Spatial Map of Mask Pattern Defects in Photolithography
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Solution Overview
Problem
The increasing complexity and miniaturization of mask patterns in photolithography processes lead to computational challenges in verifying mask patterns, making it difficult to ensure that resulting wafer patterns match desired target patterns without unwanted distortions and defects, which complicates the identification and correction of defects.
Innovation Solution
A computer system that calculates the pattern produced at an image plane during photolithography, determines defects by comparing it to a target pattern, and provides a spatial map of defects, allowing for the identification and correction of critical defects in the mask pattern design process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography processes use decreasing minimum dimensions to increase feature density, then manufacturing precision is improved, but device complexity increases making verification difficult
Solution Approach 1:
The patent segments the complex mask pattern verification into multiple manageable components: (1) generating target patterns from design data, (2) simulating aerial images through photolithography processes, (3) comparing simulated patterns with target patterns, and (4) identifying and classifying defects. This segmentation allows verification of high-precision patterns without being overwhelmed by overall complexity.
Solution Approach 2:
The patent introduces a new dimension of verification by creating spatial maps that display defect locations, densities, and types visually across the mask pattern. This spatial mapping transforms complex defect data into an intuitive two-dimensional representation, enabling easier assessment of pattern verification results.
2Manufacturing precision
If Optical Proximity Correction and Resolution Enhancement Technologies are used to pre-distort mask patterns, then manufacturing precision is improved, but device complexity increases making defect verification increasingly difficult
Solution Approach 1:
The patent performs preliminary actions by generating target patterns and simulating aerial images before actual mask fabrication and wafer processing. This pre-verification allows identification of potential defects and accuracy issues before they manifest in physical manufacturing, enabling corrective actions to be taken in the design stage rather than during production.
Solution Approach 2:
The patent creates digital copies and simulations of the mask patterns and wafer patterns through computational modeling. By working with these digital replicas rather than physical masks, the system can perform repeated verification and analysis without additional manufacturing costs or physical resource consumption.
3Manufacturing precision
If comprehensive defect analysis is performed on complex mask patterns, then manufacturing precision is improved, but loss of time increases due to computational requirements
Solution Approach 1:
The patent applies local quality by classifying defects according to their specific locations, types, and characteristics on the mask pattern. Rather than treating all defects uniformly, the system identifies critical defects that have the most significant impact on manufacturing precision and prioritizes their analysis. The spatial maps highlight areas of high defect density or critical importance, allowing focused verification efforts.
Data Source
AI summary
A technique for providing information about defects in a mask pattern is described. In this technique, defects in the mask pattern may be determined based on differences between a calculated pattern produced at an image plane in the photolithographic process, when the mask pattern, illuminated by an associated source pattern, is at an object plane in the photolithographic process, and a target pattern that excludes the defects. Then the defect information may be provided to the user, such as a spatial map of the determined defects, where the spatial map is associated with at least the portion of the mask pattern.