Structure Model Slicing for Lithography Simulation Convergence
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Solution Overview
Problem
Existing methods for simulating the interaction of radiation with structures, particularly in lithographic processes, face issues with convergence due to step changes caused by adaptive slicing techniques, leading to discontinuities in the simulation responses and potential failure to converge or reaching false solutions.
Innovation Solution
A method where the structure model is divided into slices along a first dimension, with a constant number of steps approximating sloping faces across varying parameter spaces, maintaining consistent shape approximation to reduce or eliminate discontinuities, allowing for more stable iterative processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adaptive slicing is used to approximate sloping features, then the approximation accuracy improves, but discontinuities are introduced causing convergence failure
Solution Approach 1:
The structure model is divided into slices along a first dimension, with each slice containing a constant number of steps approximating sloping faces. This segmentation approach maintains consistent shape approximation across varying parameter spaces while avoiding the discontinuities that cause convergence failure in adaptive slicing methods.
2Manufacturing precision
If the number of slices is increased to improve approximation, then the shape accuracy improves, but the computational complexity increases
Solution Approach 1:
The method allows the number of slices to vary dynamically while maintaining a constant number of steps per slice for approximating sloping faces. This dynamic approach enables flexible adaptation to different structures and parameter spaces without introducing discontinuities, balancing approximation accuracy with computational efficiency.
3Measurement precision
If adaptive slicing is used to follow parameter variations, then the model accuracy improves, but step changes cause discontinuities in simulation responses
Solution Approach 1:
The invention applies a constant number of steps locally at each slice position to approximate sloping faces, ensuring consistent shape representation throughout the structure model. This local consistency maintains simulation response continuity while preserving model accuracy across varying parameter spaces.
Data Source
AI summary
Parameters of a structure (900) are measured by reconstruction from observed diffracted radiation. The method includes the steps: (a) defining a structure model to represent the structure in a two- or three-dimensional model space; (b) using the structure model to simulate interaction of radiation with the structure; and (c) repeating step (b) while varying parameters of the structure model. The structure model is divided into a series of slices (a-f) along at least a first dimension (Z) of the model space. By the division into slices, a sloping face (904, 906) of at least one sub-structure is approximated by a series of steps (904′, 906′) along at least a second dimension of the model space (X). The number of slices may vary dynamically as the parameters vary. The number of steps approximating said sloping face is maintained constant. Additional cuts (1302, 1304) are introduced, without introducing corresponding steps.