Wafer Surface Defect Detection Using Polarized Light Interference
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Solution Overview
Problem
Existing optical detection methods for wafer defects have low accuracy in the wafer axial direction, which can lead to failures in expensive processes and product yield issues.
Innovation Solution
A defect detection device and method utilizing polarized lights with a preset shear amount, interfered to form signal light, and detected by multiple polarization and non-polarization detectors to improve longitudinal detection accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light scattering method is used for wafer defect detection, then detection speed is fast and no additional pollutions are caused, but detection accuracy in the wafer axial direction is low
Solution Approach 1:
The patent segments the detection task by dividing the wafer surface into multiple detection areas with different detection angles. Multiple detectors are arranged to detect reflected light from different axial directions, enabling independent measurement of surface height at different locations. This segmentation allows accurate axial direction detection while maintaining the simplicity of optical reflection methods.
Solution Approach 2:
The patent transitions from single-angle detection to multi-angle detection by arranging detectors in different spatial positions. By detecting reflected light from multiple axial directions simultaneously, the system extracts height information in the axial dimension without adding mechanical complexity, effectively using spatial dimensionality to solve the measurement precision problem.
2Measurement precision
If multiple polarization detectors are used to improve detection accuracy, then measurement precision increases, but device complexity increases
Solution Approach 1:
The patent makes each detector serve multiple functions: detecting both the intensity of reflected light and the polarization state simultaneously. By using polarization detectors that can measure both ordinary and extraordinary light components, the system obtains height information and defect information from a single detection event, reducing the need for additional detectors and minimizing device complexity while maintaining high precision.
Solution Approach 2:
The patent changes the detection parameter from simple light intensity to polarization state parameters (ordinary and extraordinary light components). By analyzing the polarization characteristics of reflected light, the system extracts precise height and defect information without requiring complex mechanical scanning systems, thereby improving measurement precision while keeping the device structure relatively simple.
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 achieves high-precision defect detection in the longitudinal direction with improved reliability, stability, and fast detection speed, enhancing the accuracy of defect identification on wafer surfaces.
Implementation Method 1
the first polarized light is reflected by a surface to be detected of a component to be detected to form a first echo light, and the second polarized light is reflected by the surface to be detected of the component to be detected to form a second echo light, and the first echo light and the second echo light are interfered to form a signal light
Implementation Method 2
the first detection apparatus includes two or more detectors which are all polarization detectors, and polarization detection directions of different polarization detectors are different
Implementation Method 3
the first polarized light is reflected by a surface to be detected of a component to be detected to form a first echo light
Data Source
AI summary
The present invention provides a detection device and a detection method. The detection device uses the signal light formed by the interference of the first and the second echo lights reflected on the surface of the component to be detected to obtain the first light intensity distribution information of the signal light corresponding to the sampling position on the component to be detected by the first detection device to obtain the phase distribution of the signal light according to the intensity distribution to obtain the defect distribution data of the component to be detected. Among them, the first detection apparatus includes more than two polarization detectors, or a non-polarization detector and at least one polarization detector. The present invention can effectively achieve the polarization state analysis of the signal light, achieve the high-precision detection of the component to be detected in the longitudinal direction, and have advantages of good reliability, high stability and fast detection speed.