Dual-Wavelength Substrate Inspection System for Simultaneous Surface Defect Detection
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Solution Overview
Problem
Conventional inspection systems are limited by their ability to inspect only one surface of a substrate at a time, leading to reduced throughput and increased risk of contamination when inspecting both sides.
Innovation Solution
The development of an inspection system that uses dual channels with different wavelengths of light to simultaneously inspect multiple surfaces of a substrate, including the back, front, and bulk, while maintaining high throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional inspection systems inspect only one surface of a substrate at a time, then the system complexity remains low, but the throughput is reduced and contamination risk increases
Solution Approach 1:
The inspection system is divided into two independent inspection channels: a first inspection channel for inspecting a first surface of the substrate and a second inspection channel for inspecting a second surface. Each channel has its own illuminator and detector, allowing simultaneous operation without interfering with each other, thus increasing throughput while maintaining manageable complexity through modular design
Solution Approach 2:
The patent introduces a spectral dimension by using different wavelengths of light (first wavelength and second wavelength) for different inspection channels. This allows the system to inspect multiple surfaces simultaneously by multiplexing in the spectral domain, effectively adding a new dimension to the inspection process that increases throughput without requiring additional spatial resources
2Productivity
If dual wavelength inspection is used to inspect multiple surfaces simultaneously, then throughput improves, but the device complexity increases
Solution Approach 1:
The substrate serves multiple functions in the inspection process: it is the object being inspected, and its opaque nature at the first wavelength and transparent nature at the second wavelength enable it to function as both the inspected object and an optical element that directs light paths. This multi-functionality reduces the need for additional optical components
Solution Approach 2:
The system changes the optical parameter (wavelength) to achieve different inspection modes. By using a first wavelength that makes the substrate opaque for first surface inspection and a second wavelength that makes it transparent for second surface inspection, the system can switch between inspection modes without physical reconfiguration, managing device complexity through parameter-based control
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
This approach enables simultaneous inspection of multiple surfaces with submicron sensitivity, improving throughput and reducing contamination risks by allowing for the detection of defects on both sides of the substrate in a single pass.
Implementation Method 1
Detection optics collect backscattered light from a first surface and a second surface of the substrate in response to the light
Implementation Method 2
An adjustment system in the inspection system adjusts the second angle to focus the light at the second wavelength at a specified location
Implementation Method 3
The substrate may be opaque to one of the wavelengths and at least partially transparent to the other wavelength
Data Source
AI summary
An inspection system for inspecting multiple surfaces of a substrate includes at least one illuminator that produces light at a first wavelength that is incident on the substrate at a first angle (e.g., normal) and light at a second wavelength directed that is obliquely incident on the substrate. An adjustment system adjusts the oblique angle. The substrate may be opaque to one of the wavelengths and at least partially transparent to the other wavelength. Detection optics collect backscattered light from the substrate and at least one detector generates a first image representative of the first surface of the substrate and a second image representative of a second surface or near the second surface of the substrate. The images may be compared to generate a third image representative of defects on or near the second surface of the substrate corrected for residual signals of defects on the first surface.