Photomask Retargeting for Lithography Weak Region Correction
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Solution Overview
Problem
The continuous shrinkage of feature sizes in integrated circuits leads to transfer distortion in photomasks due to optical proximity effects, which cannot be effectively addressed by optical proximity correction (OPC) techniques, resulting in lengthy and costly photomask repair processes.
Innovation Solution
A method involving OPC iterations with model-based photomask pattern correction and target pattern retargeting is employed to eliminate light intensity and peak intensity errors, focusing on local lithography weak regions through computer simulation, eliminating the need for lengthy photomask repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If OPC techniques are applied to design photomask patterns, then transfer distortion is reduced, but manufacturing time and cost increase due to multiple repair iterations
Solution Approach 1:
The patent performs preliminary identification of lithography weak regions and preliminary retargeting of target patterns before photomask pattern correction. By proactively addressing potential distortion areas in advance through simulation and analysis, the method eliminates the need for multiple iterative repairs, thus reducing manufacturing time while maintaining precision
Solution Approach 2:
The patent employs a feedback mechanism where light intensity curves are simulated and checked against standard values, and the results are used to iteratively adjust the photomask pattern. This closed-loop feedback ensures that transfer distortion is minimized while the number of iterations is reduced through intelligent initial retargeting
2Manufacturing precision
If OPC techniques are applied to design photomask patterns, then transfer distortion is reduced, but manufacturing cost increases due to multiple repair iterations
Solution Approach 1:
The patent performs preliminary identification of lithography weak regions and preliminary retargeting of target patterns before photomask pattern correction. By proactively addressing potential distortion areas in advance through simulation and analysis, the method eliminates the need for multiple iterative repairs, thus reducing manufacturing cost while maintaining precision
3Manufacturing precision
If photomask patterns are corrected through multiple iterations, then light intensity error is reduced, but design time is extended
Solution Approach 1:
The patent performs preliminary retargeting of target patterns based on simulated light intensity curves before the main correction iterations. This preliminary action positions the photomask pattern closer to the optimal solution, significantly reducing the number of correction iterations needed and thus shortening design time while maintaining precision
Solution Approach 2:
The patent employs a feedback mechanism where light intensity curves are simulated and checked against standard values, and the results are used to iteratively adjust the photomask pattern. This closed-loop feedback ensures that light intensity error is minimized while the number of iterations is reduced through intelligent initial retargeting
Data Source
AI summary
A method for forming a photomask is provided. The method includes: providing a photomask pattern for a target pattern; obtaining a first light intensity curve according to the photomask pattern by simulation; subjecting the first light intensity curve to a check on light intensities at pattern edges of the target pattern to define a light intensity error; retargeting the photomask pattern to reduce the light intensity error; identifying a lithography weak region in the target pattern; obtaining a second light intensity curve of the lithography weak region by simulation; subjecting the second light intensity curve to a check on a peak light intensity to define a peak intensity error; retargeting the target pattern to reduce the peak intensity error; and retargeting the photomask pattern again based on the modified target pattern.