Diffraction Order Truncation for Optical Metrology
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Solution Overview
Problem
The accuracy and efficiency of diffraction signal simulations in optical metrology, particularly for three-dimensional structures, are hindered by the need to balance the number of diffraction orders used, as increasing orders improve accuracy but significantly increase computation time, and reducing orders may lead to information loss.
Innovation Solution
A method is introduced to prioritize and truncate diffraction orders based on their information content, using schemas such as diamonds, squares, or circles to retain only the most informative orders, thereby reducing computation costs while maintaining accuracy.
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 significantly
Solution Approach 1:
The patent extracts and retains only the most informative diffraction orders from the complete set of diffraction orders. By identifying and removing redundant or less significant orders, the method reduces computation time while preserving the essential information needed for accurate simulation of three-dimensional structures.
Solution Approach 2:
The patent changes the parameter of diffraction order selection by introducing prioritization criteria and truncation schemes. Instead of using all diffraction orders or a fixed number, the method dynamically selects orders based on their information content and significance to the simulation accuracy, thereby optimizing the balance between computation time and simulation precision.
2Productivity
If the number of diffraction orders is reduced to decrease computation time, then productivity is improved, but information loss occurs
Solution Approach 1:
The patent extracts the essential information from the diffraction signal by retaining only the most informative orders. The prioritization process identifies which orders contain critical structural information, ensuring that reducing the total number of orders does not result in significant information loss for three-dimensional structure characterization.
Solution Approach 2:
The patent applies partial action by using a truncated subset of diffraction orders rather than the complete set. The truncation is carefully controlled to include sufficient orders to maintain simulation accuracy while excluding redundant ones, achieving productivity improvement without excessive information loss.
Data Source
AI summary
A method for improving computation efficiency for diffraction signals in optical metrology is described. The method includes simulating a set of diffraction orders for a three-dimensional structure. The diffraction orders within the set of diffraction orders are then prioritized. The set of diffraction orders is truncated to provide a truncated set of diffraction orders based on the prioritizing. Finally, a simulated spectrum is provided based on the truncated set of diffraction orders.