Identifying Repeating Design Cells for OPC Accuracy
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Solution Overview
Problem
The existing optical proximity correction (OPC) methods in photolithography processes for integrated circuit fabrication face challenges in accurately differentiating among repeating design cells due to optical proximity effects, leading to potential process failures, especially at the 180-micron node and beyond.
Innovation Solution
A method is developed to identify repeating design cells by creating a cell lookup table, performing spatial partitioning, establishing a coordinate system for overlapping cells, sorting coordinates to generate hashes, and identifying groups with identical hashes as repeating cells, allowing for accurate differentiation and enhanced OPC performance through distributed parallel processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional OPC methods are used to perform optical proximity correction, then the photolithography process can be executed, but the methods fail to accurately differentiate among repeating design cells due to optical proximity effects, leading to process failures
Solution Approach 1:
The patent segments the layout into multiple groups based on spatial relationships and overlapping regions. By dividing the design cells into distinct groups and analyzing each group separately, the method can accurately identify repeating cells even in the presence of optical proximity effects, thereby improving differentiation accuracy and process reliability
Solution Approach 2:
The patent performs preliminary identification and classification of design cells before the actual photolithography process. By pre-identifying repeating cells and their spatial relationships, the method prepares correction strategies in advance, preventing process failures that would otherwise occur during manufacturing
2Manufacturing precision
If optical proximity correction is performed on all cells individually to ensure accuracy, then manufacturing precision improves, but the computation time and processing complexity increase significantly
Solution Approach 1:
The patent merges the analysis and correction processes for repeating design cells by identifying cells with identical spatial relationships and overlapping regions. Once a group of repeating cells is identified, a single correction approach can be applied to all cells in that group, significantly reducing computation time while maintaining correction accuracy
Solution Approach 2:
The patent changes the approach from individual cell correction to group-based correction by introducing parameters such as spatial partitioning regions and overlapping cell groups. This parameter change allows the system to process multiple cells simultaneously with unified correction rules, reducing overall processing time
Data Source
AI summary
A method of identifying repeating design cells in a layout is disclosed. The method includes: providing a layout including a plurality of first leaf cells and a plurality of second leaf cells; identifying a plurality of groups each consisting of overlapping first and second leaf cells; for each of the groups, selecting a first or second leaf cell as an observational cell and establishing a coordinate system originated at a single reference position of the observational cell, thereby obtaining a plurality of coordinates of the overlapping first and second cells; for each of the groups, sorting the coordinates and generating a hash; and identifying ones of the groups having identical hashes as repeating design cells.