DE102011078231A1 - Light modulation device for use in lighting system for micro lithography projection exposure plant to manufacture e.g. semiconductor components, has prism surface whose angle is measured such that total beams are steered on another surface - Google Patents

Abstract

The device has a raster arrangement provided with multiple prisms (205) that are attached with actuators (204) in different operative positions. A transparent prism body (202) comprises three prism surfaces. The first prism surface includes a prism angle with the second prism surface. The third prism surface includes another prism angle with the first prism surface, where the latter prism angle is measured such that total reflected beams are steered on the third prism surface in a light failure direction. An independent claim is also included for a lighting system comprising a variable adjustable pupil molding unit for receiving light of a primary light source.

Description

BACKGROUND OF THE INVENTION

Field of the invention

The invention relates to a light modulation device for the spatially resolved influencing of an angular distribution of rays of a beam incident on the light modulation device and to an illumination system for a microlithography projection exposure apparatus which has at least one such light modulation device.

Description of the Prior Art

For the production of semiconductor components and other finely structured components, predominantly microlithographic projection exposure methods are used today. In this case, masks (reticles) are used, which carry the pattern of a structure to be imaged, z. B. a line pattern of a layer of a semiconductor device. A mask is positioned in a projection exposure apparatus between the illumination system and the projection objective in the area of the object surface of the projection objective and illuminated with illumination radiation provided at the front of the illumination system. The radiation changed by the mask and the pattern passes through the projection lens as projection radiation, which images the pattern of the mask onto the substrate to be exposed, which normally carries a radiation-sensitive layer (photoresist, photoresist).

In projection microlithography, the mask is illuminated by means of an illumination system that forms illuminating radiation directed onto the mask from the light of a primary light source, in particular a laser, which is defined by specific illumination parameters. The illumination radiation strikes the mask within an illumination field (area of defined shape and size, eg rectangular field or arcuately curved "ring field"), whereby the shape and size of the illumination field are generally constant, ie. H. are not variable.

As a rule, depending on the type of structures to be imaged, different illumination modes (so-called "illumination settings") are required, which can be characterized by different local intensity distributions of the illumination radiation in a pupil surface of the illumination system. In this context, one sometimes speaks of "structured illumination" or of a "structuring of the illumination pupil" or of a "structuring of the secondary light source". The pupil surface of the illumination system, in which certain definable two-dimensional intensity distributions (the secondary light sources) are to be present, is also referred to in this application as "pupil shaping surface", because essential properties of the illumination radiation are "shaped" with the aid of this intensity distribution.

The "pupil shaping surface" of the illumination system in which the desired two-dimensional intensity distribution (secondary light source) is to be located may be at or near a position optically conjugate to a pupil plane of a subsequent projection lens in a lighting system incorporated in a microlithography projection exposure apparatus. In general, the pupil shaping surface may correspond to or lie in the vicinity of a pupil surface of the illumination system. Unless the intermediate optical components change the beam angle distribution, i. H. Working angle preserving, the angular distribution of the incident on the pattern of the illumination light radiation is determined by the spatial intensity distribution in the pupil shaping surface of the illumination system. In addition, if the intermediate optical components operate to maintain the angle, the spatial intensity distribution in the pupil of the projection objective is determined by the spatial intensity distribution (spatial distribution) in the pupil shaping surface of the illumination system.

Those optical components and assemblies of the lighting system intended to receive light from a primary light source, e.g. As a laser or a mercury vapor lamp, and to produce a desired two-dimensional intensity distribution (secondary light source) in the "pupil shaping surface" of the illumination system, together form a pupil forming unit, which should be adjustable as a rule.

From the patent US 7,714,983 B2 The applicant is aware of illumination systems in which a pupil-shaping unit for receiving light from a primary light source and for generating a variably adjustable two-dimensional intensity distribution in a pupil-shaping surface of the illumination system comprises a multi-mirror-array (MMA) reflective light modulation device having a plurality includes individually controllable, multiaxial tiltable individual mirrors, with the aid of which the angular distribution of the radiation falling on the mirror elements can be targeted specifically changed so that the desired illumination intensity distribution results in the Pupillenformungsfläche.

From the patent US 7,359,103 B2 is a working with local resolution Light modulation device of the transmission type known. The light modulation device has a plurality of transparent prisms for deflecting light in a direction of departure that differs from the direction of incidence on the prisms. The prisms are held by a support structure in a free-floating position (midair position) such that the prism surfaces serving as a light exit surface can be tilted about a tilt axis with respect to a plane perpendicular to the light incident direction. Due to the tilting of the prisms, a variable deflection of the rays passing through the prism is possible. Prisms can be tilted so much that at the prism surface normally serving as a light exit surface total reflection occurs, so that the corresponding rays are coupled out and no longer emerge at the light exit side.

Reflective light modulation devices with a raster array of micromirrors allow great variability in the adjustment of the local illumination intensity distribution in the pupil shaping surface. In addition to conventional illumination settings with different degrees of coherence and off-axis illumination settings, such as dipole illumination, quadrupole illumination or annular illumination (with an annular intensity distribution in the pupil shaping surface), other symmetrical or asymmetrical spatial distributions of the illumination intensity can also be realized. However, the reflectivity at the mirror surfaces can result in a relatively high intensity loss, which may be on the order of a few percent, for example up to 5%, for currently available, highly reflective, deep ultraviolet (HR) reflective coatings. In addition, in multilayer reflective coatings with high illumination intensity, layer stresses can occur, which can also lead to surface deformations in the case of thin mirror substrates, which in turn can influence the angular distribution of the radiation reflected by a mirror in a manner which is difficult to control. Finally, in conventional reflective light modulation devices, there are also special space requirements, since a convolution of the beam path between the beam bundle incident on a mirror arrangement and the outgoing beam bundle modified by the mirror arrangement with regard to its angular distribution is necessary. Due to the optical layer property of reflection coatings, it is generally favorable if the mirror surfaces are struck at the smallest possible angles of incidence in order to achieve high reflectivities. This in turn usually means that both in front of and behind a multi-mirror arrangement, a relatively large area in which the incident and the reflected beam path overlap, should be kept free of optical elements.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a light modulation device which has substantial advantages of conventional reflective light modulation devices, but largely avoids their disadvantages. In particular, a light modulation device is to be provided in which the light losses are greatly reduced in comparison to conventional reflective light modulation devices. Furthermore, the light modulation devices should preferably be able to be integrated into an optical system with a small space requirement, in particular into an illumination system for a microlithography projection exposure apparatus. It is a further object of the invention to provide a lighting system for a microlithography projection exposure apparatus that allows for variable adjustment of different lighting settings and is characterized by lower light loss compared to conventional lighting systems.

To achieve these and other objects, the invention provides a light modulation device having the features of claim 1 and an illumination system for a microlithography projection exposure device having the features of claim 10.

Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.

According to one aspect of the invention, the light modulation device has a grid arrangement with a multiplicity of individually tiltably mounted prisms, which can be tilted individually by means of associated actuators into different working positions. The term "grid arrangement" here refers to a normally regular one- or two-dimensionally extended spatial arrangement of prisms, which are preferably designed identically. The grid arrangement is also referred to in this application as a "prism array". Each beam incident in an optically usable region of a prism leaves the prism in a direction of light emission determined by the working position of the prism and its geometry. This can be changed with respect to the light incidence direction by tilting the prism, so that each prism allows a variable beam deflection or beam deflection. Since the prisms of the grid arrangement can be individually tilted independently of one another, both direction and extent of the beam deflection are for different partial beam bundles of the incident beam different adjustable. This makes it possible to influence the angular distribution of the rays of an incident beam by means of the light modulation device with spatial resolution, ie in locally different ways, so that the angular distribution of the beams in an outgoing beam influenced by the light modulation device of the angular distribution of the incident beam different.

Each prism has a prism body, which consists of a material which is transparent in the wavelength range intended for use, ie has the lowest possible absorption. A prism body has at least three planar interfaces, namely a first prism surface, a second prism surface and a third prism surface. The relative location and orientation of the prism surfaces determines the distracting effect that the prism body has on the incident rays. The first prism surface serves as a light entry surface for receiving beams of the incident beam, the beams incident on the first prism surface from a light incident direction at a first angle of incidence. The term "angle of incidence" in this application generally refers to that angle which a light beam incident on an optical surface at the point of impact includes with the surface normal (incidence slot) of the optical surface at the point of impact. The second prism surface includes a first prism angle with the first prism surface, which is dimensioned so that rays that are directed from the first prism surface directly, ie without detour, to the second prism surface, at each working position of the prism at a second angle of incidence on the second Prism surface that is greater than a critical angle for total reflection at the second prism surface. In each working position of the prism thus those rays which are deflected at the first prism surface in the direction of the second prism surface are totally reflected at the second prism surface. Total reflection can be known under certain conditions at an interface between a more dense optical medium with refractive index n ₁ and an optically thinner medium with refractive index n ₂ <n ₁ occur. With a sufficiently steep incidence (relatively small angle of incidence), a light beam is refracted at the interface and enters the optically thinner medium through the interface. If the angle of incidence is increased, the refracted beam is parallel to the interface at a certain angle of incidence. This angle of incidence is referred to as the critical angle of total reflection or as a critical angle. If the angle of incidence exceeds the critical angle of total reflection, the light beam is completely reflected at the interface and thrown back into the (optically denser) output medium. With total reflection, there is virtually no loss of intensity. This effect is used on the second prism surface. The third prism surface includes, with the second prism surface, a second prism angle that is dimensioned so that totally reflected rays from the second prism surface are incident on the third prism surface at a third angle of incidence and are directed by the third prism surface in a light out direction. The deflection angle caused by the prism, ie the angle between the direction of light incidence and the direction of light emission of a beam, can preferably be adjusted steplessly by the extent and direction of the tilting of the prism.

By using the total reflection at the second prism surface intensity losses in the beam deflection can be significantly reduced compared to conventional, working with coated mirror elements multi-mirror arrays. Since virtually no loss of intensity occurs in total reflection, the intensity losses which a deflected light beam suffers at a prism are limited to possible losses which occur at the first prism surface and the third prism surface at the refraction and any losses due to absorption in the prism material. These losses can, however, by appropriate choice of materials and other technical measures, such. B. by anti-reflection coating (anti-reflection coating), kept low.

The second prism surface may carry an optical coating. However, total reflection can also occur at an uncoated interface. Preferably, the second prism surface carries no coating, which simplifies the manufacture of the prisms.

In order to minimize intensity losses in the refraction at the first prism surface, in some embodiments it is provided that the first prism angle is dimensioned such that the first angle of incidence at each working position of the prism is less than 15 °, in particular 10 ° or less, or deviates by 5 ° or less from a Brewster angle at the first prism face. The first prism angle, for example, be dimensioned so that the first angle of incidence deviates less than 3 ° or less than 1 ° from the corresponding Brewster angle at an untilted initial position of the prism. The Brewster angle, sometimes referred to as the angle of polarization, indicates the angle at which an incident, unpolarized light beam reflects only that component of the light (s polarization) polarized perpendicular to the plane of incidence while being polarized parallel to the plane of incidence Component (p-polarization) passes virtually lossless through the prism surface. The plane of incidence is that plane which is defined by the direction of incidence of the light beam and the surface normal of the optical surface at the point of impact is spanned. If, therefore, the first angle of incidence is close to or at the Brewster angle, the refraction at the first prism area for the p-polarized component of the incident light beam takes place largely without loss.

Alternatively or additionally, the second prism angle may be dimensioned such that the third angle of incidence deviates at each working position of the prism by less than 15 ° or less than 10 ° or by 5 ° or less from a Brewster angle valid at the third prism surface. The second prism angle can be dimensioned, for example, such that the third angle of incidence deviates less than 3 ° or less than 1 ° from the corresponding Brewster angle in the case of an untilted basic position of the prism. In this case, the refraction at the third prism surface for p-polarized light components also takes place virtually loss-free, as a result of which the intensity losses during the deflection can be kept low overall.

Since the loss of intensity for the p-polarized component of the light practically disappears in the region of the Brewster angle, a reflection-reducing coating of the prism surfaces is not required in these cases, so that the first prism surface and / or the third prism surface can remain uncoated. The elimination of a coating, the production of prisms is much easier and cheaper, since corresponding coating steps can be omitted. In addition, this improves the long-term stability of the optical properties of the prisms, since even under strong irradiation no changes in the optical properties caused by layer degradation occur.

Furthermore, since the totally reflecting second prism surface also does not have to be coated, the overall result is an arrangement which is favorable in terms of production and a structure which is stable over a long time with regard to the optical properties.

However, it is also possible that the first prism surface serving as the light entry surface and / or the third prism surface serving as the light exit surface are covered with a reflection-reducing antireflection coating. This can be particularly favorable when the incidence angles occurring at these surfaces deviate greatly from the associated Brewster angle and, for example, amount to less than 30 ° or less than 20 °. An anti-reflection coating can significantly reduce the reflection losses compared to an uncoated prism surface.

Each of the prisms is preferably tiltable about a plurality of tilting axes which are at an angle to one another, for example about two tilt axes which are perpendicular to one another. As a result, a high variability in the design of the exit angle distribution is possible.

The tilt angles are relatively small in preferred embodiments, and preferably a maximum tilt angle for each prism is less than 5 °, in particular 3 ° or less. Accordingly, the maximum achievable deflection angle may also be relatively small and z. B. 10 ° or less. The prisms can be supported by means of springs, which force the prisms into the basic position in the absence of deflecting forces. If only small maximum tilt angles are required, relatively strong metallic springs can be used, through which the heat generated in the prisms during irradiation can be transported away better.

A reflective light modulation device constructed with prisms allows different arrangements of the prisms relative to each other. In some embodiments, the prisms form a planar grid arrangement in which, in a non-tilted basic position of the prisms, all second prism areas lie in a common plane. The totally reflective second prism faces may be arranged similarly in this arrangement as the reflective surfaces of conventional planar micromirror arrays. The region of the second prism faces is accessible in this arrangement for the coupling of the associated actuators. These may, for example, engage the edge of the second prism surface outside the optically used region of the second prism surface.

Level raster arrangements of this type require, similar to conventional multiple mirror arrangements, a folded beam path. However, unlike conventional microplay arrangements, relatively large folding angles of, for example, between 70 ° and 110 °, in particular between 80 ° and 100 °, are essentially possible without sacrificing performance. The term "folding angle" here refers to the angle between the direction of light before the deflection at the prisms and the direction of light after the deflection. If the optical system comprising the raster arrangement has rotationally symmetrical optical elements, for example lenses or the like, which define an optical axis in the light direction in front of the raster arrangement and in the light direction after the raster arrangement, the term "folding angle" can also refer to the angle which is defined by the parts of the optical axis before the grid assembly and behind the grid assembly is included. In this sense, for example, generates a plane mirror, which is inclined by 45 ° relative to the inlet-side part of the optical axis, a Folding angle of 90 °. Folding angles of 90 ° can be advantageous insofar as only relatively small areas in front of and behind the grid arrangement must be kept free of optical elements. As a result, more compact designs are possible.

It is also possible to arrange the prisms of a grid arrangement in such a way that the grid arrangement as a whole works in the sense of a beam deflection "in the passage", thus eliminating a folding of the beam path. In the case of beam deflection "in the passage", the angle between the mean direction of light incidence and the mean light emergence direction is close to 0 ° or exactly 0 ° and is generally less than 20 ° or less than 10 °. In some embodiments, this arrangement possibility is achieved in that the prisms of the grid arrangement are arranged such that in a non-tilted basic position of the prisms all second prism surfaces are aligned parallel to each other and the prisms are arranged offset in a first direction perpendicular to the second prism faces. The first prism edges formed between the first prism faces and the second prism faces may lie in a common plane which extends obliquely, in particular perpendicular to the second prism faces. As a result, stacked grid arrangements are possible. For example, a grid array may have columns and rows of prisms, wherein a column of prisms includes a plurality of prisms offset from each other in a first direction perpendicular to the second prism face. The rows of prisms can be perpendicular to it. The plane in which the first prism edges lie can lie perpendicular to the mean direction of incidence of the incident beam, so that a grid arrangement that is short in the direction of transmission can be realized. This may optionally replace conventional transmission light modulating devices

As a rule, it is neither necessary nor desired to use the entire volume of the prisms enclosed by the prism surfaces as the optical volume for the radiation steering. For example, optically unused area should be provided on the prism bodies in order to mount elements of the mounting technology, ie holding elements of a holder device and / or elements of the associated actuators. For this reason, among others, it is provided in some embodiments that a raster arrangement of optical elements for concentrating radiation impinging on the optical elements is arranged on the entry side of the raster arrangement on the first prism surfaces of the respective associated prisms. The raster arrangement can be formed, for example, by a field of microlenses (microlens array), in which each microlens illuminated on the inlet side focuses the part of the incident beam incident on the microlens onto the first prism surface of a prism associated with it so that the optically used surface of the first Prism area is smaller than the first prism surface itself. For example, a small distance can remain on all sides between the optically used region of the first prism surface and the edges of the first prism surface.

The invention also relates to a lighting system suitable for a microlithography projection exposure apparatus for receiving light from a primary light source and for illuminating a lighting field with the light from the primary light source, the lighting system comprising at least one light modulation device of the type described in this application.

The illumination system preferably has a variably adjustable pupil-shaping unit for receiving light from the primary light source and for generating a variably adjustable two-dimensional intensity distribution in a pupil-shaping surface of the illumination system, the light-modulating means being disposed between the light source and the pupil-shaping surface.

A light modulation device with a prism array, that is to say a raster arrangement with a multiplicity of prisms, can under certain conditions be used wherever mirror arrays, ie raster arrays of mirrors, are used in conventional systems. However, the use of a prism array requires that for the intended useful wavelength (working wavelength) there is a sufficiently transparent optical material with a sufficiently large refractive index, which should be, for example, greater than 1.3 or greater than 1.4. Working wavelengths can z. B. in the range of visible light (VIS), but also in the range of ultraviolet light (UV) or deep ultraviolet (DUV). Accordingly, the light modulation devices of the type described here can be used not only in illumination systems for microlithographic applications, but also, for example, in beamers or in the field of telecommunications as "optical cross connect" for interconnecting fiber ends.

The foregoing and other features will become apparent from the claims and from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in embodiments of the invention and in other fields be realized and advantageous and protectable Can represent versions.

BRIEF DESCRIPTION OF THE DRAWINGS

1 shows a schematic overview of a microlithography projection exposure apparatus with a pupil-forming unit;

2 Figure 12 is a schematic view of some components of a pupil-shaping unit including an embodiment of a reflective light modulator having a two-dimensional grid array of tiltable prisms used in the passage;

3 3A and 3B are schematic representations of beam paths of a light beam through a prism of a raster array, in Fig. 3B the prism is shown in a non-tilted home position and in Fig. 3A the influence of a tilt on the exit direction of the deflected beam;

4 shows an oblique perspective view of a representative beam path through a prism;

5 schematically shows a raster arrangement of micro-lenses arranged upstream of the raster arrangement of prisms for the concentration of partial beam bundles on the light entry surfaces of prisms;

6 shows schematically a diagonal perspective view of a prism together with the representation of an optically used volume of the prism;

7 shows a schematic section of some components of a pupil shaping unit of another embodiment, in which an embodiment of a reflective light modulating device is used for the folding of the beam path;

8th shows a schematic representation of another embodiment of a usable in the passage light modulation device.

In 1 is an example of a microlithography projection exposure apparatus 100 which can be used in the manufacture of semiconductor devices and other finely-structured components and works to achieve resolutions down to fractions of a micron with light or electromagnetic ultraviolet radiation (DUV). As a primary light source 102 serves an ArF excimer laser with a working wavelength of about 193 nm, the linearly polarized laser beam coaxial with the optical axis 103 of the lighting system 190 is coupled into the lighting system. Other UV light sources, for example, F ₂ laser with 157 nm working wavelength, ArF excimer laser with 248 nm operating wavelength or mercury vapor lamps, z. B. with 365 nm or 436 nm operating wavelength, as well as primary light sources with wavelengths below 157 nm are also possible.

The polarized light of the light source 102 first enters a beam expander 104 a, for example, as a mirror arrangement according to the US 5,343,489 may be formed and used to reduce the coherence and increase the beam cross section.

The expanded laser beam has a cross-sectional area with an area, for example, in the range between 100 mm ² and 1,000 mm ² and a certain cross-sectional shape, for example, a square cross-sectional shape. The divergence of the expanded laser beam is usually smaller than the very small divergence of the laser beam before beam expansion. The divergence can z. B. between about 1 mrad and about 3 mrad lie.

The expanded laser beam enters a pupil-forming unit 150 including a plurality of optical components and groups and configured to be in a subsequent pupil shaping surface 110 of the lighting system 190 to generate a defined, local (two-dimensional) illumination intensity distribution, sometimes referred to as a secondary light source or as an "illumination pupil". The pupil shaping surface 110 is a pupil surface of the illumination system.

The pupil shaping unit 150 is variably adjustable, so that depending on the control of the pupil shaping unit different local illumination intensity distributions (ie differently structured secondary light sources) can be adjusted. In 1 For example, various illuminations of the circular illumination pupil are schematically shown by way of example. The illumination settings include, for example, the conventional illumination settings CON round illumination spots of different diameters centered around the optical axis of the illumination system (usually defined by the degree of coherence σ of the illumination) and in non-conventional, ie off-axis illumination modes the ring illumination (or annular illumination) and polar intensity distributions, for example dipole illumination DIP or quadrupole illumination QUAD. The non-conventional illumination settings for producing off-axis (oblique) illumination can serve, inter alia, to increase the depth of field by two-beam interference and to increase the resolution.

In the immediate vicinity of the pupil shaping surface 110 is an optical raster element 109 arranged. A coupling optics arranged behind it 125 transfers the light to an intermediate field level 121 in which a reticle / masking system (REMA) 122 is arranged, which serves as an adjustable field stop.

The optical raster element 109 has a two-dimensional array of diffractive or refractive optical elements and has several functions. On the one hand, the incoming radiation is shaped by the raster element so that, after passing through the subsequent coupling optics 125 in the area of the field level 121 a rectangular illumination field illuminates. The grid element, also known as field-defining element (FDE) 109 with rectangular radiation characteristic generates the majority of the light conductance and adapts it to the desired field size and field shape in the mask plane 165 optically conjugate field level 121 , The grid element 109 can be designed as a prism array, in which arranged in a two-dimensional field prisms locally introduce certain angles to the field level 121 to illuminate as desired. The through the coupling optics 125 The generated Fourier transform causes each specific angle at the exit of the raster element to a location in the field plane 121 corresponds, while the location of the grid element, ie its position with respect to the optical axis 103 , the illumination angle in the field level 121 certainly. The outgoing of the individual raster elements beam bundles are superimposed in the field level 121 , It is also possible to design the field-defining element in the manner of a multi-stage honeycomb condenser with microcylinder lenses and lenses. By suitable design of the grid element 109 or its individual elements can be achieved that the rectangle field at the field level 121 is illuminated substantially homogeneously. The grid element 109 thus serves as Feldformungs- and homogenizing element and the homogenization of the field illumination, so that can be dispensed with a separate light mixing element, for example, acting on multiple internal reflection integrator rod or a honeycomb condenser. As a result, the optical structure in this area is particularly compact axially.

The following imaging lens 140 (also called REMA lens) forms the intermediate field plane 121 with the field stop 122 on the reticle 160 (Mask, lithographic master) from a scale, the z. B. between 2: 1 and 1: 5 and in the embodiment is about 1: 1. The image is taken without an intermediate image, so that between the intermediate field level 121 representing the object plane of the imaging lens 140 corresponds, and the image plane optically conjugate to this object plane 165 of the imaging lens, the exit plane of the illumination system and at the same time the object plane of a subsequent projection objective 170 corresponds to exactly one pupil surface 145 which is a Fourier transformed surface to the exit plane 165 of the lighting system. In other embodiments, at least one intermediate image is generated in the imaging lens. One between this pupil surface 145 and the image surface arranged at 45 ° to the optical axis 103 inclined plane deflection mirror 146 makes it possible to install the relatively large lighting system (several meters in length) horizontally and the reticle 160 store horizontally. Between the intermediate field level 121 and the picture plane 165 of the imaging objective, radiation-influencing elements can be arranged, for example polarization-influencing elements for setting a defined polarization state of the illumination radiation.

Those optical components that the light of the laser 102 receive and form from the light illuminating radiation that is on the reticle 160 directed, belong to the lighting system 190 the projection exposure system.

In the direction of light behind the lighting system is a device 171 for holding and manipulating the reticle 160 arranged so that the pattern arranged on the reticle in the object plane 165 of the projection lens 170 is located and in this plane for scanner operation in a scan direction (y-direction) perpendicular to the optical axis 103 (Z direction) is movable by means of a scan drive.

Behind the reticle plane 165 follows the projection lens 170 , which acts as a reduction lens and an image of the mask 160 arranged pattern on a reduced scale, for example, on a scale of 1: 4 or 1: 5, on a wafer coated with a photoresist layer or photoresist layer 180 whose photosensitive surface is in the image plane 175 of the projection lens 170 lies. Refractive, catadioptric or catoptric projection lenses are possible. Other reduction measures, for example, greater reductions to 1:20 or 1: 200, are possible.

The substrate to be exposed, which in the example is a semiconductor wafer 180 is through a facility 181 held, which includes a scanner drive to synchronize the wafer with the reticle 160 to move perpendicular to the optical axis. Depending on the design of the projection lens 170 (eg refractive, catadioptric or catoptric, without intermediate image or with intermediate image, folded or unfolded) these movements can take place parallel to one another or counterparallel. The device 181 which is also referred to as Waferstage, as well as the facility 171 , which is also referred to as "reticle days", are an integral part a scanner device controlled by a scan controller.

The pupil shaping surface 110 is at or near a position that is optically conjugate to the next succeeding pupil surface 145 as well as the image-side pupil surface 172 of the projection lens 170 is. Thus, the spatial (local) light distribution in the pupil 172 of the projection lens by the spatial light distribution (spatial distribution) in the pupil shaping surface 110 of the lighting system. Between the pupil surfaces 110 . 145 . 172 In each case there are field surfaces in the optical beam path which are Fourier-transformed surfaces to the respective pupil surfaces. This means in particular that a defined spatial distribution of illumination intensity in the pupil shaping surface 110 a certain angular distribution of the illumination radiation in the area of the subsequent field surface 121 which in turn gives a certain angular distribution to the reticle 160 falling illumination radiation corresponds.

In 2 Fig. 2 schematically show some components of an embodiment of a pupil shaping unit 150 shown. The entering, expanded laser beam 105 meets a honeycomb condenser (fly eyes lens) 152 which decomposes the incoming radiation beam into sub-illumination beams which are subsequently transmitted through a Fourier optical system 154 on a lens array 155 ie transferred to a two-dimensional grid arrangement of lens systems. Examples of suitable Fourier optical systems are in WO 2009/135586 A1 , the disclosure of which is incorporated herein by reference. The lens array 155 concentrates the part-illumination beam 156 on individually controllable prisms of a reflective light modulation device 200 which related to 2 to 6 will be explained in more detail.

In some embodiments, a polarization adjustment device is provided in the light path in front of the light modulation device, which makes it possible to set the polarization state of the light incident on the prism array in a targeted manner. For example, such a switchable polarization setter may be configured to selectively switch between s polarizations, p polarizations (with respect to the plane of incidence on the first prism faces) and unpolarized radiation. For example, the light can be completely linearly polarized in front of the illumination system with the aid of a Brewster mirror. By using birefringent optical elements, the orientation of the linear polarization can be switched or changed or specifically adjusted.

The reflective light modulation device used in the passage serves to controllably change the angular distribution of the input side 201 On the light modulation device incident beam and ensures by the orientation of their individual prisms for a definable by means of the light modulation means angular distribution at the outlet side 202 , The exit angle distribution determines that in the pupil forming surface 110 present local intensity distribution.

The reflective light modulation device 200 has a second dimensional grid array of individually tiltably mounted prisms 205 , of which 2 shows only six in a vertical column superimposed prisms. The prisms are attached to a common support structure, not shown for reasons of clarity. Each of the prisms is by means of an associated, electrically controllable actuator 204 individually, ie independently of the other prisms of the grid arrangement, multidimensional tiltable in different working positions. The actuators are connected to a common control device (not shown). In the example, two mutually perpendicular tilt axes are provided (see. 4 ). Tilting around each of the tilting axes is infinitely possible, maximum tilt angles in both tilting directions are approx. 5 °.

Due to the tilting, a defined beam deflection can be effected for each of the partial beam bundles impinging on the prisms, so that locally different beam deflections can be set via the usable cross section of the grid arrangement. As a result, a spatially resolved or spatially resolved influencing of the angular distribution of rays of the incident from the inlet side of the light modulation device beam is possible to produce a precipitating on the exit side beam whose angular distribution can be specified by the position or orientation of the individual prisms. The outgoing from the prisms at the exit side part-beam 157 pass through a downstream lens 158 through and are by means of a subsequent condenser optics 159 into the pupil shaping surface 110 displayed. The diffuser 158 can also be omitted. It is also possible to use the diffuser between the condenser optics 159 and in the pupil forming surface 110 arranged grid element 109 (FDE) near it. The with the help of the light modulation device 200 generated angular distribution of the exiting partial beam 157 leads to a defined spatial intensity distribution of the illumination radiation in the pupil surface 110 , ie to a structured illumination pupil.

The light modulation device should work as low as possible, so that the highest possible proportion of the radiation energy provided by the light source can be used for the projection exposure process. The geometric configuration is therefore designed so that, in all working positions of the prisms, all the rays entering at the entrance side reach the optically used region of the pupil surface, ie no radiation is masked out. The unavoidable intensity losses in the area of the light modulation device should be as small as possible. Among other things, the following special features contribute to achieving this goal.

The structure of the prisms and their function as variably adjustable Strahlumlenkelemente are based on 3 explained in more detail. 3A shows with solid lines a prism 205 in its untilted basic position. In the example, the basic position is automatically taken in the absence of control signals to the actuators. This can be achieved, for example, with the aid of suitable spring elements which act on the prisms or on their carriers and force the prisms in the absence of external forces in the normal position. In other embodiments, provision may be made for the prisms to be maximally tilted in the absence of stray signals, so that the basic position is only assumed when the actuators are activated accordingly.

With dashed lines is the prism 205 shown in a tilted by a few degrees from the basic position. The left-to-right arrow symbolizes a partial beam on the left side 156 which is incident on the prism from a light entrance side in a light entrance direction and on the right side the same sub beam after exiting the prism, the beam propagating after exit in a light out direction. 3B shows the same untilted prism 205 for better illustration of the beam path through the prism.

The prism has a transparent prism body 202 For example, it may consist of fused silica or calcium fluoride (CaF ₂ ) or another material which is as transparent as possible of ultraviolet radiation (absorption-free) for applications in the deep ultraviolet range. The refractive index n _{1 of} the prism material at the operating wavelength can z. B. at about n ₁ ≈ 1.5 lie. The prism body has an isosceles triangle as base and is limited by three effective prism surfaces effective for the optical function. A first prism surface 210 serves as a light entry surface. The second prism surface 220 closes with the first prism surface 210 in the region of the first prism edge formed by the prism surfaces 212 a first prism angle 215 one. The second prism surface acts in operation as a totally reflective mirror surface. The serving as a light exit surface third prism surface 230 closes with the second prism surface 220 in the area of the second prism edge 222 a second prism angle 225 one. The third prism surface closes with the first prism surface in the region of a third prism edge 232 a third prism angle 235 one. The first and second prism angles are each about 33.6 °, so that the third prism angle is about 112.8 °. The prism edges formed at the intersections of the prism surfaces each extend parallel to an x-direction of the system-internal coordinate system. The perpendicular y-direction is oriented so that the second prism surface 220 is oriented parallel to the xy plane in the case of untilted prisms. The z-direction is perpendicular to this.

The prism can be tilted multiaxially with the aid of the associated actuators, namely around a first tilting axis running parallel to the x-direction 241 and a second tilting axis extending parallel to the y-direction 242 (see. 4 ). The other prisms of the grid arrangement are constructed identically and can be tilted in the same way.

The first prism surface 210 serves as a light entry surface. A beam incident from a light incidence direction (arrow direction) closes with the light entrance surface a first angle of incidence 211 formed by the angle between the incident light beam (arrow) and the surface normal to the first prism surface (shown in phantom) at the point of impact. Upon entry of the light from the optically thinner ambient medium (for example, air or vacuum) into the optically denser prism material, the beam is refracted in the direction of the entrance slit (surface normal) such that it is at a second angle of incidence 221 meets the second prism surface. The first prism angle 215 is dimensioned such that the refracted rays reaching directly from the point of incidence on the first prism surface to the second prism surface are totally reflected at each working position of the prism at the second prism surface. The second angle of incidence 221 is therefore greater than the critical angle for total reflection for the second prism surface for the entire radiation which is refracted in the direction of the second prism surface at the first prism surface. In the example of a prismatic body made of a material with refractive power n ₁ ≈ 1.5 in air or another gas with refractive index n ₂ ≈ 1.0, the critical angle Θ _C for the total reflection according to Θ _C = arcsin (n ₂ / n ₁ ) is approximately 41.8 ° , The second angle of incidence 221 is on the other hand at about 67.3 °, so that the conditions for total reflection are satisfied and the radiation does not leave the prism at the second prism surface, but from the second prism surface practically without loss of intensity in the direction of the third prism surface is totally reflected. The totally reflected radiation then hits at a third angle of incidence 231 on the third prism surface is broken away at this at the transition from the optically dense to the optically thinner medium by Einfallslot (dashed line) and leaves the third prism surface serving as light exit surface and thus the prism in a light exit direction. This runs in the example of 3B , ie with a non-tilted prism, parallel to the light incident direction and in extension to this.

In 3A is shown in dashed lines, such as a beam by tilting the prism by a tilt angle 240 around the first tilting axis (parallel to the x-direction) around a deflection angle 250 can be distracted. This reduces the first angle of incidence in the example case 211 as the second and third angles of incidence increase. The second angle of incidence still remains clearly above the critical angle for the total reflection, so that furthermore the beam refracted at the first prism surface is totally reflected lossless on the second prism surface in the direction of the third prism surface and then leaves the prism surface in a light exit direction which is around a deflection angle 250 differs from the direction of light emission with untilted prism. The deflection angle 250 is twice as large as the corresponding tilt angle with a tilted prism, just like a tilted mirror.

Due to the total reflections on the second prism surface, it is a reflective light modulation device. Interestingly, however, in the example, the light entrance direction and the light exit direction are substantially parallel to each other or soften, depending on the tilt position of the prisms, only a few degrees, for example less than 20 ° or less 10 ° from each other, similar to transmission type light modulation devices. The reflective light modulation device can thus in certain cases be used in optical systems where previously transmission-type light modulation devices were used.

A major advantage of the novel light modulation device is that the light loss, i. H. the loss of intensity between light entrance side and light exit side, can be very low. In total reflection at the second prism surface occurs virtually no loss of intensity. Reflective losses may occur at the first and third prism faces, but may be greatly reduced by using anti-reflective coatings if necessary. Possible absorption losses in the material of the prism body can be reduced to almost zero by a suitable choice of material.

At the in 3 The prisms shown by way of example utilize yet another effect for largely suppressing transmission losses. The first prism angle 215 and the second prism angle 225 are chosen in the example so that with unverkippten prisms (prism in basic position) of the first angle of incidence 211 and the third angle of incidence 231 each equal to the valid for the respective interface Brewster angle. Thus, in the case of uncoated prism faces, the light loss for the p-polarized component of the radiation is virtually zero. In this case, therefore, not only the internal reflection at the second prism surface, but also the passage of light through the first prism surface and the third prism surface can be made largely lossless. A further advantage is that, especially in these cases, the first prism surface and the third prism surface do not require a reflection-reducing coating and thus can remain uncoated, as shown in the example case. The production of the prisms is characterized particularly cost. In addition, no performance losses due to layer degradation can occur, resulting in improved long-term stability over coated optical components.

In typical applications of reflective light modulation devices of the type shown here, maximum tilt angles of the prisms are in the range of a few degrees, for example in the range of ± 2 °, starting from the home position. In these cases, the deviations of the relevant angles of incidence at the first and third prism surfaces from the Brewster angle are so small that the transmission losses that occur as a rule do not exceed 0.1%.

In summary, the ratio I _O / I _I between the intensity 10 the emergent rays and the intensity I _{i of} the incoming light rays are at 90% or above, in particular even at 99% or above. The ratio I _O / I _I is also referred to in this application as "total transmission" of the light modulation device or as "efficiency" of the light modulation direction. The high values of the total transmission make it clear that with the aid of the light modulation device, a specific adjustment or change in the angular distribution of light in a beam can be achieved with very low light losses, ie with high efficiency.

The light modulation device 200 is operated in the passage. When all prisms are in their non-tilted home position, then all deflection angles are zero and the outgoing beams are parallel and in extension to the associated incident rays. In this use "in the passage" are the optical components of the illumination system in the direction of light travel in front of the prism array and behind the prism array on a common axis 103 arranged without "kink" and the array "in the passage" has no effect on the lateral positioning of these components. In the area of the light modulation device, therefore, no folding of the beam path takes place (folding angle = 0 °). In other words, the optical components in the direction of light travel in front of the light modulation device (eg including the Fourier optical system 154 ) define a first part 103A the optical axis, the optical components in the direction of light travel behind the light modulation device (here, for example, including the condenser optics 159 ) define a second part 1038 the optical axis, and the second part 1036 the optical axis is coaxial with the first part 103A the optical axis.

3 clearly shows how a tilting about the first tilting axis, which is transverse, in particular substantially perpendicular to the light incident direction, leads to a beam deflection. Based on 4 It is shown that a tilting of a prism about a substantially parallel or at an acute angle to the light incident direction extending second tilt axis 242 leads to a beam deflection. The reason for this is that towards the totally reflecting second prism surface 220 broken light incident to the reflecting surface (ie to the prism bottom side), the totally reflecting surface itself being hit at a different angle than in the basic position. Even in the case of an angle of incidence of 90 °, however, a tilting of the totally reflecting second prism surface around the beam axis was ineffective, the beam deflection would be equal to zero. This means that light which grazing (angle of incidence 90 °) hits a reflecting surface, is not deflected by the tilt of this surface about an axis parallel to the light incident direction. Since, however, the first prism surface ensures that the light no longer strikes the reflective second prism surface, light can actually be deflected two-dimensionally, even if the direction of incidence is parallel to the second prism surface.

In the embodiment of 2 The bars below each prism symbolize the associated tilting actuator. The corresponding holding elements engage the prisms in the region of the totally reflecting prism base (second prism surface). If the prisms, as in the embodiment of 2 , Are arranged one above the other and next to each other, that lying on the inlet side of the first prism edges are all in a plane perpendicular to the optical axis of the illumination system, the space available for the interconnection of the actuators space between the prisms can be narrow. A simplification in terms of the accessibility of the actuators, for example, in an arrangement according to 8th given. In the grid arrangement 800 of prisms, the prisms are offset not only in the z-direction against each other, but also parallel to the y-direction, so that the second prism surfaces are at least partially accessible. Such an oblique arrangement allows the actuators and the prisms to be accessed directly from below or from above. This can be advantageous in the production of the grid arrangement. Due to the generally low required beam deflection angle of about ± 5 ° by the prism tilting this separation of the grid assembly in the direction of light travel is usually possible without affecting the function of the light modulation device.

The actuators for tilting the prisms will generally reduce the optically usable range or the fill factor of the prism array. The term "filling factor" here refers to the optically usable surface of the prism array, projected in the direction of light, relative to the total area occupied by the prism array, also projected in the light direction. To avoid light losses is in the embodiment of 2 provided in the light direction in front of the prism array for each prism a microlens or another suitable for the concentration of radiation optical element, which subdivides the incident beam into sub-beams, which are each focused on an optically usable area of the light entrance surface of an associated prism. 5 shows schematically the structure and operation of rectangular microlenses 155A of the lens array 155 , The rectangular microlenses are arranged surface-filling in a two-dimensional grid arrangement, so that each incident light beam is deflected to exactly one of the prisms. For each prism, a mircoline symbolized by a square focuses the light on the entrance side of the prism so that light losses, apart from diffraction losses, are largely avoided. Due to the focusing, the optically used volume in the prism can be kept smaller than the total volume of the prism. As a result, it can be achieved that all edges formed by the prism surfaces lie far away from the optically utilized volume and thus can be used for the attachment of actuators, without the beam path through the prism z. B. by shading or by disturbing the total reflection. In 6 the optically used volume of the prism is enclosed by dashed lines. The two black outlined square areas on the light entry surface (first prism surface) and the Light exit surface (third prism surface) are penetrated by the light, here the radiation is broken. In the hatched area of the second prism surface 220 the light is totally reflected. Outside the optically used area, mechanical elements can be glued, clamped or otherwise secured, which support the prism and connect it to the actuator.

7 schematically shows essential components of a pupil-forming unit 750 another embodiment of a lighting system for a microlithography projection exposure system. The sequence of optical components with Fourier optical system 754 , Light modulation device 700 and condenser optics 759 corresponds largely to that of the embodiment of 2 , which is why reference is made to the description there. However, the upstream lens array is missing. It can be replaced by a modified lens array to produce line foci, which will be explained in more detail below. A diffuser is not provided, but z. B. in front of or behind the condenser optics 759 be provided.

With the help of the light modulation device 700 becomes in the pupil shaping surface 710 of the illumination system set a defined local intensity distribution (lighting setting). The light modulation device 700 shows an alternative arrangement of prisms, in which the light deflection also works via lossless total reflection. In contrast to the embodiment of 2 form the prisms 705 However, a flat grid arrangement, which is characterized in that all totally reflective second prism faces 720 in a common plane 706 lie when the prisms are in their non-tilted home position. The totally reflecting second prism surfaces can thus be arranged here in a similar manner as the non-totally reflecting mirror surfaces of the individual mirrors of conventional multi-mirror arrays.

The common plane, also referred to as the mirror plane 706 is in the example at an angle of 45 ° to the optical axis 703 , which is defined by the axes of symmetry of the lens elements of the illumination system. The optical axis is folded by about 90 °, as the part 703A the optical axis in front of the prism array with the part 7038 the optical axis approximately a right angle (folding angle) include. The folding angle can z. B. between 80 ° and 100 °. On the side facing away from the prisms of the second prism surfaces are the actuators associated with the individual prisms 704 , by means of a control device 780 can be controlled independently of each other to multi-axis tilt the prisms coupled thereto (see. 4 ).

In this embodiment, the angles of incidence are at the light entry sides (first prism surfaces 711 ) and at the light exit sides (third prism surfaces 730 ) no longer in the vicinity of the associated Brewster angle, but in the vicinity of 0 °, for example in the range of ± 20 ° or ± 10 °. Therefore, both the s-polarized component and the p-polarized component at the interfaces between environment (air or other gas) and prism body is reflected to a certain extent. For this reason, it is advantageous in this embodiment if both the first prism surface and the third prism surface is coated with an antireflection coating. Although the loss of light at the interfaces is then not, as in the embodiment of 2 , in the range of less than 0.1%, but generally well below 1%, for example in the range of 0.6% or below. This is still significantly less expensive than the loss of light in typical high reflectivity mirror coatings, the reflectance of which is typically not much higher than 95%, so the light loss is typically in the range of a few percent, e.g. B. by 5%.

The oblique orientation of the grid arrangement causes a convolution of the beam path of the optical system, in which the light modulation device is integrated. Advantageously, folding angles of 90 ° are possible here so that the beam path on the light entry side and the beam path on the light exit side no longer overlap at a small distance from the light modulation device and accordingly position the optical components in front of the light modulation device and behind the light modulation device relatively close to the light modulation device could be. As a result, spatially compact arrangements are possible.

An advantage of the arrangement in 7 it is that the entire actuator, so all components required for the support and movement of the prism elements, can lie in one plane and that connections for electrical interconnection of the elements can be led away to the optically unused back without the risk that light is shadowed. Another advantage is the possible design of the prisms possible exploitation of the backdrop effect. Here are the light entry surfaces 711 the prisms seen in the light entry direction very close together. In this case, despite possible small gaps between the light entry surfaces of the individual prisms no focusing of the light on the light entry sides of the prisms necessary to avoid light losses. Because through the backdrop effect, the incoming light essentially "sees" only the as the light entry surfaces serving prism first surfaces, but not the gaps between them.

The backdrop effect, however, only arises in the 7 shown folding plane, ie in the plane passing through the parts of the folded optical axis 103 is stretched out. In the direction perpendicular to this, furthermore, a concentrator device with line focus can be favorable in order to avoid the loss of light. Such a one-dimensional focusing can be realized, for example, with the aid of cylindrical lenses. It may be advantageous over multi-dimensional focusing, inter alia because diffraction-induced effects can be reduced.

In order to optimize lithography processes, it is usually desirable to set the two-dimensional intensity distribution in the pupil shaping surface of the illumination system with high accuracy and high spatial resolution. If a light modulation device with a two-dimensional grid arrangement of individually controllable prisms is used for structuring the illumination pupil, with the aid of which the angular distribution of the incident radiation can be changed, the spatial resolution can be achieved by a correspondingly large number of prisms having an adapted response characteristic. For example, the reflective light modulation device may have more than 25 or more than 400 or more than 4000 controllable prisms or channels. On the other hand, the design may be more complex and the size larger, the more prisms are to be accommodated, so that the upper limit for the number of prisms for practical reasons is often 100,000 individual elements, possibly also less than 50,000 or fewer than 10,000 individual elements provided be. Light modulation devices with high spatial resolution usually have a surface area that is at least one or more square centimeters and, for example, between about 2 cm ² and 80 cm ² to 100 cm ² or more.

The terms "radiation" and "light" in the context of this application are to be interpreted broadly and in particular to include electromagnetic radiation from the deep ultraviolet region (DUV), for example at wavelengths of about 365 nm, 248 nm, 193 nm, 157 nm or 126 nm.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7714983 B2 [0007]
• US 7359103 B2 [0008]
• US 5343489 [0041]
• WO 2009/135586 A1 [0053]

Claims (14)

Light modulation device for the spatially resolved influencing of an angular distribution of rays of a beam incident on the light modulation device, comprising: a raster arrangement having a multiplicity of prisms ( 205 . 705 ) by means of associated actuators ( 204 . 704 ) are individually tiltable in different working positions, each prism a transparent prism body ( 202 ) having a first prism surface ( 210 . 702 ), a second prism surface ( 220 . 720 ) and a third prism surface ( 230 . 730 ) forms; the first prism surface ( 210 . 702 ) serves as a light entry surface for the reception of beams, which from a direction of light incidence at a first angle of incidence ( 211 ) on the first prism surface; the second prism surface ( 220 . 720 ) with the first prism surface a first prism angle ( 215 ) dimensioned so that at each operating position of the prism at each working position of the prism, the beams directed from the first prism surface directly to the second prism surface (FIG. 221 ) strike the second prism surface which is larger than a critical angle for total reflection at the second prism surface; and the third prism surface with the second prism surface has a second prism angle ( 225 ) which is dimensioned such that from the second prism surface ( 220 . 720 ) totally reflected rays at a third angle of incidence ( 231 ) are incident on the third prism surface and are directed by the third prism surface in a light exit direction. A light modulation device according to claim 1, wherein the second prism surface ( 220 . 720 ) does not carry any coating. A light modulation device according to claim 1 or 2, wherein the first angle of incidence ( 211 ) at each working position of the prism ( 205 ) by less than 15 °, in particular by less than 10 °, from one at the first prism surface ( 210 ) deviating Brewster angle, preferably the first prism surface ( 210 ) is uncoated. A light modulation device according to any one of the preceding claims, wherein the third angle of incidence ( 231 ) at each working position of the prism ( 205 ) differs by less than 15 °, in particular by less than 10 °, from a Brewster angle valid at the third prism surface, wherein preferably the third prism surface ( 230 ) is uncoated. A light modulation device according to any one of the preceding claims, wherein each of the prisms ( 205 . 705 ) can be tilted about a plurality of tilting axes which are at an angle to one another, in particular about two mutually perpendicular tilting axes ( 241 . 242 ). A light modulation device according to any one of the preceding claims, wherein a maximum tilt angle in each prism is less than 5 °, in particular 3 ° or less and / or wherein a maximum achievable deflection angle for each prism is 10 ° or less. Light modulation device according to one of the preceding claims, wherein the prisms ( 205 ) of the grid arrangement are arranged such that in an untilted basic position of the prisms all second prism surfaces ( 220 ) are aligned parallel to each other and the prisms are arranged offset in a first direction perpendicular to the second prism surfaces, wherein preferably the prisms are additionally arranged offset in a second direction parallel to the second prism surfaces such that the second prism surfaces at least partially accessible in the first direction are. Light modulation device according to one of claims 1 to 6, wherein the prisms ( 705 ) form a planar grid arrangement, in which in an untilted basic position of the prisms all second prism surfaces ( 720 ) in a common plane ( 706 ) lie. Light modulation device according to one of the preceding claims, wherein the prisms ( 205 . 705 ) of a raster arrangement form a two-dimensional raster arrangement. Illumination system for a microlithography projection exposure apparatus for illuminating a lighting field with the light of a primary light source, characterized by at least one light modulation device according to one of claims 1 to 9. Illumination system according to claim 10, wherein the illumination system comprises a variably adjustable pupil-shaping unit ( 150 . 750 ) for receiving light from the primary light source and for generating a variably adjustable two-dimensional intensity distribution in a pupil shaping surface ( 110 . 710 ) of the illumination system, wherein the light modulation device ( 200 . 700 ) is disposed between the light source and the pupil shaping surface. Illumination system according to claim 10 or 11, wherein between the light source and the light modulation means a raster arrangement ( 155 ) of optical elements for concentrating radiation incident on the optical elements is arranged on associated prisms of the light modulation device. Illumination system according to Claim 10, 11 or 12, in which the light modulation device ( 200 is used in the passage, wherein preferably optical components in the direction of light travel in front of the light modulation means a first part ( 103A ) of the optical axis and optical components in the direction of travel behind the light modulation device define a second part ( 103B ) of the optical axis coaxial with the first part ( 103A ) of the optical axis. Illumination system according to Claim 10, 11 or 12, in which the light modulation device ( 700 ) is used for folding the beam path, wherein preferably optical components in the direction of light travel in front of the light modulation device a first part ( 703A ) of the optical axis, optical components in the direction of travel behind the light modulation device define a second part ( 7038 ) of the optical axis, and the first part ( 703A ) with the second part ( 7038 ) of the optical axis includes a folding angle between 70 ° and 10 °, in particular between 80 ° and 100 °.

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