Joint Source-Mask Optimization for Lithography Process Window
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Solution Overview
Problem
Current lithography technologies face challenges in scaling down to the 22 nm node and beyond due to difficulties in reducing the minimum pitch through optical scaling alone, leading to blurring of images and inefficiencies in source-mask optimization processes.
Innovation Solution
A method and system for optimizing source and mask shapes in lithography processes through iterative joint light source-mask optimization, employing frequency and spatial domain optimizations, and automated processes to maximize the process window, reducing manual intervention and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If optical scaling is used to reduce minimum pitch, then feature size is reduced, but image quality deteriorates due to blurring
Solution Approach 1:
The patent merges source optimization and mask optimization into a unified joint optimization framework. By simultaneously optimizing both the light source distribution and mask pattern, the system achieves better image quality at reduced pitch than either optimization could achieve alone, resolving the contradiction between miniaturization and image quality.
Solution Approach 2:
The patent introduces iterative optimization processes that dynamically adjust source and mask parameters. Through multiple iterations of frequency domain and spatial domain optimizations, the system adaptively refines the solution to maximize process window and image quality while maintaining the required minimum pitch reduction.
2Adaptability or versatility
If manual source-mask optimization is performed, then optimization can be customized, but process time and complexity increase
Solution Approach 1:
The patent implements self-service through automated iterative optimization algorithms that perform frequency domain and spatial domain optimizations without continuous manual intervention. The system automatically iterates through multiple optimization cycles, adjusting parameters and evaluating results, thereby reducing manual time investment while maintaining flexible, customized optimization capabilities.
Solution Approach 2:
The patent performs preliminary frequency domain optimization before spatial domain optimization. This preliminary action establishes a good initial solution that accelerates the subsequent spatial domain optimization, reducing the total time required for complete source-mask optimization while maintaining adaptability.
Data Source
AI summary
Systems and methods for optimizing a source shape and a mask shape for a lithography process are disclosed. One such method includes performing a mask optimization for the lithography process in accordance with a set of parameters including at least one variable representation, at least one objective and problem constraints. Further, a light source optimization for the lithography process is performed in accordance with the set of parameters. In addition, a joint light source-mask optimization is performed in accordance with the set of parameters. The method further includes iterating at least one of the mask optimization or the light source optimization by changing at least one of the variable representation, the objective or the problem constraints to maximize a common process window for the lithography process.