# US 2018/0024448 A1 · Focus centering method for digital lithography

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- Number: US 2018/0024448 A1
- Document ID: US20180024448A1
- Status: Published application
- Kind: A1
- Application number: 15/649,249
- Filed: 2017-07-13
- Published: 2018-01-25
- Earliest claimed: 2016-07-19
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Yeishin TUNG; Douglas Joseph VAN DEN BROEKE; Antoine P. MANENS; Jang Fung CHEN
- Web page: https://patentgrep.com/patent/US20180024448A1

## CPC

- G03F 9/7026: {Focusing}
- G03F 7/70275: {Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems}
- G03F 7/70291: {Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices}
- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- G03F 7/70641: {Focus}
- 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

Embodiments disclosed herein generally relate to adjusting a focus setting for a digital lithography system. The method includes scanning a surface of a photoresist. The photoresist is formed on a substrate. A focus setting for the digital lithography system is determined. A plurality of exposure location on the photoresist are located. A sidewall width of the exposure is measured for a plurality of focus settings. The focus setting is adjusted in response to determining a minimum sidewall width.

## Claims

### Claim 1

A method of adjusting focus setting for a digital lithography system, comprising:
scanning a surface of a photoresist formed on a substrate;
determining a focus setting for the digital lithography system, comprising:
locating a plurality of exposures on the photoresist; and
measuring a sidewall width of each exposure for a plurality of focus settings; and
adjusting the focus setting in response to determining a minimum sidewall width.

### Claim 2 (depends on 1)

The method of claim 1, wherein the focus settings range from −100 μm to 100 μm.

### Claim 3 (depends on 2)

The method of claim 2, wherein the focus settings range from −30 μm to 30 μm.

### Claim 4 (depends on 1)

The method of claim 1, wherein measuring a sidewall width of the exposure for a plurality of focus settings, comprises:
measuring a sidewall width at a plurality of points along the sidewall of the exposure.

### Claim 5 (depends on 1)

The method of claim 1, wherein determining a focus setting for the digital lithography system, further comprises:
determining a focus setting for the digital lithography system for each image projection system in the digital lithography system.

### Claim 6 (depends on 1)

The method of claim 1, wherein the surface of the photoresist is scanned using a three-dimensional optical profiler.

### Claim 7 (depends on 6)

The method of claim 6, wherein the three-dimensional optical profiler uses light emitting diodes as a light source.

### Claim 8

A computer system for adjusting a focus setting for a digital lithography system, comprising:
a processor; and
a memory storing instructions that, when executed by the processor, cause the computer system to:
scanning a surface of a photoresist formed on a substrate;
determining a focus setting for the digital lithography system, comprising:
locating a plurality of exposures on the photoresist; and
measuring a sidewall width of each exposure for a plurality of focus settings; and
adjusting the focus setting in response to determining a minimum sidewall width.

### Claim 9 (depends on 8)

The computer system of claim 8, wherein the focus settings range from −100 μm to 100 μm.

### Claim 10 (depends on 9)

The computer system of claim 9, wherein the focus settings range from −30 μm to 30 μm.

### Claim 11 (depends on 8)

The computer system of claim 8, wherein measuring a sidewall width of the exposure for a plurality of focus settings, comprises:
measuring a sidewall width at a plurality of points along the sidewall of the exposure.

### Claim 12 (depends on 8)

The computer system of claim 8, wherein determining a focus setting for the digital lithography system, further comprises:
determining a focus setting for the digital lithography system for each image projection system in the digital lithography system.

### Claim 13 (depends on 8)

The computer system of claim 8, wherein the surface of the photoresist is scanned using a three-dimensional optical profiler.

### Claim 14 (depends on 8)

The computer system of claim 8, wherein the three-dimensional optical profiler uses light emitting diodes as a light source.

### Claim 15

A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause a computer system to adjust a focus setting for a digital lithography system, by performing the steps of:
scan a surface of a photoresist formed on a substrate;
determine a focus setting for the digital lithography system, comprising:
locate a plurality of exposures on the photoresist; and
measure a sidewall width of each exposure for a plurality of focus settings; and
adjust the focus setting in response to determining a minimum sidewall width.

### Claim 16 (depends on 15)

The non-transitory computer-readable medium of claim 15, wherein the focus settings range from −100 μm to 100 μm.

### Claim 17 (depends on 16)

The non-transitory computer-readable medium of claim 16, wherein the focus settings range from −30 μm to 30 μm.

### Claim 18 (depends on 15)

The non-transitory computer-readable medium of claim 15, wherein measuring a sidewall width of the exposure for a plurality of focus settings, comprises:
measuring a sidewall width at a plurality of points along the sidewall of the exposure.

### Claim 19 (depends on 15)

The non-transitory computer-readable medium of claim 15, wherein determining a focus setting for the digital lithography system, further comprises:
determining a focus setting for the digital lithography system for each image projection system in the digital lithography system.

### Claim 20 (depends on 15)

The non-transitory computer-readable medium of claim 15, wherein the surface of the photoresist is scanned using a three-dimensional optical profiler.