# US 11,029,515 B2 · Optical element, and method for correcting the wavefront effect of an optical element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,029,515 B2 - Document ID: US11029515B2 - Status: Granted - Kind: B2 - Application number: 17/008,229 - Filed: 2020-08-31 - Published: 2020-12-17 - Granted: 2021-06-08 - Earliest claimed: 2018-03-05 - Assignees: Carl Zeiss SMT GmbH - Applicants: Carl Zeiss SMT GmbH - Inventors: Kerstin Hild; Toralf Gruner; Vitaliy Shklover - Web page: https://patentgrep.com/patent/US11029515B2 ## CPC - G02B 27/0068: {having means for controlling the degree of correction, e.g. using phase modulators, movable elements (controlling the phase of light using moving or deformable elements G02B26/06)} - G02B 26/06: for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00}) - G03F 7/70191: {Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like} - G03F 7/70266: {Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction} - G03F 7/70308: {Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift} - G03F 7/70316: {Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract An optical element for an optical system, in particular an optical system of a microlithographic projection exposure apparatus or mask inspection apparatus, and a method for correcting the wavefront effect of an optical element. The optical element has at least one correction layer (12, 22) and a manipulator that manipulates the layer stress in this correction layer such that a wavefront aberration present in the optical system is at least partially corrected by this manipulation. The manipulator has a radiation source for spatially resolved irradiation of the correction layer with electromagnetic radiation (5). This spatially resolved irradiation enables a plurality of spaced apart regions (12a, 12b, 12c, . . . ; 22a, 22b, 22c, . . . ) to be generated, equally modified in terms of their respective structures, in the correction layer. ## Claims ### Claim 1 An optical element configured for an optical system, comprising: a substrate; an optically effective layer system; at least one correction layer exhibiting a layer stress, wherein the correction layer is an auxiliary layer provided in addition to the substrate and the optically effective layer system; and a manipulator arranged to manipulate the layer stress in the correction layer such that a wavefront aberration present in the optical system is corrected at least partially by the manipulation; wherein the manipulator comprises a radiation source arranged for spatially resolved irradiation of the correction layer with electromagnetic radiation; and wherein the spatially resolved irradiation produces locally restricted structure modifications within the correction layer, in a plurality of spaced apart regions that are modified mutually equally in terms of their respective structures. ### Claim 2 (depends on 1) The optical element as claimed in claim 1, wherein the manipulation of the layer stress is obtained through the modifications in the layer structure within the correction layer. ### Claim 3 (depends on 2) The optical element as claimed in claim 2, wherein the modifications in the layer structure are at least partially irreversible. ### Claim 4 (depends on 2) The optical element as claimed in claim 2, wherein the manipulation of the layer stress in the correction layer over a lateral distance of 10 mm produces a layer stress modification in the correction layer of at least 10%. ### Claim 5 (depends on 1) The optical element as claimed in claim 1, wherein a distance between the spaced apart regions is determined by the radiation source. ### Claim 6 (depends on 1) The optical element as claimed in claim 1, wherein the optical element is configured as a mirror. ### Claim 7 (depends on 1) The optical element as claimed in claim 1, wherein the optical element is configured for an operating wavelength of less than 30 nm. ### Claim 8 (depends on 1) A method for correcting a wavefront effect of an optical element as claimed in claim 1, comprising: a) ascertaining a given wavefront effect of the optical element; and b) manipulating the wavefront effect in accordance with a model which describes dependence of the wavefront effect on a local distribution of the layer stress in the correction layer and the ascertained wavefront effect. ### Claim 9 (depends on 8) The method as claimed in claim 8, wherein the ascertaining of the given wavefront effect and the manipulating of the wavefront effect are carried out repeatedly in an iterative process. ### Claim 10 (depends on 8) The method as claimed in claim 8, wherein the model is ascertained with a finite element method. ### Claim 11 (depends on 8) The method as claimed in claim 8, further comprising: carrying out a calibration in advance of the ascertaining, to set up the model, within which calibration a change of figure resulting from a given modification in the layer stress or a corresponding modification in the wavefront effect is determined experimentally for given values. ### Claim 12 (depends on 11) The method as claimed in claim 11, wherein the experimental determination is implemented for a plurality of sampling points, and wherein the method further comprises: carrying out interpolation between the sampling points. ### Claim 13 (depends on 1) An optical system of a microlithographic projection exposure apparatus, comprising: at least one optical element as claimed in claim 1; and additional components of at least one of an illumination device or a projection lens. ### Claim 14 (depends on 1) A microlithographic projection exposure apparatus comprising: an illumination device and a projection lens, wherein at least one of the illumination device and the projection lens comprises an optical element as claimed in claim 1. ### Claim 15 (depends on 1) The optical element as claimed in claim 1, wherein the auxiliary layer is formed between the substrate and the optically effective layer system.