MEEF-Aware Mask Rule Check for Lithography
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Solution Overview
Problem
Current optical lithography systems face challenges in scaling down feature sizes due to light diffraction issues, where conventional mask rule check (MRC) corrections by equally pulling back features may not be effective, leading to inefficiencies in IC manufacturing.
Innovation Solution
A method is introduced that uses a mask error enhancement factor (MEEF) index to determine customized pullback ratios for main and context segments, allowing for differential pulling back in horizontal and vertical directions to correct space and corner space violations, ensuring minimum space requirements are met during the mask rule check process in optical lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional MRC correction pulls back each feature by the same distance, then the correction process is simple, but the correction effectiveness is insufficient
Solution Approach 1:
The patent applies local quality by calculating different pullback distances for different features based on their individual MEEF values. Each feature receives a customized pullback correction tailored to its specific characteristics (main segment vs. context segment, horizontal vs. vertical orientation), rather than applying a uniform pullback distance to all features. This localized approach improves correction effectiveness while maintaining process feasibility.
Solution Approach 2:
The patent changes the parameter of pullback distance from a fixed uniform value to a variable value determined by MEEF calculations. By computing pullback distances based on different MEEF parameters for different segments and orientations, the system dynamically adjusts correction parameters to optimize manufacturing precision for each specific feature.
2Productivity
If feature size is scaled down to increase functional density, then production efficiency increases and costs decrease, but light diffraction becomes a more significant obstacle
Solution Approach 1:
The patent applies preliminary anti-action by performing MEEF-based pullback corrections before mask fabrication. By anticipating and compensating for light diffraction effects through calculated pullback distances, the system pre-corrects the layout to counteract the harmful diffraction effects that will occur during lithography, enabling successful scaling to smaller feature sizes.
Solution Approach 2:
The patent uses feedback by calculating MEEF values based on the interaction between main segments and context segments, then using these calculated values to determine appropriate pullback distances. This feedback loop allows the system to adaptively adjust corrections based on the specific geometric relationships and diffraction risks of each feature configuration.
3Loss of time
If uniform pullback is applied to all features, then the MRC process is faster and simpler, but space violations may not be adequately corrected
Solution Approach 1:
The patent applies segmentation by dividing features into main segments and context segments, and further categorizing them by orientation (horizontal/vertical). This segmentation allows the system to calculate and apply differentiated pullback distances for each segment type, improving space violation correction effectiveness while maintaining computational efficiency through systematic categorization.
Data Source
AI summary
The present disclosure describes methods of forming a mask. In an example, the method includes receiving an integrated circuit (IC) design layout, modifying the IC design layout data using an optical proximity correction (OPC) process, thereby providing an OPCed IC design layout, and modifying the OPCed IC design layout data using a mask rule check (MRC) process, wherein the MRC process corrects rule violations of the OPCed IC design layout data using a mask error enhancement factor (MEEF) index, thereby providing a MRC/OPCed IC design layout.