Optical 3D Surface Roughness Measurement Across Variable Exposure
Find Innovative SolutionsGenerate Solutions
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 techniques.
Innovation Solution
A method involving optical three-dimensional measurements with varying brightness levels or exposures of a light source and image sensor, combined with computational methods to determine a single accurate surface roughness value, using data processing systems to filter and analyze measurement 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 computation to produce a final surface roughness value that is more accurate than any single measurement alone.
2Measurement precision
If multiple measurements are performed with different brightness levels to improve accuracy, then the measurement precision improves, but the productivity decreases due to increased measurement time
Solution Approach 1:
The patent replaces complex mechanical adjustment systems with an optical-based measurement system that varies brightness levels or exposure settings. This substitution allows multiple measurements to be taken quickly by adjusting optical parameters rather than mechanical components, maintaining high productivity while achieving improved measurement precision through multiple data points.
3Measurement precision
If camera parameters are tuned to eliminate external interferences for accurate measurement, then the measurement precision improves, but the adaptability decreases for different specimen types with varying reflection characteristics
Solution Approach 1:
The system changes optical parameters (brightness levels and exposure settings) to adapt to different specimen types with varying reflection characteristics. By taking measurements across a range of brightness levels rather than optimizing for a single setting, the system maintains measurement accuracy for diverse specimens including those with different reflectivity properties.
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
AI summary
The disclosure relates to a method for determining a surface roughness of a specimen surface of a specimen. The method comprises: 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.