# US 10,120,176 B2 · Catadioptric projection objective comprising deflection mirrors and projection exposure method

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- Number: US 10,120,176 B2
- Document ID: US10120176B2
- Status: Granted
- Kind: B2
- Application number: 15/783,482
- Filed: 2017-10-13
- Published: 2018-04-05
- Granted: 2018-11-06
- Earliest claimed: 2009-09-29
- Assignees: Carl Zeiss SMT GmbH
- Applicants: Carl Zeiss SMT GmbH
- Inventors: Thomas Schicketanz; Toralf Gruner
- Web page: https://patentgrep.com/patent/US10120176B2

## CPC

- G02B 17/0892: {specially adapted for the UV}
- G02B 13/14: for use with infrared or ultraviolet radiation ({G02B13/008, } G02B13/16 take precedence)
- G02B 17/08: Catadioptric systems {(used in non-imaging applications G02B19/00)}
- G02B 17/0896: {with variable magnification or multiple imaging planes, including multispectral systems (systems with only refractive elements G02B15/14)}
- G03F 1/26: Phase shift masks [PSM]; PSM blanks; Preparation thereof
- G03F 7/702: {Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems}
- G03F 7/70225: {Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements}
- G03F 7/70258: {Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system}
- G03F 7/70266: {Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction}
- G03F 7/70275: {Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems}
- 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}
- G03F 7/70441: {Optical proximity correction [OPC]}
- G03F 7/70791: {Large workpieces, e.g. glass substrates for flat panel displays or solar panels}
- 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

A method for manufacturing an integrated circuit includes scanning a wafer with respect to a catadioptric projection objective and imaging a pattern on a mask onto a wafer while scanning the wafer. The imaging includes illuminating the mask with radiation; imaging, using the radiation, the pattern into a first intermediate image, the first intermediate image to a second intermediate image, and the second intermediate image into an image field arranged in an image surface where the wafer is arranged; and, manipulating one or more of optical elements while scanning the wafer to reduce errors in the image at the image field. A concave mirror arranged in a region of a pupil surface reflects the radiation. The projection objective also includes mirrors to deflect the radiation from the object field towards the concave mirror and to deflect the radiation from the concave mirror towards the image field. The deflection mirrors are mechanically coupled to a displacement device arranged to displace the first and second deflection mirrors.

## Claims

### Claim 1

A lithographic method for manufacturing an integrated circuit, the method comprising:
scanning a wafer with respect to a catadioptric projection objective comprising a plurality of optical elements;
imaging a pattern on a mask onto a wafer while scanning the wafer with respect to the catadioptric projection objective, the imaging comprising;
illuminating the mask arranged in an object surface of a catadioptric projection objective with radiation;
imaging, using the radiation, the pattern into a first intermediate image using a first objective part of a catadioptric projection objective;
imaging, using the radiation, the first intermediate image to a second intermediate image using a second objective part of the catadioptric projection objective, wherein imaging the first intermediate image to the second intermediate image comprises reflecting light from a concave mirror arranged in a region of a pupil surface in the second objective part;
imaging, using the radiation, the second intermediate image into an image field arranged in an image surface using a third objective part of the catadioptric projection objective, the wafer being arranged at the image surface,
wherein the catadioptric projection objective comprises a first deflection mirror configured to deflect the radiation from the object field towards the concave mirror in the second objective part and a second deflection mirror configured to deflect the radiation from the concave mirror towards the image field, the first and second deflection mirrors being mechanically coupled to a displacement device arranged to displace the first and second deflection mirrors along a first direction; and
manipulating one or more of the optical elements while scanning the wafer with respect to the catadioptric projection objective to reduce errors in the image at the image field.

### Claim 2 (depends on 1)

The method of claim 1, wherein the errors in the image at the image field that are reduced comprise a distortion.

### Claim 3 (depends on 2)

The method of claim 2, wherein the distortion is in a direction orthogonal to a scan direction of the wafer with respect to the image field.

### Claim 4 (depends on 2)

The method of claim 2, wherein the distortion is an anamorphic distortion.

### Claim 5 (depends on 2)

The method of claim 2, wherein the distortion is reduced without increasing fading in the image at the image field.

### Claim 6 (depends on 2)

The method of claim 2, wherein the distortion is reduced without inducing a loss of contrast in the image at the image field.

### Claim 7 (depends on 1)

The method of claim 1, wherein manipulating one or more of the optical elements causes a magnification of the projection objective to change.

### Claim 8 (depends on 1)

The method of claim 1, wherein the second objective part has an imaging scale between −0.8 and −1.2.

### Claim 9 (depends on 8)

The method of claim 8, wherein the imaging scale of the second objective part is close to or is −1 in a first image direction.

### Claim 10 (depends on 9)

The method of claim 9, wherein the imaging scale of the second objective part is close to or is +1 in a second image direction orthogonal to the first image direction.

### Claim 11 (depends on 1)

The method of claim 1, further comprising displacing the first and second deflection mirrors between a first position and a different second position, wherein when the first deflection mirror is in its first position, radiation from the illumination system for imaging the object at an object field into an image field impinges on a first reflection region of the first deflection mirror, and when the first deflection mirror is in its second position, the radiation impinges on a second reflection region of the first deflection mirror, and the second reflection region of the first deflection mirror is offset from the first reflection region of the first deflection mirror in a direction parallel the first direction.

### Claim 12 (depends on 11)

The method of claim 11, wherein a distribution of reflectivity of the first reflection region of the first deflection mirror is different from a distribution of reflectivity of the second reflection region of the first deflection mirror.

### Claim 13 (depends on 11)

The method of claim 11, wherein a reflection coating of the first deflection mirror has a thickness that changes linearly in a direction parallel to the first direction.

### Claim 14 (depends on 11)

The method of claim 11, wherein a reflectivity of the first reflection region of the first deflection mirror is constant, and a thickness of a reflection coating of the first deflection mirror is non-constant in the second reflection region of the first deflection mirror.

### Claim 15 (depends on 1)

The method of claim 1, further comprising synchronously displacing first and second deflection mirrors parallel to the first direction.

### Claim 16 (depends on 1)

The method of claim 1, wherein the first and second deflection surfaces are supported by perpendicularly oriented surfaces of a prism.

### Claim 17 (depends on 1)

The method of claim 1, wherein the wafer supports a photoresist sensitive to the radiation.