EP4222540A1

EP4222540A1 - Digital micromirror device for an illumination optical component of a projection exposure system

Info

Publication number: EP4222540A1
Application number: EP21785834.9A
Authority: EP
Inventors: Michael Patra
Original assignee: Carl Zeiss SMT GmbH
Current assignee: Carl Zeiss SMT GmbH
Priority date: 2020-09-30
Filing date: 2021-09-28
Publication date: 2023-08-09
Also published as: US20230221649A1; KR20230074272A; CN116249919A; WO2022069426A1; DE102020212351A1

Abstract

The invention relates to a digital micromirror device (23d) which is part of an illumination optical component (22) of a projection exposure system for projection lithography. A multiplicity of micromirrors (23a) are arranged in groups in a plurality of mirror modules (23b) which each have a rectangular module boundary (23c). The mirror modules (23b) are arranged in module columns (26). At least some of the module columns (26) are shifted in relation to one another along a column borderline (27) in such a way that at least some of the mirror modules (26i, 26i+1) which are mutually adjacent via the borderline (27) are shifted in relation to one another. This causes the module boundary sides (28) thereof extending transversely to the borderline (27) to not be aligned with one another. This results in a digital micromirror device which can be produced with maximum standardisation and, in the event that the digital micromirror device is the last illumination optical component before a reflective object to be illuminated, a smallest possible reflection fold angle can be implemented on the object.

Description

Micromirror array for an illumination-optical component of a projection exposure system

The present patent application claims the priority of German patent application DE 10 2020 212 351.9, the content of which is incorporated herein by reference.

The invention relates to a micromirror array for an illumination-optical component of a projection exposure system. The invention also relates to an optical illumination component with such a micromirror array, an optical assembly with such an optical illumination component, illumination optics with such an illumination optical component or with such an optical assembly, an optical system with such illumination optics, an illumination system with a such illumination optics or with such an optical system, a projection exposure system for projection lithography with such an illumination system, a method for producing a micro- or nano-structured component using such a projection exposure system, and a micro- or nano-structured component produced with such a method.

A micromirror array of the type mentioned at the outset is known from WO 2015/028 451 A1, WO 2013/167 409 A1 and WO 2009/100 856 A1.

It is an object of the present invention to develop a micromirror array for an illumination-optical component of a projection exposure system of the type mentioned in such a way that on the one hand a production of the micromirror array that is as standardized as possible is possible, on the other hand with the micromirror array in the event that this represents a last illumination-optical component in front of a reflective object to be illuminated, the smallest possible reflection folding angle on the object can be realized.

According to the invention, this object is achieved by a micromirror array having the features specified in claim 1 and by a micromirror array having the features specified in claim 2 .

According to the invention, it was recognized that conflicting requirements, namely on the one hand moving away from allowing boundary lines between mirror modules to run parallel to an object displacement direction, as was recognized in WO 2015/028 451 A1 and WO 2013/167 409 A1 and on the other hand standardized production of a micromirror array, which is necessary due to the production costs, can be reconciled with one another in such a way that only an advantageously small overhang between sections of the mirror module not used for reflection and a boundary of the micromirror array can be realized.

For this purpose, according to claim 1, the module columns in which the mirror modules are arranged are shifted relative to one another in such a way that, on the one hand, the micromirror array can reflect a predetermined total illumination light bundle, and on the other hand, despite a regularly necessary tilting of the mirror modules to an object displacement direction, there is no overhang used mirror module sections to enable small reflection fold angles is not undesirably large. In particular, this makes it possible to use the micromirror array as part of an illuminated optical component that is used as the last component in front of a reflective object to be illuminated, so that due to the small overhang of the sections of the mirror modules not used for reflection, a small reflection fold angle on the object, i.e. an angle of incidence of illumination light close to a vertical incidence on the object , is realizable. Such a small reflection fold angle enables, for example, a small angle of incidence of the illumination light on the reflecting object, for example in the range of 2° and 8°.

According to claim 2, a displacement of the module columns along the boundary line can be less than half an extension of the respective mirror module along the boundary line and can be, for example, less than 50%, less than 40%, less than 30%, less than 20% or even less than 10% than the mirror module extension along the boundary line. The shift is regularly greater than 1% of the extension of the respective mirror module along the boundary line.

In these configurations of the micromirror array, some or all of the module columns of the micromirror array that are adjacent to one another can be shifted relative to one another. This also makes it possible, in particular, to use the micromirror array as part of an illumination-optical component that is used as the last component in front of a reflective object to be illuminated, with the smallest possible reflection fold angle on the object, i.e. an angle of incidence of illumination light close to a vertical incidence , is realizable. Such a small angle of incidence, which can be in the range between 2° and 8°, for example, has proven to be advantageous in particular for illuminating mask structures of lithography masks that are used in projection lithography. The mirror modules of the micromirror array can have square borders. Alternatively or additionally, the micromirror array can also be equipped with rectangular, non-square mirror modules. An arrangement of the mirror modules, in which the module columns are shifted relative to one another, can take place in a non-Cartesian grid.

As a rule, the module columns each have several mirror modules. Individual module columns can also have exactly one mirror module. Depending on the design, all module columns can also have several mirror modules. The number of mirror modules per module column can be in the range between 1 and 100, in the range between 1 and 75, in the range between 1 and 65 and in the range between 2 and 50, for example.

The above object is also achieved according to the invention by a micromirror array for an illumination-optical component of a projection exposure system for projection lithography, comprising a multiplicity of micromirrors which are arranged in groups in a multiplicity of mirror modules, the mirror modules each having a rectangular module boundary, with the mirror modules are arranged in module columns, with at least some of the module columns being shifted relative to one another along a column boundary line in such a way that at least some of the mirror modules bordering one another across the boundary line are arranged shifted relative to one another, so that their module boundary sides running transversely to the boundary line are not aligned with each other, with the micromirror array being arranged on a carrier, wherein the carrier has a near boundary side which is closest to an arrangement area of the mirror modules of the micromirror array on the carrier, wherein at least one of the boundary lines between the module columns encloses a smallest angle with a normal on a carrier boundary direction of the near boundary side, which is less than 45°.

This configuration of the micromirror array can be combined with features of the other configurations of the micromirror arrays discussed above.

The micromirror array can be part of an illumination-optical component, in particular part of a facet mirror. In the beam path from the illumination light, the illumination-optical component can be the last component in front of an object to be illuminated.

The illumination-optical component can be part of an optical assembly, which includes an object holder for holding a lithography mask in an object field, wherein the object holder can be displaced along a displacement direction via an object displacement drive. At least one of the boundary lines between the module columns of the micromirror array can enclose a smallest angle with the displacement direction, which is in the range between 0° and 90° and which is in particular smaller than 45°.

The illumination-optical component or the optical assembly can be part of an illumination optics for transferring the illumination light into an object field in which an object to be imaged can be arranged. The illumination optics can be part of an optical system to which additional Lich includes a projection optics for imaging the object field in an image field in which a wafer can be arranged.

A partition can be arranged between the illumination optics and the projection optics, which is used in particular for the thermal separation of the components of the illumination optics and the components of the projection optics. The angular relationship between the boundary lines and the module columns of the micromirror array and the normal on the carrier boundary direction of the near boundary side leads in particular when the micromirror array is the last optical component in the beam path of illumination or imaging light in front of an object to be illuminated is, to the fact that a small reflection fold angle can be realized on the object. An angle of incidence of the illumination light guided by the micromirror array onto the object can be close to the perpendicular incidence in the range, for example, between 2° and 8°.

The illumination system can include a light source for the illumination light.

The illumination system can be part of a projection exposure system, which also has a wafer holder for holding the wafer.

A tilting of the boundary lines to the near boundary side according to claim 3 makes it possible to arrange the boundary lines tilted relative to an object displacement direction of an object to be imaged during operation of the projection exposure system. This smallest angle, which the boundary lines between the module columns enclose with a normal on a carrier boundary direction of the near boundary side, can be unequal to 45°, can be smaller than 45° and can be 37° or 25°, for example be. As a result, the boundary lines between the mirror modules do not run parallel to an object displacement direction as soon as such a micromirror array is mounted.

The advantages of the illumination result, in particular the scan-integrated averaging effects, which have already been discussed in particular in WO 2013/167 409 A1.

An arrangement of the mirror modules according to claim 5 additionally simplifies the production of the micromirror array. Alternatively, the arrangement of the mirror modules can also be non-periodic.

The advantages of an illumination-optical component according to claim 6 correspond to those which have been explained above with reference to the micromirror array.

The advantages of an optical assembly according to claim 7 correspond to those that have already been explained above in connection with claim 3 in particular. The smallest angle between at least one of the boundary lines and the object displacement direction may not be equal to 45°, may be smaller than 45° and may be 37° or 25°, for example.

The advantages of an illumination optics according to claim 8 correspond to those that have already been explained above in connection with the micromirror array or the optical assembly. The micromirror array can be a second faceted element of a specular reflector of the illumination optics or can represent a pupil facet mirror of the illumination optics. The advantages of an optical system according to claim 9, an illumination system according to claim 10, a projection exposure system according to claim 11, a manufacturing method according to claim 12 and a micro- or nano-structured component according to claim 13 correspond to those already mentioned above with reference to the illumination optics were explained. For example, a semiconductor chip can be produced with an extremely high integration density, in particular with a very high storage density.

At least one exemplary embodiment of the invention is described below with reference to the drawing. Show in the drawing:

1 shows a schematic meridional section of a projection exposure system for EUV projection lithography;

Fig. 2 is a plan view of mirror modules of a second faceted mirror or second facet mirror of an illumination optics of the projection exposure system according to Fig. 1, seen from viewing direction II in Fig. 1, with a partition wall between the illumination-optical and projection-optical components of the projection exposure system also being shown and with a edge contour of an envelope of a total bundle of illumination light is drawn, which is reflected with micromirrors of the mirrors of the second facetted element, the second facetted mirror being designed as a specular reflector; FIG. 3 shows a further embodiment of a mirror module arrangement of the second faceted mirror in a representation similar to FIG. 2; FIG.

FIG. 4 shows a further embodiment of a mirror module arrangement of the second faceted mirror in a representation similar to FIG. 2; FIG.

FIG. 5 shows a further embodiment of a mirror module arrangement of the second faceted mirror in a representation similar to FIG. 2; FIG.

FIG. 6 shows the embodiment according to FIG. 5, with reflection of an alternative overall bundle edge contour of the illumination light;

FIG. 7 shows a further embodiment of a mirror module arrangement of the second faceted mirror in a representation similar to FIG. 2; FIG.

FIG. 8 shows the mirror module arrangement according to FIG. 5 together with a carrier component of the second faceted mirror for the mirror modules; and

9 shows the embodiment according to FIG. 5, with reflection of an alternative overall bundle edge contour of the illumination light, with the second facetted mirror being designed as a pupil facet mirror. The essential components of a projection exposure system 1 for microlithography are described below by way of example, initially with reference to FIG. The description of the basic structure of the projection exposure system 1 and its components should not be understood as limiting here.

One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a radiation source or light source 3, illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case the lighting system does not include the light source 3 .

A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8 . The reticle holder 8 can be displaced via a reticle displacement drive 9, in particular in a scanning direction.

A Cartesian xyz coordinate system is drawn in for explanation in FIG. 1 and also in the following figures. The x-direction runs perpendicular to the plane of the drawing. The y-direction is horizontal and the z-direction is vertical. In FIG. 1, the scanning direction runs along the y-direction. The z-direction runs perpendicular to the object plane 6.

The projection exposure system 1 includes a projection optics 10. The projection optics 10 is used to image the object field 5 in an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle different from 0° between the object plane 6 and the image plane 12 is also possible.

A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12 . The wafer 13 is held by a wafer holder 14 . The wafer holder 14 can be displaced in particular along the y-direction via a wafer displacement drive 15 . The displacement of the reticle 7 via the reticle displacement drive 9 on the one hand and the wafer 13 on the other hand via the wafer displacement drive 15 can be synchronized with one another.

The radiation source 3 is an EUV radiation source. The radiation source 3 emits in particular EUV radiation 16, which is also referred to below as useful radiation, illumination radiation or illumination light. In particular, the useful radiation has a wavelength in the range between 5 nm and 30 nm. The radiation source 3 can be a plasma source, for example an LPP source (laser produced plasma, plasma generated with the aid of a laser) or a DPP Source (Gas Discharged Produced Plasma). It can also be a synchrotron-based radiation source. The radiation source 3 can be a free-electron laser (free-electron laser, FEL).

The illumination radiation 16 emanating from the radiation source 3 is bundled by a collector 17 . The collector 17 can be a collector with one or more ellipsoidal and/or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be in grazing incidence (Grazing Incidence, Gl), ie with incidence angles greater than 45°, or in normal incidence (Normal Incidence, NI), ie with angles of incidence smaller than 45°, are exposed to the illumination radiation 16 . The collector 17 can be structured and/or coated on the one hand to optimize its reflectivity for the useful radiation and on the other hand to suppress stray light.

After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

The illumination optics 4 includes a deflection mirror 19 and a first facet mirror 20 downstream of this in the beam path. Alternatively or additionally, the deflection mirror 19 can be designed as a spectral filter, which separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 which is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 includes a multiplicity of individual first facets 21, which are also referred to below as field facets. Some of these facets 21 are shown in FIG. 1 only by way of example.

The first facets 21 can be embodied as macroscopic facets, in particular as rectangular facets or as facets with curved shaped or partially circular edge contour. The first facets 21 can be embodied as planar facets or alternatively as convexly or concavely curved facets.

As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can each also be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 can be embodied in particular as a microelectromechanical system (MEMS system). Reference is made to DE 10 2008 009 600 A1 for details.

The illumination s radiation 16 runs horizontally between the collector 17 and the deflection mirror 19, ie along the y-direction.

A second facet mirror 22 is arranged downstream of the first facet mirror 20 in the beam path of the illumination optics 4 . The second facet mirror 22 can be arranged at a distance from a pupil plane of the illumination optics 4 . In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006/0132747 A1, EP 1 614 008 B1 and US Pat. No. 6,573,978. If the second facet mirror 22 is alternatively arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror.

The second facet mirror 22 includes a plurality of second facets 23. The second facets 23 are composed of micro-mirrors 23a (see FIG. 2) mirror modules 23b, each having a have rectangular, namely in this case square, module boundary 23c.

The arrangement of the mirror modules 23b of the second facet mirror 22 results in a micromirror array 23d. The mirror modules 23b and their arrangement are explained in more detail below. Reference is also made to DE 10 2008 009 600 A1 with regard to an embodiment of the second facets 23 as micromirrors. The second facets 23 or groups of these second facets are also referred to as pupil facets in the case of a pupil facet mirror.

The second facets 23 can have plane or alternatively convexly or concavely curved reflection surfaces.

The illumination optics 4 thus forms a double-faceted system. This basic principle is also known as a honeycomb condenser (Fly's Eye Integrator).

It can be advantageous not to arrange the second facet mirror 22 exactly in a plane which is optically conjugate to a pupil plane of the projection optics 7 when it is designed as a pupil facet mirror. In particular, the pupil facet mirror 22 can be arranged tilted with respect to a pupil plane of the projection optics 7, as is described, for example, in DE 10 2017 220 586 A1.

In the embodiment as a pupil facet mirror, the individual first facets 21 are imaged in the object field 5 with the aid of the second facet mirror 22 . The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5.

In a further embodiment of the illumination optics 4 (not shown), transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to the imaging of the first facets 21 in the object field 5. The transmission optics can have exactly one mirror, but alternatively also have two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4 . The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirror, normal incidence mirror) and/or one or two mirrors for grazing incidence (Gl mirror, gracing incidence mirror).

In the embodiment shown in FIG. 1, the illumination optics 4 has exactly three mirrors after the collector 17, namely the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and transmission optics in the object plane 6 is generally only an approximate imaging. The projection optics 10 includes a plurality of mirrors Mi, which are numbered consecutively according to their arrangement in the beam path of the projection exposure system 1 .

In the example shown in FIG. 1, the projection optics 10 includes six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or another number of mirrors Mi are also possible. The projection optics 10 are doubly obscured optics. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and which, for example, is 0.7 or 0.75.

Reflection surfaces of the mirrors Mi can be designed as free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optics 4, the mirrors Mi can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

The projection optics 10 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction can be something like this be as large as a z-distance between the object plane 6 and the image plane 12. The projection optics 10 can in particular be anamorphic. In particular, it has different image scales β _x , β _y in the x and y directions. The two magnifications ß _x , ß y of the projection optics 10 are preferably at (ß _x , ß _y ) = (+ / - 0.25, / + - 0.125). A positive image scale ß means an image without image reversal. A negative sign for the imaging scale ß means imaging with image reversal.

The projection optics 7 thus leads to a reduction in the ratio 4:1 in the x-direction, that is to say in the direction perpendicular to the scanning direction.

The projection optics 10 leads to a reduction of 8: 1 in the y-direction, i.e. in the scanning direction.

Other imaging scales are also possible. Image scales with the same sign and absolutely the same in the x and y directions, for example with absolute values of 0, 125 or 0.25, are also possible.

The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, can be different. Examples of projection optics with different numbers of such intermediate images in the x and y directions are known from US 2018/0074303 A1.

In each case one group of micromirrors 23a of the second facets 23 is assigned to precisely one of the first facets 21 in order to form a respective illumination channel for illuminating the object field 5 . In particular, this can result in lighting based on the Köhler principle result. The entire bundle of illumination radiation 16 is broken down into a large number of object fields or object field sections 5 with the aid of the first facets 21 .

In the configuration of the illumination optics 4 with a field facet mirror 20 and a pupil facet mirror 22, the first facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to them. The field facets 21 are each superimposed by an assigned pupil facet 23 to illuminate the object field 5 imaged onto the reticle 7.

In particular, the illumination of the object field 5 is as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

The illumination of the entrance pupil of the projection optics 10 can be defined geometrically by arranging the second facets. The intensity distribution in the entrance pupil of the projection optics 10 can be set by selecting the illumination channels, in particular the subset of the second facets that guide light. This intensity distribution is also referred to as illumination setting or illumination pupil filling.

A likewise preferred pupil uniformity in the area of defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels. Further aspects and details of the illumination of the object field 5 and in particular the entrance pupil of the projection optics 10 are described below.

The projection optics 10 can in particular have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

The projection optics 10 may have different positions of the entrance pupil for the tangential and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7 . With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

In the arrangement of the components of the illumination optics 4 shown in FIG. 1, the second facet mirror 22 is arranged in a surface conjugate to the entrance pupil of the projection optics 10 . The first facet mirror 20 is arranged tilted to the object plane 5 . The first facet mirror 20 is tilted relative to an arrangement plane that is defined by the deflection mirror 19 .

The first facet mirror 20 is tilted relative to an arrangement plane that is defined by the second facet mirror 22 .

Between the illumination optics 4 and the projection optics 10 there is a partition 24 shown in sections in FIG. nents of the illumination optics 4 from the components of the projection optics 10 is used.

FIG. 2 shows a plan view of an arrangement of the mirror modules 23b of the second facet mirror 22. The partition wall 24 adjacent to this mirror module arrangement is also shown, which is only very slightly spaced from the mirror modules 23b in the y-direction. Figures 2 et seq. show an exemplary number of mirror modules 23b to clarify details of their positional relationship. In the case of a second facet mirror used in practice, of the type of the second facet mirror 22, the number of mirror modules 23b can be very much larger.

Furthermore, an edge contour 25 of an envelope of an entire bundle of the illumination light 16 on the second facet mirror 22 is shown in FIG. The mirror modules 23b are arranged in such a way that the entire interior of this edge contour 25 is covered with the micromirrors 23a.

The edge contour 25 results when the illumination optics 4 are designed as specular reflectors as a folding of a boundary shape of the object field 5 with a boundary shape of the illumination pupil of the illumination optics 4. In the example according to FIG a stadium shape of the edge contour 25 results as a fold. This edge contour 25 is also referred to as the footprint of the illumination light 16 on the second facet mirror 22 .

The micromirrors 23a are combined in groups of thirty-six micromirrors 23a in the mirror modules 23b. Every game gel module 23b is constructed as a 6×6 grid of square micromirrors 23a. Depending on the design of the mirror module 23b, it can have a number of micromirrors 23a in the range between ten and several hundred. The number of micromirrors 23a per mirror module 23b can be in the range between 100 and 1000, in particular between 400 and 900, for example. The mirror module 23b can have a square border as in the embodiments of the second facet mirror according to FIGS. 2 et seq., but can also be designed with a rectangular border, for example.

In the embodiment shown in FIG. 2, the mirror modules 23b are arranged in a total of six module columns 26i, 262, 263, 264, 265 and 260. Between adjacent ones of these module columns 26i, 26i+i there are in each case column boundary lines 27 which run parallel to one another. An angle a between the boundary lines 27 and the y-axis, ie an object displacement direction of the projection exposure system 1, is 25° in the embodiment according to FIG. This angle a can also have another value in the range between 0° and 90°, for example 10°, 37° or 65°. The angle a is regularly not equal to 45°. The smallest angle that the column boundary lines 27 enclose with the y-axis is then less than 45° and can be less than 30°, for example 25°. This angle is regularly greater than 1°, greater than 5° or also greater than 10°.

Depending on the design of the second facet mirror 22, the number of module columns 26i can be in the range between three and one hundred, in particular between 25 and 65.

The second facet mirror 22 has a total of nineteen mirror modules 23b. The respective adjacent module columns 26i, 26i+i are shifted relative to one another along the intermediate boundary line 27 in such a way that the mirror modules of the adjacent module columns 26i, 26i+i bordering one another via this boundary line 27 are arranged shifted relative to one another. In the illustrated embodiment, this displacement is such that module boundary sides 28 running transversely to the intermediate boundary line 27 are not aligned with one another.

In the mirror module arrangement according to FIG. 2, a displacement between the two module columns 26i and 262 arranged on the left is small and amounts to less than an edge length of a micromirror 23a. The two module columns 262, 263 are offset from one another by approximately one micromirror edge length. The module columns 263 and 264 are offset from one another by approximately 2.5 micromirror edge lengths. The module columns 264 and 265 are offset from one another by approximately three micromirror edge lengths. The module columns 26s and 260 are in turn shifted relative to one another by approximately 2.5 micromirror edge lengths. This shift can be less than 50%, less than 40%, less than 30%, less than 20% or even less than 10% of the extent, regardless of the number of micromirrors along the micromirror edge length of a mirror module 23b along the respective boundary line 27 of the mirror module 23b along the boundary line 27. This displacement is generally greater than 1% of the extent of the respective mirror module 23b along the boundary line 27.

Overall, therefore, practically all adjacent module columns 26i, 26i+i in the mirror module arrangement according to FIG. 2 are by individual path lengths shifted from each other, so that a non-periodic grid of the mirror modules 23b is the result.

Due to the displacement of the module columns 26i relative to one another, the arrangement of the mirror modules 23b is an arrangement in a non-Cartesian grid.

The micromirror array 23d is arranged on a carrier 29, the boundary of which is indicated only broken in FIG. The carrier 29 has a near boundary side 30. Compared to other boundary sides of the carrier 29, this is closest to the mirror modules 23b of the micromirror array 23d on the carrier 29, particularly in the top view according to FIG. All other boundary sides of the carrier 29 are therefore at a greater distance from the arrangement of the mirror modules 23b than the near boundary side 30. The boundary lines 27 or at least one of these boundary lines 27 between the module columns 26i, 26i+i closes with a carrier boundary direction x of the near boundary Page 30 a smallest angle ß, which is in the range between 0 ° and 90 °, which is in particular smaller than 90 °. In the case of the arrangement according to FIG. 2, β is 90° - α and is therefore 65°. A normal N on the boundary direction 30 in turn encloses the angle a with the at least one boundary line 27 .

The displacements of the module columns 26i relative to one another are such that, on the one hand, the entire edge contour 32 is covered with as few mirror modules 23b as possible, and on the other hand, unused sections of the mirror modules 23b protrude beyond the edge contour 32 in the direction of the partition wall 24 as little as possible. FIG. 3 shows a further embodiment of a second facet mirror 31, which can be used instead of the second facet mirror 22 according to FIG. 2 in a variant of the illumination optics 4 of the projection exposure system 1 according to FIG. Components and functions that correspond to those that have already been explained above with reference to FIGS. 1 and 2 have the same reference numerals and will not be discussed again in detail.

In the case of the second facet mirror 31, the module column arrangement of the mirror modules 23b is such that an edge contour 32 of an entire bundle of the illumination light 16, which is shaped differently compared to the illumination according to Figure 2, is completely separated from the micromirrors 23a of the mirror modules 23b for guiding the illumination light 16 in the Illumination optics 4 is reflected.

The second facet mirror 31 is used instead of the second facet mirror 22 in an embodiment of the illumination optics 4 of the projection exposure system 1 in which a curved object field 5 is illuminated instead of a rectangular object field. Folding this arcuate object field 5 with the round pupil of the illumination optics 4 leads to an approximately kidney-shaped or bean-shaped edge contour 32. In the embodiment of the illumination optics 4, for which the second facet mirror 31 can be used, the edge contour 32 is from the partition 24 curved away, so that a convex longitudinal side of the edge contour 32 of the partition wall 34 faces.

The second facet mirror 31 has a total of five module columns 26i to 26s. The two module columns 26i and 262 shown on the far left in FIG. 3 are not opposed along the column boundary line 27 between them. nander shifted so that the module boundary sides 28, which run transversely to the boundary line 27, are aligned. The other module columns 263, 264 and 265 are shifted to one another and to the module column 262 along the boundary lines 27 in between, as has already been explained above in connection with the second facet mirror 22 in FIG. Since an x-extension of the kidney-shaped edge contour 32 is somewhat smaller than the x-extension of the beam-line-shaped edge contour 25, one module column 26i less is required for the second facet mirror 31 according to Figure 3 than for the second facet mirror 22.

FIG. 4 shows a further embodiment of a second facet mirror 33, which in turn can be used instead of the second facet mirror 22 or 31 in a further embodiment of the illumination optics 4. Components and functions that correspond to those that have already been explained above with reference to FIGS. 1 to 3 have the same reference numerals and will not be discussed again in detail.

The illumination optics 4, in which the second facet mirror 33 is used, is in turn designed to illuminate an arc-shaped object field 5. The design of the illumination optics 4 on the one hand and the subsequent projection optics 10 on the other hand is such that an edge contour 34 of an entire bundle of the illumination light 16 is again kidney-shaped or bean-shaped as a fold with the round illumination pupil, with a curvature of the edge contour 34 in this case the partition wall 24 is closed, so that in the case of the edge contour 34 a concave contour section on the longitudinal side faces the partition wall 24 . The second facet mirror 33 has five module columns 26i to 26s. In the case of the second facet mirror 33, the adjacent module columns 26i, 26i+i are in turn shifted relative to one another along the respective intermediate column boundary lines 27 in such a way that the most efficient possible occupation of the edge contour 34 with the mirror modules 23b The consequence is, with the secondary condition being that the least possible overhang of unused sections of the mirror modules 23b beyond the edge contour 34 in the direction of the partition wall 24 is present. Like the second facet mirror 31 according to FIG. 3, the second facet mirror 33 has a total of seventeen modules 23b.

In the case of the facet mirror 33, all module columns 26i are in turn shifted to one another in pairs in such a way that the module boundary sides 28 running transversely to the column boundary lines 27 are not aligned with one another.

FIG. 5 shows a further embodiment of a second facet mirror 35, which can be used instead of the second facet mirror 22 according to FIG. Components and functions that correspond to those that have already been explained above with reference to FIGS. 1 to 4 have the same reference numbers and will not be discussed again in detail.

In the case of the second facet mirror 35, the mirror modules 23b are arranged in a periodic grid. The module columns 23b can thus be converted into one another by translation in the x-direction. Due on the one hand to the tilting of the module columns 26i to the Cartesian coordinates xy and on the other hand to the displacement of adjacent module columns 26i, 26i+i along the intermediate column boundary lines 27 in such a way that the module boundary sides 28 running transversely to the respective boundary lines 27 are not aligned with one another, the result is an arrangement of the mirror modules 23b in a non-Cartesian grid.

Shown in solid lines in FIG. 5 are those mirror modules 23b which are required, at least in part, for reflecting the entire bundle of illumination light 16 with the stadium-shaped edge contour 25. Two mirror modules 23b' at the bottom left and at the top right of the module arrangement according to FIG. 5, which belong to the periodic module arrangement per se, are shown in broken lines in FIG. 5 because they do not contribute to the reflection of the illuminating light 16 and could therefore also be omitted.

This displacement is the same between all module columns 26i, 26i+i and is approximately three edge lengths of the micromirrors 23a. The displacement is approximately half the edge length of a mirror module 23b.

In the case of the second facet mirror 35, there are a total of twenty-two mirror modules 23b used for reflection.

FIG. 6 shows a further embodiment of a second facet mirror 36, which can be used instead of the second facet mirror 31 according to FIG. Components and functions that correspond to those that have already been explained above with reference to FIGS. 1 to 5 have the same reference numbers and will not be discussed again in detail. The second facet mirror 36 is designed in accordance with the second facet mirror 35 according to FIG. 5 as a periodic, non-Cartesian grid of the mirror modules 23b. A total of eighteen mirror modules 23b are then required for the complete reflection of the edge contour 32. A maximum overhang of unused sections of the mirror modules 23b beyond the edge contour 32 in the direction of the partition wall 24 is as large in the second facet mirror 36 as in the second facet mirror 31.

FIG. 7 shows a further embodiment of a second facet mirror 37, which can be used, for example, instead of the facet mirror 22 according to FIG. 2 and 35 according to FIG. Components and functions that correspond to those that have already been explained above with reference to FIGS. 1 to 6 have the same reference numerals and will not be discussed again in detail.

In the case of the second facet mirror 37, the column boundary lines 27 run at an angle a of 65° to the y-axis, ie to the direction of object displacement. Correspondingly, the angle β between the column boundary lines 27 and the partition 24 or the near boundary side 30 closest to it is 25°. One direction of the column boundary lines 27 is additionally highlighted by arrows in FIG.

The angle a of 65° is also present between the normal N on the partition wall 24 or on the near boundary side 30 on the one hand and the column boundary lines 27 on the other hand.

The mirror module arrangement is again not periodic in the case of the second facet mirror 37 and also, due to the shift in relation to one another adjacent module columns 26i, 26i+i along the intermediate boundary lines 27, non-Cartesian.

The second facet mirror 37 has a total of eighteen mirror modules 23b, which contribute to the reflection of the illumination light 16 within the edge contour 25 at least in sections.

A maximum projection of unused sections of the mirror modules 23b beyond the edge contour 25 in the direction of the partition wall 24 is greater in the case of the second facet mirror 37 according to Figure 7 than in the case of the second facet mirror 22 according to Figure 2. In this respect, the second facet mirror 22 according to Figure 2 is more advantageous than the second facet mirror 37 according to Figure 7.

FIG. 8 shows the second facet mirror 22 according to FIG. 5, including the carrier 29 for holding the micromirror array 23d.

The carrier 29 is mounted on a frame of the illumination optics 4 (not shown in the drawing) via three retaining bushes 38 . 8 also shows the near edge side 30 of the edge contour of the carrier 29. This near edge side 30 runs parallel to the partition wall 24. The near edge side 30 is, as already explained above in connection with FIG entire edge contour of the carrier 29, which is the mirror modules 23b of the micromirror array 23d of the second facet mirror 22 next adjacent.

FIG. 9 shows the second facet mirror 35 according to FIG. 5 when used as a pupil facet mirror in a corresponding illumination optics 4 of the projection exposure system 1. In this embodiment, an edge contour 39 of the entire bundle of the illumination light 16 has the shape of a used the pupil of the illumination optics 4 and is elliptical in this embodiment of the illumination optics 4 on the pupil facet mirror 35, which can result, for example, from an anamorphic design of the projection optics.

During projection exposure using the projection exposure system 1, at least part of the reticle 7 in the object field 5 is applied to an area of the light-sensitive layer on the wafer 13 in the image field 11 for the lithographic production of a microstructured or nanostructured component, in particular a semiconductor component, for example of a microchip, shown. In this case, the reticle 7 and the wafer 13 can be moved in a time-synchronized manner in the scanning direction y.

Claims

patent claims

1. Micro-mirror array (23 d) for an illumination-optical component (22; 31; 33; 35; 36; 37) of a projection exposure system (1) for projection lithography, comprising a plurality of micro-mirrors (23 a), the groups in a plurality of mirror modules (23b), the mirror modules (23b) each having a rectangular module border (23 c), the mirror modules (23b) being arranged in module columns (26), with at least some of the module columns (26) being so longitudinal a column boundary line (27) are shifted relative to each other, that at least some of the mirror modules (26i, 26i+i) adjoining one another via the boundary line (27) are arranged shifted relative to one another, so that their module boundary Pages (28) are not aligned with one another, the module columns (26) along the column boundary line (27) being shifted from one another in such a way that, on the one hand, the micromirror array (23 d) has a predetermined illumination light-Ges Office bundle can reflect, on the other hand, a projection of sections of the mirror modules (23b), which are not used for reflecting illumination light, is not undesirably large to enable small reflection folding angles.

2. Micromirror array (23d) for an illumination-optical component (22; 31; 33; 35; 36; 37) of a projection exposure system (1) for projection lithography, comprising a multiplicity of micromirrors (23a), which are arranged in groups in a plurality of mirror modules (23b) are arranged, wherein the mirror modules (23b) each have a rectangular module boundary (23 c), wherein the mirror modules (23b) are arranged in module columns (26), with at least some of the module columns (26) facing each other along a column boundary line (27). are shifted, that at least some of the mirror modules (26i, 26i+i) adjoining one another via the boundary line (27) are arranged shifted relative to one another, so that their module boundary sides (28) running transversely to the boundary line (27) are not aligned with one another, wherein the displacement of the module columns (26) shifted relative to one another along the column boundary line (27) is less than half the extension of the respective mirror module (23b) along the column boundary line (27).

3. Micromirror array according to claim 1 or 2, arranged on a carrier (29), wherein the carrier (29) has a near boundary side (30) which has an arrangement area of the mirror modules (23b) of the micromirror array (23a). is closest to the carrier (29), with at least one of the boundary lines (27) between the module columns (26i, 26i+i) making a smallest angle (a) with a normal (N) on a carrier boundary direction of the near boundary side (30) includes, which is in the range between 0 ° and 90 °.

4. Micromirror array according to claim 3, characterized in that at least one of the boundary lines (27) between the module columns (26i, 26i+i) with the normal (N) on the carrier boundary direction of the near boundary side (30) has a smallest Angle (a) includes, which is in the range between 0 ° and 45 °.

5. Micromirror array according to one of claims 1 to 4, characterized in that the mirror modules (23b) are arranged in a periodic, non-Cartesian grid.

6. Illumination-optical component (22; 31; 33; 35; 36; 37) with a micromirror array according to any one of claims 1 to 5.

7. Optical assembly with an illumination-optical component (22; 31; 33; 35; 36; 37) according to claim 6, with an object holder (8) for holding a lithography mask (7) in an object field (5), which has an object displacement drive ( 9) is displaceable along a direction of displacement (y), wherein at least one of the boundary lines (27) between the module columns (26i, 26i+i) encloses a smallest angle (a) with the direction of displacement (y) which is in the range between 0° and 90°.

8. Illumination optics (4) with an illumination-optical component (22; 31; 33; 35; 36; 37) according to claim 6 or with an optical assembly according to claim 7 for transferring illumination light (16) into an object field (5) in which an object (7) to be imaged can be arranged.

9. Optical system with illumination optics according to claim 8 and with projection optics (10) for imaging the object field (5) in an image field (11) in which a wafer (13) can be arranged.

10. Illumination system with illumination optics according to claim 8 or with an optical system according to claim 9 and with a light source (3) for the illumination light (16).

11. Projection exposure system (1) for projection lithography with an illumination system according to claim 10, with an object holder (8) for holding a lithography mask (7) and with a wafer holder (14) for holding a wafer (13).

12. Method for producing a micro- or nano-structured component with the following method steps:

Providing a wafer (13) on which a layer of a light-sensitive material is applied at least partially, providing a reticle (7) which has structures to be imaged,

Providing a projection exposure system (1) according to claim 11,

Projecting at least part of the reticle (7) onto a region of the layer using projection optics (10) of the projection exposure system (1).

13. Component manufactured by means of a manufacturing method according to claim 12.