Post-OPC Pattern Rotation for Inter-Pattern Spacing
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Solution Overview
Problem
In the deep submicron era of semiconductor fabrication, optical proximity correction (OPC) processes lead to image distortion and size discrepancies in pattern transfer due to narrowing of pattern-to-pattern spaces, which existing solutions attempt to address through advanced mask fabrication or reduced OPC accuracy.
Innovation Solution
A method involving OPC process followed by rotating post-OPC patterns violating manufacturing rules to increase inter-pattern distances without requiring advanced mask fabrication or reducing OPC accuracy, utilizing a rotation angle of 30-60 degrees, preferably 45 degrees, to maintain pattern size accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional OPC is performed on layout patterns, then image distortion and pattern deviations are corrected, but the distance between post-OPC patterns is narrowed below the minimum achievable mask fabrication space
Solution Approach 1:
The patent applies a rotation transformation to the post-OPC patterns, changing their spatial orientation by 45 degrees. This dimensional transformation increases the effective distance between adjacent patterns without altering the OPC-corrected pattern sizes, thereby resolving the contradiction between maintaining pattern accuracy and achieving sufficient inter-pattern spacing for mask fabrication
Solution Approach 2:
The patent modifies the rotational angle parameter of the patterns (specifically 45 degrees) as a controllable variable to optimize the inter-pattern distance. By adjusting this geometric parameter, the solution achieves the minimum required spacing for mask fabrication while preserving the precision of OPC-corrected pattern dimensions
2Ease of manufacture
If OPC accuracy is reduced to ensure minimum pattern spacing, then mask fabrication feasibility is improved, but pattern size accuracy on the substrate deteriorates
Solution Approach 1:
The patent extracts the inter-pattern spacing issue from the OPC process itself by applying a separate rotation transformation after OPC is completed. This separates the pattern size correction function (performed by OPC) from the spacing adjustment function (performed by rotation), allowing both OPC accuracy and mask fabrication feasibility to be optimized independently
Solution Approach 2:
The patent performs the rotation transformation as a preliminary step before mask fabrication, ensuring that the inter-pattern distances are adequately spaced for manufacturing requirements while the OPC-corrected pattern sizes remain intact. This preliminary geometric transformation prevents spacing-related manufacturing issues without compromising pattern accuracy
Data Source
AI summary
A method of layout pattern modification includes the following steps: step 1: performing an OPC process on a layout containing a plurality of square patterns to obtain a plurality of post-OPC patterns in correspondence with the plurality of square patterns; step 2: performing a manufacturing rule check on each of the plurality of post-OPC patterns to identify, from the plurality of post-OPC patterns, one or more post-OPC patterns violating the manufacturing rule; and step 3: rotating at least one of the one or more post-OPC patterns violating the manufacturing rule; and step 4: performing a manufacturing rule check on each of the rotated and non-rotated post-OPC patterns, if no post-OPC pattern violating the manufacturing rule is identified, finishing the process; otherwise, if one or more post-OPC patterns violating the manufacturing rule are identified, continuing to perform step 3 and step 4.