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CN-114341740-B - Mirror assembly and optical assembly with hydrogen barrier

CN114341740BCN 114341740 BCN114341740 BCN 114341740BCN-114341740-B

Abstract

The invention relates to a mirror mount (30) comprising a substrate (31) having a front face (31 a) and a rear face (31 b), the front face (31 a) having a mirror surface (32 a) for reflecting radiation (5) and the rear face (31 b) facing away from the front face (31 a), and at least one actuator (27) for producing a deformation of the mirror surface (32 a). The at least one actuator (27) is fixed to the back surface (31 b) of the substrate (31), and the mirror assembly (30) has a hydrogen barrier (38), the hydrogen barrier (38) being designed to protect a hydrogen sensitive material (M) on the back surface (31 b) of the substrate (31), in particular on the at least one actuator (27), from hydrogen from the environment of the mirror assembly (30). The invention also relates to an optical assembly, in particular an EUV lithographic apparatus (1), comprising a mirror assembly (30) of this type.

Inventors

  • A. Pazidis
  • K. Hilde
  • T. Pollack
  • NOY MAKSIM
  • J. Nasser
  • D. Klein Henz

Assignees

  • 卡尔蔡司SMT有限责任公司

Dates

Publication Date
20260505
Application Date
20200716
Priority Date
20190903

Claims (20)

  1. 1. A mirror arrangement (30), comprising: A substrate (31) having a front face (31 a) and a back face (31 b), the front face (31 a) having a mirror face (32 a) for reflecting radiation (5) and the back face (31 b) facing away from the front face (31 a), and At least one actuator (27) for producing a deformation of the reflecting mirror surface (32 a), It is characterized in that the method comprises the steps of, The at least one actuator (27) is fixed on the back side (31 b) of the substrate (31) and the mirror arrangement (30) has a hydrogen barrier (38) configured to protect a hydrogen sensitive material (M) on the back side (31 b) of the substrate (31) from hydrogen (37) from the surrounding environment (36) of the mirror arrangement (30), wherein the at least one actuator (27) is fixed on the back side (31 a) of the substrate (31) by means of an adhesive layer (33), Wherein the surface (41 a,44 a) of the hydrogen barrier (38) facing the surrounding environment (36) is hydrophobic and/or the hydrogen barrier (38) comprises at least one hydrophobic material, and Wherein the exposed surface areas (33 a-c) of the continuous adhesive layer (33) formed in the interstices between the actuators are protected from attack by hydrogen (37) by the hydrogen barrier (38).
  2. 2. Mirror arrangement according to claim 1, wherein the hydrogen sensitive material (M) is on the at least one actuator (27).
  3. 3. Mirror arrangement according to claim 1, wherein the hydrogen barrier (38) forms a water vapor diffusion barrier for protecting the adhesive layer (33) from water vapor (39).
  4. 4. Mirror arrangement according to any of the preceding claims, wherein the hydrogen diffusion coefficient (DW) of the hydrogen barrier (38) is less than 5 x 10 -14 m 2 /s.
  5. 5. Mirror arrangement according to claim 4, wherein the hydrogen diffusion coefficient (DW) is less than 1 x 10 -17 m 2 /s.
  6. 6. Mirror arrangement according to claim 4, wherein the hydrogen diffusion coefficient (DW) is less than 1 x 10 -21 m 2 /s.
  7. 7. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier (38) comprises at least one material and/or a combination of materials having a lower solubility for hydrogen (37) than the hydrogen sensitive material (M).
  8. 8. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier (38) comprises at least one material in the form of an oxygen-containing compound having a free enthalpy of formation of less than-400 kJ/mol O 2 .
  9. 9. Mirror arrangement according to claim 8, wherein the free enthalpy of formation of the oxygen containing compound is less than-800 kJ/mol O 2 .
  10. 10. Mirror arrangement according to claim 8, wherein the free enthalpy of formation of the oxygen containing compound is less than-1000 kJ/mol O 2 .
  11. 11. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier (38) comprises at least one material in the form of a nitrogen-containing compound having a free enthalpy of formation of less than-200 kJ/mol N 2 .
  12. 12. Mirror arrangement according to claim 11, wherein the free enthalpy of formation of the nitrogen-containing compound is less than-350 kJ/mol N 2 .
  13. 13. Mirror arrangement according to claim 11, wherein the free enthalpy of formation of the nitrogen-containing compound is less than-600 kJ/mol N 2 .
  14. 14. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier (38) comprises at least one metal oxide.
  15. 15. Mirror arrangement according to claim 14, wherein the metal oxide is selected from the group ：Al 2 O 3 、MgO、CaO、La 2 O 3 、TiO 2 、ZrO 2 、Ta 2 O 5 、Y 2 O 3 、Ce 2 O 3 comprising and compounds thereof.
  16. 16. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier (38) comprises at least one material selected from the group comprising Al, au, ag, zn, mo, si, W, ti, sn, sb, pt, ni, fe, co, cr, V, cu, mn, pb, their oxides, borides, nitrides and carbides, and C and B 4 C.
  17. 17. Mirror arrangement according to any of the preceding claims, wherein the hydrogen barrier has a coating or forms a coating (38) which at least partly covers the hydrogen sensitive material (M).
  18. 18. Mirror arrangement according to claim 17, wherein the coating (38) completely covers the hydrogen sensitive material (M).
  19. 19. Mirror arrangement according to claim 17, wherein the coating (38) comprises at least one hydrogen barrier layer (44).
  20. 20. Mirror arrangement according to claim 19, wherein the at least one hydrogen barrier layer (44) is applied on the other layer (43).

Description

Mirror assembly and optical assembly with hydrogen barrier Cross Reference to Related Applications This patent application claims priority from german patent application DE 10 2019 213 349.5 filed on 2019, 9, 3, the entire contents of which are incorporated herein by reference. Background The invention relates to a mirror arrangement comprising a substrate with a front side having a mirror surface for reflecting radiation and a back side facing away from the front side, and one or more actuators in the form of actuator mounts, for example, for producing a deformation of the mirror surface. The invention also relates to an optical arrangement, in particular an EUV lithographic apparatus, having at least one such mirror arrangement. The above-described mirror arrangement enables targeted (local) deformation of the mirror surface formed on the front side of the substrate by means of the actuator. For example, the purpose of the mirror surface deformation may be to purposefully correct aberrations of the EUV lithographic apparatus in which the mirror arrangement is provided. US 5,986,795 describes a deformable mirror for EUV radiation, in which an actuator is arranged between a front plate forming the back of the mirror and a reaction plate and is coupled to both plates, so that a deformation is produced on the mirror surface of the deformable mirror. For example, in an optical arrangement such as an (EUV) lithography unit, it may be necessary to mix hydrogen permanently or e.g. during a cleaning cycle to the surroundings of the mirror arrangement. In this case, hydrogen may be present in the excited state in its entirety as a molecule (H 2), in the form of an atom, in the form of an excited molecule or atom, or in the form of a hydrogen ion. The presence of hydrogen in different excited states is promoted by the presence of EUV radiation. Many materials are damaged by hydrogen attack and are therefore hydrogen sensitive. It is therefore necessary to select a material that is stable to attack by hydrogen or to protect hydrogen sensitive materials from attack by hydrogen. Object of the Invention It is an object of the present invention to provide a mirror arrangement and an optical arrangement having at least one such mirror arrangement, wherein the hydrogen sensitive material is effectively protected from attack by hydrogen. Disclosure of Invention This object is achieved by a mirror arrangement of the above-mentioned type, wherein the at least one actuator is fixed to the back side of the substrate, and wherein the mirror arrangement comprises a hydrogen barrier configured to protect hydrogen sensitive material of the back side of the substrate, in particular hydrogen sensitive material on the at least one actuator, from attack by hydrogen from the environment surrounding the mirror arrangement. The invention proposes to fix the actuators to the back side of the substrate and that they, as well as any other hydrogen sensitive material present on the back side of the substrate, be protected by a hydrogen barrier from the hydrogen of the environment surrounding the mirror arrangement. The hydrogen sensitive material may be, for example, the actuator itself or an actuator housing, an insulating layer, a conductor cable/conductor track, etc., mounted on the back side of the substrate. The substrate itself may also be protected from hydrogen attack by a hydrogen barrier if the substrate is exposed at the back side and if the substrate is a hydrogen sensitive material. The actuators may be fixed in a regular arrangement or grid (array of actuators) on the back side of the substrate, but in principle any desired arrangement of actuators on the back side of the substrate is possible. In general, adjacent actuators or adjacent groups of interconnected actuators (actuator assemblies) are not directly adjacent to each other at the back of the substrate, but are spaced apart from each other, in other words, there is a void or gap between pairs of adjacent actuators or actuator assemblies. In one embodiment, the at least one actuator is fixed on the back side of the substrate by means of an adhesive layer, the exposed surface area of which is at least partially, in particular completely, protected from attack by hydrogen by a hydrogen barrier. In this case, the actuator is directly or indirectly (i.e. through one or more intermediate layers on the back side of the substrate) adhered to the substrate. Typically, a continuous adhesive layer is used to secure the actuators, which means that the adhesive layer also extends into the interstices between adjacent actuators and/or between groups of interconnected actuators. The surface area of the adhesive layer exposed to the surrounding environment may, for example, be formed in the interspace between the actuators. In the area of the gap, the adhesive layer may be thicker than in the area between the respective actuator and the back side of the substrate, but it is also possibl