Wafer Scratch Inspection Using Total Internal Reflection
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Solution Overview
Problem
Conventional Automated Optical Inspection (AOI) systems struggle to effectively detect wafer scratches during the manufacturing of integrated circuits.
Innovation Solution
A wafer defect inspection system utilizing the principle of total reflection, employing a line light source, camera, and electronic device to control inspection light for detecting scratches and impurities by capturing and analyzing images using total reflection principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AOI systems are used for wafer inspection, then general surface defects can be detected, but wafer scratches cannot be effectively detected
Solution Approach 1:
The patent changes the inspection parameter from conventional optical reflection to total internal reflection by adjusting the light incident angle to be greater than the critical angle. This parameter change enables the detection of scratches that were previously undetectable by conventional AOI systems, directly resolving the technical contradiction between measurement precision for scratches and detection reliability
2Measurement precision
If total reflection principle is applied to detect scratches, then scratch detection capability is improved, but the inspection system complexity increases
Solution Approach 1:
The patent inverts the conventional inspection approach by using total internal reflection instead of conventional reflection. The light is directed from the back surface of the wafer at an angle greater than the critical angle, causing total internal reflection at the front surface. This inversion simplifies the optical system while achieving superior scratch detection capability
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
Effectively identifies wafer scratches and impurities by capturing defect features through total reflection, enhancing the detection capabilities of AOI systems.
Implementation Method 1
an included angle between the inspection light and the edge surface is adjusted so as to cause the inspection light travel inside the wafer according to the principle of total reflection after being incident on the wafer
Data Source
AI summary
A wafer defect inspection system is disclosed, and comprises a line light source, a camera and a processor, wherein the processor is configured to control the line light source to provide an inspection light to be incident on a wafer, wherein an included angle between the inspection light and the surface of the wafer ranges from 45° to 90°. After incidence on the wafer, the inspection light travels inside the wafer according to the principle of total reflection, and when encountering a crack, part of the inspection light exits from the surface of the wafer through the crack. Moreover, the processor controls the camera to obtain a wafer image containing at least one defect feature, and after processing the wafer image into an inspection wafer image, compares the wafer image with a reference wafer image, so as to know the at least one defect feature.