# US 2022/0276554 A1 · Enforcing mask synthesis consistency across random areas of integrated circuit chips

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- Number: US 2022/0276554 A1
- Document ID: US20220276554A1
- Status: Published application
- Kind: A1
- Application number: 17/749,952
- Filed: 2022-05-20
- Published: 2022-09-01
- Earliest claimed: 2019-07-18
- Assignees: Synopsys, Inc.
- Applicants: Synopsys, Inc.
- Inventors: Thomas Christopher Cecil; Kevin Hooker
- Web page: https://patentgrep.com/patent/US20220276554A1

## CPC

- G03F 1/70: Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging
- G06F 30/39: Circuit design at the physical level (physical level design for reconfigurable circuits G06F30/347)
- G03F 1/36: Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
- G03F 1/44: Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
- G03F 1/78: by charged particle beam [CPB], e.g. electron beam patterning of masks
- G06F 16/51: Indexing; Data structures therefor; Storage structures
- G06F 30/392: Floor-planning or layout, e.g. partitioning or placement
- G06F 2111/20: Configuration CAD, e.g. designing by assembling or positioning modules selected from libraries of predesigned modules
- 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)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A system generates a mask for a circuit design while enforcing symmetry and consistency across random areas of the mask. The system builds a mask solutions database mapping circuit patterns to mask patterns. The system uses the mask solutions database to replace circuit patterns of the circuit design with mask patterns. The system identifies properties in circuit patterns of the circuit design and enforces the same property in the corresponding mask patterns. Examples of properties enforced include symmetry within circuit patterns and similarity across circuit patterns. The system combines mask patterns in different regions of the circuit and resolves conflicts that occur when there are multiple masks within a region.

## Claims

### Claim 1

A method to perform mask synthesis for a circuit design, the method comprising:
receiving the circuit design representing a physical layout of a circuit, the circuit design comprising geometric shapes;
receiving a mask design for the circuit design;
identifying one or more circuit patterns within the circuit design;
identifying one or more mask patterns, each mask pattern corresponding to a circuit pattern from the one or more circuit patterns;
determining a property of the one or more circuit patterns, the property based on geometric shapes within the one or more circuit patterns;
determining, by a processing device, a mask pattern based on the one or more mask patterns such that the determined mask pattern has a corresponding property as the one or more circuit patterns; and
replacing at least a portion of the mask design using the determined mask pattern.

### Claim 2 (depends on 1)

The method of claim 1, wherein the property of the one or more circuit patterns represents more than a threshold degree of similarity between the one or more circuit patterns, and wherein modifying the one or more mask patterns comprises:
determining an aggregate mask pattern by aggregating the one or more mask patterns; and
using the aggregate mask pattern instead of each of the one or more mask patterns.

### Claim 3 (depends on 2)

The method of claim 2, wherein determining the aggregate mask pattern comprises:
rasterizing each of the one or more mask patterns to generate an image representation of each of the one or more mask patterns;
aggregating the image representations of the one or more mask patterns to generate an aggregated image representation; and
generating the aggregate mask pattern by converting the aggregated image representation to a vector representation.

### Claim 4 (depends on 3)

The method of claim 3, wherein aggregating comprises averaging the one or more mask patterns.

### Claim 5 (depends on 3)

The method of claim 3, wherein aggregating comprises selecting a mask pattern from the one or more mask patterns with the best lithographic performance.

### Claim 6 (depends on 1)

The method of claim 1, wherein the property of the one or more circuit patterns represents a symmetry in a circuit pattern, the method further comprising:
modifying a mask pattern corresponding to the circuit pattern having the symmetry to enforce the symmetry in the mask pattern.

### Claim 7 (depends on 6)

The method of claim 6, wherein the symmetry is one of:
rotation symmetry;
mirror symmetry;
translation symmetry;
fractional pitch symmetry; or
a combination thereof.

### Claim 8

A non-transitory computer readable storage medium storing instructions to perform mask synthesis for a circuit design, the instructions when executed by one or more computer processors cause the one or more computer processors to:
receive the circuit design representing a physical layout of a circuit, the circuit design comprising geometric shapes;
receive a mask design for the circuit design;
identify one or more circuit patterns within the circuit design;
identify one or more mask patterns, each mask pattern corresponding to a circuit pattern from the one or more circuit patterns;
determine a property of the one or more circuit patterns, the property based on geometric shapes within the one or more circuit patterns;
determine, by a processing device, a mask pattern based on the one or more mask patterns such that the determined mask pattern has a corresponding property as the one or more circuit patterns; and
replace at least a portion of the mask design using the determined mask pattern.

### Claim 9 (depends on 8)

The non-transitory computer readable storage medium of claim 8, wherein the property of the one or more circuit patterns represents more than a threshold degree of similarity between the one or more circuit patterns, and wherein instructions to modify the one or more mask patterns cause the one or more computer processors to:
determine an aggregate mask pattern by aggregating the one or more mask patterns; and
use the aggregate mask pattern instead of each of the one or more mask patterns.

### Claim 10 (depends on 9)

The non-transitory computer readable storage medium of claim 9, wherein instructions to determine the aggregate mask pattern cause the one or more computer processors to:
rasterize each of the one or more mask patterns to generate an image representation of each of the one or more mask patterns;
aggregate the image representations of the one or more mask patterns to generate an aggregated image representation; and
generate the aggregate mask pattern by converting the aggregated image representation to a vector representation.

### Claim 11 (depends on 10)

The non-transitory computer readable storage medium of claim 10, wherein instructions to aggregate perform averaging of the one or more mask patterns.

### Claim 12 (depends on 10)

The non-transitory computer readable storage medium of claim 10, wherein instructions to aggregate cause the one or more computer processor to select a mask pattern from the one or more mask patterns with the best lithographic performance.

### Claim 13 (depends on 8)

The non-transitory computer readable storage medium of claim 8, wherein the property of the one or more circuit patterns represents a symmetry in a circuit pattern, wherein the instructions further cause the one or more computer processors to:
modify a mask pattern corresponding to the circuit pattern having the symmetry to enforce the symmetry in the mask pattern.

### Claim 14 (depends on 13)

The non-transitory computer readable storage medium of claim 13, wherein the symmetry is one of:
rotation symmetry;
mirror symmetry;
translation symmetry;
fractional pitch symmetry; or
a combination thereof.

### Claim 15

A computer system comprising:
one or more computer processors; and
a non-transitory computer readable storage medium storing instructions to perform mask synthesis for a circuit design, the instructions when executed by the one or more computer processors cause the one or more computer processors to:
receive the circuit design representing a physical layout of a circuit, the circuit design comprising geometric shapes;
receive a mask design for the circuit design;
identify one or more circuit patterns within the circuit design;
identify one or more mask patterns, each mask pattern corresponding to a circuit pattern from the one or more circuit patterns;
determine a property of the one or more circuit patterns, the property based on geometric shapes within the one or more circuit patterns;
determine, by a processing device, a mask pattern based on the one or more mask patterns such that the determined mask pattern has a corresponding property as the one or more circuit patterns; and
replace at least a portion of the mask design using the determined mask pattern.

### Claim 16 (depends on 15)

The computer system of claim 15, wherein the property of the one or more circuit patterns represents more than a threshold degree of similarity between the one or more circuit patterns, and wherein instructions to modify the one or more mask patterns cause the one or more computer processors to:
determine an aggregate mask pattern by aggregating the one or more mask patterns; and
use the aggregate mask pattern instead of each of the one or more mask patterns.

### Claim 17 (depends on 16)

The computer system of claim 16, wherein instructions to determine the aggregate mask pattern cause the one or more computer processors to:
rasterize each of the one or more mask patterns to generate an image representation of each of the one or more mask patterns;
aggregate the image representations of the one or more mask patterns to generate an aggregated image representation; and
generate the aggregate mask pattern by converting the aggregated image representation to a vector representation.

### Claim 18 (depends on 17)

The computer system of claim 17, wherein instructions to aggregate cause the one or more computer processor to select a mask pattern from the one or more mask patterns with the best lithographic performance.

### Claim 19 (depends on 15)

The computer system of claim 15, wherein the property of the one or more circuit patterns represents a symmetry in a circuit pattern, wherein the instructions further cause the one or more computer processors to:
modify a mask pattern corresponding to the circuit pattern having the symmetry to enforce the symmetry in the mask pattern.

### Claim 20 (depends on 19)

The computer system of claim 19, wherein the symmetry is one of: