# US 12,007,697 B2 · Method for process metrology

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- Number: US 12,007,697 B2
- Document ID: US12007697B2
- Status: Granted
- Kind: B2
- Application number: 17/836,066
- Filed: 2022-06-09
- Published: 2022-10-13
- Granted: 2024-06-11
- Earliest claimed: 2016-09-12
- Assignees: ASML Netherlands B.V.
- Applicants: Asml Netherlands B.V.
- Inventors: Bert Verstraeten; Hugo Augustinus Joseph Cramer; Thomas Theeuwes
- Web page: https://patentgrep.com/patent/US12007697B2

## CPC

- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- G03F 7/70641: {Focus}
- G03F 7/70683: {Mark designs}
- 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 of evaluating a patterning process, the method including: obtaining the result of a first measurement of a first metrology target; obtaining the result of a second measurement of a second metrology target, the second metrology target having a structural difference from the first metrology target that generates a sensitivity difference and/or an offset, of a process parameter of the patterning process between the first and second metrology targets; and determining a value pertaining to the patterning process based on the results of the first and second measurements.

## Claims

### Claim 1

A method of generating a set of metrology targets to evaluate a patterning process, the method comprising:
obtaining a pattern target; and
generating, by a computer system, a first metrology target from the pattern target, the first metrology target having a structural difference from the pattern target that generates a sensitivity difference and/or an offset, of a process parameter of the patterning process between the pattern target and the first metrology target such that a Bossung curve measured for the first metrology target is shifted from a Bossung curve measured for the pattern target.

### Claim 2 (depends on 1)

The method of claim 1, further comprising generating a second metrology target, the second metrology target having a structural difference from the pattern target and the first metrology target that generates a sensitivity difference and/or an offset, of a process parameter of the patterning process between the second metrology target and both the pattern target and the first metrology target such that a Bossung curve measured for the second metrology target is shifted from a Bossung curve measured for the pattern target and the first metrology target respectively.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
obtaining a result of a first measurement of the pattern target;
obtaining a result of a second measurement of the second metrology target; and
determining a value pertaining to the patterning process based on the results of the first and second measurements.

### Claim 4 (depends on 1)

The method of claim 1, wherein the process parameter comprises focus or dose of a patterning step of the patterning process.

### Claim 5 (depends on 1)

The method of claim 1, wherein the pattern target is a pattern of, or for forming, a device.

### Claim 6 (depends on 1)

The method of claim 1, wherein the process parameter is focus of a patterning step of the patterning process and wherein the first metrology target has a best focus different than that for the pattern target while the pattern target and the first metrology target have substantially equal depth of focus and, at a substantially equal dose, the first metrology target at its best focus and the pattern target at its best focus have substantially equal critical dimension.

### Claim 7

A non-transitory computer program product comprising machine-readable instructions therein, the instructions, when executed, are configured to cause a processor system to at least:
obtain a pattern target; and
generate a first metrology target to evaluate a patterning process from the pattern target, the first metrology target having a structural difference from the pattern target that generates a sensitivity difference and/or an offset, of a process parameter of the patterning process between the pattern target and the first metrology target such that a Bossung curve measured for the first metrology target is shifted from a Bossung curve measured for the pattern target.

### Claim 8 (depends on 7)

The computer program product of claim 7, wherein the instructions are further configured to cause the processor system to generate a second metrology target, the second metrology target having a structural difference from the pattern target and the first metrology target that generates a sensitivity difference and/or an offset, of a process parameter of the patterning process between the second metrology target and both the pattern target and the first metrology target such that a Bossung curve measured for the second metrology target is shifted from a Bossung curve measured for the pattern target and the first metrology target respectively.

### Claim 9 (depends on 8)

The computer program product of claim 8, wherein the instructions are further configured to cause the processor system to:
obtain a result of a first measurement of the pattern target;
obtain a result of a second measurement of the second metrology target; and
determine a value pertaining to the patterning process based on the results of the first and second measurements.

### Claim 10 (depends on 7)

The computer program product of claim 7, wherein the process parameter comprises focus or dose of a patterning step of the patterning process.

### Claim 11 (depends on 7)

The computer program product of claim 7, wherein the pattern target is a pattern of, or for forming, a device.

### Claim 12 (depends on 7)

The computer program product of claim 7, wherein the process parameter is focus of a patterning step of the patterning process and wherein the first metrology target has a best focus different than that for the pattern target while the pattern target and the first metrology target have substantially equal depth of focus and, at a substantially equal dose, the first metrology target at its best focus and the pattern target at its best focus have substantially equal critical dimension.

### Claim 13 (depends on 7)

A system comprising:
an inspection or metrology apparatus configured to provide a beam of radiation on a metrology target and to detect radiation redirected by the target to determine a parameter of a patterning process; and
the non-transitory computer program product of claim 7.

### Claim 14

A non-transitory set of metrology targets to evaluate a patterning process, the set of metrology targets comprising a first metrology target and a second metrology target, a difference between the first metrology target and the second metrology target generating a sensitivity difference and/or an offset, of a process parameter of the patterning process between the first and second metrology targets, wherein the offset represents a difference in formation of the first and second metrology targets when subject to a particular same value of the process parameter.

### Claim 15 (depends on 14)

The set of metrology targets of claim 14, wherein the first and second metrology targets generate a sensitivity difference and/or an offset, of the process parameter relative to a third metrology target.

### Claim 16 (depends on 14)

The set of metrology targets of claim 14, wherein the first metrology target and the second metrology target are based on a common product pattern of a device pattern.

### Claim 17 (depends on 14)

The set of metrology targets of claim 14, wherein the difference is generated using an optical proximity correction and/or an assist feature using an optical proximity correction on a patterning device and/or is an assist feature on the patterning device.

### Claim 18 (depends on 14)

The set of metrology targets of claim 14, wherein the process parameter comprises focus or dose of a patterning step of the patterning process.

### Claim 19 (depends on 13)

A non-transitory computer-readable medium comprising data therein that encodes physical characteristics of the set of metrology targets of claim 13.

### Claim 20 (depends on 13)

A substrate comprising physical embodiments of the set of metrology targets of claim 13.