Photomask Pattern Splitting for Double Exposure Lithography
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Solution Overview
Problem
The double exposure lithography process in semiconductor manufacturing faces issues with uneven distribution of patterns during the split process, affecting the quality of the exposure process due to the proximity of critical and non-critical patterns.
Innovation Solution
A method that includes a first split process for critical patterns and a second split process for non-critical patterns, ensuring that both are decomposed into distinct groups for even distribution on separate photomasks, thereby improving the exposure process quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single split process is used for all patterns, then the process is simple, but the distribution of patterns on photomasks becomes uneven
Solution Approach 1:
The patent divides the pattern decomposition process into two distinct stages: a first split process that separates critical patterns into first and second patterns, and a second split process that separates non-critical patterns into third and fourth patterns. This segmentation allows different handling strategies for different pattern types, ensuring even distribution across photomasks while maintaining operational clarity through structured process separation.
2Device complexity
If critical and non-critical patterns are mixed in one split process, then the process is straightforward, but exposure quality deteriorates due to uneven distribution
Solution Approach 1:
The patent applies different processing treatments to different regions of the pattern set by identifying critical patterns versus non-critical patterns. Critical patterns undergo the first split process while non-critical patterns undergo the second split process. This local differentiation ensures that each pattern type is optimally distributed, preventing exposure quality deterioration while managing overall process complexity through targeted rather than universal processing.
3Productivity
If patterns are not evenly distributed on photomasks, then the split process is simple, but the exposure quality becomes poor
Solution Approach 1:
The patent performs preliminary classification of patterns into critical and non-critical categories before the actual splitting occurs. This preliminary action enables subsequent split processes to be optimized for each category, ensuring even distribution on photomasks before exposure. By preparing the pattern sets in advance with appropriate classification, the method achieves both efficient decomposition and high exposure quality without requiring complex real-time adjustments during exposure.
Data Source
AI summary
A method for separating photomask pattern, including the following steps: first, a layout pattern is provided, wherein the layout pattern is defined to have at least one critical pattern and at least one non-critical pattern. Then, a first split process is performed to separate the critical pattern into a plurality of first patterns and a plurality of second patterns. A second split process is performed to separate the non-critical pattern into a plurality of third patterns and a plurality of fourth patterns. Finally, the first patterns and the third patterns are output to a first photomask, and the second patterns and the fourth patterns are output to a second photomask.