Photomask Stitching with Weighted ILT Boundary Transitions
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Solution Overview
Problem
Optical lithography processes in semiconductor manufacturing often result in resist pattern defects due to layout pattern degradation, necessitating iterative OPC and ILT operations which are time-consuming and can cause mask rule check (MRC) violations during pattern merging.
Innovation Solution
The method involves dividing the layout pattern into enhancement regions, applying OPC and ILT operations iteratively within these regions, and using weighted functions to smoothly transition between enhanced and surrounding patterns, thereby avoiding MRC violations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If iterative OPC and ILT operations are applied to the layout pattern, then resist pattern defects are corrected, but time consumption increases
Solution Approach 1:
The layout pattern is divided into multiple enhancement regions based on defect density and pattern complexity. Different regions are processed with different levels of OPC and ILT operations, allowing critical regions to receive full iterative processing while less critical regions receive simplified processing, thus reducing overall time consumption while maintaining resist pattern quality.
Solution Approach 2:
The patent applies different processing intensities to different regions: high-density defect regions receive full iterative OPC and ILT operations, while low-density regions receive reduced processing. This local differentiation optimizes the balance between correction effectiveness and processing time by concentrating computational resources where most needed.
2Productivity
If multiple enhancement regions are processed independently, then processing efficiency improves, but mask rule check violations may occur at boundaries
Solution Approach 1:
Transition regions are introduced between adjacent enhancement regions to serve as intermediaries. These transition zones apply gradual blending of processing intensity, smoothly connecting high-processing and low-processing regions while maintaining mask rule compliance at boundaries. The transition regions prevent abrupt changes that would cause MRC violations.
Solution Approach 2:
The processing intensity is dynamically adjusted across different regions and even within regions based on local pattern characteristics. The patent uses adaptive algorithms that modify processing parameters in real-time based on defect density and pattern complexity, allowing efficient parallel processing while maintaining boundary compliance through dynamic parameter adjustment.
3Manufacturing precision
If full OPC and ILT operations are applied to the entire layout pattern, then pattern accuracy improves, but computational complexity increases
Solution Approach 1:
The layout pattern is segmented into enhancement regions based on defect density thresholds and pattern complexity metrics. Only regions meeting specific criteria are selected for full OPC and ILT processing, while other regions receive simplified or no processing. This segmentation dramatically reduces computational complexity while maintaining pattern accuracy in critical areas.
Solution Approach 2:
The patent dynamically adjusts processing parameters such as optimization iterations, mesh density, and correction intensity based on local pattern characteristics. In simple regions, parameters are reduced to minimize computation, while in complex regions with high defect density, full parameter settings are applied to ensure accuracy, thus optimizing the computational complexity-accuracy tradeoff.
Data Source
AI summary
A method of manufacturing a photo mask includes determining an enhancement region, in a simulation zone, of a layout pattern of a photo mask. The method includes determining a stitching mobility zone inside the simulation zone, determining an optimization mobility zone inside the stitching mobility zone, and performing an inverse lithographic transformation (ILT) operation of the layout pattern in the simulation zone to generate an ILT adjusted layout pattern in the simulation zone. The method includes combining a weighted sum of the ILT adjusted layout pattern and the layout pattern in the simulation zone to generate an enhanced layout pattern of the photo mask in the simulation zone using a first weighting function inside enhancement region, a second weighting function between boundaries of the enhancement region and the optimization mobility zone, and a third weighting function between boundaries of the optimization mobility zone and the stitching mobility zone.