Mask Corner Rounding Calibration for Lithography Accuracy
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Solution Overview
Problem
Conventional semiconductor process models lack accuracy in modeling mask corner rounding effects, leading to inaccuracies in optical proximity correction and resolution enhancement techniques, especially at high integration densities where precise physical modeling is crucial.
Innovation Solution
A system that modifies mask layouts near corners to account for mask corner rounding effects by adding bevel or notch artifacts, allowing for calibration of process models using empirical data to improve accuracy, employing either a single-layer or multi-layer approach to capture the distinct effects on inner and outer corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional process models are used without modeling mask corner rounding effects, then the process model calibration is simpler and faster, but the process model accuracy deteriorates leading to inaccuracies in optical proximity correction
Solution Approach 1:
The patent segments the mask layout into multiple layers: the original mask layout layer and additional mask layers that specifically represent mask corner rounding effects. This segmentation allows the process model to account for MCR effects separately, improving accuracy without requiring complete remodelling of the entire process chain.
Solution Approach 2:
The patent applies preliminary action by pre-modifying the mask layout to include estimated mask corner rounding effects before the actual lithography process. Triangular shapes are added to or deleted from corners according to prescribed rules, creating a pre-corrected layout that compensates for anticipated MCR effects during subsequent processing.
2Manufacturing precision
If mask corner rounding effects are modeled by modifying mask layouts and adding multiple mask layers, then process model accuracy improves, but the computational complexity and processing time increase
Solution Approach 1:
The patent applies local quality by focusing modifications only on corner regions of the mask layout where MCR effects occur, rather than uniformly processing the entire layout. The additional mask layers contain patterns specifically relating to corners, allowing targeted improvement of pattern accuracy at critical locations without unnecessary computational overhead elsewhere.
3Reliability
If simple mask layouts are used without corner modifications, then the layout processing is faster and easier, but the printed pattern accuracy deteriorates due to unmodeled mask corner rounding effects
Solution Approach 1:
The patent introduces an intermediary representation by creating additional mask layers that serve as mediators between the original mask layout and the lithography process. These intermediate layers capture MCR effects and facilitate accurate pattern transfer, improving reliability of downstream applications without requiring direct modification of the original design layout.
Data Source
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AI summary
An embodiment provides systems and techniques for determining an improved process model which models mask corner rounding (MCR) effects. During operation, the system may receive a mask layout and process data which was generated by applying a photolithography process to the mask layout. The system may also receive an uncalibrated process model which may contain a set of MCR components. Next, the system may identify a set of corners in the mask layout. The system may then modify the mask layout in proximity to the set of corners to obtain a modified mask layout. Alternatively, the system may determine a set of mask layers. Next, the system may determine an improved process model by calibrating the uncalibrated process model using the modified mask layout and/or the set of mask layers, and the process data.