Optical Module for Surface Inspection Using Polarized Light
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Solution Overview
Problem
The manufacturing of semiconductor devices and displays faces increasing challenges in detecting defects in substrates and during the manufacturing process, as existing inspection methods struggle to accurately identify a wide variety of defects, impacting product precision and yield.
Innovation Solution
An optical module for surface inspection is developed, comprising a first light source unit, a second light source unit, a direction of polarization changing unit, and a detection unit, which illuminates and captures light from the substrate using both bright-field and dark-field imaging techniques, allowing for precise detection of defects by utilizing polarized light and beam splitters to enhance defect visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple separate light sources are used for bright-field and dark-field imaging, then inspection capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple light sources (first light source for bright-field imaging and second light source for dark-field imaging) into a single integrated optical module. The module includes a substrate holder, objective lens, beam splitter, and detector all arranged in one compact unit, allowing both imaging modes to be performed simultaneously without requiring separate inspection devices.
Solution Approach 2:
The optical module is designed as a universal inspection device that can perform both bright-field and dark-field imaging functions using a single integrated structure. The beam splitter directs light from different sources to the same substrate and detector, enabling one device to replace multiple specialized inspection devices.
2Measurement precision
If additional light sources are added to enhance dark-field imaging, then defect detection precision is improved, but device complexity increases
Solution Approach 1:
The patent integrates the second light source specifically for dark-field imaging into the same optical module as the first light source, using a beam splitter to direct both light paths through a common objective lens and detector system. This merging approach enhances defect detection precision while avoiding the complexity of having completely separate inspection systems.
3Measurement precision
If polarized light is used to illuminate the substrate, then defect visibility is improved, but the number of optical components increases
Solution Approach 1:
The beam splitter acts as an intermediary optical component that manages the polarized light paths. It directs the first light (for bright-field imaging) and the second polarized light (for dark-field imaging) through the system, separating their paths while maintaining their respective functions and reducing the need for additional polarization management components.
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 optical module effectively increases light usage for dark-field imaging, reduces the need for additional light sources, and allows for precise detection of defects by illuminating substrates with light polarized in different directions, enhancing defect identification and production yield.
Implementation Method 1
a first beam splitter that changes the direction along which the first light propagates from the first light source
Implementation Method 2
the direction of polarization changing unit comprises optics which convert the second light received into third light polarized in a second direction, perpendicular to the first direction
Implementation Method 3
fifth light that is a product of the second light scattered from the imaging plane
Data Source
AI summary
An optical module for surface inspection includes a first light source unit that illuminates a substrate with first light produced by a first light source and a first beam splitter that changes the path of the first light, a second light source unit that illuminates the substrate with second light polarized in a first direction, a direction of polarization changing unit that illuminates the substrate with the third light polarized in a second direction perpendicular to the first direction, and a detection unit that detects fourth light which is a product of the first light reflecting from the substrate, fifth light which is a product of the second light scattered from the substrate, and sixth light which is a product of the third light scattered from the substrate. The third light is produced by changing the direction of polarization of the second light reflected from the inspected substrate.