Laser Spot Shape Detection on Semiconductor Wafer
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Solution Overview
Problem
The existing methods for detecting the spot shape of a pulsed laser beam on a semiconductor wafer are inaccurate and time-consuming, relying on visual inspection which is operator-dependent and prone to errors due to impurities settling on optical components, causing distortion in the laser beam focus.
Innovation Solution
A method involving an inspection wafer, imaging, and automated analysis to assess the shape of laser spots formed on the wafer, comparing the captured images to an ideal profile to determine similarity and report any deviations from proper shape, thereby allowing for efficient and stable detection without operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection by operator is used to confirm laser beam spot shape, then the spot shape can be confirmed, but the accuracy is unstable and time required is relatively long
Solution Approach 1:
The patent replaces the manual visual inspection method with an automated imaging system. A camera captures images of the laser spot, and image processing algorithms automatically analyze the spot shape, replacing the operator's visual assessment with mechanical/optical detection systems.
Solution Approach 2:
The patent creates a visual copy (image) of the laser spot using imaging means, then analyzes this copy through image processing. This allows the spot shape to be examined without directly observing the actual laser spot, enabling automated analysis and recording for quality control.
2Productivity
If operator visual inspection is used to confirm laser spot shape, then the spot shape can be assessed, but the process depends on operator skill and is time-consuming
Solution Approach 1:
The patent replaces human visual inspection with an automated system comprising imaging means and image processing capabilities. This eliminates variability in operator skill levels and provides consistent, reliable detection results while significantly improving assessment speed and productivity.
Solution Approach 2:
The system performs self-assessment of the laser spot quality through automated image capture and processing. The imaging system and analysis algorithms work autonomously to evaluate spot shape without requiring human intervention, ensuring consistent and reliable results.
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 method provides accurate and rapid assessment of laser spot shapes, reducing the reliance on operator skill and shortening the time required to determine proper spot formation, ensuring efficient processing by identifying and addressing any distortions caused by impurities on optical components.
Implementation Method 1
applies a pulsed laser beam having a wavelength absorbable by the inspection wafer continuously to the inspection wafer
Data Source
AI summary
A method of detecting a spot shape of a pulsed laser beam, includes applying a pulsed laser beam having a wavelength absorbable by an inspection wafer held on a chuck table continuously to the inspection wafer with a focused point on an upper surface of the inspection wafer thereby to form a plurality of laser spots on the upper surface of the inspection wafer. An image of the laser spots is captured, and profiles of shapes of the laser spots are extracted from the captured image of the laser spots. A degree of similarity between the captured image and the profile of an ideal laser spot shape is calculated and stored in a memory. The shapes of the laser spots are found to be improper if the calculated degree of similarity is lower than a threshold value.