Wafer Edge Defect Imaging via Segmented Macro-Micro Inspection
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Solution Overview
Problem
Existing methods for inspecting wafers fail to acquire high-resolution images of defects on the upper surface of the wafer edge due to focusing issues, particularly for defects near the edge.
Innovation Solution
A method involving the determination of defect positions on the wafer edge, followed by transfer to a micro-inspection device where appropriate focusing methods (laser or TV focus) are selected based on the defect's proximity to the edge, using multiple microscope objectives for optimal imaging and automatic alignment and image acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If macro-inspection is used to capture the whole wafer surface, then the wafer edge area is included, but high-resolution imaging of defects on the wafer edge is not achieved
Solution Approach 1:
The inspection system is divided into two functional segments: a macro-inspection device for capturing the entire wafer surface including the edge area, and a micro-inspection device for high-resolution imaging of specific defects. The macro-device identifies defect positions on the wafer edge, then coordinates with the micro-device to capture detailed images of those specific defects, thus resolving the contradiction between wide area coverage and high resolution.
2Productivity
If automatic defect acquisition is performed on the wafer edge, then processing efficiency is improved, but focusing problems occur for defects near the edge
Solution Approach 1:
The macro-inspection device serves as an intermediary that first identifies and locates defects on the wafer edge, then provides this position information to the micro-inspection device. This intermediary step allows the system to automatically acquire defect positions without manual intervention, while the micro-device uses this information to properly focus on each defect, thus maintaining both high productivity and focus accuracy.
3Device complexity
If a single microscope objective is used, then the device complexity is reduced, but the ability to detect defects at various positions optimally is limited
Solution Approach 1:
The micro-inspection device is designed with multiple interchangeable objectives that can be selected based on the defect position and size. This multi-functional capability allows the same device to optimally image both small defects near the wafer edge and larger defects in other areas, achieving universal applicability without requiring separate specialized devices for each defect type.
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
Enables the acquisition of high-resolution images of defects on the wafer edge without focusing problems, allowing for precise detection and storage of images, even for defects near the edge, through the use of appropriate focusing techniques and automatic alignment.
Implementation Method 1
a laser focus, a TV focus or combinations of both focusing methods are used to focus on a defect
Implementation Method 2
at least one defect is imaged in the device for micro-inspection using a microscope including several objectives of various magnifications
Data Source
AI summary
A method for acquiring high-resolution images of defects on the upper surface of the wafer edge is disclosed. For this purpose, first the position of at least one defect on the upper surface of the wafer edge is determined. The thus determined position of the defect is stored. Then the wafer is transferred into device for micro-inspection, in which the defect is examined more closely and imaged. The images acquired in the device for micro-inspection are deposited in a directory.