OPC Model Correction for Photomask Pattern Accuracy
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Solution Overview
Problem
The semiconductor process faces challenges in ensuring that the actual pattern of fabricated photomasks matches the predetermined pattern due to variations in photomask fabrication processes across different photomask houses, leading to discrepancies in pattern density, position, and shape.
Innovation Solution
A photomask design correction method that involves obtaining pattern information data from fabricated photomasks, analyzing differences with the OPC process database, and correcting the OPC model to generate corrected photomask data that aligns with the desired pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OPC process is performed using standard database to generate photomask data, then photomask fabrication can be completed efficiently, but the actual pattern of fabricated photomask deviates from predetermined pattern due to process variations
Solution Approach 1:
The patent implements a feedback mechanism where actual photomask pattern data obtained after fabrication is compared with the original layer information data, and the OPC model is corrected based on the difference. This closed-loop feedback system continuously improves pattern accuracy by using real fabrication results to adjust the OPC process parameters, resolving the contradiction between efficient standard fabrication and accurate pattern reproduction.
Solution Approach 2:
The patent changes the parameters of the OPC model based on the analyzed difference between actual and predetermined patterns. By adjusting OPC parameters such as bias values, shape factors, and other process-specific parameters, the system adapts to variations in photomask fabrication processes across different photomask houses, thereby improving pattern accuracy while maintaining fabrication efficiency.
2Adaptability or versatility
If different photomask houses use their own fabrication processes, then each house can optimize their own manufacturing, but the actual patterns of photomasks from different houses show great differences
Solution Approach 1:
The patent applies local quality by correcting the OPC model specifically for each photomask house based on their actual fabrication results. Each photomask house has its own corrected OPC model that accounts for their specific process characteristics, equipment, and materials. This allows each house to maintain their process flexibility while achieving consistent pattern quality through house-specific parameter optimization.
Solution Approach 2:
The patent performs preliminary correction of the OPC model using actual pattern data obtained from initial fabrications at each photomask house. This preliminary action establishes a corrected OPC model before mass production, ensuring that subsequent photomasks fabricated at that house will have consistent and accurate patterns without requiring continuous adjustments.
3Manufacturing precision
If OPC model is corrected based on actual pattern data, then photomask pattern accuracy is improved, but additional detection and analysis steps are required
Solution Approach 1:
The patent implements a self-service approach where the system automatically performs detection, data acquisition, difference analysis, and OPC model correction without requiring extensive manual intervention. The automated workflow reduces the complexity burden by having the system serve itself through integrated tools and algorithms that streamline the correction process, making the additional steps manageable and efficient.
Data Source
AI summary
A photomask design correction method is provided. The photomask design correction method includes the following steps. A layer information data is provided. An OPC process is performed on the layer information data to obtain a first photomask data. A photomask is fabricated based on the first photomask data. A pattern information data of the photomask is obtained after the photomask is fabricated. The difference between the pattern information data and a database of the OPC process is analyzed. An OPC model of the OPC process is corrected based on the difference to obtain a corrected OPC model. The OPC process is performed using the corrected OPC model on the layer information data to obtain a second photomask data.