Photomask Layout Generation for IC Pattern Quality
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Solution Overview
Problem
Conventional photolithography techniques face limitations in miniaturization and manufacturability, particularly due to optical proximity effects and polishing issues like dishing, which require the effective distribution of dummy and feature patterns on photomasks, necessitating improved methods for generating photomask layouts.
Innovation Solution
A method involving the classification of feature patterns into first and second patterns, generation of dummy pad patterns, and combination with mandrel and geometric patterns to form multiple photomasks, allowing for optical proximity correction and improved pattern transfer to semiconductor substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography techniques are used for miniaturization, then manufacturing capability is maintained, but optical proximity effects and polishing issues deteriorate pattern quality
Solution Approach 1:
The layout pattern is segmented into multiple photomasks (first photomask with combined pattern, second photomask with mandrel patterns, third photomask with geometric patterns) to distribute harmful effects across separate masks, allowing each mask to be optimized independently for its specific pattern type and reducing cumulative optical proximity effects and polishing issues
Solution Approach 2:
Dummy pad patterns are introduced as intermediary elements between feature patterns to act as buffers that mitigate optical proximity effects and distribute polishing loads, preventing direct harmful interactions between adjacent feature patterns while maintaining overall pattern integrity
2Manufacturing precision
If dummy patterns are added to prevent optical problems and polishing issues, then pattern transfer quality improves, but photomask complexity increases
Solution Approach 1:
The complex pattern set is segmented across three separate photomasks, with dummy pad patterns primarily concentrated on the first photomask where they can be managed more effectively, reducing the complexity burden on any single mask while maintaining overall pattern transfer quality
Solution Approach 2:
Different types of patterns (feature patterns, mandrel patterns, geometric patterns) are assigned to different photomasks based on their specific requirements, allowing each mask to be optimized with appropriate dummy patterns and features localized to where they are most effective
3Measurement precision
If feature patterns are classified and distributed across multiple photomasks, then optical proximity correction effectiveness improves, but manufacturing process complexity increases
Solution Approach 1:
Feature patterns are segmented by size into first feature patterns (smaller dimensions) and second feature patterns (larger dimensions), with different patterns assigned to different photomasks, allowing optical proximity correction to be applied more effectively to each group with appropriate correction parameters optimized for their specific dimensional characteristics
Solution Approach 2:
Different photomasks are designed with different pattern types and dimensional parameters (first photomask with combined feature and dummy pad patterns, second photomask with mandrel patterns, third photomask with geometric patterns), enabling optical proximity correction parameters to be optimized for each mask's specific characteristics
Data Source
AI summary
A method for generating a layout pattern of integrated circuit (IC) is provided. First, feature patterns are provided to a computer system and dummy pad patterns are generated in a space among the feature patterns. The layout pattern is then split into first feature patterns and second feature patterns. The dimensions of the first feature patterns are less than the dimensions of the second feature patterns. Afterwards, the dummy pad patterns are combined with the second features pattern to form a combined pattern. Then, mandrel patterns are generated in a space between the first feature patterns and the geometric patterns are generated according to the positions of the first feature patterns. Finally, the combined pattern, the mandrel patterns, and the geometric patterns are respectively outputted to form a first, a second, and a third photomasks.