Device and method for wavefront analysis

Patent metadata

Field	Value
Publication number	US-10386728-B2
Application number	US-201816015757-A
Country	US
Kind code	B2
Filing date	Jun 22, 2018
Priority date	Dec 22, 2015
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

A device and a method for wavefront analysis. The device is designed for analyzing the wavefront of at least one light wave passing through an optical system, and has at least one illumination mask ( 105, 205, 305, 405, 406, 407 ), at least one first grating ( 120, 220, 320, 420 ), at least one second grating ( 130, 230, 330, 430 ) arranged in the predefined plane and at least one detector ( 140, 240, 340, 440 ) for detecting said superimposition pattern. The at least one first grating has at least one first grating structure and generates an interferogram in a predefined plane from a wavefront to be analyzed which proceeds from the illumination mask and passes through the optical system. The at least one second grating has at least one second grating structure and generates a superimposition pattern by the superimposition of the second grating structure with the interferogram generated by the first grating.

First claim

What is claimed is:

1. Device for wavefront analysis, configured to analyse a wavefront of at least one light wave passing through an optical system, comprising
at least one illumination mask;
at least one first grating, which has at least one first grating structure and is configured to generate an interferogram in a predefined plane from the wavefront being analysed, which proceeds from the illumination mask and passes through the optical system;
at least one second grating, which is arranged in the predefined plane, wherein the at least one second grating has at least one second grating structure and is configured to generate a superimposition pattern through superimposition of the second grating structure with the interferogram generated by the first grating; and
at least one detector configured to detect the superimposition pattern, wherein the second grating is arranged on a coherence-destroying substrate.

2. Device according to claim 1 , wherein the second grating structure differs structurally from the first grating structure.

3. Device according to claim 1 , wherein the at least one second grating structure is configured in accordance with a setpoint interference pattern which would be generated by the first grating for a setpoint wavefront of the light wave after passing through the optical system.

4. Device according to claim 1 , wherein the detector comprises a radiation-sensitive sensor.

5. Device according to claim 4 , wherein the detector further comprises an imaging optical unit configured to image the superimposition pattern onto the radiation-sensitive sensor.

6. Device according to claim 4 , wherein the second grating is arranged on the radiation-sensitive sensor.

7. Device according to claim 4 , wherein the second grating is arranged on a faceplate configured to fiber-optically transmit the superimposition pattern onto the radiation-sensitive sensor.

8. Device according to claim 7 , wherein the radiation-sensitive sensor is arranged on a light exit surface of the faceplate.

9. Device according to claim 1 , further comprising a changer configured to exchange the first grating structure configured to generate the interferogram.

10. Device according to claim 1 , further comprising a changer configured to exchange the second grating structure superimposed with the interferogram generated by the first grating.

11. Device according to claim 1 , wherein the optical system has an optical system axis, and wherein the first grating and/or the second grating are/is configured to move along the optical system axis.

12. Device according to claim 1 , wherein the second grating comprises a plurality of mutually differing segments, which differ from one another with regard to the second grating structure situated in the respective segment.

13. Device according to claim 1 , further comprising a plurality of measuring channels, wherein each of the measuring channels is assigned a respective light source, a respective illumination mask, a respective first grating structure, and a respective second grating structure.

14. Optical system for microlithography, comprising:
an imaging optical unit, and
a device configured to analyse a wavefront of at least one light wave passing through the optical unit, comprising
at least one illumination mask;
at least one first grating, which has at least one first grating structure and is configured to generate an interferogram in a predefined plane from the wavefront being analysed, which proceeds from the illumination mask and passes through the optical unit;
at least one second grating, which is arranged in the predefined plane, wherein the at least one second grating has at least one second grating structure and is configured to generate a superimposition pattern through superimposition of the second grating structure with the interferogram generated by the first grating; and
at least one detector configured to detect the superimposition pattern, wherein the detector comprises a radiation-sensitive sensor, and wherein the second grating is arranged on a faceplate configured to fiber-optically transmit the superimposition pattern into the radiation-sensitive sensor.

15. Optical system according to claim 14 , configured as a microlithographic projection exposure apparatus.

16. Method for wavefront analysis, wherein a wavefront of at least one light wave passing through an optical system is analysed, comprising:
generating an interferogram in a predefined plane from the wavefront being analysed with at least one first grating having at least one first grating structure;
with at least one second grating arranged in the predefined plane and having at least one second grating structure, generating a superimposition pattern by superimposing the second grating structure with the interferogram generated by the first grating; and
detecting the superimposition pattern with at least one detector, wherein the second grating is arranged on a coherence-destroying substrate.

17. Method according to claim 16 , wherein the at least one second grating structure is configured in accordance with a setpoint interference pattern which would be generated by the first grating for a setpoint wavefront of the light wave after passing through the optical system.

18. Method according to claim 16 , wherein the optical system has an optical system axis, wherein the method for analysing different partial regions of a wavefront comprises at least one of:
variable positioning of the first grating along the optical system axis;
varying the respectively effective grating structure of the first grating;
variable positioning of the second grating including the detector along the optical system axis; and
varying the respectively effective grating structure of the second grating.

19. Method according to claim 18 , further comprising combining partial wavefronts detected by the detector during the analysis of the entire wavefront.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Wegmann Ulrich

Classifications

• G01J9/02

  by interferometric methods (using interferometers for measuring optically the linear dimensions of objects G01B9/02) · CPC title

• G01J2009/0219

  using two or more gratings · CPC title

• G03F7/70266

  Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction · CPC title

• G01M11/0271

  by using interferometric methods · CPC title

• G03F7/70141

  Illumination system adjustment, e.g. adjustments during exposure or alignment during assembly of illumination system · CPC title