Wafer Edge Defect Inspection Using Multi-Angle Camera Carrier
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Solution Overview
Problem
Existing devices for visually evaluating defects in the edge area of a wafer are inefficient as they lack optimal camera positioning and illumination, leading to suboptimal image acquisition and display of defects on the upper, front, and lower surfaces.
Innovation Solution
A device with three cameras arranged on a common carrier movable in a perpendicular direction, combined with a bright field illumination system, allows for precise positioning and image acquisition of defects on the wafer's edge areas, enabling effective visualization and display of defects on the upper, front, and lower surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If three cameras are used to inspect the wafer edge, then the coverage of defect detection is improved, but the device complexity increases
Solution Approach 1:
The patent combines three cameras (first camera for upper bevel, second camera for front surface, third camera for lower bevel) into a single integrated inspection device with a common control unit. This merging approach allows comprehensive defect detection coverage while managing system complexity through unified control and coordinated operation of multiple cameras.
Solution Approach 2:
The inspection system is segmented into three specialized camera units, each responsible for a specific viewing angle (upper bevel, front surface, lower bevel). This segmentation allows each camera to be optimized for its specific function while collectively providing complete defect detection coverage of the wafer edge.
2Measurement precision
If cameras are positioned closer to the wafer edge, then the image acquisition quality is improved, but the positioning precision requirements increase
Solution Approach 1:
The patent employs a movable carrier that can dynamically adjust the position of the cameras relative to the wafer edge. This dynamic positioning capability allows the system to optimize image acquisition quality by moving cameras closer to the wafer while compensating for positioning requirements through controlled movement rather than fixed precision mounting.
Solution Approach 2:
The patent introduces a movable carrier as an intermediary between the cameras and the wafer edge. This carrier serves as a mediator that can be precisely positioned and moved, thereby indirectly controlling camera positions with respect to the wafer. The carrier absorbs the positioning precision requirements, making it easier to achieve high-quality image acquisition without requiring extremely precise direct camera-to-wafer positioning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables optimal positioning of cameras for defect inspection, achieving clear image acquisition and display of defects on all relevant surfaces, improving the efficiency of wafer edge defect evaluation.
Implementation Method 1
at least one illumination means (80) designed such that the first, second and third cameras (25, 26, 27) are arranged in bright field arrangement
Data Source
AI summary
A device for evaluating defects in the edge area of a wafer (6) is disclosed. The evaluation may also be performed automatically. In particular, the device includes three cameras (25, 26, 27), each provided with an objective (30), wherein a first camera (25) is arranged such that the first camera (25) is opposite to an edge area on the upper surface (6a) of the wafer (6), wherein a second camera (26) is arranged such that the second camera (26) is opposite to a front surface (6b) of the wafer (6), and wherein a third camera (27) is arranged such that the third camera (27) is opposite to an edge area on the lower surface (6c) of the wafer (6).