Etch Proximity Correction for Micro-Photolithography
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Solution Overview
Problem
The increasing complexity of micro-photolithography requires more accurate etch proximity correction methods to minimize etch effects and achieve fine pattern accuracy, as existing methods struggle to account for the interactions between adjacent patterns and the micro-loading effect during the etch process.
Innovation Solution
An etch proximity correction method that calculates an accurate etch bias value by considering a non-project area and a project area within a proximity region, using a model that incorporates visible and blocked areas, density, and trigonometric functions to correct the target position in the layout, thereby improving the precision of pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing etch proximity correction methods are used, then the correction process is simple, but the accuracy of etch bias calculation is insufficient to account for interactions between adjacent patterns
Solution Approach 1:
The proximity region is divided into multiple segments based on pattern density and type (e.g., isolated patterns, dense patterns, line-end patterns). Each segment is assigned a specific etch bias value calculated from its local characteristics. This segmentation allows the method to account for interactions between adjacent patterns while maintaining a structured calculation approach that balances accuracy and complexity.
2Manufacturing precision
If the proximity region is fully considered in etch bias calculation, then the accuracy of pattern formation is improved, but the calculation time and complexity increase
Solution Approach 1:
The method pre-calculates etch bias values for different pattern configurations and density levels before the actual photomask fabrication process. These pre-calculated values are stored and applied during layout correction, eliminating the need for complex real-time calculations. This preliminary action reduces calculation time while maintaining high pattern formation accuracy by considering the full proximity region effects.
3Productivity
If the etch bias value is calculated without considering non-project area, then the calculation is faster, but the micro-loading effect is not adequately addressed
Solution Approach 1:
The method applies different calculation approaches to different areas within the proximity region. The project area (blocked by patterns) and non-project area (open spaces) are treated differently, with the non-project area contributing to the micro-loading effect calculation. This local quality differentiation ensures that the calculation captures etch process variations accurately while maintaining reasonable computational efficiency through targeted rather than exhaustive calculation.
Data Source
AI summary
Provided is an etch proximity correction method in which an accurate etch bias value is calculated. The etch proximity correction method includes creating an etch bias value from a project area corresponding to an area blocked by a pattern region within a linear distance projected from a target position selected in a target layout to an outermost portion of the proximity region and a non-project area corresponding to an area projected into an edge linear distance from an edge of the pattern region blocked in the linear distance to the outermost portion of the proximity region and correcting the target position in the layout using the etch bias value. Since an etch bias model includes the project area and the non-project area, the accurate etch bias value may be calculated.