Multiple-Exposure Lithography Mask Pattern Decomposition
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Solution Overview
Problem
The increasing complexity and computational challenges in determining mask patterns for photolithography processes, particularly due to the difficulty in designing and manufacturing photo-masks for advanced IC and semiconductor wafer features, and the deviations caused by light wave distortions, necessitate a method to simplify the determination of write patterns and mask patterns without pre-distortion techniques.
Innovation Solution
A method for determining mask patterns in a multiple-exposure photolithographic process by identifying critical regions in an initial mask pattern, decomposing it into first and second mask patterns with decreased spatial frequency, and using these patterns in a double-exposure or double-patterning process to achieve improved resolution and process control, with the first and second mask patterns overlapping features near the critical region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple-exposure lithography is used to print smaller features, then manufacturing precision is improved, but device complexity increases due to the difficulty of decomposing arbitrary mask patterns
Solution Approach 1:
The patent divides a complex initial mask pattern into multiple simpler sub-patterns (first mask pattern, second mask pattern, etc.) that can be processed separately through multiple exposures. This segmentation reduces the complexity of individual patterns while maintaining the capability to print smaller features by combining multiple lower-resolution exposures.
2Manufacturing precision
If Optical Proximity Correction or resolution enhancement technologies are used to pre-distort mask patterns, then manufacturing precision is improved, but computation time and processing requirements increase
Solution Approach 1:
Instead of applying complex pre-distortion calculations to a single high-resolution pattern, the patent segments the pattern into multiple lower-resolution sub-patterns. This reduces the computational burden of each individual processing step while achieving the same manufacturing precision through cumulative exposure.
3Productivity
If demand for increased density of features is pursued with decreasing minimum dimensions, then productivity is improved, but device complexity increases due to significantly increased computational complexity
Solution Approach 1:
The patent enables increased feature density by dividing complex high-resolution patterns into multiple simpler exposures. This segmentation approach reduces the computational complexity required for each individual pattern while achieving the desired high feature density through the combination of multiple exposures.
Solution Approach 2:
The patent employs multiple periodic exposure steps to build up the final high-resolution pattern. Each exposure step contributes a portion of the final pattern, and the periodic repetition of the exposure process with different sub-patterns achieves the desired feature density without requiring computationally complex single-step patterning.
Data Source
AI summary
A method for determining mask patterns to be used on photo-masks in a multiple-exposure photolithographic process is described. During the method, an initial mask pattern, which is intended for use in a single-exposure photolithographic process, and a target pattern that is to be printed are used to determine a first mask pattern and a second mask pattern, which are intended for use in the multiple-exposure photolithographic process. In particular, the first mask pattern includes a first feature and the second mask pattern includes a second feature, and the first feature and the second feature overlap an intersection between features in the initial mask pattern. Moreover, the first mask pattern and the second mask pattern have at least one decreased spatial frequency relative to the initial mask pattern along at least one direction in the initial mask pattern.