Optical Wafer Inspection Scan Planning for Higher Resolution
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Solution Overview
Problem
Existing optical wafer inspection (OWI) systems face challenges in reducing the amount of image data stored, movement required for defect detection, and improving resolution without modifying optics and hardware, while maintaining accuracy in defect detection.
Innovation Solution
Creating scanning plans that identify identical regions within a circuit design, comparing optical signatures of overlapping regions within the same die to enhance resolution and accuracy by reducing data storage and movement, and identifying defect locations with tighter tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional OWI systems scan entire die areas to ensure defect detection coverage, then defect detection accuracy is maintained, but the amount of image data stored and movement required increases
Solution Approach 1:
The patent divides the die into multiple regions and identifies identical regions within the circuit design. By segmenting the inspection area and leveraging the repetitive nature of circuit patterns, the system inspects only representative regions rather than the entire die, thereby reducing image data storage requirements while maintaining defect detection accuracy through comparative analysis of identical regions.
Solution Approach 2:
The patent uses optical signatures from identical regions as references to compare against each other. Instead of storing and analyzing all image data from the entire die, the system creates reference copies from identical regions and uses these for defect detection, significantly reducing the quantity of image data that must be stored and processed.
2Measurement precision
If traditional OWI systems scan entire die areas to ensure defect detection coverage, then defect detection accuracy is maintained, but the movement required for scanning increases
Solution Approach 1:
By dividing the die into regions and identifying identical ones, the system reduces the total scanning distance. The inspection head only needs to move to scan representative identical regions rather than traversing the entire die area, thereby reducing movement while maintaining defect detection coverage through comparative analysis.
Solution Approach 2:
The system performs preliminary identification of identical regions and their locations before actual defect detection scanning. This preliminary action allows the inspection head to be positioned directly at relevant regions, minimizing unnecessary movement and optimizing the scanning path while ensuring all critical areas are covered.
3Measurement precision
If OWI systems use overlapping region scanning with multiple scans, then resolution is enhanced, but the amount of image data stored increases
Solution Approach 1:
The patent segments the die into identical regions and uses overlapping scans only within these identical regions rather than across the entire die. This localized segmentation approach maintains the resolution benefits of overlapping scans while minimizing the total image data generated, as overlaps are confined to repetitive circuit patterns rather than the whole die area.
Solution Approach 2:
By using optical signatures from identical regions as references, the system can perform overlapping scans on a single representative region and compare the results against the reference copy. This approach achieves the resolution enhancement of overlapping scans without proportionally increasing overall image data storage, as the reference copy is reused across multiple comparisons.
Data Source
AI summary
A circuit design may be partitioned into a set of regions. Regions in the set of regions that are substantially identical to one another may be identified and overlaps between the set of regions may be determined. A scanning plan may be created based on the set of regions, the regions in the set of regions that are substantially identical to one another, and the overlaps between the set of regions. The scanning plan may be provided to an OWI system which inspects a set of dies fabricated based on the circuit design. A scan result may be received from the OWI system based on inspecting a die in the set of dies. A defect location in the die may be identified based on the scan result and the scanning plan.