Illumination system, projection illumination apparatus and projection illumination method

Abstract

An illumination system (ILL) for a microlithographic projection illumination device for illuminating a sample arranged in the region of an object plane (OS) of a downstream projection lens (PO) with illumination light generated from light from a primary light source (LS), the illumination system being designed as a dual-field illumination system, the invention relates to a dual-field illumination system for receiving a single light beam from a primary light source (LS) and thereby generating two illumination light beams (BS1, BS2), a first illumination light beam (BS1) being guidable along a first illumination light beam path to a first illumination field (ILF1) arranged in an exit plane (ES) of the illumination system outside an optical axis of a projection lens, and a second illumination light beam (BS2) being guided along a second illumination light beam path to a second illumination field (ILF1) arranged in an exit plane (ES) of the illumination system outside the optical axis of the projection lens. At the same time, the second illumination beam (BS2) can be guided along a second illumination beam path to a second illumination field (ILF), which is opposite the first illumination field (ILF1) with respect to the optical axis (AX) and is arranged outside the optical axis in the exit plane. The illumination system comprises a refractive pupil-forming unit (PFU) for receiving light from a primary light source (LS) and for generating a two-dimensional intensity distribution in a pupil-forming surface (PUP) of the illumination system, and a refractive field-forming system (FFS) optically downstream of the pupil-forming unit, said field-forming system having a homogenizing unit (HOM) for homogenizing the intensity distribution in the pupil-forming surface (PUP) of the illumination system. And a light splitting unit for homogenizing the light received from the pupil forming unit and for splitting the illumination light into a first illumination beam (SB1) and a second illumination beam (SB2).

Description

[0001] The following disclosure is based on the German patent application with the document reference number 102022205273.0 filed on May 25, 2022. The disclosure content of this patent application becomes the content of the present application by reference. Technical Field

[0002] The invention relates to an illumination system for illuminating a pattern arranged in the object plane of a projection lens. The invention also relates to a projection exposure apparatus having such an illumination system and a projection exposure method which can be performed with the aid of the illumination system. Background Art

[0003] At present, microlithography projection exposure methods are mainly used for the production of semiconductor devices and other finely structured components. In this case, a mask (reticle) is used which carries or produces a pattern of the structure to be imaged (for example, a line pattern of a layer of a semiconductor device). The pattern is arranged in the projection exposure device in the region of the object plane of the projection lens, between the illumination system and the projection lens, and is illuminated in the region of the effective object field with illumination radiation provided by the illumination system. The effective object field is the part of the object field that can be used for the image, which is actually used for the image. The radiation changed by the pattern travels as a projection beam through the projection lens, which images the pattern in the region of the effective image field, which is optically conjugated with the effective object field, onto the substrate to be exposed. The substrate usually carries a layer (photoresist) that is sensitive to the projection radiation.

[0004] When selecting suitable projection exposure apparatus and methods for a lithographic process, different technical and economic criteria have to be taken into account, which are based inter alia on the typical structure dimensions of the structures to be produced in the exposed substrate.

[0005] Projection exposure apparatuses with high NA projection lenses, which typically operate at operating wavelengths in the deep ultraviolet radiation (DUV) range, for example at about 193 nm, are used to produce relatively fine critical structures.

[0006] In contrast, for the production of medium critical or non-critical layers with typical structure sizes significantly greater than 150 nm, projection exposure apparatuses designed for operating wavelengths greater than 200 nm are conventionally used. In this wavelength range, purely refractive (dioptric) reduction lenses are usually used.

[0007] Projection exposure devices for operating wavelengths of 365.5 nm ± 2 nm (so-called i-line systems) have been used for a long time. They use i-line mercury vapor lamps, whose natural bandwidth is limited by filters or in other ways to a narrower use bandwidth Δλ, for example about 2 nm. In such light sources, a relatively broad band of ultraviolet light is used in projection.

[0008] Most conventional projection exposure apparatus are designed to image a single effective object field into a single effective image field.There are also methods to use two beam paths simultaneously, for example to increase throughput.

[0009] Patent specification US Pat. No. 8,634,060 B2 describes a projection exposure apparatus that can expose two masks and two wafers simultaneously. Light from a single light source is transmitted alternately via fast optical switching through two separate, identical projection systems, each comprising an illumination system and a projection lens.

[0010] US 2008 / 259440 A1 describes a projection exposure apparatus which works with two separate masks and two separate illumination systems, wherein the projection beam paths in the projection lenses are merged via a triangular prism.

[0011] US2010 / 0053738 (corresponding to US 8,705,170 B1) describes a projection lens which uses a single mask and branches the projection beam path in the projection lens by means of a deflecting mirror in such a way that two separate image-side lens parts are formed, which produce two image fields so that two wafers can be exposed simultaneously. Document US2010 / 0053583 A1 discloses a suitable illumination system which can simultaneously illuminate two separate illumination fields located at a certain distance from each other on the same mask. A diffractive optical element or a prism is provided for separating the light beam from the light source. A lens array of a fly's eye lens is provided for homogenization of the illumination radiation.

[0012] A projection exposure apparatus with two projection beam paths is described, for example, in patent specification US Pat. No. 8,384,875 B2 using a schematic example. For illuminating the mask, two illumination systems are provided, which can be constructed separately from one another or integrated into a common illumination system (FIG. 12). There is also a schematic example of a catadioptric projection lens. No specification data for reworking the system are disclosed. Summary of the invention

[0013] Against this background, it is an object of the present invention to provide a practical and feasible concept for a dual-field illumination system, a projection exposure apparatus equipped with a dual-field illumination system and a projection exposure method which can be performed using the same.

[0014] According to the wording of the invention, this object is achieved by an illumination system having the features of claim 1, a projection exposure apparatus having the features of claim 9 and a projection exposure method having the features of claim 11. Advantageous developments are given in the dependent claims. The wording of all claims is incorporated by reference into the description.

[0015] According to one wording of the invention, an illumination system for a microlithography projection exposure apparatus is provided. The illumination system is configured to illuminate a pattern arranged in the region of an object plane of a downstream projection lens with illumination light, the illumination light being generated by light from a primary light source. The illumination system is designed as a dual-field illumination system for receiving a single light beam originating from the primary light source and for generating two illumination beams therefrom. In operation, a first illumination beam is directed along a first illumination beam path to a first illumination field, which is arranged in an exit plane of the illumination system outside the optical axis of the projection lens. At the same time, a second illumination beam is directed along a second illumination beam path to a second illumination field, which is opposite to the first illumination field with respect to the optical axis and is arranged in the exit plane outside the optical axis. The exit plane of the illumination system corresponds to the object plane of the projection lens.

[0016] The illumination system comprises a refractive pupil shaping unit for receiving light from a primary light source and for generating a two-dimensional intensity distribution in a pupil shaping surface of the illumination system. The two-dimensional intensity distribution in the pupil shaping surface substantially determines the angular distribution of the light rays directed to the exit plane. Furthermore, a refractive field shaping system is provided optically downstream of the pupil shaping unit, comprising a homogenizing unit for homogenizing the light received from the pupil shaping unit and for splitting the illumination light into a first and a second illumination beam.

[0017] The pupil shaping unit shapes the two-dimensional intensity distribution solely with the aid of refractive optical elements, i.e. by refracting the light to be adjusted at a correspondingly designed smooth surface of the optical element. The use of one or more diffractive optical elements is dispensed with. Although diffractive optical elements in principle offer the possibility of generating one or more output beams with very individually adjustable properties from an input beam, beam shaping via diffraction is usually associated with light losses and generates stray light, which can have a negative impact on the functionality. On the other hand, if the pupil shaping unit is constructed solely with refractive optical elements, pupil illumination can be generated with low optical losses.

[0018] In order to ensure that the illumination field is illuminated as evenly as possible by the light from the light source and that at the same time light losses between the pupil shaping surface and the exit surface are kept low, a refractive field shaping system is provided comprising a homogenization unit for homogenizing the light received from the pupil shaping unit and for splitting the illumination light into a first and a second illumination beam.

[0019] The component thus has a dual function, specifically the task of homogenizing the illumination radiation and splitting it into two illumination beams. This splitting is due to the special design of the optics of the homogenization unit. By integrating several functions (homogenization and splitting) by means of the optics of the homogenization unit, it can also be helpful to illuminate the pattern with the least possible intensity loss using the light from the primary light source and thus to increase the throughput.

[0020] There are functionally different ways of implementing this concept.

[0021] In one set of embodiments, the homogenization unit has a first grid arrangement and a downstream second grid arrangement,

[0022] A first grid arrangement has a first refractive grid element for receiving light of a two-dimensional intensity distribution and for generating a grid arrangement of a secondary light source, and a downstream second grid arrangement has a second refractive grid element for receiving light from the secondary light source and at least partially superimposing the light from the secondary light source in an exit plane. The first grid element is used to split the light beam into a plurality of optical channels. Each of the first grid elements generates an optical channel belonging to the secondary light source. The shape or aperture of the first grid element generally determines the shape of the illumination field. For example, the first grid element may be rectangular.

[0023] Each of the second grid elements is assigned to two adjacent first grid elements and is formed by a lens element having a first portion located in the first optical channel and a second portion located in the second optical channel, wherein the portions have different surface shapes and therefore different optical effects.

[0024] Preferably, the arrangement is such that adjacent first grid elements in one direction are alternately assigned to the first illumination field and the second illumination field. This contributes to a uniform distribution of the intensity distribution originating from the pupil shaping surface over the illumination fields. Since each illumination field actually receives intensity from closely adjacent locations in the pupil shaping surface, the two illumination fields have substantially the same angular distribution, with the result that the illumination conditions of the patterns in the two illumination fields are also substantially the same.

[0025] In order to achieve the most uniform distribution of intensity over the two illumination fields, preferably at least one surface of the lens elements in the second grid element is aspherically curved. Another surface can be spherically curved, which simplifies manufacturing. However, preferably, the entrance surface and the exit surface are aspherically curved, so that the second grid element is similar to a double aspherical lens in this respect.

[0026] In order to achieve a very sharp separation of the radiation incident on the lens element into two illumination fields to be illuminated, preferably, on at least one surface of the lens element, a flexure curve is provided between a first part and a second part of the lens element, i.e. a line forming a transition between adjacent parts, which transition is not continuously differentiable.

[0027] The first grid arrangement and the second grid arrangement can be considered as components of a specially designed fly's eye lens, wherein the second grid arrangement is essentially composed of off-axis lens element sections, at least one side of the off-axis lens element section is aspherical, and the size of each lens element section corresponds to the size of the assigned first grid element. In the second grid arrangement, a dense arrangement of refractive powers with a non-continuously differentiable transition is obtained. In particular, a dense arrangement of refractive powers alternating in a spatial direction with two different surface shapes can be provided.

[0028] In another group of embodiments, the homogenization unit comprises an integrator rod arrangement, which comprises an incident integrator rod having an incident surface and an exit surface, a first exit integrator rod optically coupled to a first partial surface of the exit surface, and a second exit integrator rod optically coupled to a second partial surface of the exit surface, wherein the exit surface of the first exit integrator rod is assigned to the first illumination field and the exit surface of the second exit integrator rod is assigned to the second illumination field.

[0029] This homogenization unit uses a different principle of light mixing. The integrator rod is basically a long rod made of a material that is transparent to the illumination light. The cross section of the rod is usually polygonal, for example rectangular. The rod has an incident surface that is optically facing the light source and an opposite exit surface. Light entering the incident surface at a suitable angle is optionally reflected several times by total internal reflection at the side surface of the integrator rod and then exits through the exit surface in a substantially uniform form. By setting the angular distribution at the entrance, the number of total internal reflections of the light at the side surface can be influenced, thereby affecting the homogenization effect.

[0030] In the integrator rod arrangement, the splitting into two illumination beam paths occurs at the exit surface of the incident integrator rod. There is a virtual split point between the first and second partial surfaces in order to split the exit light on two non-intersecting exit integrator rods operating in parallel. The exit integrator rod can be coupled directly to the exit surface of the incident integrator rod without the need for additional intermediate optical elements. One or more optical elements for deflecting the passing radiation can also be arranged between the incident integrator rod and the exit integrator rod.

[0031] In some embodiments, the incident integrator rod and the exit integrator rod each have a constant cross-sectional shape and cross-sectional size in the axial direction, and arranged between the exit surface of the incident integrator rod and each incident surface of the exit integrator rod is a prism arrangement for redirecting the light beam from a position close to the axis relative to the central axis of the incident integrator rod to a position of the exit integrator rod away from the axis and at a distance from the central axis of the incident integrator rod. With reference to the central axis, the incident surface of the incident integrator rod is centered relative to the central axis, while the exit surface of the exit integrator rod is located at a distance from the central axis on the opposite side of the central axis.

[0032] There are also embodiments without an intermediate prism arrangement. According to an exemplary embodiment, the first exit integrator rod and the second exit integrator rod are formed as "conical integrators" in which the cross-sectional dimensions decrease continuously from the entrance side to the exit side. Here, too, the entrance surface is preferably directly coupled to the first and second partial surfaces of the exit surface of the entrance integrator rod. If desired, a prism arrangement can be provided, for example for beam deflection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further advantages and aspects of the present invention are apparent from the claims and the description of exemplary embodiments of the invention, which will be explained below with reference to the drawings.

[0034] Figure 1 A schematic diagram showing a projection exposure apparatus according to an exemplary embodiment;

[0035] Figure 2 Schematic top view of the object plane of a projection lens with two effective off-axis object fields;

[0036] Figure 3 shows a schematic diagram of a first exemplary embodiment of a dual-field illumination system with an integrator rod arrangement;

[0037] Figure 4 Shown in detail Figure 3 The arrangement of integrating rods in ;

[0038] Figures 5A to 5D Variations of the integrator rod arrangement of other exemplary embodiments are shown;

[0039] Figure 6 An integrator rod arrangement with two tapered exit integrator rods is shown;

[0040] Figure 7 shows a schematic overview of an exemplary embodiment for a dual-field illumination system with grid elements in a homogenization unit;

[0041] Figure 8 Shown in detail Figure 7 homogenization unit.

[0042] Fig. 9 A schematic meridional lens element cross-sectional view showing a projection lens according to a first exemplary embodiment;

[0043] Fig.10 Shows Fig. 9 an enlarged portion of the area of ​​the deflection unit in the projection lens;

[0044] Figures 11A to 11C Three folding situations are shown comparatively;

[0045] Figures 12A to 12BA variation of single field scanning is shown;

[0046] Figures 13A to 13B A variation of dual-field scanning is shown;

[0047] Fig.14 Schematic meridional lens element cross-section diagram showing a catadioptric projection lens having two intermediate images, a concave reflector, a two-stage reflective deflection unit, and a single-stage deflection unit; DETAILED DESCRIPTION

[0048] In the following description of preferred embodiments, the term "optical axis" denotes a straight line or a series of straight line sections passing through the center of curvature of an optical element. The optical axis is folded at a folding mirror (deflecting mirror) or other reflecting surface. In an example, the object is a mask (reticle) with a pattern of an integrated circuit; it can also involve a different pattern, such as a pattern of a grating. In an example, the image is projected onto a wafer provided with a photoresist layer, which serves as a substrate. Other substrates are also possible, such as elements for liquid crystal displays or substrates for gratings.

[0049] Figure 1 An example of a microlithography projection exposure apparatus PBA is shown, which can be used in the production of semiconductor devices and other finely structured components and which operates with light or electromagnetic radiation from the ultraviolet (UV) range to obtain a resolution down to the micrometer range. A mercury vapor lamp is used as the primary radiation source or light source LS. The lamp emits a broad spectrum with emission lines of relatively high intensity I in a wavelength range with central wavelengths of approximately 436 nm (visible light, blue, g-line), approximately 405 nm (visible light, violet, h-line) and approximately 365.5 nm (near ultraviolet light, UV-A, i-line).

[0050] The projection exposure apparatus is an i-line system which uses only light from the i-line, ie UV light around a central operating wavelength of about 365.5 nm. By means of filters or otherwise, the natural full bandwidth of the i-line is limited to a narrower used bandwidth Δλ, for example about 2 nm.

[0051] In its exit surface ES, the illumination system ILL connected downstream of the light source LS generates in each case from the light coming from this single primary light source two large, clearly defined and essentially uniformly illuminated illumination fields ILF1, ILF2, said illumination fields ILF1, ILF2 having required beam angles adapted to the telecentricity of the projection lens PO arranged downstream thereof in the optical path.

[0052] The optical component which receives the light from the light source LS and forms the illumination radiation directed to the mask M from the light is part of the illumination system ILL of the projection exposure apparatus. The illumination system is a dual-field illumination system. Figures 3 to 8 Exemplary embodiments are explained.

[0053] The illumination system ILL has means for setting different illumination modes (illumination settings) and can, for example, switch between conventional on-axis illumination and off-axis illumination with different coherences σ.

[0054] Arranged downstream of the illumination system is a device RS for holding and manipulating a mask M (reticle) so that the pattern arranged at the reticle is located in the object plane OS of the projection lens PO, which coincides with the exit plane ES of the illumination system and is also referred to here as reticle plane OS.

[0055] The substrate to be exposed, in the exemplary case a semiconductor wafer W, is held by means WS, which comprises a scanner drive in order to move the wafer in a scanning direction (y-direction) perpendicular to the optical axis OA in synchronization with the reticle M. The means WS (also called "wafer stage") and the means RS (also called "reticle stage") are components of a scanner arrangement controlled by a scanning control which, in the present embodiment, is integrated in a central control unit CU of the projection exposure apparatus PBA.

[0056] Figure 2 A schematic top view of the object plane OS of the projection lens PO (corresponding to the exit plane ES of the illumination system) is shown. As shown in this example, the illumination system ILL illuminates two off-axis illumination fields ILF1, ILF2 with light from a light source in the exit plane (reticle plane, object plane of the projection lens). Each of these illumination fields is rectangular, can be sharply or softly delimited, and is substantially uniformly illuminated. Each of the illumination fields defines an effective object field actually used in the projection exposure, such that a first effective object field OF1 and a second effective object field OF2 are located in the reticle plane. Two nominally identically sized rectangular effective object fields are located on opposite sides of the optical axis OA in the y-direction, each at a certain distance outside the optical axis and have a height A* measured parallel to the y-direction and a width B*>A* measured perpendicular to the y-direction (in the x-direction or cross-scanning direction). For example, the aspect ratio AR=B* / A* can be, for example, 2, 2.5, 3, 5, 10 or 15.

[0057] In the example case, the effective rectangular fields (i.e., those actually used for imaging) each have a width B*=104 mm and a height A*=56 mm. The distance ABF (field distance) between the corresponding field peripheries in the y-direction is twice the distance d* of the field from the optical axis, i.e. 2×38 mm, plus the field height (56 mm), i.e. 132 mm. The circle OBC is generated by a rectangle with side B* (=104 mm) in the x-direction and side 2*(A*+d*) (=188 mm) in the y-direction (scanning direction).

[0058] In a rotationally symmetric system, a circle OBC centered with respect to the optical axis OA, which surrounds the effective object fields OF1, OF2 and touches their corners, determines the size of the object field circle, wherein the optical correction must correspond to the specifications at all field points. This also applies to all field points in the effective object field. The larger the object field must be, the more complex the correction of aberrations becomes. In this case, the size of the circle is parameterized by the object field radius OBH or half the object field diameter OBH, which at the same time corresponds to the maximum field height of the object field points. The object field height OBH is approximately 107 mm

[0059] The effective image fields IF1, IF2 in the image surface IS optically conjugated to the effective object fields OF1, OF2 have the same shape and the same aspect ratio between height A and width B as the associated effective object fields, but the absolute field size is reduced by the imaging ratio β of the projection lens for a reduced projection lens (with (│β│<1)), i.e. A=|β|A* and B=|β|B*.

[0060] The distance ABF (field distance) between the edges of the effective object field located on the same side in the y direction, measured in the scanning direction (y direction), is chosen so that the respective distance between the respective longer edges of the effective image fields IF1, IF2 is exactly the length of the "die" to be exposed. This length is 33 mm in the current standard. In semiconductor and microsystem technology, the term "die" refers to a single non-enclosed part of a semiconductor wafer, such as a single semiconductor chip without a housing or package.

[0061] Figure 3 A schematic diagram of a first exemplary embodiment of an illumination system ILL is shown. The primary light source LS is a mercury vapor lamp with a collector reflector that reflects the light collected into the inlet of the illumination system. An alternative (not shown) uses a laser as the light source, for example a frequency tripled solid-state laser with a wavelength of about 355 nm.

[0062] The primary light source is followed by a pupil shaping unit PFU, which consists only of refractive optical components and is designed to produce a defined local (two-dimensional) intensity distribution in a subsequent pupil surface PUP of the illumination system ILL and which is sometimes also referred to as secondary light source or illumination pupil. Since the essential properties of the illumination radiation are influenced or shaped by this local intensity distribution, this pupil surface is also referred to as pupil shaping surface PUP.

[0063] The pupil shaping unit PFU may be adjustable such that different local illumination intensity distributions in the circular illumination pupil may be set depending on control of the optical components of the pupil shaping unit, such as a conventional illumination setup with a circular illumination spot centered on the optical axis AX, dipole illumination or quadrupole illumination.

[0064] The refractive field shaping system FFS is optically connected downstream of the pupil shaping unit PFU. It comprises optical components which shape the illumination intensity distribution in the exit surface ES of the illumination system depending on the light coming from the pupil shaping surface. The field shaping system FSF comprises a homogenization unit HOM for homogenizing the light received from the pupil shaping unit. The homogenization unit has a dual functionality, since the optical components are also designed such that the illumination light is split into a first illumination beam BS1 and a second illumination beam BS2 which are incident on the exit plane at a mutual distance from each other. The field shaping system FFS comprises an input coupling optical unit EK, which collects the light coming from the pupil shaping surface and couples it into the incident surface EF1 of the integrator rod arrangement ISA. This is done in a manner which is convenient for the operator to use in the illumination system. Figure 4 Shown enlarged in .

[0065] The integrator rod arrangement ISA comprises an incident integrator rod IE having a planar incident surface EF1, a planar exit surface EF2 parallel thereto and four planar side surfaces, which form a rectangular cross section. The incident integrator rod is made of a material transparent to the illumination light. The light is mixed in the incident integrator rod by multiple total internal reflections at the uncoated or optionally coated outer surfaces (side surfaces) of the integrator rod and is thus homogenized, and is emitted in an at least partially homogenized form at the exit surface AF1. The incident integrator rod has a continuous rectangular cross section and defines a longitudinal center axis located on the optical axis AX of the illumination system.

[0066] The integrator rod arrangement further comprises a first exit integrator rod IA1 and a second exit integrator rod IA2, each of which has an incident surface EF2-1 and EF2-2 and an exit surface AF2-1 and AF2-2, respectively. The two exit integrator rods IA1 and IA2 each have a rectangular cross-sectional shape and a cross-sectional area that is substantially half the cross-sectional area of ​​the incident integrator rod IE.

[0067] The exit integrator rods IA1, IA2 are arranged on two opposite sides of the diameter at a distance from the optical axis AX of the illumination system. The first exit integrator rod IA1 is optically coupled to the first partial surface TF1 of the exit surface of the incident integrator rod, so that the light exiting through the first partial surface TF1 enters only the first exit integrator rod IA1. The same applies to the opposite side, where the light from the partial surface TF2 enters the second exit integrator rod IA2.

[0068] Between the incident integrator rod IE and the two exit integrator rods IA1, IA2, two prisms P1 and P2 of the prism arrangement PA are arranged. The first prism P1 has a rectangular, planar incident surface, which directly follows the first partial surface TF1 with an intermediate air gap LS and receives the radiation emerging from this partial surface. The planar exit surfaces have the same size and are directly in front of the incident surface of the first exit integrator rod IA1 with an intermediate air gap. In addition, the prism has two planar side surfaces, which are oriented at 45° to the incident surface and the exit surface and have a reflective coating respectively. They can be made reflective, for example, by applying an aluminum layer or a dielectric coating.

[0069] The two deflections at the mirror surface of the prism with parallel offset deflect the light emerging from the partial surface TF to a position further away from the optical axis. Thus, each prism optically connects one of the exit integrator rods IA1, IA2 to the assigned partial surface TF1, TF1 of the exit surface AF1 of the entrance integrator rod and directs the light from a position close to the axis to a position far from the axis.

[0070] With this arrangement, light entering the incident integrator rod IE is substantially evenly divided into equal parts on the exit surface AF2-1 of the first exit integrator rod and the exit surface AF2-2 of the second exit integrator rod, and is simultaneously mixed in the incident integrator rod and the exit integrator rod by multiple total internal reflections.

[0071] The intermediate field plane ZE of the illumination system is immediately adjacent to the exit of the first exit integrator rod IA1. An adjustable field diaphragm BL1 is arranged there, which allows infinite adjustment of the actual usable field size of the first illumination field IF1. A corresponding second field diaphragm BL2 is arranged at the exit of the second exit integrator rod.

[0072] The subsequent lens REMA, also called REMA lens, images the intermediate field plane of the reticle mask system onto the exit plane of the illumination system or the object plane of the subsequent projection lens. There, the first illumination beam generates a first illumination field ILF1 on one side of the optical axis AX, while the second illumination field ILF2 is illuminated on the opposite side at a certain distance from the optical axis by means of the second illumination beam SB2.

[0073] Figures 5A to 5C Several variations of this basic concept are shown. Figure 5A Variations and Figure 4 The example of is different in that the prisms P1 and P2 there are replaced by a pair of triangular prisms. The hypotenuse surfaces of the triangular prisms are reflective in each case, the entrance and exit surfaces are plane and adjoin the upstream or downstream element via an air gap.

[0074] Figure 5BIt is shown that a further integrator rod ISW1 , ISW2 can be integrated in each case between the entrance integrator rod IE and the two exit integrator rods IA1 , IA2 .

[0075] Figure 5C and Figure 5D It is shown that the prism arrangement PA which results in a split into two illumination beam paths does not necessarily have to be coupled directly to the exit side of the incident integrator rod. Instead, further deflection elements and / or integrator rod elements can be inserted.

[0076] exist Figure 6 In the exemplary embodiment of , there are no intermediate prisms and / or other optical elements between the incident integrator rod IE and the two exit integrator rods IA1 and IA2. In this exemplary embodiment, the two exit integrator rods are each designed as a so-called "conical integrator". In each exit integrator rod IA1, IA2, the size of the rectangular incident surface EF1, EF2 corresponds substantially to half the area of ​​the exit surface AF1 of the incident integrator rod IE, with the result that the light emerging from the relevant partial surface is fully coupled into the exit integrator rod. However, while in the previous examples the integrator rods each had a constant cross-sectional shape and cross-sectional dimensions over their length, in Figure 6 In the example of , the cross-sectional area of ​​the exit integrator varies continuously between the entrance surface and the exit surface, so that the two exit surfaces AF2-1 and AF2-2 are arranged diametrically opposite the optical axis at a distance from the optical axis. By increasing the angle during the passage through the tapered integrator rod, different illumination may be required at the entrance of the incident integrator rod, and the rod illumination is adapted so that no violation of the conservation of optical etendue occurs.

[0077] based on Figure 7 ff, different exemplary embodiments of the illumination system ILL will now be described. For the sake of clarity, functional groups having similar or corresponding functions as in the first exemplary embodiment are designated accordingly. A significant difference from the previous exemplary embodiments is the construction and operation of the homogenization unit HOM, which is basically constructed by means of a modified fly's eye lens. Details on the construction and the functions are described in Figure 8 Shown in.

[0078] The homogenization unit HOM comprises a first grid arrangement RA1 with a plurality of first refractive grid elements RE1, which receives light of the two-dimensional intensity distribution of the pupil shaping surface PUP and generates therefrom a grid arrangement of secondary light sources SL1, SL2, etc., which are formed downstream thereof approximately at a distance of the focal length F1 of the first grid elements RE1. In this way, the illumination beam from the pupil shaping surface is decomposed into a plurality of optical channels, wherein each illuminated first grid element and the associated secondary light source are part of a separate optical channel.

[0079] There is a second grid arrangement RA2 with second refractive grid elements RA2, which is arranged optically downstream of the first grid arrangement, for example in the region of a secondary light source SL1 or the like, and serves to receive light from a corresponding optical channel or secondary light source and to contribute to at least partial superposition of light from different optical channels in the region of an exit plane or image plane of the illumination system ILL. This superposition results in a homogenization of the light intensity in the exit plane.

[0080] The cross-sectional area or aperture of the first grid element RE1 determines the shape of the illuminated illumination field and is rectangular in the example case.The first grid element RE1 is also referred to as field cell.

[0081] The second grid elements RE2 are also called pupil cells and are arranged close to the corresponding secondary light sources. They image the first grid elements RE1 onto the intermediate field plane FE of the illumination system via the downstream field lens element. The intermediate field plane is then imaged into the exit plane of the illumination system, as in the example above.

[0082] A special feature of this homogenizing unit consists in the fact that each of the first grid elements RE1 generates (as in a conventional fly's eye lens) an optical channel belonging to the secondary light source.

[0083] However, each of the second grid elements RE2 is assigned not only to one first grid element, but also to two immediately adjacent first grid elements, for example grid elements RE1-1 and RE1-2. The second grid elements are each formed by a lens element which is divided into two differently shaped parts. The first part AB1 acts exclusively on the light of the first grid element distributed in its optical channel. The second part AB2 is formed as a single piece with the first part, is located only in the adjacent second optical channel, and accordingly influences its light propagation.

[0084] In the example case, the first optical channel generated by the grid element R1-1 is affected by the lower half of the subsequent second grid element or its first part AB1, so that the light is input into the first illumination beam BS1 via the field lens FL, while the light coupled into the second optical channel by the adjacent first grid element R1-2 is affected by the second part AB2 of the second grid element, so that it is coupled into the second illumination beam BS2, which propagates on the opposite side relative to the first illumination beam with respect to the optical axis AX.

[0085] In order to achieve strongly different optical effects at the second grid element RE2, it is preferably provided that the entrance surface and the exit surface are aspherical in the first part AB1 and the second part AB2, respectively. The surface shapes of the first part and the second part do not merge smoothly into each other; instead, a flexion line is formed as a separation line between the two parts on the surface of the second grid element.

[0086] Thus, the hybrid concept is characterized in that in the region of the pupil honeycomb (second grid element RE2), a dense arrangement of a number of refractive powers with two different surface shapes alternating in one spatial direction is produced. In particular, there is a dense arrangement of refractive powers with a transition that is not continuously differentiable. The second grid element RE2 (pupil honeycomb) can be considered as a lens element composed of off-axis lens elements, which is preferably aspherical on at least one side, and the size of each corresponds to the size of the associated field honeycomb.

[0087] Fig. 9 Schematic cross-sectional view of a meridional lens element of an embodiment of a catadioptric projection lens PO, where the selected beam is used to illustrate the imaging beam path of the projection radiation passing through the projection lens during operation. The projection lens is provided as an imaging system with a reduction effect, for imaging the pattern of a mask arranged in its object plane OS to its image plane IS at a reduced scale (e.g., scale 1:4), and the image plane IS is oriented parallel to the object plane.

[0088] The projection lens is designed according to an embodiment of the claimed invention and has an image-side numerical aperture NA in the range of 0.2 < NA < 0.4, for example, NA = 0.3.

[0089] The projection lens is designed as a dual-field projection lens. It is capable of imaging a first effective object field OF1 arranged outside the optical axis OA in the object plane OS along a first projection beam path RP1 to a first effective image field IF1 located outside the optical axis OA in the image plane IS, and simultaneously imaging a second effective object field OF2 arranged outside the optical axis in the object plane and arranged opposite the first object field with respect to the optical axis along a second projection beam path RP2 to a second effective image field IF2 located outside the optical axis in the image plane.

[0090] The projection lens includes a plurality of optical elements, which include a plurality of lens elements (e.g., 15 to 25 lens elements) and exactly two concave mirrors CM1, CM1, where there is exactly one concave mirror in each projection beam path.

[0091] Most of the lens elements (more than 50%, especially 60% or more, or 70% or more, or 80% or more) are arranged along a first part OA1 of the optical axis OA, where these first parts extend coaxially and perpendicular to each other with respect to the object plane OS and the image plane IS. The concave mirrors CM1, CM2 are arranged on opposite sides of the first part OA1 and define a second part OA2 of the optical axis, which together with the first part defines an axis plane (which is located in Fig. 9 the drawing plane in). The concave mirrors in this example are arranged coaxially with each other on opposite sides of the first part, and the second part OA2 of the optical axis is perpendicular to the first part OA1, thus producing a cross shape.

[0092] The optical elements are arranged and formed mirror-symmetrically with respect to a symmetry plane SYM, which extends perpendicularly to the axis plane (here the drawing plane) through the first portion OA1. For each of the concave mirrors, there is a first deflection unit ULE1 for deflecting radiation from the object plane OS to the concave mirror and a second deflection unit ULE2 for deflecting radiation from the concave mirror in the direction of the image plane IS in the assigned projection beam path. The deflection units ULE1, ULE2 are respectively arranged on the side of the symmetry plane SYM facing the assigned concave mirrors CM1 and CM2.

[0093] Between the object plane and the image plane, exactly two real intermediate images (generally referred to as IMIs) of the assigned effective object field are generated in each of the projection beam paths RP1, RP2, specifically IMI1-1, IMI2-1 in the first projection beam path and IMI1-2 and IMI2-2 in the second projection beam path (see Fig.10 ).

[0094] The first lens portion OP1, which is composed only of transparent optical elements and therefore has refractive (dioptric) properties, is designed so that each pattern in the irradiated effective object field is imaged slightly reduced (the imaging ratio is, for example, in the range of about 1.85:1 to about 1.75:1) into the first intermediate image IMI1-1, IMI1-2 of the corresponding projection beam path.

[0095] The second catadioptric lens section OP2 images the first intermediate images of the projection beam paths onto the corresponding second intermediate images IMI2 substantially without changing their size. The second lens section OP2 comprises separate concave mirrors CM1, CM2 and three upstream dual-pass lens elements for each projection beam path. In the second lens section, the projection beam paths separate and travel along separate optical paths through separate partial lenses before the separate partial lenses are recombined into a shared lens element in the region of the second intermediate image IMI2. The second intermediate image IMI2 is located between the two separate mirrors of ULE2, i.e. the projection beam paths are still separate at the second mirror of ULE2 and only then are they recombined.

[0096] The third refractive lens part OP3 is designed to image the second intermediate images IMI2-1, IMI2-2 into the image plane IS at a reduced scale.

[0097] All lens elements of the first lens part OP1 and all lens elements of the third lens part OP3 and therefore all lens elements on the first portion OA1 of the optical axis are common to both projection beam paths. The footprint of the projection beam paths on the surfaces of the individual lens elements, i.e. the surface area illuminated by the radiation, is symmetrical with respect to the symmetry plane SYM. Thus, possible lens heating effects, in particular in the near-field lens elements, are essentially symmetrical with respect to the symmetry plane, thereby simplifying possible corrections.

[0098] A pupil plane or pupil planes P1, P2, P3 are located in each projection beam path between the object plane and the first intermediate image, between the first intermediate image and the second intermediate image, and between the second intermediate image and the image plane, at which the chief ray CR of the optical imaging intersects the optical axis OA. The aperture of the system can be arranged in the region of the pupil plane P3 of the third lens portion OP3. The pupil plane P2 in the catadioptric second lens portion OP2 is located in the immediate vicinity of the corresponding concave mirror CM.

[0099] To support chromaticity correction, a negative group NG with at least one diffuse negative lens is arranged in each of the two projection beam paths in the immediate vicinity of the associated concave reflector CM1, CM2 in the region near the pupil. The "region near the pupil" is the region where the imaged marginal ray height (MRH) is greater than the chief ray height (CRH). The marginal ray height in the region of the negative group may be at least twice the chief ray height.

[0100] To provide background: While the contributions of lens elements with positive refractive power and lens elements with negative refractive power to the total refractive power, image field curvature and chromatic aberrations in an optical system act in opposite directions, a concave mirror has exactly the same positive refractive power as a positive lens element, but has the opposite effect on the image field curvature compared to a positive lens element. Furthermore, a concave mirror does not introduce chromatic aberrations. Therefore, a catadioptric system component with a concave mirror close to the pupil and an adjacent negative lens (Schupmann achromatometer) is a very suitable device for an achromatic projection lens. Between the corresponding deflection unit and the negative group, a two-pass positive lens PL can be arranged, which can also be omitted in other exemplary embodiments (see Table 3).

[0101] A special technical feature relates to the design of the deflection units ULE1, ULE2. These deflection units are not designed as single reflection plane mirrors or deflection reflection mirrors. Instead, the first deflection unit ULE1 and the second deflection unit ULE2 each have a substantially planar first reflection surface RF1 and directly follow a substantially planar second reflection surface RF2. The reflection surfaces are tilted at different tilt angles relative to the symmetry plane SYM around a tilt axis, the tilt axis being orthogonal to the first part and the second part. The first reflection surface RF1 is used to deflect radiation from the object plane OS to the second reflection surface RF2, and the second reflection surface is used to deflect radiation from the first reflection surface RF1 in the direction of the image plane.

[0102] In each projection beam path, the first reflection surface RF1 is a reflection surface that receives the light beams from the last lens element of the first lens section OP1 and reflects them in the direction of the second reflection surface RF2 that follows immediately thereafter. The latter then reflects the light beams within the second lens section OP2 to the associated concave reflection mirror CM. After being reflected at the concave reflection mirror and passing through the three upstream lens elements twice, the light beams are then incident on the second deflection unit ULE2, whose first reflection surface RF1 deflects the light beams to the second reflection surface RF2, which reflects in the direction of the first lens element of the third lens section OP3.

[0103] If the tilt angle KW of the reflecting surface is defined as the angle enclosed by the surface normal NOR of the reflecting surface and the incident-side optical axis, the tilt angle of the first reflecting surface on the first lens portion side is 67.5° in each case. For the second reflecting surface following immediately in each beam path, the tilt angle is only 22.5°, i.e. corresponds to the supplementary angle of the first tilt angle, the sum of which is 90°. The same applies to the second deflection units ULE2, i.e. those deflection units which deflect the light beam from the corresponding concave reflector CM in the direction of the third lens portion OP3, wherein the second part OA2 of the optical axis is now counted as the incident-side optical axis.

[0104] With respect to the incident side optical axis, a 90° deflection is thus achieved in two directly successive steps, to be exact, once by x degrees and a second time by 90-x°. The two associated reflective surfaces of the deflection unit are located on the same side of the symmetry plane SYM, to be exact, on the side where the associated concave reflector CM is located.

[0105] The two reflection surfaces RF1, RF2 of the deflection unit ULE are each located in the optical vicinity of the first intermediate image IMI1 of the associated projection beam path, with the result that the footprint of the beam on the reflection surface appears more or less rectangular with rounded corners and is located at a distance from the optical axis, but close to the optical axis. More specifically, the first intermediate image is located between the two reflection surfaces RF1, RF2; in this way, both reflection surfaces are close to the intermediate image. At imaging scales of the first lens part OP1 with at most very small magnification or slight reduction, the size of the intermediate image is not or only slightly larger than the size of the generated effective object field OF, so that a mirror surface with compact dimensions is sufficient to reflect the entire beam to the downstream optical element without vignetting. This applies in particular to the reflection from the first reflection surface RF1 to the second reflection surface RF2, the size of the second reflection surface RF2 can also be very compact, since it is still located in the optical vicinity of the first intermediate image, in particular in the region where the subaperture ratio SAR is less than 0.3 in absolute value. The SAR is preferably between 0.2 and 0.3.

[0106] For explanation purposes: In this application the optical proximity or optical distance of an optical surface to a reference plane (e.g. a field plane or pupil plane) is described by the so-called subaperture ratio SAR. For the purposes of this application, the subaperture ratio SAR of an optical surface is defined as follows:

[0107] SAR=sign(CRH) * (MRH / (|CRH|+|MRH|))

[0108] Where MRH denotes marginal ray height, CRH denotes chief ray height, and the sign function sign(x) denotes the sign of x, where by convention sign(0)=1. The chief ray height is the ray height of the chief ray of the field point of the object field having the maximum field height in absolute value. The ray heights are to be understood here as being signed. The marginal ray height is the ray height of the ray with the maximum aperture starting from the intersection of the optical axis and the object plane. This field point need not contribute to the transfer of a pattern arranged in the object plane - in particular in off-axis image fields.

[0109] The subaperture ratio is a symbolic variable which is a measure of the field vicinity or pupil vicinity of a plane in the beam path. By definition, the subaperture ratio is normalized to a value between -1 and +1, where the subaperture ratio is zero in each field plane and where the subaperture ratio jumps from -1 to +1 or vice versa in the pupil plane. A subaperture ratio of 1 in absolute value thus specifies the pupil plane.

[0110] The near field plane thus has a subaperture ratio close to 0, whereas the near pupil plane has a subaperture ratio close in absolute value to 1. The sign of the subaperture ratio indicates the position of the plane in front of or behind the reference plane.

[0111] The reflective surfaces can be designed nominally as planar surfaces, ie defining a mathematical plane except for manufacturing tolerances. It is also possible to design individual or all reflective surfaces with defined deviations from a plane, with the result that the reflective surfaces can be used as correction surfaces for aberrations such as distortion.

[0112] exist Fig. 9 In the illustrative example of , the reflective surfaces are each manufactured as a separate mirror and housed in a separate mount. Fig.10 The examples of show that in each case two of the deflection mirrors or reflective surfaces can be designed in combination as triangular prisms. These triangular prisms can be mounted together in the middle of the star-shaped cross section of the deflection unit. Alternatively, all the mirrors necessary for the deflection can be combined and designed as a complex prism with star-shaped side surfaces. The prism can, for example, consist of a plurality of individual prisms that are glued or contact-bonded to one another.

[0113] To illustrate the advantages provided by this dual-reflection deflection unit compared to the prior art, Figures 11A to 11C Three folding situations are shown for comparison. Fig.11A A "classical" folding in a catadioptric projection lens with a single concave mirror CM is shown. A first deflecting mirror FS1, which reflects radiation from the object plane OS to the concave mirror CM, is located on the side of the part of the optical axis perpendicular to the object plane and the image plane facing away from the concave mirror. The same applies to the second deflecting mirror, which deflects the rays from the concave mirror into the third lens part.

[0114] If two fields are to be used simultaneously, the fold mirrors of each field will block the corresponding beam path of the opposite field. Therefore, imaging of only a single field is possible.

[0115] In order to allow (simultaneous) imaging of both fields, the deflection unit should be located on the side of the optical axis facing the associated horizontal arm or concave mirror. Fig. 11B An attempt at an implementation using a conventional flat mirror is shown. Fig. 11B In the folding variant in , the folding mirror FS reflects in each case in the other direction, i.e. the concave mirror is located on the side opposite to the effective object field. In this case, the folding mirrors are arranged in their own beam path. As a result, there is no functioning system.

[0116] Fig. 11B and 11C The difference lies in the fact that: Fig. 11C The light in is located at the first deflection unit on the left side (on the object side) of the optical axis of the horizontal arm (OA2), and after reflection at the concave mirror is located at the second deflection unit on the right side (on the image side) of OA2. Fig. 11BAs a result, the second deflection unit will have to be to the left of the first deflection mirror (ie closer to the object plane) and thus in the beam path object - first deflection mirror.

[0117] Fig. 11C A folding with two deflection mirrors per 90° deflection is shown for comparison, ie with a two-stage reflective deflection unit according to an exemplary embodiment of the invention. It can be seen that in this way a separation of the beam paths to the individual concave mirrors can be achieved.

[0118] Some practical advantages of a dual-field projection lens are explained below. By the possibility of exposing two off-axis fields simultaneously, an increase in the throughput (parts exposed per unit time) can be achieved. In the projection lens, this is achieved in particular by two catadioptric partial lenses being contained in the second lens part, i.e. in two horizontal arms, each arm containing a concave mirror. The lens part containing the concave mirror is symmetrical with respect to a symmetry plane. The axis of symmetry is an imaginary line extending through the optical axis OA and parallel to the broadside of the effective image field.

[0119] The field distance ABBF of the two effective image fields in the scanning direction (y direction) is ideally such that the sum of the slit width (A*) of one field and the distance between the two fields corresponds exactly to the width of the stepper field (see Figure 2 The situation in which the object scene is shown).

[0120] The double field can be used for double exposure scanning or by means of a step-and-scan method.

[0121] In the first case, two identical structures have to be arranged next to each other on the reticle or mask. During scanning, the substrate (e.g. a wafer) is exposed in rapid succession by a first field with the first structure and then by a second field with the second identical structure. During normal scanning, areas at the far periphery of the wafer are exposed only once. This can be prevented if the scan is started with some overflow. It is conceivable that the second image field is blocked in the overflow area.

[0122] In the second case, two different structures can also be arranged next to each other on the reticle, which can be combined to form a structure that is twice as large. The necessary step-and-scan operation will then scan both fields and then jump to the next double field in a stepping step.

[0123] The following figures are used to explain some special features of scanning. Fig. 12A A schematic top view of a wafer is shown on which a number of directly adjacent rectangular exposure unit dies (die) having the current standard dimensions of 26 mm wide and 32 mm long are provided. Fig. 12A and Fig. 12BThe enlarged section in Figure 1 shows a typical conventional scanning operation. The wafer is bent under the projection lens or the image field or scanning slit used for exposure. There are two different states. Fig. 12A , 12B In the scanning phase, which is shown in solid lines in FIG, the substrate and mask or wafer and reticle are moved at a uniform and adapted speed (depending on the imaging scale of the projection lens) and the die is exposed. After each scanning operation, a change of direction occurs, which is Fig. 12A , 12B This stops the movement of the mask while the wafer is moving. The movement consists of a deceleration phase, a movement perpendicular to the scanning direction, and then an acceleration in the opposite direction. There is no exposure during the change of direction, so this phase is not productive. Fig. 12A , 12B The temporal sequence of the two phases is schematically shown.

[0124] For comparison, Fig. 13B Different phases of a scanning operation are shown with the aid of a projection exposure apparatus having a double field and two rigidly coupled scanning slits, the scanning slits having Fig.13A The geometry schematically shown in . It is obvious that the scanning phase now extends over the length of two immediately consecutive dies, so that both dies can be exposed simultaneously during the scanning phase. Compared to the scanning phase, unproductive changes of direction occur only half as often as in classical scanning operation, because in classical operation the change of direction occurs after scanning the die, while in the case of the double field the change of direction occurs only after scanning both dies.

[0125] In order to achieve this type of scanning, Fig.13A Two scanning slits or effective image fields in the exemplary embodiment are arranged.

[0126] In terms of reticle and wafer movement, scanning operation with double exposure corresponds to scanning operation with a single field. In each case one die is exposed the first time and the adjacent die is exposed the second time. The difference from scanning operation with a single field is that at the top and bottom periphery of the wafer, the illumination of one of the two fields must be switched off so that it is not exposed beyond the periphery of the wafer.

[0127] The previous example shows that two-stage folding at two deflection units per projection beam path allows the use of a dual field. There are other potential uses and advantages over a single fold. One example is avoiding the so-called "image flip" with a catadioptric projection lens having a single concave mirror and two intermediate images.

[0128] Such projection lenses offer advantages, for example in terms of correction of chromatic aberrations, but have the disadvantage of producing an "image flip" during imaging. This means that features described in the right-handed coordinate system on the reticle are described with the left-handed coordinate system in the image plane. This unfavorable property results from the fact that at each intermediate image and at each reflection the handedness changes between the object plane and the image plane. If the sum of the number of intermediate images and the number of reflections is an odd number, the result is an image flip. If the sum is an even number, an image flip is avoided. This will be used hereinafter according to Fig.11A The classic projection lens and Fig.14 A comparison between the projection lenses PO-X is explained.

[0129] Fig.14 A cross section through the lens elements of a catadioptric projection lens PO-X is shown, which images an effective object field in an object plane located outside the optical axis into an off-axis effective image field in an image plane. Two real intermediate images IMI1-X and IMI2-X are generated between the object plane and the image plane. The projection lens has a single concave mirror with an upstream negative group to support the correction of chromatic aberrations. A first deflection unit ULE1-X directs radiation from the object plane in the direction of the concave mirror. A second deflection unit ULE2-X directs radiation reflected by the concave mirror in the direction of the image plane. While the second deflection unit is formed by a simple plane mirror and causes a single reflection, the first deflection unit ULE-X is designed as a two-stage reflective deflection unit. The latter has a first reflection surface RF1-X, which deflects radiation from the object in the direction of a subsequent second reflection surface RF2-X. The latter then reflects the radiation in the direction of the concave mirror. The two reflective surfaces can then be arranged on separate individual mirrors; preferably, they are formed on a common carrier element in order to fix their mutual orientation. There are two intermediate images and a total of four reflections between the object plane and the image plane, so that the sum of the intermediate images and the reflections is an even number. Thus, the image flipping present in conventional systems of this type is avoided (see Fig.11A ). Alternatively, the first deflection unit can be single-stage and the second deflection unit can be two-stage. As in the classical system, the deflection mirrors are each arranged in the optical vicinity of the associated intermediate image, ie in the near field region.

[0130] The use of a two-stage reflective deflection unit of the type described in the present application is not limited to the exemplary embodiments. Such a deflection unit can also be used in projection lenses that produce only an intermediate image between the object plane and the image plane or produce direct imaging without an intermediate image. It is possible that the two-stage reflective deflection unit is arranged in the projection beam path behind an upstream plane mirror and / or in front of a downstream deflection mirror.

[0131] The following table summarizes the specifications of two exemplary embodiments. Tables 1 and 1A apply to NA = 0.3 Fig. 9 2A apply to an exemplary embodiment not shown in the image with NA=0.28 and no positive lens element in the dual-pass beam path between the deflection unit and the concave mirror.

[0132] These tables summarize the specifications of the corresponding designs in tabular form. The "SURF" column indicates the number of the refractive surface or surfaces with different characteristics, the "RADIUS" column indicates the radius r of the surface (in mm), the "THICKNESS" column indicates the distance d of the surface from the next surface (in mm), and the "MATERIAL" column indicates the material of the optical component. The "INDEX1", "INDEX2" and "INDEX3" columns indicate the refractive index of the material at wavelengths of 365.5 nm (INDEX1), 364.5 nm (INDEX2) and 366.5 nm (INDEX3). The "SEMIDIAM" column indicates the available free radius or semi-free optical diameter of the lens element or optical element (in mm). The radius r = 0 (in the "RADIUS" column) corresponds to a plane surface. Some optical surfaces are aspherical. Tables with the suffix "A" indicate the corresponding aspherical surface data, where the aspherical surface is calculated according to the following rules:

[0133]

[0134] The reciprocal value of the radius represents the surface curvature, and h represents the distance of the surface point from the optical axis (i.e., the ray height). Therefore, p(h) indicates the sag height, i.e., the distance of the surface point from the surface vertex in the z direction (the direction of the optical axis). The coefficients K, C1, C2, C2, ...., are shown in the table with the suffix "A".

[0135] Table 1

[0136]

[0137]

[0138] Table 1A

[0139]

[0140] Table 3

[0141]

[0142] Table 3A

[0143]

Claims

1. An illumination system (ILL) for a microlithography projection exposure apparatus for illuminating a pattern arranged in the region of an object plane (OS) of a downstream projection lens (PO) with illumination light generated from light from a primary light source (LS), in, The illumination system is designed as a dual-field illumination system for receiving a single light beam from the primary light source (LS) and for generating two illumination light beams (BS1, BS2) from the single light beam, wherein a first illumination light beam (BS1) can be guided along a first illumination light beam path to a first illumination field (ILF1), the first illumination field (ILF1) being arranged outside the optical axis of the projection lens in an exit plane (ES) of the illumination system, and simultaneously a second illumination light beam (BS2) can be guided along a second illumination light beam path to a second illumination field (ILF), the second illumination field (ILF) being arranged opposite to the first illumination field (ILF1) with respect to the optical axis (AX) and being located outside the optical axis in the exit plane, include: a refractive pupil shaping unit (PFU) for receiving light from said primary light source (LS) and for generating a two-dimensional intensity distribution in a pupil shaping surface (PUP) of said illumination system, and A refractive field shaping system (FFS), which is optically downstream of the pupil shaping unit, comprises a homogenization unit (HOM), which is used to homogenize the light received from the pupil shaping unit and to split the illumination light into the first illumination beam (SB1) and the second illumination beam (SB2).

2. The lighting system according to claim 1, characterized in that The homogenization unit (HOM) comprises an integrator rod arrangement (ISA), the integrator rod arrangement (ISA) having an incident integrator rod (IE) with an incident surface (EF1) and an exit surface (AF1), and a first exit integrator rod (IA1) optically coupled to a first partial surface (TF1) of the exit surface (AF1), and a second exit integrator rod (IA2) optically coupled to a second partial surface (TF2) of the exit surface (AF1), wherein an exit surface (AF2-1) of the first exit integrator rod is assigned to the first illumination field (ILF1), and an exit surface (AF2-2) of the second exit integrator rod is assigned to the second illumination field (ILF2).

3. The lighting system according to claim 2, characterized in that The incident integrator rod (IE) and the exit integrator rod (IA1, IA2) each have a constant cross-sectional shape and cross-sectional size in the axial direction, and arranged between the exit surface of the incident integrator rod and each incident surface of the exit integrator rod is a prism device (PA) for deflecting the light beam from a position close to the axis to a position away from the axis, located at a certain distance from the optical axis (AX).

4. The lighting system according to claim 2 or 3, characterized in that: The first exit integrator rod (IA1) and the second exit integrator rod (IA2) are formed as tapered integrators in which the cross-sectional size decreases continuously from the inlet side to the outlet side.

5. The lighting system according to claim 1, characterized in that: the homogenizing unit (HOM) having a first grid arrangement (RA1) having first refractive grid elements (RE1) for receiving light of the two-dimensional intensity distribution and for generating a grid arrangement of secondary light sources (SL1, SL2, ...), and a downstream second grid arrangement (RA2) having second refractive grid elements (RE2) for receiving light from the secondary light sources (SL1, SL2) and for at least partially superimposing the light from the secondary light sources in the exit plane, wherein each first grid element (RE1) generates an optical channel, and each of the second grid elements (RE2) is assigned to two adjacent first grid elements (RE1) and is formed by a lens element having a first portion (AB1) located in the first optical channel and a second portion (AB2) located in the second optical channel, and the portions have different surface shapes.

6. The lighting system according to claim 5, characterized in that First grid elements (RE1) adjacent in one direction are alternately assigned to the first illumination field (ILF1) and the second illumination field (ILF2).

7. The lighting system according to claim 5 or 6, characterized in that: At least one surface of the lens elements of the second grid arrangement (RA2) is aspherically curved, wherein preferably the entrance surface and the exit surface are aspherically curved.

8. The lighting system according to claim 5, 6 or 7, characterized in that: A flexure curve extends between the first portion (AB1) and the second portion (AB2) on at least one surface of the lens elements of the second grid arrangement (RA2).

9. A projection exposure apparatus for exposing a radiation-sensitive substrate arranged in the region of an image plane of a projection lens with at least one image of a pattern of a mask arranged in the region of an object plane of the projection lens, comprising: an illumination system (ILL) for receiving light from a single light source and for shaping illumination radiation, said illumination radiation illuminating a first effective object field, which is arranged in the object plane outside the optical axis of the projection lens, and said illumination radiation simultaneously illuminating a second effective object field, which is arranged opposite the first object field, which is arranged in the object plane outside the optical axis; a projection lens configured to image the first effective object field into a first effective image field located in the image plane outside the optical axis along a first projection beam path, and simultaneously to image the second effective object field into a second effective image field located in the image plane outside the optical axis along a second projection beam path; means for holding the mask between the illumination system and the projection lens such that the pattern is arranged in the region of an object plane of the projection lens; means for holding the substrate such that the radiation-sensitive surface of the substrate is arranged in the region of an image plane of the projection lens, It is characterized in that A lighting system as claimed in any one of claims 1 to 8 is formed.

10. The projection exposure apparatus according to claim 9, characterized in that The projection lens is a catadioptric projection lens having a plurality of optical elements, the optical elements comprising lens elements and a concave mirror (CM) and arranged along an optical axis (OA) between the object plane (OS) and the image plane (IS), wherein preferably, Each projection beam path comprises a first deflection unit (ULE1) for deflecting radiation from the object plane (OS) to a concave mirror and a second deflection unit (ULE2) for deflecting radiation from the concave mirror in the direction of the image plane (IS); The optical element forms a first lens portion (OP1), a second lens portion (OP2) and a third lens portion (OP3), the first lens portion (OP1) being used to image each effective object field (OF1, OF2) of the object plane into a first real intermediate image (IMI1), the second lens portion (OP2) being used to generate a second real intermediate image (IMI2) using radiation from the first lens portion (OP1), the third lens portion (OP3) being used to image the second real intermediate image (IMI2) into the image plane (IS), and the concave mirror (CM) of the projection beam path is arranged in the region of a pupil plane (P2) between the first intermediate image and the second intermediate image, the first deflection unit (FM1) is arranged in the optical vicinity of the first intermediate image (IMI1), and the second deflection unit (FM2) is arranged in the optical vicinity of the second intermediate image (IMI2), and / or Arranged in the projection beam path is at least one two-stage reflection deflection unit, which includes a first reflection surface (RF1) and a subsequent second reflection surface (RF2), wherein the first reflection surface (RF1) is arranged to deflect radiation from the object plane (OS) to the second reflection surface (RF2), and the second reflection surface (RF2) is arranged to deflect radiation from the first reflection surface in the direction of the image plane (IS).

11. A projection exposure method for exposing a radiation-sensitive substrate with at least one image of a pattern of a mask, comprising the following steps: providing a pattern between an illumination system of a projection exposure apparatus and a projection lens such that the pattern is arranged in the region of an object plane of the projection lens; holding the substrate such that the radiation-sensitive surface of the substrate is arranged in the region of an image plane of the projection lens optically conjugate to the object plane; illuminating two illumination areas of the mask with illumination radiation from a single primary light source provided by the illumination system; wherein two illumination light beams (BS1, BS2) are generated, wherein a first illumination light beam (BS1) is guided along a first illumination light beam path to a first illumination field (ILF1), which is arranged in an exit plane (ES) of the illumination system and outside the optical axis of the projection lens, and simultaneously a second illumination light beam (BS2) is guided along a second illumination light beam path to a second illumination field (ILF), which is located opposite the first illumination field (ILF1) relative to the optical axis (AX) and outside the optical axis in the exit plane; projecting the portion of the pattern located in the illumination field onto a designated image field on the substrate by means of the projection lens, Therein, an illumination system as claimed in any one of claims 1 to 8 and / or a projection exposure apparatus as claimed in any one of claims 9 or 10 is used.

Images