Photomask Defect Tracking Across Multiple Inspections
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Solution Overview
Problem
Current photomask inspection systems face challenges in accurately tracking and comparing defects across multiple inspections from various brands and models, due to different reference points and orientations, leading to inefficient defect management and data handling.
Innovation Solution
A method that translates inspection reports into a common set of fields and populates a relational database, allowing for the comparison and tracking of defects across different inspection systems, independent of coordinate systems, rotations, and orientations, using a unique identifier to link reports from various inspection tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple inspection systems from different brands are used to inspect photomasks, then inspection coverage and detection capability are improved, but defect tracking and comparison become complex due to different reference points and orientations
Solution Approach 1:
The patent introduces an intermediary coordinate transformation system that acts as a mediator between different inspection systems. The system transforms defect coordinates from various inspection systems' reference frames into a common reference frame, enabling consistent defect tracking across multiple inspections without requiring changes to the inspection systems themselves.
Solution Approach 2:
The patent changes the parameter representation of defect locations by transforming coordinates from different reference systems into a unified reference system. This involves adjusting positional parameters (X, Y coordinates) and orientation parameters to ensure consistency across multiple inspection reports from different systems.
2Loss of information
If manual defect classification is performed for each inspection report, then defect understanding is improved, but operator time and processing efficiency deteriorate
Solution Approach 1:
The patent performs preliminary defect classification during the initial inspection, and the classification results are stored and reused in subsequent inspections. This preliminary action eliminates the need for operators to re-classify the same defects in repeated inspections, significantly reducing operator time while preserving defect classification knowledge.
Solution Approach 2:
The system implements feedback by storing defect classification results from previous inspections and using them to inform subsequent inspections. The classification knowledge is fed back into the inspection process, allowing the system to automatically recognize and categorize recurring defects without requiring fresh manual classification.
3Adaptability or versatility
If defect coordinates are reported with respect to different reference points in different inspections, then flexibility in inspection setup is improved, but defect location accuracy and comparability worsen
Solution Approach 1:
The patent introduces a coordinate transformation intermediary that converts defect coordinates from various reference points into a common reference frame. This intermediary maintains the flexibility of using different reference points in different inspections while ensuring accurate defect location comparability through mathematical transformation.
Solution Approach 2:
The system achieves universality by creating a reference frame transformation capability that works with any inspection setup. The same system can handle inspections with different reference points, orientations, and configurations, transforming them all into a common framework for accurate defect location comparison.
Data Source
AI summary
This invention allows tracking of a defect across multiple inspections. The inventive solution translates every inspection record into a common set of fields that are first archived into a relational database. Then the defect coordinates from the inspection records of the same mask are all transformed into a common reference frame having the same origin and orientation with respect to the mask coordinate system. Following this, the defect having coordinates within a given tolerance distance are paired up and reported to the user.