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CN-121986305-A - Facet mirror suitable for use as a first facet mirror for an illumination optical unit for projection lithography

CN121986305ACN 121986305 ACN121986305 ACN 121986305ACN-121986305-A

Abstract

A facet mirror (6) for an illumination optical unit for projection lithography, which is adapted to use as a first facet mirror such that individual mirror groups of the facet mirror (6) as first facets are imaged with the aid of a transmission optical unit at least into a part of an object field of the illumination optical unit in which an object can be arranged and displaced through the object field in an object displacement direction (y) during a projection exposure. The facet mirror (6) has an array configuration of individual mirror units (26), wherein each of the individual mirror units (26) is implemented as a sub-array of NxM individual mirrors (21). The facet mirror (6) comprises at least two pre-tilt types (32 1 ,32 2 ) of individual mirror units (26). The first pretilt type (32 1 ) comprises an individual mirror unit (26) which in the neutral position has a first pretilt angle relative to a base tilt angle specified by the carrier geometry of the facet mirror (6). The second pre-tilt type (32 2 ) includes individual mirror units (26) having a second pre-tilt angle. The pre-tilt angles of the different pre-tilt types (32 1 ,32 2 ) are different from each other. This results in a facet mirror with relaxed requirements for the tilt actuator system used to tilt the individual mirrors of the facet mirror.

Inventors

  • M. Endries

Assignees

  • 卡尔蔡司SMT有限责任公司

Dates

Publication Date
20260505
Application Date
20240917
Priority Date
20231004

Claims (20)

  1. 1. A facet mirror (6) for an illumination optical unit (11) for projection lithography, which is adapted to be used as a first facet mirror such that an individual mirror group (30) of the facet mirror (6) is imaged as a first facet with the aid of a transmission optical unit (7) at least into a part of an object field (8) of the illumination optical unit (11) in which object field an object (12) can be arranged and which is displaced through the object field (8) in an object displacement direction (y) during a projection exposure, An array configuration with individual mirror units (26), wherein each of the individual mirror units (26) is implemented as a sub-array of NxM individual mirrors (21), At least two pre-tilt types (32 i ) comprising the individual mirror units (26), Wherein the first pretilt type (32 1 ) comprises an individual mirror unit (26) which in the neutral position has a first pretilt angle with respect to a base tilt angle specified by the carrier geometry of the facet mirror (6), Wherein the second pre-tilt type (32 2 ) comprises an individual mirror unit (26) having a second pre-tilt angle in the neutral position with respect to the base tilt angle, Wherein the pre-tilt angles of the different pre-tilt types (32 1 , 32 2 ) differ from each other, -Wherein the pre-tilt angle is in the range between 10 mrad and 500 mrad.
  2. 2. Facet mirror according to claim 1, characterized in that the individual mirror units (26) of one of the pretilt types (32 1 , 32 2 ) are arranged in groups of individual mirror units (26) in at least one continuous mirror surface pretilt type section (34 i ) of the facet mirror (6).
  3. 3. The facet mirror according to claim 2, characterized by a dual or multiple rotationally symmetrical arrangement of mirror surface pretilt type sections (34 i ), wherein different pretilt types of the pretilt types (32 i ) are arranged.
  4. 4. A facet mirror according to claim 2 or 3, characterized in that the respective mirror surface pre-tilt section (34 i ) is imaged by the illumination optics unit (11) along a range of field height coordinates (x) of the facet mirror (6) to field height coordinates (x) of an object displacement coordinate (y) perpendicular to the object field (8), which range is larger than an original image width (x SP ) of the object field (8) on the facet mirror (6) along the field height coordinates (x).
  5. 5. Facet mirror according to one of claims 2 to 4, characterized in that the mirror surface pre-tilt type sections (34 i ) are arranged on the facet mirror (6) row by row.
  6. 6. An illumination optical unit is provided, which comprises a light source, Having a first facet mirror (6), -Having a transmission optical unit (7), Wherein the illumination optics are embodied such that the individual mirror groups (30) of the first facet mirrors (6) are imaged as first facets with the aid of the transmission optics (7) at least in a partial field of an object field (8) of the illumination optics (11) in which an object (12) can be arranged and which is displaced through the object field (12) in an object displacement direction (y) during a projection exposure, -Wherein the first facet mirror (6) comprises: -a regular array configuration of individual mirror units (26), wherein each of said individual mirror units (26) is implemented as a sub-array of NxM individual mirrors (21), -At least two coating types (37 i ) of the individual mirror units (26), Wherein the first coating type (37 1 ) comprises individual mirror units (26) which are optimized in a neutral position for a first angle of incidence of the illumination light (3) on the individual mirror units (26) of the coating type (37 1 ), -Wherein the second coating type (37 2 ) comprises individual mirror units (26) which in the neutral position are optimized for a second angle of incidence of the illumination light (3) on the individual mirror units (26) of the coating type (37 2 ), Wherein the angles of incidence of the different coating types (37 1 , 37 2 ) differ from each other, Having a second facet mirror (7) for reflecting the illumination light (3) reflected by the first facet mirror (6) to the object field (8), Wherein the second facet mirror (7) comprises a second facet (25) which images the group (30) of individual mirrors (21) of the first facet mirror (6) as a first facet at least into a partial field of the object field (8) by means of the illumination light component beam, -Wherein at least two target surface areas (38 2 , 38 3 ; 38 4 , 38 1 ) are present on the second facet mirror (7) along a field height configuration coordinate (σ x ) of the second facet mirror (7) of the illumination optical unit (11), which corresponds to a field height coordinate (x) of the first facet mirror (6), which is imaged by the illumination optical unit (11) to a field height coordinate (x) perpendicular to an object displacement direction coordinate (y) of the object field (8), wherein each of said target surface areas (38 i ) is provided for guiding illumination light (3) via a pre-tilt type (32 i ) in each case and/or via a coating type (37 i ) of the first facet mirror (6) in each case.
  7. 7. Illumination optical unit according to claim 6, characterized in that the individual mirror units (26) of at least one of the coating types (37 i ) of the first facet mirror (6) are arranged in groups of individual mirror units (26) in at least one continuous mirror surface coating type section of the facet mirror (6).
  8. 8. Illumination optical unit according to claim 6 or 7, characterized in that at least two target surface areas (38 2 , 38 4 ; 38 3 , 38 1 ) are present on the second facet mirror (7) along an object displacement configuration coordinate (σ y ) of the second facet mirror (7), which corresponds to an object displacement coordinate (y) of the first facet mirror (6), which is imaged by the illumination optical unit (11) to an object displacement direction coordinate (y) of the object field (8), wherein each of the target surface areas (38 i ) is provided for guiding illumination light (3) in each case via a pretilt type (32 i ) and/or via a coating type (37 i ) of the first facet mirror (6) in each case.
  9. 9. Illumination optical unit according to any of claims 6 to 8, characterized in that the target surface area (38 i ) is configured to at least partially overlap on the second facet mirror (7).
  10. 10. An illumination optical unit (11), Having a first facet mirror (6; 45) with a first facet for reflecting a component beam of the guided illumination light (3), -Having a transmission optical unit (7), Having a second facet mirror (7) for reflecting the illumination light (3) reflected by the first facet mirror (6) to the object field (8), Wherein the illumination optics are embodied such that the first facet (21) of the first facet mirror (6) is imaged with the aid of the transmission optics into at least part of the field of the object field (8) of the illumination optics (11), the transmission optics comprising the second facet (25) of the second facet mirror (7) in which an object can be arranged and which is displaced through the object field (8) in an object displacement direction (y) during a projection exposure, -Wherein the second facet mirror (7) comprises: -at least two pre-tilt types (43 1 to 43 4 ; 43 1 to 43 5 ; 43 1 to 43 9 ) of said second facet (25), Wherein the first pretilt type (43 1 ) comprises a second facet (25) which in the neutral position has a first pretilt angle with respect to a base tilt angle specified by the carrier geometry of the facet mirror (7), Wherein the second pre-tilt type (43 2 ) comprises a second facet (25) having a second pre-tilt angle in the neutral position with respect to the base tilt angle, -Wherein the pre-tilt angles of the different pre-tilt types (43 i ) are different from each other, And/or -At least two coating types (44 i ) of the second facet (25), Wherein the first coating type (44 1 ) comprises a second facet (25) and/or individual mirror units (26) which are optimized for a first interval of the angle of incidence of the illumination light (3) on said second facet (25) and/or individual mirror units (26) of the coating type (44 i ), Wherein the second coating type (44 2 ) comprises a second facet (25) and/or individual mirror units (26) which are optimized for a second interval of the angle of incidence of the illumination light (3) on said second facet (25) and/or individual mirror units (26) of the coating type (44 2 ), -Wherein the incidence angle intervals of the different coating types (44 1 , 44 2 ) are different from each other, Wherein said second facet (25) of the second facet mirror (7) images the first facet via the illumination light component beam at least into a partial field of the object field (8), -Wherein at least two initial surface areas (42 i ) are present on the first facet mirror (6; 45) along a field height coordinate (x) of the first facet mirror (6; 45) of the illumination optical unit (11), which field height coordinate is imaged by the illumination optical unit (11) to a field height coordinate (x) of an object displacement coordinate (y) perpendicular to the object field (8), wherein each of said initial surface areas (42 i ) is provided for guiding an illumination light component beam in each case via a pre-tilt type (43 i ) and/or via a coating type (44 i ) of the second facet mirror (7) in each case.
  11. 11. Illumination optical unit according to claim 10, characterized by an array configuration of individual mirror units (26) of the second facet mirror (7), wherein each of the second facets (25) is implemented as a sub-array of NxM individual mirrors of the respective individual mirror unit (26), and all individual mirrors (21) of the individual mirror units (26) are of exactly one pre-tilt type.
  12. 12. Illumination optical unit according to claim 10 or 11, characterized in that adjacent individual mirror units (26) of the second facet mirror (7) are of different pretilt types (43 i ).
  13. 13. Illumination optical unit according to claim 10, characterized in that each of the second facets (25) is embodied as a monolithic facet.
  14. 14. Illumination optical unit according to claim 13, characterized in that adjacent second facets (25) belong to different pre-tilt types.
  15. 15. Illumination optical unit according to any one of claims 10 to 14, characterized in that at least two initial surface areas (42 i ) are present on the first facet mirror (6; 45) along an object displacement coordinate (y) of the first facet mirror (6; 45), which object displacement coordinate is imaged by the illumination optical unit (11) to an object displacement direction coordinate (y) of the object field (8), wherein each of the initial surface areas (42 i ) is provided for guiding an illumination light component beam in each case by a pretilt type (43 i ) and/or in each case by a coating type (44 i ).
  16. 16. Illumination optical unit according to any one of claims 10 to 15, characterized in that the initial surface area (42 i ) is configured to at least partially overlap on the first facet mirror (6).
  17. 17. An illumination system having an illumination optical unit as claimed in any one of claims 6 to 16 and having a light source (2).
  18. 18. An optical system having an illumination optical unit as claimed in any one of claims 6 to 16 and having a projection optical unit (10) for imaging the object field (8) to an image field (17).
  19. 19. Projection exposure apparatus having an optical system as claimed in claim 18 and a light source (2).
  20. 20. A method for producing a microstructured component, comprising the following method steps; providing a reticle (12), Providing a wafer (19) with a coating sensitive to the illumination light (3), Projecting at least one section of the reticle (12) onto the wafer (19) with the aid of a projection exposure apparatus (1) as claimed in claim 19, -Developing the photosensitive layer exposed by the illumination light (3) on the wafer (19).

Description

Facet mirror suitable for use as a first facet mirror for an illumination optical unit for projection lithography The content of the german patent application DE 10 2023 209 710.9 and DE 10 2023 209 709.5 is incorporated by reference. Technical Field The invention relates to a facet mirror for an illumination optical unit for projection lithography, which is suitable for use as a first facet mirror. Furthermore, the invention relates to an illumination optical unit having such a faceted mirror, an illumination system having such an illumination optical unit, an optical system having such an illumination optical unit, a projection exposure apparatus having such an optical system, a method for producing a micro-or nanostructured component using such a projection exposure apparatus, and a micro-or nanostructured component produced using such a method. Background DE 10 2015 208 512 A1 discloses a facet mirror of the type mentioned at the outset. Disclosure of Invention The problem addressed by the present invention is to develop a facet mirror of the type mentioned at the beginning, thereby relaxing the requirements regarding the tilt actuator system for tilting the individual mirrors of the facet mirror. According to the invention, this problem is solved by a facet mirror having the features as specified in claim 1, by an illumination optical unit having the features as specified in claim 6, and by an illumination optical unit having the features as specified in claim 10. According to the invention, it has been determined that the provision of at least two types of pre-tilting of the facets of the facet mirror in particular relaxes the structural requirements of the tilting actuator system of the facet mirror. In particular, the required tilting range can be reduced in this case. The facet mirror has at least two types of pretilt, which differ in the pretilt angle relative to the base tilt angle. The pretilt angle may be in the range between 10 mrad and 500 mrad, for example between 20 mrad and 200 mrad, in particular between 30 mrad and 80 mrad. The different pre-tilt types are also referred to as handover categories. The number of individual mirror units belonging to a respective pre-tilt type can be so large that they differ by no more than 10%. Alternatively, a first number of associated individual mirror units may be assigned to a specific pre-tilt type, and for example a smaller number of individual mirror units to a further pre-tilt type. If the number of individual mirror units belonging to a respective one of the pretilt types does not differ significantly from each other, they may differ by not more than 10%, not more than 5%, not more than 2%, or not more than 1%. The number of individual mirror units belonging to a respective one of the pretilt types may also be the same for some or for all different pretilt types. The facet mirror may comprise exactly two types of pretilt, or more than two types of pretilt, for example three, four, five or even more types of pretilt. The facet mirrors typically have fewer than 20 pretilt types. Due to the pre-tilting of the individual mirror groups, relaxing the requirements on the tilt actuator system for tilting the individual mirrors of the individual mirror units allows the use of tilt actuators with a smaller overall tilt range. This makes the type of tilt actuator readily available, especially in the context of mass production techniques. A reduction in the maximum angle of incidence and a reduction in the maximum angle of incidence travel on the individual mirrors can be achieved. This optimizes the reflectivity of the faceted mirror. Individual mirror units may be present in the form of a regular array configuration with e.g. K rows and L columns. The rows or columns may also be arranged in a manner displaced from each other. The design of the facet mirrors according to claim 2 allows a high packing density of individual mirror groups of the first facet mirrors of the same pretilt type, which groups are imaged via the other facet mirror of the illumination optical unit at least to a partial field of the object field. The larger the continuous mirror surface pre-tilt type section of the facet mirror, the lower the probability that the corresponding individual mirror group will be cut at the edge of the mirror surface pre-tilt type section, which cut will reduce the efficiency of the illumination light flux of an illumination optical unit with such a facet mirror. When the faceted mirror is subdivided into mirror surface pretilt type sections comprising respective groups of individual mirror units, a compromise can be found in each case between the objective of "high illumination luminous flux of the illumination optical unit with faceted mirror" and "good light mixing achieved due to the use of individual mirror groups spaced apart on the faceted mirror". In this process, when switching between different illumination angle distributions provided by the illu