Substrate Defect Detection via Thermal Gradient Imaging
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Solution Overview
Problem
Current methods for inspecting wafers, such as scanning acoustic microscopy, are inefficient for high production rates and often miss defects located away from the wafer edges, requiring extensive time and limited analysis to specific areas.
Innovation Solution
A method involving the generation of a temperature gradient across the substrate surface using a heat source and detection of heat radiation to determine damage, allowing for rapid and comprehensive defect identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scanning acoustic microscopy is used to detect defects, then measurement precision is improved, but productivity deteriorates due to long analysis time
Solution Approach 1:
The patent replaces the mechanical scanning acoustic microscopy system with a thermal imaging system that uses infrared cameras to detect temperature variations caused by defects. This substitution eliminates the need for mechanical scanning and coupling media, enabling parallel detection of multiple defects simultaneously across the entire wafer surface, thus dramatically improving productivity while maintaining measurement precision
Solution Approach 2:
The patent applies periodic thermal excitation to the wafer surface and detects the periodic thermal response to identify defects. By using periodic heating and synchronization with the detection system, the method achieves rapid defect identification across the entire wafer without requiring sequential scanning, thereby resolving the contradiction between precision and productivity
2Measurement precision
If scanning acoustic microscopy is used to detect defects, then measurement precision is improved, but loss of time increases due to extensive inspection required
Solution Approach 1:
The patent replaces the time-consuming mechanical scanning process with a thermal imaging system that captures the entire wafer surface simultaneously using infrared cameras. This allows parallel detection of all defects across the wafer in a single measurement cycle, eliminating the sequential scanning time and dramatically reducing loss of time while maintaining measurement precision
Solution Approach 2:
The patent applies preliminary thermal excitation to the wafer before detection, causing temperature variations that reveal defect locations. This preliminary action prepares the sample in advance, allowing the detection system to immediately capture defect information without requiring time-consuming scanning or signal processing, thus reducing inspection time while maintaining precision
3Productivity
If analysis is restricted to wafer edges to save time, then productivity is improved, but measurement precision deteriorates by missing star cracks in the middle
Solution Approach 1:
The patent creates a universal inspection system that can detect defects anywhere on the wafer surface (edges, center, and intermediate regions) using thermal imaging. The system applies thermal excitation and detection across the entire wafer surface simultaneously, making the inspection method universally applicable to all regions without requiring separate procedures, thus achieving both high productivity and complete defect coverage
Solution Approach 2:
The patent uses periodic thermal excitation that propagates across the entire wafer surface, allowing synchronous detection of temperature variations throughout the wafer including the center region. This periodic action enables the system to detect star cracks and other defects anywhere on the wafer simultaneously, eliminating the need to restrict analysis to edges while maintaining high inspection speed
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 fast and effective detection of defects in substrates, potentially within seconds, without the need for a priori knowledge of damage locations, improving production efficiency and defect detection accuracy.
Implementation Method 1
generating a temperature gradient along a surface of the substrate
Implementation Method 2
detecting a heat radiation emitted from the substrate
Data Source
AI summary
A method of examining a substrate is provided. The method may include: generating a temperature gradient along a surface of the substrate; detecting a heat radiation emitted from the substrate; and determining as to whether the substrate is damaged based on the detected heat radiation.