# US 10,120,283 B2 · Illumination method, illumination optical device, and exposure device

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- Number: US 10,120,283 B2
- Document ID: US10120283B2
- Status: Granted
- Kind: B2
- Application number: 14/123,876
- Filed: 2011-11-30
- Published: 2014-08-07
- Granted: 2018-11-06
- Earliest claimed: 2011-06-06
- Assignees: Nikon Corporation
- Applicants: Yasushi Mizuno
- Inventors: Yasushi Mizuno
- Web page: https://patentgrep.com/patent/US10120283B2

## CPC

- G03F 7/20: Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00)
- G03F 7/70116: {Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets}
- G03F 7/70133: {Measurement of illumination distribution, in pupil plane or field plane}
- G03F 7/7085: {Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load}
- G03F 7/70: {Microphotolithographic exposure; Apparatus therefor (photo-masks G03F1/00)}
- 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

There is provided an illumination method for illuminating an illumination objective surface by using a light from a light source. The illumination method includes setting control amount for controlling a plurality of optical elements, to control a state of an incident light coming into each of the plurality of optical elements, the plurality of optical elements being arranged in parallel and being capable of controlling the state of the incident light; illuminating the illumination objective surface with the light from the light source via the plurality of optical elements; monitoring integrated energy of the light from the light source; and correcting the control amount for the plurality of optical elements on the basis of a result of the monitoring of the integrated energy.

## Claims

### Claim 1

An illumination method for illuminating an illumination objective surface by using a light from a light source, the illumination method comprising:
setting a control amount for controlling a plurality of optical elements, to control a state of an incident light coming into each of the plurality of optical elements, the plurality of optical elements being arranged in parallel and being capable of controlling the state of the incident light;
illuminating the illumination objective surface with the light from the light source via the plurality of optical elements;
monitoring time-integrated energy of the light from the light source; and
correcting the control amount for the plurality of optical elements based on a result of the monitoring of the time-integrated energy.

### Claim 2 (depends on 1)

The illumination method according to claim 1, further comprising:
detecting an intensity distribution of the light coming via the plurality of optical elements on a plane different from the illumination objective surface or on a plane different from a plane conjugate with the illumination objective surface, wherein:
the correcting of the control amount for the plurality of optical elements includes correcting of the control amount based on the result of the monitoring of the time-integrated energy and a result of detection of the intensity distribution.

### Claim 3 (depends on 2)

The illumination method according to claim 2, wherein the detection of the intensity distribution of the light coming via the plurality of optical elements includes detection of the intensity distribution of the light coming via the plurality of optical elements on a plane equivalent to a plane conjugate with an exit pupil of an optical system for guiding the light from the plurality of optical elements to the illumination objective surface or a plane in a vicinity of the plane equivalent to the plane conjugate with the exit pupil of the optical system.

### Claim 4 (depends on 1)

The illumination method according to claim 1, further comprising:
determining a corresponding relationship between the time-integrated energy and an intensity distribution of the light coming via the plurality of optical elements on a detection plane, the detection plane being a plane different from the illumination objective surface or a plane different from a plane conjugate with the illumination objective surface; and
storing, as a control table, the time-integrated energy and a correction amount of the control amount for the plurality of optical elements in a state in which the time-integrated energy and the correction amount correspond to one another, based on the corresponding relationship, wherein:
the control table is used in a case that the control amount for the plurality of optical elements is corrected.

### Claim 5 (depends on 4)

The illumination method according to claim 4, wherein:
the illumination objective surface is a pattern formation plane formed with a pattern to be transferred to a substrate held by a substrate stage; and
the intensity distribution is detected on a detection plane on a side of the substrate stage in a case that the corresponding relationship is determined.

### Claim 6 (depends on 1)

The illumination method according to claim 1, wherein:
the optical element is a reflecting element having a reflecting surface for reflecting the incident light; and
the control amount for controlling the optical element to control the state of the incident light is a driving signal to set at least one of a position in a normal direction of the reflecting surface and an angle of inclination of the reflecting surface.

### Claim 7

An illumination optical apparatus for illuminating an illumination objective surface by using a light from a light source, the illumination optical apparatus comprising:
a spatial light modulator which is arranged in an optical path for the light from the light source and which has a plurality of optical elements capable of controlling a state of an incident light coming into each of the plurality of optical elements;
a monitor unit which monitors time-integrated energy of the light from the light source; and
a control system which sets a control amount for controlling the plurality of optical elements, to control the state of the incident light, and which corrects the control amount based on the time-integrated energy monitored by the monitor unit.

### Claim 8 (depends on 7)

The illumination optical apparatus according to claim 7, further comprising:
a detecting unit which detects an intensity distribution of the light coming via the plurality of optical elements on a plane different from the illumination objective surface or a plane different from a plane conjugate with the illumination objective surface, wherein:
the control system corrects the control amount based on the time-integrated energy monitored by the monitor unit and the intensity distribution detected by the detecting unit.

### Claim 9 (depends on 8)

The illumination optical apparatus according to claim 8, wherein the detecting unit detects the intensity distribution of the light coming via the plurality of optical elements on a plane equivalent to a plane conjugate with an exit pupil of the illumination optical apparatus or a plane in a vicinity of the plane equivalent to the plane conjugate with the exit pupil of the illumination optical apparatus.

### Claim 10 (depends on 8)

The illumination optical apparatus according to claim 8, wherein:
the illumination objective surface is a pattern formation plane formed with a pattern to be transferred to a substrate held by a substrate stage; and
the detecting unit is provided on the substrate stage.

### Claim 11 (depends on 7)

The illumination optical apparatus according to claim 7. further comprising:
a storage unit which stores a control table in which the time-integrated energy and a correction amount of the control amount for the plurality of optical elements correspond to one another, wherein:
the control system uses the control table when the control amount for the plurality of optical elements is corrected.

### Claim 12 (depends on 7)

The illumination optical apparatus according to claim 7, wherein:
the optical element is a reflecting element having a reflecting surface which reflects the incident light; and
the control amount for controlling the optical element to control the state of the incident light is a driving signal to set at least one of a position in a normal direction of the reflecting surface and an angle of inclination of the reflecting surface.

### Claim 13 (depends on 7)

The illumination optical apparatus according to claim 7, wherein:
the spatial light modulator is a part of an optical system which forms the light intensity distribution at a predetermined position in an illumination optical path of the illumination optical apparatus; and
the illumination optical apparatus further comprises a surface light source forming optical system which forms a surface light source having a light intensity distribution equivalent to the light intensity distribution from the light from the spatial light modulator.

### Claim 14 (depends on 7)

An exposure apparatus for illuminating a pattern with an exposure light and exposing a substrate with the exposure light via the pattern and a projection optical system, the exposure apparatus comprising:
the illumination optical apparatus as defined in claim 7, wherein:
a light from the illumination optical apparatus is used as the exposure light.

### Claim 15 (depends on 14)

A method for producing a device, comprising:
forming a pattern of a photosensitive layer on a substrate by using the exposure apparatus as defined in claim 14; and
processing the substrate formed with the pattern.

### Claim 16

An illumination method for illuminating an illumination objective surface by using a light from a light source, the illumination method comprising:
setting a posture control amount for a plurality of optical elements which are arranged in parallel and a posture of each of which is changeable;
measuring an energy of the light propagating from the light source to the illumination objective surface; and
changing the posture control amount for the plurality of optical elements so as to reduce posture changes of the plurality of optical elements by using an information related to the measured energy of the light,
wherein the measured energy of the light indirectly corresponds to an average temperature of the plurality of optical elements.

### Claim 17 (depends on 16)

The illumination method according to claim 16, further comprising:
detecting an intensity distribution of one or more lights, which propagate in an illumination path from the plurality of optical elements to the illumination objective surface, on a plane different from the illumination objective surface or on a plane different from a plane conjugate with the illumination objective surface, wherein:
changing the posture control amount for the plurality of optical elements includes changing the posture control amount for the plurality of optical elements using the information related to the measured energy of the light and a result of detection of the intensity distribution.

### Claim 18 (depends on 17)

The illumination method according to claim 17, wherein detecting the intensity distribution of the one or more lights includes detecting the intensity distribution of the one or more lights on an equivalent plane equivalent to a plane conjugate with an exit pupil of an optical system which guides the light from the plurality of optical elements to the illumination objective surface or a plane in a vicinity of the equivalent plane.

### Claim 19 (depends on 18)

The illumination method according to claim 18, further comprising storing, as a control table, the information related to the measured energy of the light and the posture control amount for the plurality of optical elements in a state in which the information related to the measured energy of the light and the posture control amount correspond to one another.

### Claim 20 (depends on 17)

The illumination method according to claim 17, further comprising determining a corresponding relationship between the information related to the measured energy of the light and the intensity distribution of the one or more lights on the plane different from the illumination objective surface or on the plane different from the plane conjugate with the illumination objective surface.

### Claim 21 (depends on 16)

An exposure method for exposing an object with an exposure light including illuminating a predetermined pattern using the illumination method as defined in claim 16.

### Claim 22 (depends on 21)

The exposure method according to claim 21, further comprising projecting an image of the predetermined pattern onto the object.

### Claim 23 (depends on 21)

A method for producing a device, comprising:
forming a photosensitive layer on an object,
forming a pattern of the photosensitive layer by using the exposure method as defined in claim 21 to expose the photosensitive layer; and
processing the object formed with the pattern.

### Claim 24 (depends on 16)

The illumination method according to claim 16, wherein the posture control amount is related to propagation direction of light from the optical element.

### Claim 25 (depends on 24)

The illumination method according to claim 24, further comprising distributing light from the plurality of optical elements on an illumination pupil.

### Claim 26 (depends on 16)

The illumination method according to claim 16, wherein the information related to the measured energy of the light represents a temperature of the plurality of optical elements affected by a light coming into the plurality of optical elements.

### Claim 27

An illumination optical apparatus for illuminating an illumination objective surface by using a light from a light source, the illumination optical apparatus comprising:
a spatial light modulator having a plurality of optical elements which are arranged in parallel and a posture of each of which is changeable;
a sensor which measures an energy of the light propagating from the light source to the illumination objective surface; and
a controller which controls the spatial light modulator,
wherein the controller performs:
setting a posture control amount for the plurality of optical elements; and
changing the posture control amount for the plurality of optical elements so as to reduce posture changes of the plurality of optical elements by using an information related to the measured energy of the light, and
wherein the measured energy of the light indirectly corresponds to an average temperature of the plurality of optical elements.

### Claim 28 (depends on 25)

The illumination optical apparatus according to claim 25, further comprising:
a photo detector which detects an intensity distribution of one or more lights, which propagate in an illumination path from the plurality of optical elements to the illumination objective surface, on a plane different from the illumination objective surface or a plane different from a plane conjugate with the illumination objective surface, wherein:
the controller changes the control amount for the plurality of optical elements using the information related to the measured energy of the light and a result of detection of the intensity distribution.

### Claim 29 (depends on 28)

The illumination optical apparatus according to claim 28, wherein the photo detector detects the intensity distribution of the one or more lights on an equivalent plane equivalent to a plane conjugate with an exit pupil of an optical system which guides a light from the plurality of optical elements to the illumination objective surface, or a plane in a vicinity of the equivalent plane.

### Claim 30 (depends on 29)

The illumination optical apparatus according to claim 29, wherein the controller determines a corresponding relationship between the information related to the measured energy of the light and the intensity distribution of the one or more lights.

### Claim 31 (depends on 28)

The illumination optical apparatus according to claim 28, further comprising a memory which stores, as a control table, the information related to the measured energy of the light and the control amount for the plurality of optical elements in a state in which the information related to the measured energy of the light and the control amount correspond to one another.

### Claim 32 (depends on 27)

An exposure apparatus for exposing an object with an exposure light comprising the illumination optical apparatus as defined in claim 27 for illuminating a predetermined pattern.

### Claim 33 (depends on 32)

The exposure apparatus according to claim 32, further comprising a projection optical system which projects an image of the predetermined pattern onto the object.

### Claim 34 (depends on 25)

The illumination optical apparatus according to claim 25, wherein the posture control amount is related to propagation direction of light from the optical element.

### Claim 35 (depends on 34)

The illumination optical apparatus according to claim 34, further comprising an optical system which is arranged between the spatial light modulator and the illumination objective surface and which distributes light from the plurality of optical elements on an illumination pupil of the illumination optical apparatus.

### Claim 36 (depends on 27)

The illumination apparatus according to claim 27, wherein the information related to the measured energy of the light represents a temperature of the plurality of optical elements affected by a light coming into the plurality of optical elements.