Wafer Inspection Defect Enlargement for Compression
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Solution Overview
Problem
Existing methods for inspecting flat objects like wafers and displays face challenges in efficiently compressing images for storage and transmission while maintaining defect information, often losing small defect details during compression and overwhelming observers with numerous unimportant defect representations.
Innovation Solution
The method involves enlarging detected defects by adding adjacent image points before compression, allowing for selective enlargement based on size, shape, or position, and storing only important defect areas to reduce storage and transmission requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If images are compressed to reduce storage space, then storage capacity requirements are reduced, but information about small defects is lost
Solution Approach 1:
The patent applies preliminary action by enlarging defects before compression. The method detects defects, enlarges them by a factor of 2-5 times, and then compresses the modified image. This ensures that small defects are amplified to a size that maintains their visibility and information content even after compression, resolving the contradiction between reducing storage space and preserving defect information.
Solution Approach 2:
The patent applies local quality by selectively enlarging only the defect regions while keeping the rest of the image at original resolution. The enlargement is applied locally to defect areas identified through difference imaging, allowing compression to reduce overall image size while maintaining high quality in defect regions where information is most critical.
2Quantity of substance
If all defects are represented as simple points in defect maps, then storage and transmission requirements are reduced, but the ability to identify important defects is lost
Solution Approach 1:
The patent applies local quality by differentiating the representation of defects based on their characteristics. Important defects with specific shapes, sizes, or patterns are preserved with their original detail in the enlarged image regions, while less significant defects can be represented more simply. This allows the system to maintain the ability to identify important defects while still reducing overall data size through selective compression.
Solution Approach 2:
The patent applies segmentation by dividing the defect representation into different levels of detail. The method segments defect information into critical attributes (position, size, shape) and non-critical attributes, allowing selective storage and transmission of only the most important defect characteristics while reducing overall data requirements.
3Measurement precision
If high resolution imaging is used to detect small defects, then measurement precision is improved, but storage capacity requirements increase
Solution Approach 1:
The patent applies preliminary action by performing defect detection and enlargement before final image storage. The system first captures the image at high resolution for precise defect detection, then enlarges detected defects and compresses the overall image. This sequence allows high measurement precision during detection while reducing storage requirements in the final compressed image.
Solution Approach 2:
The patent applies segmentation by separating the high-resolution imaging requirement from the storage requirement. The full-resolution image is used only for defect detection and analysis, while the final stored image is a compressed version with enlarged defects. This segmentation allows the system to maintain high measurement precision for defect detection while reducing storage capacity requirements for the actual stored data.
Data Source
AI summary
A method for inspecting flat objects, especially wafers, comprising the steps of scanning a digital image of the object surface; detecting defects on the object surface; generating a binary image of the scanned image where only detected defects are represented; and compressing the binary image; and wherein detected defects are enlarged before compressing by adding additional, adjacent image points to the image points of the defects. It may be advantageous if only defects having a selected size, shape or position are enlarged.