Optical 3D Surface Roughness Measurement Across Variable Exposure
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Solution Overview
Problem
Accurate, fast, and reliable determination of surface roughness of etched semiconductor wafers is challenging due to variations in size, material, and reflection characteristics, necessitating improved measurement and computation methods.
Innovation Solution
A method involving multiple optical three-dimensional measurements with varying brightness levels or exposures, combined with computational analysis to determine a single accurate surface roughness value, using data processing systems to filter and compute surface topology data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single optical measurement is performed to determine surface roughness, then the measurement speed is fast, but the measurement precision is insufficient due to variations in brightness levels and exposure
Solution Approach 1:
The measurement process is segmented into multiple optical measurements taken at different brightness levels or exposure settings. Each measurement captures surface topology data under specific lighting conditions, and the results are combined through computational analysis to produce a comprehensive surface roughness value that is independent of brightness variations.
2Measurement precision
If multiple measurements with different brightness levels are performed to improve accuracy, then the measurement precision improves, but the productivity decreases due to increased measurement time
Solution Approach 1:
Multiple optical measurements at different brightness levels are performed in advance as a preliminary step. The computational analysis then processes these pre-captured data sets to determine the final surface roughness value, eliminating the need for repeated measurements and enabling faster throughput while maintaining high precision.
3Measurement precision
If conventional single-point measurement methods are used, then the device complexity is low, but the measurement precision is insufficient for specimens with varying reflection characteristics
Solution Approach 1:
The measurement system varies the brightness level or exposure parameter across multiple measurements to capture surface topology data under different lighting conditions. This parameter variation enables the system to obtain accurate surface roughness measurements for specimens with diverse reflection characteristics without requiring complex hardware modifications.
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
Provides reproducible and precise surface roughness measurements independent of specimen characteristics, enabling effective control of wet etching processes for consistent quality.
Implementation Method 1
optical three-dimensional measurement of the specimen surface by an image sensor
Data Source
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AI summary
The disclosure relates to a method (300) for determining a surface roughness of a specimen surface of a specimen (1), the method (300) comprising: - obtaining several measurement data, each one of the measurement data being indicative of a surface topology of the specimen surface based on an optical three-dimensional measurement of the specimen surface by an image sensor, wherein each one of the measurement data is associated with a different brightness level of a light source illuminating the specimen surface or with a different exposure of the image sensor; - obtaining first computation data indicative of surface roughnesses of the specimen surface for each one of the measurement data; and - determining second computation data indicative of a surface roughness of the specimen surface for all measurement data based on the first computation data.