Dense OPC Grid Sampling for Edge Placement Error
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Solution Overview
Problem
Conventional photolithographic processing faces inefficiencies in estimating optical and process corrections for small features, leading to time-consuming and inaccurate simulations due to the need for dense and overlapping simulation sites.
Innovation Solution
A method using a substantially uniform grid of sample points to calculate process conditions, with contour lines of constant values, allowing for the estimation of edge placement errors and subsequent OPC corrections, thereby simplifying the estimation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If simulation sites are densely distributed to improve estimation accuracy for small features, then measurement precision is improved, but the quantity of simulations increases significantly leading to loss of time
Solution Approach 1:
The layout is divided into multiple tiles, each processed independently with its own uniform grid of sample points. This segmentation allows the overall simulation to be broken into manageable chunks that can be processed in parallel, reducing total simulation time while maintaining adequate sampling density in each local region
Solution Approach 2:
A uniform grid of sample points is applied locally within each tile rather than using a single dense grid across the entire layout. This local approach provides sufficient sampling density for accurate EPE estimation in each small region without requiring excessive sample points globally, thereby reducing overall computation time
2Measurement precision
If simulation sites are densely distributed to capture all edge segments, then measurement precision is improved, but device complexity increases due to overlapping and redundant simulations
Solution Approach 1:
The layout is divided into non-overlapping tiles with clear boundaries, eliminating redundant simulations at tile edges. Each tile is processed independently with uniform sample point distribution, avoiding the complexity of managing overlapping simulation regions while maintaining comprehensive coverage of all edge segments
Solution Approach 2:
Instead of placing simulation sites based on edge segment locations (which causes clustering and overlap), the approach inverts the methodology by first establishing a uniform grid and then determining which edge segments fall within each sample point's influence zone. This reversal eliminates redundant simulations while ensuring all edges are captured
Data Source
AI summary
A method of calculating process conditions for performing optical and process correction (OPC) or other resolution enhancement techniques on a layout design. Process conditions are estimated on a layout database on a substantially uniform grid. Contour curves are created from the estimated process conditions. The contour curves are then compared against the features in the layout to determine edge placement errors. From the edge placement errors, OPC or other corrections for the features can be made.