# US 12,222,641 B2 · Method and device for optimizing mask parameters

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- Number: US 12,222,641 B2
- Document ID: US12222641B2
- Status: Granted
- Kind: B2
- Application number: 17/773,668
- Filed: 2021-11-08
- Published: 2024-05-30
- Granted: 2025-02-11
- Earliest claimed: 2021-10-29
- Assignees: Institute of Microelectronics, Chinese Academy of Sciences
- Applicants: Institute of Microelectronics, Chinese Academy of Sciences
- Inventors: Jianfang He; Yayi Wei; Yajuan Su; Lisong Dong; Libin Zhang; Rui Chen; Le Ma
- Web page: https://patentgrep.com/patent/US12222641B2

## CPC

- G03F 1/44: Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
- G03F 1/70: Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging
- 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

The present disclosure provides a method for optimizing mask parameters, and the method includes: acquiring a test pattern, light source parameters, and initial mask parameters, the initial mask parameters including a mask thickness and an initial mask sidewall angle; generating multiple sets of candidate mask parameters according to the initial mask sidewall angle in the initial mask parameters; the multiple sets of candidate mask parameters including different mask sidewall angles and the same mask thickness; obtaining an imaging contrast of each set of candidate mask parameters based on the test pattern and the light source parameters; and selecting an optimal mask sidewall angle from the multiple sets of candidate mask parameters according to the imaging contrasts. By generating multiple sets of candidate mask parameters including different mask sidewall angles and the same mask thickness, and simulating these sets of candidate mask parameters respectively, the imaging contrast of each set of candidate mask parameters is obtained, so that the optimal mask sidewall angle is found according to the imaging contrasts. Therefore, by optimizing the mask parameters of the multi-layer film lens structure, the imaging contrast can also be significantly improved, and the imaging resolution can be improved.

## Claims

### Claim 1

A method for optimizing mask parameters, the method comprising:
acquiring a test pattern, light source parameters, and initial mask parameters, the initial mask parameters comprising a mask thickness and an initial mask sidewall angle;
generating multiple sets of candidate mask parameters according to the initial mask sidewall angle in the initial mask parameters; wherein the multiple sets of candidate mask parameters comprising different mask sidewall angles and the same mask thickness;
obtaining an imaging contrast of each set of candidate mask parameters based on the test pattern and the light source parameters; and
selecting an optimal mask sidewall angle from the multiple sets of candidate mask parameters according to the imaging contrasts.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the generating multiple sets of candidate mask parameters according to the initial mask sidewall angle in the initial mask parameters comprises:
starting from the initial mask sidewall angle, generating one mask sidewall angle every other preset step until the generated mask sidewall angle is larger than a preset sidewall angle; and
forming each generated mask sidewall angle and the mask thickness into a set of candidate mask parameters.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the obtaining an imaging contrast of each set of candidate mask parameters based on the test pattern and the light source parameters comprises:
for each set of candidate mask parameters, under the condition of the set of candidate mask parameters, obtaining a maximum light intensity and a minimum light intensity of an aerial image formed in a photoresist coated on a base layer by using the test pattern and the light source parameters; and
determining the imaging contrast of the set of candidate mask parameters according to the maximum light intensity and the minimum light intensity.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the selecting an optimal mask sidewall angle from the multiple sets of candidate mask parameters according to the imaging contrasts comprises:
determining the mask sidewall angle in the candidate mask parameters corresponding to a maximum value of the imaging contrast, as the optimal mask sidewall angle.

### Claim 5

A device for optimizing mask parameters, the device comprising:
an acquisition module, which is configured to acquire a test pattern, light source parameters, and initial mask parameters, the initial mask parameters comprising a mask thickness and an initial mask sidewall angle;
a candidate parameter generation module, which is configured to generate multiple sets of candidate mask parameters according to the initial mask sidewall angle in the initial mask parameters; wherein the multiple sets of candidate mask parameters comprising different mask sidewall angles and the same mask thickness;
a simulation module, which is configured to obtain an imaging contrast of each set of candidate mask parameters based on the test pattern and the light source parameters; and
an optimal value selection module, which is configured to select an optimal mask sidewall angle from the multiple sets of candidate mask parameters according to the imaging contrasts.

### Claim 6 (depends on 5)

The device according to claim 5, wherein the candidate parameter generation module is specifically configured to: starting from the initial mask sidewall angle, generate one mask sidewall angle every other preset step until the generated mask sidewall angle is larger than a preset sidewall angle; and form each generated mask sidewall angle and the mask thickness into a set of candidate mask parameters.

### Claim 7 (depends on 5)

The device according to claim 5, wherein the simulation module is specifically configured to: for each set of candidate mask parameters, under the condition of the set of candidate mask parameters, obtain a maximum light intensity and a minimum light intensity of an aerial image formed in a photoresist coated on a base layer by using the test pattern and the light source parameters; and determine the imaging contrast of the set of candidate mask parameters according to the maximum light intensity and the minimum light intensity.

### Claim 8 (depends on 5)

The device according to claim 5, wherein the optimal value selection module is specifically configured to: determine the mask sidewall angle in the candidate mask parameters corresponding to a maximum value of the imaging contrast, as the optimal mask sidewall angle.