OPC Model Correction Using Slit-Specific TCC Division
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Solution Overview
Problem
Existing optical proximity correction (OPC) methods in lithography systems face challenges in accurately predicting critical dimensions (CD) for each slit position due to the optical proximity effect and shadowing effects, leading to suboptimal distribution and yield in semiconductor manufacturing.
Innovation Solution
The proposed solution involves dividing the transmission cross coefficient (TCC) for each slit region, generating an OPC model with the divided TCC, measuring apodization values for each slit position, fitting CD data to a simulation CD of the OPC model, and correcting the OPC model using the fitted CD data to improve CD predictive power and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single TCC model is applied to overall chips for OPC, then the device complexity is reduced, but the manufacturing precision of critical dimensions deteriorates due to shadowing effects varying by slit position
Solution Approach 1:
The patent divides the TCC into multiple slit-region-specific TCCs, where each slit region has its own dedicated TCC model. This segmentation allows the OPC system to account for position-dependent shadowing effects across different slit regions, improving CD accuracy without requiring a single overly complex unified model.
Solution Approach 2:
The patent applies local quality by creating region-specific TCCs tailored to each slit region's characteristics. Each slit region receives a customized TCC that reflects its specific optical properties and shadowing behavior, rather than applying a uniform TCC across the entire chip, thereby improving local CD precision.
2Manufacturing precision
If position-dependent TCCs are applied for each slit region, then the manufacturing precision of critical dimensions is improved, but the device complexity increases
Solution Approach 1:
The patent segments the illumination aperture into multiple discrete slit regions, with each region having its own TCC. This segmentation strategy manages complexity by breaking down the overall OPC problem into smaller, independent sub-problems that can be handled separately and then combined.
Solution Approach 2:
The patent applies TCC division to the extent necessary to capture significant shadowing effects, rather than attempting to model every possible variation. This partial action approach achieves sufficient CD accuracy without unnecessarily increasing model complexity beyond what is needed for practical OPC.
3Reliability
If apodization values are measured and fitted for each slit position, then the predictive power of the OPC model is improved, but the measurement precision requirements increase
Solution Approach 1:
The patent implements a feedback mechanism where apodization values are measured from actual wafer CDs, compared against simulation predictions, and used to refine and correct the OPC model. This iterative feedback process improves predictive power by continuously aligning the model with real-world measurements.
Solution Approach 2:
The patent performs preliminary apodization value measurements and fitting procedures during the OPC model setup phase, before actual production lithography. This preliminary action establishes accurate baseline parameters that enhance the model's predictive capability for subsequent manufacturing runs.
Data Source
AI summary
An optical proximity correction method of a lithography system includes dividing a transmission cross coefficient (TCC) for each slit region; generating an optical proximity correction (OPC) model to which the divided TCC is applied; measuring an apodization value for each slit position; fitting critical dimension (CD) data for each slit position to a simulation CD of the OPC model; and correcting the OPC model using the fitted CD data.