Optimizing Mask Pattern Auxiliary Structures for Lithography Resolution
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Solution Overview
Problem
Current exposure apparatuses face challenges in maintaining pattern resolution and accuracy due to variations in illumination shape, limiting the ability to correct for resolution performance such as contrast and depth of focus, and existing methods either restrict the degrees of freedom or fail to determine optimal illumination conditions for mask patterns.
Innovation Solution
A method for generating data for a mask pattern that includes an auxiliary pattern, where the generation condition is optimized to ensure the image quality meets a tolerance range, involving a series of calculations and adjustments to the exposure condition and mask pattern parameters using techniques like the Nelder-Mead method to improve resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If OPC is performed to correct transfer pattern shape, then line width and edge shift are improved, but resolution performance such as contrast and depth of focus cannot be corrected
Solution Approach 1:
The invention changes the parameters of the illumination shape (effective light source distribution) to optimize resolution performance. By adjusting illumination parameters such as angular distribution and intensity profile, the system can correct contrast and depth of focus issues that OPC alone cannot address, while maintaining line width precision through coordinated mask pattern adjustments.
Solution Approach 2:
The invention separates the correction process into two distinct components: OPC for shape correction (line width, edge shift) and illumination shape optimization for resolution performance (contrast, depth of focus). This segmentation allows each technique to specialize in its strength while working together to achieve comprehensive pattern quality improvement.
2Manufacturing precision
If illumination shape is changed to optimize resolution, then contrast and depth of focus are improved, but transfer pattern deviates from target pattern requiring additional OPC
Solution Approach 1:
The invention merges the illumination shape optimization process with the mask pattern design process. By simultaneously determining both the optimal illumination parameters and the corresponding mask pattern (including auxiliary patterns), the system achieves resolution performance improvement without requiring separate, iterative OPC steps for each illumination change, thus reducing overall process complexity.
Solution Approach 2:
The invention performs preliminary optimization of the illumination shape together with mask pattern design, rather than making illumination changes and then correcting patterns afterward. This preliminary coordinated optimization reduces the need for subsequent OPC iterations by designing the mask pattern specifically tailored to the optimized illumination conditions from the outset.
3Ease of manufacture
If existing methods are used to generate auxiliary patterns, then pattern formation is simplified, but optimal illumination conditions cannot be determined
Solution Approach 1:
The invention creates a unified optimization framework that simultaneously handles both auxiliary pattern generation and illumination condition optimization. This multi-functional approach allows the system to determine optimal illumination parameters while generating auxiliary patterns, achieving both manufacturing simplicity and precision improvement in a single integrated process.
Data Source
AI summary
The present invention provides a generation method of generating data for a mask pattern to be used for an exposure apparatus including a projection optical system for projecting a mask pattern including a main pattern and auxiliary pattern onto a substrate, including a step of setting a generation condition under which the auxiliary pattern is generated, and a step of determining whether a value of an evaluation function describing an index which indicates a quality of an image of the mask pattern calculated, wherein if it is determined that the value of the evaluation function falls outside a tolerance range, the generation condition is changed to set a new generation condition.