Photolithography Mask Layout With Iterative SRAF Placement

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Solution Overview

Problem

Existing semiconductor manufacturing techniques for generating sub-resolution assist features (SRAFs) in photolithography masks face challenges in accuracy and efficiency, with rule-based methods being quick but inaccurate, and inverse lithography technology being time-consuming, leading to suboptimal mask generation and integrated circuit production.

Innovation Solution

A method that generates SRAF and main patterns simultaneously based on a target pattern, using iterative processes and cost function optimization, allowing for accurate placement of SRAFs on a blank mask without relying on a pre-existing main pattern, thereby improving the quality of photolithography masks and integrated circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If rule-based SRAF insertion techniques are used, then turn-around time is short, but accuracy is far-from-ideal

Engineering Contradiction:

Improveturn-around timeVSAvoidSRAF placement accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements an iterative feedback mechanism where the main pattern is first generated, then SRAFs are inserted based on rules, and the process repeats with optimization. Each iteration uses the results of the previous iteration to improve SRAF placement accuracy while maintaining reasonable turn-around time through controlled iteration cycles.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transitions from static rule-based SRAF insertion to a dynamic iterative process where SRAF placement is continuously refined based on pattern recognition and optimization criteria. The system adapts SRAF positions across multiple iterations to achieve better accuracy without excessive time consumption.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If numerous iterations of mask optimization are used to achieve outstanding accuracy, then SRAF placement accuracy is improved, but turn-around time becomes long

Engineering Contradiction:

ImproveSRAF placement accuracyVSAvoidturn-around time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies partial iteration by performing a limited number of optimization cycles rather than exhaustive iterations. The rule-based SRAF insertion is applied selectively after main pattern generation, providing sufficient accuracy improvement without requiring numerous full optimization iterations, thus balancing accuracy with turn-around time.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of manufacture

If SRAFs are inserted based on a pre-generated main pattern, then the process is simplified, but accuracy is compromised due to estimation errors

Engineering Contradiction:

Improveprocess simplicityVSAvoidpattern accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs preliminary generation of the main pattern using estimated parameters before inserting SRAFs. This preliminary main pattern serves as a foundation for subsequent SRAF placement rules, enabling the process to proceed systematically while allowing for later optimization to correct estimation errors and improve accuracy.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250004383A1Method of producing mask data for semiconductor device manufacturing

Publication Date: 2025.01.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A process for forming a photolithography mask includes generating a sub-resolution assist feature (SRAF) pattern from a blank mask layout based on a target layout. The SRAF pattern can be generated using an iterative process including finding the gradient of a cost function. A main pattern can be generated simultaneously with the SRAF pattern or after generation of the SRAF pattern.