Hotspot Correction via ILT and OPC Segmentation
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Solution Overview
Problem
Conventional lithographic processes face challenges in achieving precise pattern size and overlay accuracy due to rounding distortion of right-angled pattern corners during the photomask layout exposure, leading to hotspot issues and reduced process windows, which existing OPC methods struggle to address effectively.
Innovation Solution
A hotspot correction method combining inverse lithography technique (ILT) and optical proximity correction (OPC), where hotspot regions are corrected using ILT and extension regions are corrected using the resulting OPC, to form corrected photomask patterns, thereby preventing pattern distortion and reducing calculation demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inverse lithography technique (ILT) is used to correct hotspot regions, then manufacturing precision is improved, but calculation time increases significantly
Solution Approach 1:
The patent divides the correction process into two segments: hotspot regions are corrected using ILT for high precision, while extension regions are corrected using conventional OPC for speed. This segmentation allows the system to apply computational resources selectively, achieving high precision where needed while maintaining overall efficiency.
Solution Approach 2:
Different correction methods are applied to different regions based on their specific requirements. Hotspot regions receive ILT correction with higher computational intensity for maximum precision, while extension regions use standard OPC. This local quality approach optimizes the balance between precision and calculation time by matching method intensity to regional needs.
2Loss of time
If conventional OPC method is used, then calculation time is reduced, but manufacturing precision deteriorates due to improper segmentation and assist patterns
Solution Approach 1:
The patent performs preliminary identification of hotspot regions and defines extension regions around them before the correction process. This preliminary action allows the subsequent correction steps to be targeted and optimized, preventing the creation of new hotspots in extension regions while maintaining overall correction precision.
Solution Approach 2:
Extension regions act as an intermediary zone between the hotspot regions requiring ILT correction and the rest of the layout. By applying OPC to extension regions with the corrected hotspot patterns as reference, the method prevents distortion propagation while maintaining a reasonable balance between precision and calculation time.
3Manufacturing precision
If global ILT correction is performed, then manufacturing precision is improved, but device complexity increases due to enormous calculation capability demands
Solution Approach 1:
The patent segments the correction task into local hotspot regions corrected by ILT and surrounding extension regions corrected by OPC. This segmentation reduces the overall computational complexity by applying the computationally intensive ILT method only where absolutely necessary, while using lighter OPC for the remaining regions.
Solution Approach 2:
Instead of applying full ILT correction globally, the patent applies ILT partially only to identified hotspot regions. This partial action approach achieves sufficient precision for critical areas while avoiding the excessive computational complexity that would result from global ILT application.
Data Source
AI summary
A hotspot correction method is provided. The layout patterns in the hotspot regions are accurately corrected by using an ILT method. Then the layout patterns in the extension regions are corrected by using an OPC method. As a result, the layout patterns in the hotspot regions can be accurately corrected while pattern distortion of the extension regions generated due to the regional ILT correction can be prevented. Moreover, high demanding of calculation capability and long calculation time of global ILT correction can be avoided.