Mask Pattern Decision Method for Lithography Optimization
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Solution Overview
Problem
Current exposure technologies face limitations in optimizing mask patterns and illumination shapes for semiconductor miniaturization, particularly in achieving high imaging performance and correcting image contrast, depth of focus, and resolving performance, due to the need for iterative calculations and limited degrees of freedom in existing methods.
Innovation Solution
A decision method for determining mask patterns and exposure conditions in an exposure apparatus that includes a projection optical system, which calculates the image of a mask pattern formed on a substrate while changing settings, and decides whether to generate a new auxiliary pattern based on generation conditions, optimizing the mask pattern and exposure conditions to achieve high imaging performance efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If iterative calculations are performed to optimize illumination shape and mask pattern, then imaging performance is improved, but calculation time and processing complexity increase significantly
Solution Approach 1:
The patent performs preliminary classification of pattern types and pre-determination of auxiliary pattern generation conditions before the main optimization process. By categorizing patterns in advance and pre-establishing generation rules, the system avoids repeated iterative calculations during optimization, significantly reducing calculation time while maintaining imaging performance
Solution Approach 2:
The system uses the calculated aerial image data to automatically determine whether auxiliary patterns should be generated, without requiring external intervention or complex iterative optimization. The calculation results themselves drive the decision-making process for auxiliary pattern generation, making the system self-sufficient and reducing overall processing time
2Manufacturing precision
If auxiliary patterns are generated for all pattern types, then resolving performance is improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent applies different auxiliary pattern generation strategies to different pattern types based on their specific characteristics. By classifying patterns into different types and applying localized optimization rules to each type rather than a uniform approach, the system improves resolving performance where needed while avoiding unnecessary processing overhead for patterns that don't require auxiliary patterns
Solution Approach 2:
The system changes the parameter of auxiliary pattern generation from a fixed binary decision to a conditional parameter based on pattern type classification. This allows the generation of auxiliary patterns only when specific conditions are met, optimizing resolving performance for critical patterns while reducing complexity for others
3Manufacturing precision
If OPC is applied repeatedly to match transfer pattern with target pattern, then pattern accuracy is improved, but correction capability is limited to shape parameters only
Solution Approach 1:
The patent segments the correction process into two distinct parts: OPC for shape correction and auxiliary pattern generation for contrast and depth of focus correction. This segmentation allows each method to specialize in its strengths, with OPC handling edge and line width corrections while auxiliary patterns handle contrast and focal depth issues, thereby expanding overall correction capability beyond just shape parameters
Data Source
AI summary
The present invention provides a decision method which decides a mask pattern used in an exposure apparatus comprising a projection optical system that projects a mask pattern including a main pattern and an auxiliary pattern onto a substrate, and an exposure condition in the exposure apparatus, the method including a step of calculating an image of a mask pattern formed on the substrate by the projection optical system while changing settings of the mask pattern and the exposure condition, and deciding the mask pattern and the exposure condition based on the image of the mask pattern, wherein the step includes determining whether or not to generate a new auxiliary pattern after the settings are changed.