Stitched Metrology Libraries for Wide Process Range
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Solution Overview
Problem
Current methods for generating wide process range libraries in optical metrology, such as RCWA, face challenges in achieving accuracy and efficiency due to the need for high computation with increasing diffraction orders, making it difficult to cover large process ranges effectively.
Innovation Solution
The method involves generating multiple libraries with overlapping process ranges and stitching them together iteratively, using a convex combination approach with a logistic sigmoid function to extend the process range, allowing for a gradual and accurate expansion of the library's coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of diffraction orders is increased to improve simulation accuracy, then measurement precision is improved, but computation time increases nonlinearly
Solution Approach 1:
The patent segments the wide process range into multiple overlapping sub-ranges, with each sub-range having its own optimized library. This allows each sub-library to use a tailored number of diffraction orders appropriate for its specific range, avoiding the need to use high computation resources across the entire wide range.
Solution Approach 2:
The patent changes the parameter of diffraction order selection based on the process range being simulated. Different numbers of diffraction orders are used for different sub-ranges, optimizing the balance between accuracy and computation time for each specific range.
2Adaptability or versatility
If the process range is extended to cover larger variations, then adaptability is improved, but computation resources increase
Solution Approach 1:
The patent divides the wide process range into multiple overlapping sub-ranges, each with its own library. This segmentation allows the system to handle large process variations adaptability while keeping computation resources manageable by focusing on smaller sub-ranges individually.
Solution Approach 2:
The patent performs preliminary action by pre-computing multiple sub-libraries for different process ranges before actual measurements. This allows the system to handle a wide process range adaptability without incurring high computation costs during actual measurements, as the computational work has already been done in advance.
3Adaptability or versatility
If multiple overlapping libraries are generated and stitched to extend process range, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent uses an intermediary approach by introducing overlapping regions between sub-libraries and using weighted combinations to stitch them together. This intermediary mechanism smoothly transitions between different sub-libraries, managing the complexity of having multiple libraries while maintaining adaptability across the wide process range.
Data Source
AI summary
Methods of generating wide process range libraries for metrology are described. For example, a method includes generating a first library having a first process range for a first parameter. A second library is generated having a second process range for the first parameter. The second process range is overlapping with the first process range. The second library is stitched to the first library to generate a third library having a third process range for the first parameter. The third process range is wider than each of the first and second process ranges.