝K·h (2)wobei g die Gitterkonstante, K die Brechkraft und h wiederum die Randstrahlhöhe am Ort des DOE angeben. Da die wesentliche technologische Grenze i.d.R. durch die minimal erreichbare Gitterkonstante g gegeben ist, wird somit zur Optimierung des Terms K·h² zwecks Minimierung von Farblängsfehlern das DOE an einer Position mit maximaler Randstrahlhöhe eingesetzt, wobei diese Position i.d.R. in der zweiten (bildebenenseitig letzten) Pupillenebene liegt.It should be noted that in a projection objective having at least two pupil planes, correction of longitudinal chromatic aberrations when used in the first pupil plane closest to the object plane is not as effective as when used in the second pupil plane closest to the image plane, since the marginal ray height is in the second pupil plane is greater and the longitudinal chromatic aberration is quadratically dependent on the edge beam height. For the contribution Δ _{CHL of} an optical element to the longitudinal chromatic aberration, the following proportionality relationship applies:

where h denotes the marginal ray height at the location of this optical element, K the refractive power, and n _u the Abbe number (where the Abbe number n _u is positive for refractive lenses, and where the Abbe number n _u for a DOE is proportional to -λ and thus is negative). From the relation (1), it follows that, for optimum correction of color longitudinal errors, the term K · h ^{2 is} actually to be maximized with respect to the insertion position of the DOE. It should be noted that for the refractive power K of a DOE as a function of its lattice constant g in the first approximation the following proportionality relationship applies: 1 G ΑK · h (2) where g indicates the lattice constant, K the refractive power and h in turn the marginal beam height at the location of the DOE. Since the essential technological limit is usually given by the minimum achievable lattice constant g, the DOE is thus used at a position with maximum marginal beam height to optimize the term K · h ^{2 in} order to minimize longitudinal chromatic aberrations, this position usually being in the second (last image plane last) Pupil plane lies.

On the other hand, for the contribution Δ _{PV of} a refractive lens to the Petzval curvature, the following proportionality relationship applies: Δ PV α K n (3) where n indicates the refractive index of the lens material. From the relationship (3) it is first clear that when using a DOE with the refractive power K instead of a refractive lens with the same refractive power, the corresponding contribution Δ _PV to Petzval curvature is eliminated from the overall optical system, as with the use of the DOE's positive As a result, due to the elimination of the above contribution Δ _PV, the overall structure of the imaging system changes with respect to the Petzval correction since, overall, less negative Petzval curvature needs to be corrected in that in order to optimize the correction of the Petzval curvature by the DOE, it is necessary to directly maximize the refractive power K. Considering that the lattice constant g is technologically limited, this implies according to the relationship (2) that the use according to the invention in a pupil plane with a smaller plane Marginal jet height leads to a larger contribution Δ _PV Insertion in a pupil plane in general is furthermore advantageous because the principal ray height is zero there and no contribution of this DOE to linearly dependent on the main ray height lateral chromatic aberration (also called color magnification error or main ray chromatic aberration) for a DOE used in a pupil plane.

According to one Another aspect, a projection lens according to the invention a optical axis, a first pupil plane in which a marginal ray, which emanates from an object point on the optical axis ray bundle limited, a first edge beam height has at least one second pupil plane, in which a marginal ray, which delimits a bundle of rays emanating from an object point on the optical axis, a second edge beam height wherein the second marginal ray height is greater than the first marginal ray height, and at least one diffractive optical element located in the Essentially arranged in the first pupil plane.

According to one Another aspect, a projection lens according to the invention a optical axis and at least one diffractive optical element on, which is arranged along the optical axis in a plane is, in which a marginal ray, which one from an object point on the optical axis outgoing bundle of rays limited, a first Marginal ray height wherein the first marginal beam height is less than 60% of the maximum Marginal ray height in the projection lens.

According to one preferred embodiment is Here, the first edge beam height less than 50%, preferably less than 40%, more preferably less as 30% of the maximum marginal beam height in the projection lens.

• (a) COMP1 ist kleiner als 11;
• (b) COMP2 ist kleiner als 250;
• (c) COMP3 ist kleiner als 80.

According to a further aspect, a projection objective of a microlithographic projection exposure apparatus, for imaging a mask positionable in an object plane onto a photosensitive layer positionable in an image plane, has a maximum lens diameter D _max , a maximum field height y ', an image-side numerical aperture NA, a lens number N _L and a number of subsystems N _op , which are interconnected by intermediate images, wherein the projection lens has at least one diffractive optical element, and wherein for the parameters COMP1, COMP2 and COMP3 with COMP1 = D Max / (Y '· NA 2 ) COMP2 = D Max · N L / (Y '· NA 2 ) and COMP3 = D Max · N L / (N operating room · Y '· NA 2 ) at least one of the following conditions is met:

• (a) COMP1 is less than 11;
• (b) COMP2 is less than 250;
• (c) COMP3 is less than 80.

The Invention is according to this further aspect thus characterized in that as a result of the use of the DOE a particularly compact design of the lens is achieved which - as explained in more detail below - by the conditions for the above-mentioned Parameter is expressed.

According to a preferred embodiment, this particular compactness is achieved, wherein the lens has not more than two different lens materials (that is, for example, only lenses made of quartz glass, or only lenses made of quartz glass or CaF ₂ ).

According to one another preferred embodiment in this case the projection objective has a first pupil plane, which closest to the object plane Pupil plane of the projection lens, and a second pupil plane which is closest to the image plane Pupil plane of the projection lens is.

According to one another preferred embodiment The diffractive optical element has a positive focal length which is at most 300 mm, preferably at most 250 mm, more preferably at most 200 mm, and more preferably at most 150 mm.

According to one another preferred embodiment this causes the diffractive optical element in the projection lens a partial correction of the longitudinal chromatic aberration except for a residual longitudinal chromatic aberration, this residual color longitudinal error at least 200 nm / pm.

According to one another preferred embodiment has the projection lens according to the invention at least one second diffractive optical element. Prefers is the second diffractive optical element substantially in the second closest to the image plane Arranged pupil plane.

According to one another preferred embodiment have the first diffractive optical element and / or the second diffractive optical element has a diameter which is less than 0.5 times, preferably less than 0.4 times the maximum marginal beam height.

According to one another preferred embodiment has the projection lens according to the invention apart from diffractive optical elements a purely refractive Structure on, in particular so no mirrors.

According to one another preferred embodiment has the projection lens according to the invention a catadioptric structure in which at least one real Intermediate image is generated.

According to one another preferred embodiment the projection lens has only one mirror with refractive power, which is preferably arranged substantially in a pupil plane is.

According to one another preferred embodiment is the projection lens for a wavelength of less than 250 nm, preferably less than 200 nm or less than 160 nm designed.

The The invention further relates to a microlithographic projection exposure apparatus for producing microstructured components with a projection objective according to the invention, a method for the microlithographic production of microstructured Components and a microstructured produced by such a method Component.

Further Embodiments of the invention are the description and the dependent claims to remove.

The Invention is described below with reference to the accompanying drawings illustrated embodiments explained in more detail.

It demonstrate:

1 a meridional overall section through a complete catadioptric projection lens according to a first embodiment of the present invention;

2 a meridional overall section through a complete catadioptric projection lens according to a second embodiment of the present invention;

3 a meridional overall section through a complete purely refractive projection lens according to a third embodiment of the present invention;

4 a meridional overall section through a complete catadioptric projection lens according to a fourth embodiment of the present invention; and

5 the schematic structure of a microlithography projection exposure system.

According to 1 is a projection lens 100 according to a first embodiment of the present invention. The design data of this projection lens 100 are listed in Table 1; Radii and thicknesses are given in millimeters. The surfaces specified in Table 2 are aspherically curved, the curvature of these surfaces being given by the following aspherical formula:

there P are the height of the arrow the area concerned parallel to the optical axis, h the radial distance from the optical Axis, r the radius of curvature the area concerned, cc is the conic constant (indicated by K in Table 2) and C1, C2, ... listed in Table 2 Asphärenkonstanten.

According to 1 points the projection lens 100 According to the first embodiment in a catadioptric structure, a first optical subsystem 110 , a second optical subsystem 120 and a third optical subsystem 130 on. For the purposes of the present application, a "subsystem" is always to be understood as meaning an arrangement of optical elements by which a real object is imaged into a real image or intermediate image. In other words, each subsystem comprises, starting from a specific object or intermediate image plane, always all optical elements to the next real image or intermediate image.

The first optical subsystem 110 includes an array of refractive lenses 111 - 117 , wherein on the light exit surface of the fifth lens 115 a diffractive optical element (DOE) 115a is arranged.

mit:

r

= x² + y²

k:

Beugungsordnung

λ₀:

Designwellenlänge

A diffractive optical element introduces a phase function, which according to equation (5) is described by a power series:

With:

r

= x ² + y ²

k:

diffraction order

λ ₀ :

Design wavelength

The associated design data of the DOE 115a are shown in Table 3 (in Tables 3, 6, 9 and 12, the diffraction order k is designated "HOR" and the design wavelength λ _{0 is} "HWL").

The first optical subsystem 110 forms the object plane "OP" in a first intermediate image IMI1 whose approximate location in 1 indicated by an arrow. This first intermediate image IMI1 is replaced by the second optical subsystem 120 imaged in a second intermediate image IMI2, whose approximate location in 1 also indicated by an arrow. The second optical subsystem 120 includes a first concave mirror 121 and a second concave mirror 122 which are in each case in such a way "cut off" in the direction perpendicular to the optical axis, that a light propagation respectively from the reflective surfaces of the concave mirror 121 . 122 The second intermediate image IMI2 is replaced by the third optical subsystem 130 imaged in the image plane IP. The third optical subsystem comprises an array of refractive lenses 131 - 142 ,

In the projection lens 100 According to the first embodiment, two pupil planes are generated outside the mirror arrangement of the second subsystem, in which the main beam intersects the (dashed) optical axis OA and their position in 1 is indicated by the dashed arrows denoted by PP1 and PP2. Between the concave mirrors 121 and 122 there is another, mechanically not usable pupil plane (not shown).

How out 1 can be seen, is the diffractive optical element 115a arranged in the first pupil plane PP1. The diffractive optical element 115a has a lattice constant of 1900 L / mm at the edge and a diameter of 88 mm. The diffractive power of the diffractive optical element 115a is about K ≈ 7.7 m ^-1 , which corresponds to a focal length f = 1 / K ≈ 130 mm. The comparison of the system with the off The system without DOE shows that the maximum diameter could be reduced by more than 15%. As a result of this diameter reduction, the color longitudinal error was reduced from 350 nm / pm to 210 nm / pm, ie by 40%.

According to 2 is a projection lens 200 according to a second embodiment of the present invention. The design data of this projection lens 200 are in to the projection lens 100 analogous representation in Table 4 listed. The surfaces specified in Table 5 are aspherically curved, the curvature of these surfaces being determined by the above aspherical formula (FIG. 4 ) given is.

According to 2 owns the projection lens 200 according to the second embodiment, a substantially to the projection lens 100 out 1 comparable structure and has a first optical subsystem in a catadioptric structure 210 , a second optical subsystem 220 and a third optical subsystem 230 on.

The first optical subsystem 210 includes an array of refractive lenses 211 - 217 , wherein on the light exit surface of the fifth lens 215 a first diffractive optical element 215a is arranged.

The first optical subsystem 210 forms the object plane "OP" in a first intermediate image IMI1 (indicated by an arrow). This first intermediate image IMI1 is replaced by the second optical subsystem 220 imaged in a second intermediate image IMI2 (also indicated by an arrow). The second optical subsystem 220 includes as in 1 a first concave mirror 221 and a second concave mirror 222 which are in each case in such a way "cut off" in the direction perpendicular to the optical axis, that a light propagation of each of the reflective surfaces of the concave mirror 221 . 222 The second intermediate image IMI2 is replaced by the third optical subsystem 230 imaged in the image plane IP.

The third optical subsystem comprises an array of refractive lenses 231 - 242 , wherein on the light exit surface of the eighth lens 238 of the third optical subsystem, a second diffractive optical element 238a is arranged.

The design data of the DOE's 215a and 238a are apparent from Table 6 in conjunction with equation (5) above.

In the projection lens 200 According to the second embodiment, as in the projection lens 100 two pupil planes outside the mirror arrangement of the second subsystem 220 generated, whose location in 2 is indicated by the dashed arrows denoted by PP1 and PP2. Between the concave mirrors 221 and 222 there is another, but not mechanically usable pupil plane (not shown).

How out 2 can be seen, is the diffractive optical element 215a arranged in the first pupil plane PP1, and the second diffractive optical element 238a is arranged in the second pupil plane PP2.

The first diffractive optical element 215a has a lattice constant of 1250 L / mm. The diffractive power of the diffractive optical element 215a is therefore about K ≈ 4.545 m ^-1 , which corresponds to a focal length f = 1 / K ≈ 220 mm. The second diffractive optical element 238a has a lattice constant of 1930 L / mm. The diffractive power of the second optical element 238a is therefore about K ≈ 3.03 m ^-1 , which corresponds to a focal length f = 1 / K ≈ 330 mm.

The analysis of the longitudinal chromatic aberration of 2 shown system that this could be reduced to 7 nm / pm, which corresponds to a nearly complete correction. The reduction of the diameter of the posterior pupil plane achieved by the use of a DOE in the anterior pupil plane facilitates the manufacturability of the DOE used for the complete correction of the longitudinal chromatic aberration. The DOE has a diameter of 228 mm. Thus, it can be produced on known laser writing systems. The state of the art for producing such DOE is a maximum diameter of 12 "or 305 mm.

According to 3 is a projection lens 300 according to a third embodiment of the present invention. The design data of this projection lens 300 are in to the projection lens 100 respectively. 200 analogous representation in Table 7 listed. The surfaces specified in Table 8 are aspherically curved, the curvature of these surfaces being given by the above aspherical formula (4).

The projection lens 300 According to the third embodiment, in a (apart from the DOE) purely refractive structure, a first optical subsystem 310 and a second optical subsystem 350 on. The first optical subsystem 310 maps the object plane "OP" into an intermediate image IMI whose approximate location is in 3 indicated by an arrow. This intermediate image IMI is replaced by the second optical subsystem 350 shown in the image plane "IP".

The first optical subsystem 310 includes an array of refractive lenses 311 - 324 , wherein on the light exit surface of the eighth lens 318 a diffractive optical element 318a is arranged. The design data of the DOE 318a are seen from Table 9 in conjunction with equation (5) above.

The second optical subsystem 350 includes an array of refractive lenses 351 - 363 without diffractive optical element.

In the projection lens 300 According to the third embodiment, a total of two pupil planes are generated whose position in 3 is indicated by the dashed arrows denoted by PP1 and PP2. How out 3 can be seen, is the diffractive optical element 318a in the vicinity of the first pupil plane PP1, but at a small distance therefrom.

The diffractive optical element 318a has a lattice constant of 1400 L / mm and a diameter of 115 mm. The diffractive power of the diffractive optical element 318a is about K ≈ 5 m ^-1 , which corresponds to a focal length f = 1 / K ≈ 200 mm.

Compared to a corresponding design without DOE, the maximum diameter of the lenses of the 3 also reduced by about 10%, whereby the chromatic aberration of the system is reduced by more than 30%. To completely correct the color aberration may be the design of the projection lens 300 be modified so that another DOE (analogous to the second embodiment according to 2 ) is provided in the second pupil plane PP2.

According to 4 is a projection lens 400 according to a fourth embodiment of the present invention.

The design data of this projection lens 400 are in to the projection lenses 100 - 300 analogous representation in Table 10 listed. The surfaces specified in Table 11 are aspherically curved, the curvature of these surfaces being given by the above aspherical formula (4).

The projection lens 400 has a first optical subsystem in a catadioptric design 410 , a second optical subsystem 430 and a third optical subsystem 450 on.

The first optical subsystem 410 includes an array of refractive lenses 411 - 421 and a first folding mirror 422 , wherein on the light entrance surface of the fifth (formed as a plane-parallel plate) lens 415 a diffractive optical element 415a is arranged. Of course, as with the previous embodiments, it does not depend on the arrangement of the DOE at the light entry or light exit surface, and the diffractive optical element 415a may alternatively also formed on the light exit surface of the plane-parallel plate lens 415 be educated.

The first optical subsystem 410 forms the object plane "OP" in a first intermediate image IMI1, which in the light propagation direction after the first folding mirror 422 arranged and whose approximate position is indicated by an arrow. This first intermediate image IMI1 is replaced by the second optical subsystem 430 shown in a second intermediate image IMI2 whose approximate position is also indicated by an arrow. The second optical subsystem 430 includes two diffusing meniscus lenses 431 . 432 and a concave mirror 433 , where the meniscus lenses 431 . 432 from to the concave mirror 433 leading or coming from him beam path are crossed twice.

The second intermediate image IMI2 is replaced by the third optical subsystem 450 which is a second folding mirror 451 and an array of refractive lenses 452 to 466 includes, imaged in the image plane IP, being between the image plane last lens 466 and the image plane IP is an immersion liquid (water in the embodiment).

The design data of the DOE 415a are seen from Table 12 in conjunction with the above equation (5), again in Table 12, the diffraction order k with "HOR" and the design wavelength λ ₀ with "HWL" is designated.

The diffractive optical element 415a has a lattice constant of 770 L / mm (corresponding to a minimum grating period of 1.3 μm) and a diameter of 90 mm. The diffractive power of the diffractive optical element 415a is about K ≈ 3.3 m ^-1 , which corresponds to a focal length f = 1 / K ≈ 303 mm. Compared to a corresponding design without DOE, the maximum diameter of the lenses of the 4 reduced system by about 7, wherein the chromatic aberration of the system is reduced by about 50% to 50 nm / pm.

In the projection lens 400 According to the fourth embodiment, a total of three pupil planes are generated, in which the main beam intersects the (dashed) optical axis OA and their position in 4 is indicated by the dashed arrows denoted by PP1, PP2 and PP3. How out 4 can be seen, is the diffractive optical element 415a arranged in the first pupil plane PP1.

All lenses of the projection lens 400 are made of quartz glass. Alternatively, individual lenses (eg the last lens on the image side) may be made of another suitable material (for example CaF ₂ ).

The projection lens 400 points in contrast to the projection lenses 100 and 200 out 1 and 2 only a mirror with refractive power in the form of the concave mirror 433 which is arranged substantially in the pupil plane PP3. This has the further advantage that this concave mirror 433 can be used with its optically effective surface rotationally symmetrical to the optical axis, which in turn has a relatively simpler production and adjustment result. In addition, can be with the help of this concave mirror 433 Also, for example, correct operational or aging aberrations, especially spherical aberrations, subsequently good.

According to a further, not shown embodiment, in a modification of the in 4 shown at least one other DOE be provided, in which case such a further DOE can be located in particular in the last image plane past pupil level PP2.

Table 13 shows an overview of system parameters of the projection objectives 100 - 400 from 1 - 4 , from each of the compactness of these systems can be seen.

The parameters given in the columns of Table 13 are in this order: Number of associated 1 - 4 or the associated embodiment, the image-side numerical aperture NA, the maximum image field height y ', the number of lenses N _L , the number of (interconnected by intermediate _images ) subsystems N _op , the maximum lens diameter D _max , the diameter D _maxF of the image plane ( IP) closest to the nose, as well as the COMP1-COMP3 and COMP12-COMP32 used to describe the compactness.

The parameters COMP1, COMP2 and COMP3 are defined as follows: COMP1 = D Max / (Y '· NA 2 ) (6) COMP2 = COMP1 * N L = D Max · N L / (Y '· NA 2 ) (7) COMP3 = COMP1 * N L / N operating room = D Max · N L / (N operating room · Y '· NA 2 ) (8th)

The parameter COMP1 is thus smaller (and the system is more "compact"), the smaller the maximum lens diameter of the lens at a certain maximum image field height y 'and a specific numerical aperture NA, so that as small as possible values of In addition, the parameter COMP2 takes into account the number of lenses N _L and thus the total material consumption and is also preferably as low as possible The parameter COMP3 also takes into account the number of subsystems N _op and is also preferably as small as possible, since the necessary space with the number of subsystems is growing.

For a system which is as compact as possible, at least one of the following conditions is preferably fulfilled: COMP1 <11 (9)

More preferably, COMP1 <10.8, more preferably COMP1 <10.5. COMP2 <250 (10)

More preferably, COMP2 <220, more preferably COMP2 <200. COMP3 <80 (11)

Further preferably COMP3 <75, more preferably COMP2 <70.

The other parameters COMP12, COMP22 and COMP32 given in Table 13 are defined as follows: COMP12 = D maxf / (Y '· NA 2 ) (12) COMP22 = COMP1 * N L = D maxf · N L / (Y '· NA 2 ) (13) COMP32 = COMP1 * N L / N operating room = D maxf · N L / (N operating room · Y '· NA 2 ) (14)

In this case, D _{maxF denotes} the diameter of the closest to the image plane IP abdomen of the lens (ie, for example, in 1 the diameter of the lens 138 ). By the formulation of the above-mentioned further criteria (12) - (14) is in the embodiments of 1 and 2 the diameter of the closest to the image plane IP abdomen of the respective lens 100 respectively. 200 used for the calculation of the respective compactness parameter, even if immediately after the mirror group of the second subsystem ( 120 in 1 ) still lenses 131 . 132 with a larger diameter than that of this abdomen. In the embodiments of 3 and 4 On the other hand, the values for COMP12, COMP22 and COMP32 are the same as the values for COMP1, COMP2 and COMP3, respectively. The parameter set COMP12, COMP22, COMP32 accordingly describes a relaxed compactness term in relation to the parameter set COMP1, COMP2, and COMP3 for a certain class of designs. For the compactness parameters COMP12, COMP22 and COMP32 as well, preferably at least one of the following conditions is fulfilled for a system which is as compact as possible: COMP12 <11 (15)

More preferably, COMP12 <10.8, more preferably COMP12 <10.5. COMP22 <250 (16)

More preferably, COMP22 <220, more preferably COMP22 <200. COMP32 <80 (17)

Further preferably COMP32 <75, more preferably COMP22 <70.

5 shows a schematic representation of the structure of a microlithographic projection exposure apparatus in which a projection lens according to the present invention can be used.

According to 5 has a projection exposure system 500 a lighting device 501 and a projection lens 502 on. The projection lens 502 includes a lens assembly 503 with an aperture diaphragm AP, wherein by the only schematically indicated lens arrangement 503 an optical axis OA is defined. Between the lighting device 501 and the projection lens 502 is a mask 504 arranged by means of a mask holder 505 is held in the beam path. Such masks used in microlithography 504 have a structure in the micrometer to nanometer range, by means of the projection lens 502 for example, by a factor of 4 or 5 reduced to an image plane IP is mapped. In the image plane IP is a through a substrate holder 507 positioned photosensitive substrate 506 , or a wafer held. The still resolvable minimum structures depend on the wavelength λ of the light used for the illumination and on the image-side numerical aperture of the projection objective 502 with the maximum achievable resolution of the projection exposure system 500 with decreasing wavelength λ of the illumination device 501 and with the image-side numerical aperture of the projection lens 502 increases.

If the invention has also been described with reference to specific embodiments, tap for the skilled person numerous variations and alternative embodiments, e.g. by combination and / or exchange of features of individual Embodiments. Accordingly, it is understood by those skilled in the art that such Variations and alternative embodiments are covered by the present invention, and the range the invention only in the sense of the appended claims and their equivalents limited is.

Claims (35)

Projection lens ( 100 . 200 . 300 . 400 ) of a microlithographic projection exposure apparatus for imaging a mask positionable in an object plane (OP) on a photosensitive layer positionable in an image plane (IP), comprising: • a first pupil plane (PP1) which is the pupil plane closest to the object plane (OP) of the projection objective ; • at least one second pupil plane (PP2), which is the pupil plane closest to the image plane (IP) of the projection objective; and at least one diffractive optical element ( 115a . 215a . 318a . 415a ), which is arranged substantially in the first pupil plane (PP1). Projection lens ( 100 . 200 . 300 . 400 ) of a microlithographic projection exposure apparatus, for imaging a mask positionable in an object plane (OP) on a photosensitive layer positionable in an image plane (IP), comprising: • an optical axis (OA); A first pupil plane (PP1), in which a marginal ray which delimits a bundle of rays originating from an object point on the optical axis (OA) has a first marginal ray height; and • at least one second pupil plane (PP2), in which a marginal ray which delimits a bundle of rays emanating from an object point on the optical axis (OA) has a second marginal ray height, the second marginal ray height being greater than the first marginal ray height; and at least one diffractive optical element ( 115a . 215a . 318a . 415a ), which is arranged substantially in the first pupil plane (PP1). Projection lens ( 100 . 200 . 300 . 400 ) of a microlithographic projection exposure apparatus for imaging a mask which can be positioned in an object plane (OP) on a photosensitive layer which can be positioned in an image plane (IP), comprising: an optical axis OA and at least one diffractive optical element 115a . 215a . 318a . 415a ) disposed along the optical axis (OA) in a plane in which an edge beam which delimits a beam of rays originating from an object point on the optical axis (OA) has a first edge beam height; • wherein the first edge beam height is less than 60% of the maximum edge beam height in the projection lens. Projection objective according to Claim 3, characterized that the first edge beam height less than 50%, preferably less than 40%, more preferably less as 30% of the maximum marginal beam height in the projection lens is. Projection objective according to claim 3 or 4, characterized in that it has a first pupil plane (PP1) which the closest to the object plane (OP) Pupil plane of the projection lens, and a second pupil plane (PP2), which is the closest to the image plane (IP) pupil level of the projection lens. Projection objective according to one of the preceding claims, characterized in that the diffractive optical element ( 115a . 215a . 318a . 415a ) has a positive focal length which is at most 300 mm, preferably at most 250 mm, more preferably at most 200 mm, and more preferably at most 150 mm. Projection objective according to one of the preceding claims, characterized in that the diffractive optical element ( 115a . 215a . 318a . 415a ) in the projection lens causes a partial correction of the longitudinal chromatic aberration, except for a residual longitudinal chromatic aberration, this residual chromatic aberration being at least 200 nm / pm. Projection objective according to one of the preceding claims, characterized in that the projection objective has a maximum lens diameter D _max , a maximum field height y ', a picture-side numerical aperture NA, a lens number N _L and a number of subsystems N _op , which are interconnected by intermediate images, wherein the projection lens has at least one diffractive optical element ( 115a . 215a . 238a . 415a ), and wherein for parameters COMP1, COMP2 and COMP3 with COMP1 = D Max / (Y '· NA 2 ) COMP2 = D Max · N L / (Y '· NA 2 ) and COMP3 = D Max · N L / (N operating room · Y '· NA 2 ) at least one of the following conditions is met: (a) COMP1 is less than 11; (b) COMP2 is less than 250; (c) COMP3 is less than 80. Projection objective according to Claim 8, characterized COMP1 is less than 11 and COMP2 is less than 250. Projection objective according to Claim 8, characterized COMP1 is less than 11, COMP2 is less than 250, and COMP3 is less than 80. Projection _objective according to one of the preceding claims, characterized in that the projection _{objective has} a diameter D _maxF of the _abdominal plane closest to the image plane (IP), a maximum image field _height y ', an image-side numerical aperture NA, a lens number N _L and a number of subsystems N _op , which are interconnected by intermediate images, the projection objective having at least one diffractive optical element ( 115a . 215a . 238a . 415a ), and wherein for parameters COMP12, COMP22 and COMP32 with COMP12 = D maxf / (Y '· NA 2 ) COMP22 = D maxf · N L / (Y '· NA 2 ) and COMP32 = D maxf · N L / (N operating room · Y '· NA 2 ) at least one of the following conditions is met: (a) COMP12 is less than 11; (b) COMP22 is less than 250; (c) COMP32 is less than 80. Projection objective according to Claim 11, characterized COMP12 is less than 11 and COMP22 is less than 250. Projection objective according to Claim 11, characterized COMP12 is less than 11, COMP22 is less than 250, and COMP32 is less than 80. Projection lens ( 100 . 200 . 300 . 400 ) of a microlithographic projection exposure apparatus, for imaging a mask which can be positioned in an object plane (OP) on a photosensitive layer which can be positioned in an image plane (IP), comprising: • at least one diffractive optical element ( 115a . 215a . 318a . 415a ) having a positive focal length; • this focal length is a maximum of 300 mm. Projection objective according to Claim 14, characterized that the focal length is a maximum of 250 mm, preferably a maximum of 200 mm, and more preferably not more than 150 mm. Projection lens ( 100 . 200 . 300 . 400 ) of a microlithographic projection exposure apparatus, for imaging a mask which can be positioned in an object plane (OP) on a photosensitive layer which can be positioned in an image plane (IP), comprising: • at least one diffractive optical element ( 115a . 215a . 318a . 415a ), which causes a partial correction of the longitudinal chromatic aberration in the projection lens except for a residual longitudinal chromatic aberration; • this residual chromatic aberration is at least 200 nm / pm. Projection objective of a microlithographic projection exposure apparatus for imaging a mask positionable in an object plane (OP) on a photosensitive layer positionable in an image plane (IP), the projection objective having a maximum lens diameter D _max , a maximum image field height y ', an image-side numerical aperture NA, a Lens number N _L and a number of subsystems N _op , which are interconnected by intermediate images, wherein the projection lens at least one diffractive optical element ( 115a . 215a . 238a . 415a ), and wherein for parameters COMP1, COMP2 and COMP3 with COMP1 = D Max / (Y '· NA 2 ) COMP2 = D Max · N L / (Y '· NA 2 ) and COMP3 = D Max · N L / (N operating room · Y '· NA 2 ) at least one of the following conditions is met: (a) COMP1 is less than 11; (b) COMP2 is less than 250; (c) COMP3 is less than 80. Projection objective according to Claim 17, characterized COMP1 is less than 11 and COMP2 is less than 250. Projection objective according to Claim 17, characterized COMP1 is less than 11, COMP2 is less than 250, and COMP3 is less than 80. Projection objective of a microlithographic projection exposure apparatus, for imaging a mask positionable in an object plane (OP) on a photosensitive layer positionable in an image plane (IP), the projection _{objective having} a diameter D _maxF of the _{abdominal wall closest} to the image plane (IP), a maximum image field _height y ', an image-side numerical aperture NA, a lens number N _L and a number of subsystems N _op , which are interconnected by intermediate images, wherein the projection objective comprises at least one diffractive optical element ( 115a . 215a . 238a . 415a ), and wherein for parameters COMP12, COMP22 and COMP32 with COMP12 = D maxf / (Y '· NA 2 ) COMP22 = D maxf · N L / (Y '· NA 2 ) and COMP32 = D maxf · N L / (N operating room · Y '· NA 2 ) at least one of the following conditions is met: (a) COMP12 is less than 11; (b) COMP22 is less than 250; (c) COMP32 is less than 80. Projection objective according to claim 20, characterized COMP12 is less than 11 and COMP22 is less than 250. Projection objective according to claim 20, characterized COMP12 is less than 11, COMP22 is less than 250, and COMP32 is less than 80. Projection lens according to one of the preceding Claims, characterized in that it is not more than two different ones Has lens materials. Projection objective according to one of claims 14 to 23, characterized in that it has a first pupil plane (PP1), which closest to the object plane (OP) pupil plane of the projection lens, and at least one second pupil plane (PP2), which is the closest to the image plane (IP) pupil level of the projection lens, wherein the diffractive optical Element arranged substantially in the first pupil plane (PP1) is. Projection lens according to one of the preceding Claims, characterized in that this has a catadioptric structure in which generates at least one real intermediate image becomes. Projection objective according to Claim 25, characterized that it only has a mirror with refractive power. Projection objective according to Claim 26, characterized that this mirror is arranged substantially in a pupil plane is. Projection objective according to one of claims 1 to 24, characterized in that it has no mirror. Projection objective according to one of the preceding claims, characterized in that it comprises at least one second diffractive optical element ( 238a ) having. Projection objective according to Claim 29, characterized in that the second diffractive optical element ( 238a ) is arranged substantially in the pupil plane (PP2) closest to the image plane (IP). Projection objective according to one of the preceding claims, characterized in that the first diffractive optical element ( 115a . 215a . 318a ) and / or the second diffractive optical element ( 238a ) has a diameter which is less than 0.5 times, preferably less than 0.4 times the maximum marginal beam height. Projection lens according to one of the preceding Claims, characterized in that it is for a wavelength of less than 250 nm, preferably less than 200 nm or less than 160 nm is designed. Microlithographic projection exposure apparatus ( 500 ) for the production of microstructured components, with a projection objective ( 100 . 200 . 300 . 400 ) according to any one of the preceding claims. Process for the microlithographic production of microstructured components comprising the following steps: 506 ), to which, at least in regions, a layer of a photosensitive material is applied; • Providing a mask ( 504 ) having structures to be imaged; Providing a projection exposure apparatus ( 500 ) with a projection lens ( 100 . 200 . 300 . 400 ) according to any one of claims 1 to 32; • projecting at least part of the mask ( 504 ) to a region of the layer using the projection exposure apparatus ( 500 ). Microstructured device that works by a method is made according to claim 34.