# US 9,519,224 B2 · Lithographic apparatus and method

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- Number: US 9,519,224 B2
- Document ID: US9519224B2
- Status: Granted
- Kind: B2
- Application number: 14/351,012
- Filed: 2012-09-21
- Published: 2014-10-23
- Granted: 2016-12-13
- Earliest claimed: 2011-10-20
- Assignees: ASML Netherlands B.V.
- Applicants: ASML Netherlands B.V.
- Inventors: Arjan Gijsbertsen; Hubertus Antonius Geraets; Bart Peter Bert Segers; Natalia Viktorovna Davydova
- Web page: https://patentgrep.com/patent/US9519224B2

## CPC

- G03F 7/702: {Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems}
- G01T 1/02: Dosimeters (G01T1/15 takes precedence)
- G03F 7/70558: {Dose control, i.e. achievement of a desired dose}
- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- G03F 7/70641: {Focus}
- G03F 9/7026: {Focusing}
- G03F 9/7084: {Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels}
- 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)
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)

## Abstract

A lithographic apparatus comprising a support structure constructed to support a patterning device, the patterning device being capable of imparting an EUV radiation beam with a grating in its cross-section to form a patterned EUV radiation beam, and a projection system configured to project the patterned EUV radiation beam onto a target portion of the substrate, wherein the support structure is provided with a grating comprising a series of first reflective portions which alternates with a series of second reflective portions, the second reflective portions having a reflectivity which is less than the reflectivity of at least part of the first reflective portions and which is greater than zero.

## Claims

### Claim 1

A lithographic apparatus comprising:
a support structure comprising first and second portions, wherein:
the first portion is different from the second portion;
the first portion is configured to support a patterning device,
the second portion comprises a grating,
the grating comprises first and second reflective portions,
the first and second reflective portions are positioned in an alternating pattern,
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions, the first reflectivity being greater than zero, and
the patterning device is configured to impart an EUV radiation beam with a pattern in its cross-section to form a patterned EUV radiation beam; and
a projection system configured to project the patterned EUV radiation beam onto a target portion of a substrate.

### Claim 2 (depends on 1)

The lithographic apparatus of claim 1, wherein the first and second reflective portions comprise unpatterned areas.

### Claim 3 (depends on 2)

The lithographic apparatus of claim 2, wherein the first and second reflective portions comprise rectangular shapes.

### Claim 4 (depends on 1)

The lithographic apparatus of claim 1, wherein:
each of the first reflective portions comprises a sub-grating having reflective lines and absorbing lines; and
each of the second reflective portions comprises an unpatterned area.

### Claim 5 (depends on 4)

The lithographic apparatus of claim 4, wherein the grating is configured such that the first reflectivity substantially matches a mean reflectivity of the reflective lines and the absorbing lines.

### Claim 6 (depends on 1)

The lithographic apparatus of claim 1, wherein the grating further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.

### Claim 7 (depends on 1)

The lithographic apparatus of claim 1, wherein the grating is configured such that a mean intensity of radiation reflected by the first reflective portions and received by the substrate is substantially equal to a mean intensity of radiation reflected by the second reflective portions and received by the substrate.

### Claim 8 (depends on 1)

The lithographic apparatus of claim 1, wherein:
each of the second reflective portions comprises a layer of absorbing material located over a mirror;
the layer of absorbing material is configured to allow transmission of at least a portion of the EUV radiation beam towards the mirror; and
the mirror is configured to reflect at least a sub-portion of the at least a portion of the EUV radiation beam towards the layer of absorbing material.

### Claim 9 (depends on 1)

The lithographic apparatus of claim 1, wherein the first reflectivity is half of the second reflectivity.

### Claim 10 (depends on 1)

The lithographic apparatus of claim 1, wherein the support structure further comprises a second grating having an opposite orientation to the grating.

### Claim 11 (depends on 1)

The lithographic apparatus of claim 1, wherein the support structure further comprises another grating extending in a transverse direction to the grating.

### Claim 12 (depends on 1)

The lithographic apparatus of claim 1, wherein the grating is configured such that a first radiation dose per unit area projected onto the substrate from the second reflective portions is substantially equal to a second radiation dose per unit area projected onto the substrate from the first reflective portions.

### Claim 13 (depends on 1)

The lithographic apparatus of claim 1, further comprising an alignment apparatus configured to:
measure a center of gravity of an image of the grating projected onto the substrate; and
measure a dose of the EUV radiation beam received by the substrate based on the center of gravity.

### Claim 14 (depends on 1)

The lithographic apparatus of claim 1, further comprising an alignment apparatus configured to:
measure a position of an image of the grating projected onto the substrate; and
determine a location of a focal plane of the projection system based on the position of the image of the grating.

### Claim 15 (depends on 1)

The lithographic apparatus of claim 1, wherein the support structure further comprises another grating having a pattern that is a mirror image of a pattern of the grating.

### Claim 16

A patterning device comprising:
first and second reflective portions, wherein:
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions;
each of the first reflective portions comprises a sub-grating having reflective lines and absorbing lines;
the first reflectivity is greater than zero and substantially matches a mean reflectivity of the reflective lines and the absorbing lines; and
each of the second reflective portions comprises an unpatterned area.

### Claim 17 (depends on 16)

The patterning device of claim 16, wherein the patterning device further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.

### Claim 18

A support structure of a lithography apparatus comprising:
first and second portions, wherein:
the first portion is different from the second portion;
the first portion is configured to support a patterning device;
the second portion comprises a grating;
the grating comprising first and second reflective portions;
the first and second reflective portions are positioned in an alternating pattern;
the second reflective portions have a first reflectivity smaller than a second reflectivity of at least sub-portions of the first reflective portions; and
the first reflectivity is greater than zero.

### Claim 19 (depends on 18)

The support structure of claim 18, wherein the grating further comprises an absorbing portion located between a pair of first and second reflective portions from among the first and second reflective portions.