Defect Inspection Reference Image Generation
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Solution Overview
Problem
Current defect inspection methods for substrates with varying lithography conditions face challenges in achieving high accuracy, particularly when inspecting shot regions near the boundary of the proper lithography margin, leading to erroneous noise detection and reduced comparison accuracy.
Innovation Solution
The defect inspection apparatus compares images of adjacent shot regions, replaces inconsistent patterns with consistent ones to generate a reference image, and performs defect inspection using this optimized reference image, thereby improving inspection accuracy by classifying patterns and determining correct and incorrect patterns based on error thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If images of adjacent shot regions are compared directly for defect inspection, then inspection speed is maintained, but inspection accuracy deteriorates due to lithography condition variations causing erroneous noise detection
Solution Approach 1:
The patent introduces a reference image as an intermediary element for comparison. Instead of directly comparing images of shot regions with different lithography conditions (which causes erroneous noise detection), the system compares each shot region image against a standardized reference image. This reference image serves as a mediator that eliminates the harmful effect of lithography condition variations, enabling accurate defect inspection without the noise problems that arise from direct adjacent-region comparison.
2Measurement precision
If multiple comparison processes are performed to improve accuracy, then inspection accuracy improves, but processing time increases
Solution Approach 1:
The patent performs preliminary classification of patterns into correct and incorrect types before the actual defect inspection process. By预先 categorizing patterns based on their consistency across multiple shot regions, the system prepares reference images and pattern classifications in advance. This preliminary action reduces the complexity of subsequent comparison operations, allowing multiple comparison processes to be performed efficiently without excessive processing time, thus improving accuracy while minimizing time loss.
Data Source
AI summary
According to one embodiment, in a defect inspection apparatus, a controller acquires an image of a second actual pattern in a first shot region which corresponds to a design pattern identical to a design pattern corresponding to a first actual pattern, which is consistent in a first comparison process, and which is consistent in a second comparison process. The controller replaces the image of one actual pattern of the first actual pattern and the second actual pattern in the first shot region with the image of the other actual pattern so as to generate a reference image of the first shot region. The controller compares the reference image and the image of the second shot region so as to perform a defect inspection of the second shot region.