Semiconductor Wafer Chamfer Inspection via Multi-Angle Imaging
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Solution Overview
Problem
Existing semiconductor wafer inspection methods cannot simultaneously detect defects and determine the abnormality of the chamfered surface shape, leading to decreased throughput in inspection processing.
Innovation Solution
A semiconductor wafer inspection method that involves taking images of the chamfered surface from multiple angles using line-symmetrical imaging devices, calculating the width ratio of the chamfered surface from different perspectives, and determining the shape abnormality based on predetermined ranges, while also detecting defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate step of determination of whether or not the shape of the chamfered portion is abnormal is required, then the detection of defect can be performed, but the throughput of inspection processing is decreased
Solution Approach 1:
The patent combines defect detection and shape abnormality determination into a single integrated inspection process. By using multiple imaging devices to capture images from different positions (main surface side, back surface side, and radial direction) and processing these images through a unified system, the inspection method simultaneously performs both defect detection and shape verification without requiring separate inspection steps, thereby improving throughput while maintaining measurement precision.
Solution Approach 2:
The inspection system is designed with multi-functionality to perform both defect detection and shape abnormality determination using the same imaging devices and processing system. The first, second, and third imaging devices capture images that serve dual purposes: detecting defects such as cracks and projections while also providing data for shape verification through width ratio calculations, eliminating the need for dedicated separate inspection equipment.
2Measurement precision
If images are taken from multiple positions to detect defects, then defect detection accuracy is improved, but the complexity of the inspection system increases
Solution Approach 1:
The inspection system is segmented into multiple independent imaging devices positioned at different locations (main surface side, back surface side, and radial direction), each capturing images from its specific viewpoint. This segmentation allows the system to achieve comprehensive defect detection coverage without requiring a single complex multi-functional device, as each imaging unit can be independently optimized and controlled.
Solution Approach 2:
The patent introduces a third imaging device that captures images from the radial direction (inside of the semiconductor wafer), adding a new dimensional perspective to the inspection. This third dimension complements the first (main surface side) and second (back surface side) imaging devices, providing comprehensive three-dimensional coverage of the chamfered surface for improved defect detection accuracy while maintaining manageable system complexity through modular device architecture.
Data Source
AI summary
A semiconductor wafer inspection method includes: an imaging step in which a first image being an image of the chamfered surface seen from the main surface side and a second image being an image of the chamfered surface seen from the back surface side are taken; a calculation step in which a first width is obtained based on the first image, the first width being a width of the chamfered surface seen from the main surface side, a second width is obtained based on the second image, the second width being a width of the chamfered surface seen from the back surface side, and a ratio of the first width to the second width thus obtained is calculated; and a shape determination step in which a form of the chamfered surface is determined to be abnormal in a case where the ratio is out of a predetermined range.