Substrate Inspection via Dichroic Fluorescence Contrast
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Solution Overview
Problem
Current inspection techniques for electronic devices such as wafers and circuit boards face challenges in detecting anomalies or defects, particularly on metallic layers, due to limited contrast in imaging, especially when metallic materials do not fluoresce, leading to difficulties in identifying potential electrical failures.
Innovation Solution
An optical system that uses a dichroic beam splitter to separate excitation light from fluorescent light, allowing for improved contrast by filtering out non-fluorescent metallic defects and highlighting fluorescent contaminants, coupled with image processing techniques to quantify intensity discrepancies and identify candidate defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging techniques are used to inspect substrates, then the inspection process is simple, but the contrast between metallic defects and the substrate is insufficient, leading to poor defect detection capability
Solution Approach 1:
The inspection system segments the detection process into multiple wavelength channels: a first wavelength for imaging the substrate structure and a second wavelength for specifically detecting fluorescent contaminants. This segmentation allows each channel to be optimized for its specific detection target, improving overall defect detection capability while maintaining systematic organization.
Solution Approach 2:
The patent introduces fluorescent markers as intermediaries that bind to metallic defects. These markers convert non-fluorescent metallic defects into fluorescent signals that can be detected by the imaging system. The intermediary (fluorescent marker) bridges the gap between the metallic defect and the detection system, enabling high-contrast visualization of previously undetectable defects.
2Measurement precision
If fluorescent markers are used to enhance defect visibility, then the contrast and detection accuracy improve, but the manufacturing process becomes more complex
Solution Approach 1:
The fluorescent markers are applied to the substrate before the final inspection stage, allowing them to bind to metallic defects in advance. This preliminary action ensures that when the dual-wavelength inspection occurs, the markers are already in position to highlight defects, integrating the enhancement process seamlessly into the manufacturing workflow without requiring post-processing steps.
3Measurement precision
If multiple wavelength imaging is performed to differentiate defect types, then the detection accuracy improves, but the inspection time increases
Solution Approach 1:
The system performs periodic switching between the first wavelength (for substrate imaging) and the second wavelength (for fluorescent contaminant detection). This periodic action allows both types of inspection to be conducted in a time-multiplexed manner, achieving comprehensive defect differentiation without requiring simultaneous multi-wavelength capture that would significantly increase inspection time.
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
Enhances the ability to detect and differentiate anomalies on substrates, reducing false positives and improving the identification of potential electrical failures by providing clear contrast and accurate defect detection, thereby enhancing the yield and reliability of semiconductor devices.
Implementation Method 1
illuminating a substrate with a first wavelength to obtain a first image of the substrate and illuminating the substrate with a second wavelength to obtain a second image of the substrate
Implementation Method 2
An optical system that uses a dichroic beam splitter to separate excitation light from fluorescent light
Data Source
AI summary
Concepts presented herein relate to approaches for performing substrate inspection. In one aspect, the concepts relate to detecting anomalies or candidate defects on the substrate based on contrast in images obtained of the substrate.