Photomask Hole Pattern Design Grid Method
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Solution Overview
Problem
Conventional methods for arranging hole patterns on photomasks in semiconductor manufacturing face challenges such as distortion, connection of auxiliary patterns, and difficulty in securing a broad enough focus margin, particularly due to the dependence of focus margin on hole pattern density, which requires different optimal exposure conditions for dense and sparse layouts.
Innovation Solution
A method involving a grid with a space smaller than the minimum pitch for placing hole patterns at lattice points, with auxiliary patterns positioned at distances not less than the minimum pitch from the hole patterns' gravity centers, and optimizing pattern arrangements to ensure uniform optical conditions and improved focus margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary patterns are arranged densely to broaden focus margin, then focus margin is improved, but auxiliary patterns are transferred onto photoresist layer and connected with each other causing distortion
Solution Approach 1:
The patent applies local quality by making auxiliary patterns selectively invisible to the exposure system. By designing auxiliary patterns with specific optical properties (different reflectivity or transmissivity than hole patterns), they provide focus margin benefits in dense regions without being transferred onto the photoresist layer, thus avoiding distortion while maintaining reliability.
Solution Approach 2:
The patent changes the optical parameters of auxiliary patterns to differentiate their behavior during exposure. By adjusting parameters such as pattern size, material composition, or optical contrast, auxiliary patterns become invisible to the exposure system at certain conditions while still serving their function of broadening focus margin in dense layouts.
2Manufacturing precision
If minimum necessary number of auxiliary patterns are provided to avoid transfer and connection problems, then pattern shape accuracy is maintained, but focus margin cannot be fully broadened
Solution Approach 1:
The patent applies local quality by making auxiliary patterns selectively invisible to the exposure system. By designing auxiliary patterns with specific optical properties (different reflectivity or transmissivity than hole patterns), they provide focus margin benefits in dense regions without being transferred onto the photoresist layer, thus avoiding distortion while maintaining reliability.
Solution Approach 2:
The patent changes the optical parameters of auxiliary patterns to differentiate their behavior during exposure. By adjusting parameters such as pattern size, material composition, or optical contrast, auxiliary patterns become invisible to the exposure system at certain conditions while still serving their function of broadening focus margin in dense layouts.
3Reliability
If auxiliary pattern size and layout are optimized for each pattern to achieve isotropic arrangement, then focus margin is improved, but design complexity and work burden become extremely complicated and troublesome
Solution Approach 1:
The patent applies universality by creating a standardized auxiliary pattern design that can be applied across different hole pattern configurations. By establishing general design rules and parameters for auxiliary patterns that work effectively in various scenarios, the need for complex individual optimization is eliminated, reducing design complexity while maintaining focus margin benefits.
Solution Approach 2:
The patent changes the optical parameters of auxiliary patterns to differentiate their behavior during exposure. By adjusting parameters such as pattern size, material composition, or optical contrast, auxiliary patterns become invisible to the exposure system at certain conditions while still serving their function of broadening focus margin in dense layouts.
Data Source
AI summary
A method of designing hole patterns for arranging hole patterns on a pattern drawing of a photomask used during an exposure process in semiconductor integrated circuit manufacturing, wherein a grid is provided on the pattern drawing with a space smaller than a minimum pitch allowed by the design rule of the semiconductor integrated circuit, and the hole patterns are provided at lattice points, which are the intersections of the grid. Flexibility of hole pattern arrangement is improved and the quality of hole pattern arrangement can be easily evaluated.