Optical Metrology Device for Simultaneous Bright and Dark Field Inspection
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Solution Overview
Problem
Current optical inspection methods for semiconductor substrates require sequential bright field and dark field illumination, increasing inspection time and reducing productivity due to the difficulty in simultaneously detecting discoloration and scratches effectively.
Innovation Solution
An optical metrology device that simultaneously illuminates the substrate with first and second illumination lights of different wavelengths at distinct angles, integrating dark field and bright field images using a multichannel camera to generate a single original image, which is then corrected and separated to analyze defects efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential bright field and dark field illumination are performed, then various types of defects can be effectively detected, but the inspection time increases
Solution Approach 1:
The patent combines bright field and dark field inspection systems into a single integrated optical metrology device. Multiple illumination sources (bright field LED, dark field LED, oblique illumination LED) and corresponding imaging channels are merged to operate simultaneously on the substrate, enabling both inspection types to be performed in parallel rather than sequentially, thus reducing inspection time while maintaining comprehensive defect detection capability
Solution Approach 2:
The optical metrology device is designed with multi-functionality to perform both bright field and dark field inspections using a single device. The system includes multiple illumination units and imaging channels that can simultaneously execute different inspection functions, making the device universal for detecting various defect types (discoloration, scratches, particles) without requiring separate inspection equipment
2Reliability
If bright field inspection is performed, then discoloration can be effectively detected, but scratches are difficult to detect
Solution Approach 1:
The inspection system is segmented into multiple independent illumination and imaging channels, each optimized for specific defect types. The bright field channel with normal incident illumination is optimized for detecting discoloration, while the dark field channel with oblique illumination is optimized for detecting scratches and particles. This segmentation allows each channel to excel at its specialized detection task while working simultaneously
3Reliability
If dark field inspection is performed, then scratches can be effectively detected, but discoloration is difficult to detect
Solution Approach 1:
The inspection system is segmented into multiple independent illumination and imaging channels, each optimized for specific defect types. The dark field channel with oblique illumination is optimized for detecting scratches and particles, while the bright field channel with normal incident illumination is optimized for detecting discoloration. This segmentation allows each channel to excel at its specialized detection task while working simultaneously
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 allows for the simultaneous detection of various defects without additional time, improving productivity by integrating dark field and bright field inspections within the same image acquisition process, thus reducing the overall inspection time and enhancing the detection of discoloration and scratches.
Implementation Method 1
illuminate first illumination light and second illumination light, having different wavelengths, at different angles of incidence on a surface of a substrate
Implementation Method 2
a dark field image based on scattered light according to the first illumination light and a bright field image based on direct-reflected light according to the second illumination light
Data Source
AI summary
An optical metrology device includes a lighting unit configured to simultaneously illuminate first illumination light at a first angle of incidence having a difference more than a critical angle from a measurement angle, and second illumination light having a wavelength, different from a wavelength of the first illumination light, at a second angle of incidence having a difference of equal to or less than the critical angle from the measurement angle, onto a surface of a substrate; an optical system configured to collect reflected light from the surface of the substrate according to the first illumination light and the second illumination light; and a multichannel camera configured to generate an original image in which a dark field image and a bright field image of the surface of the substrate are integrated, based on the reflected light collected by the optical system.