Non-Planar Reflectors With Laser Scanning for Wafer Edge Detection
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Solution Overview
Problem
Existing semiconductor wafer edge detection methods struggle to accurately differentiate the edge from adjacent regions due to planar surfaces reflecting coherent light uniformly, making it difficult to implement precise process control.
Innovation Solution
Integrate non-planar reflection surfaces with coherent light scan, using tilted light reflection devices and a light detector to distinguish the wafer edge by detecting changes in reflected light patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If planar surfaces are used for wafer edge detection, then the structure is simple and easy to manufacture, but the edge differentiation from adjacent regions is inaccurate
Solution Approach 1:
The patent applies curved reflection surfaces (cylindrical or spherical segments) instead of planar surfaces to create non-uniform light reflection patterns. The curvature causes light reflected from the wafer edge to follow different paths compared to adjacent regions, generating detectable signal variations that enable accurate edge differentiation while maintaining manufacturing feasibility through standard optical component fabrication
2Measurement precision
If coherent light scan is used on planar surfaces, then the scanning process is simple, but the reflected light pattern does not provide sufficient edge differentiation
Solution Approach 1:
The curved reflection surfaces transform the uniform coherent light scan into a non-uniform reflection pattern where the wafer edge produces distinct optical signals compared to adjacent regions. The curvature geometry ensures that light paths from the edge are differentiated from those of surrounding areas, creating detectable signal variations without requiring complex scanning mechanisms
Solution Approach 2:
The patent applies different reflection surface geometries (cylindrical vs. spherical segments) tailored to specific detection needs and wafer positions. Each local region of the reflection surface is optimized to produce characteristic light patterns that enhance edge detection accuracy for that particular zone, allowing the system to achieve high measurement precision through localized optical property variations
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 precise detection of the wafer edge, allowing for improved process control and alignment through the use of non-planar reflection surfaces that enhance the differentiation of the edge from adjacent regions.
Implementation Method 1
The wafer surface of the wafer and the first light reflection surface of the first light reflection device can reflect the incident light to generate reflection light
Data Source
AI summary
Aspects of the present disclosure provide an apparatus. For example, the apparatus can include a wafer holder for holding a wafer, a light reflection device located beside a wafer edge and having a light reflection surface tilted with respect to a wafer surface, and a coherent light source for generating incident light to perform a scan on the wafer surface and the light reflection surface, which can reflect the incident light to generate reflection light, which can be detected by a light detector. The coherent light source, the light reflection device and the light detector can be arranged such that the incident light passes by the wafer edge and the reflection light generated by the light reflection surface is detected by the light detector or the reflection light generated by the light reflection surface passes by the wafer edge and is detected by the light detector.