Wafer Groove Alignment for Accurate Cross-Section Measurement
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Solution Overview
Problem
Existing methods for measuring the shape of grooves on wafers require large data storage and processing capacity, and struggle with data loss and inaccurate shape generation due to steep inclined surfaces, especially when using three-dimensional image assembly of two-dimensional images.
Innovation Solution
An alignment method is employed to match the extending direction of the groove with the array direction of camera pixels, followed by one-dimensional conversion of images to generate cross-sectional shapes, reducing data requirements and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-dimensional image assembly of two-dimensional images is used to measure groove shape, then three-dimensional image information can be generated, but large data storage capacity and processing capability are required which increases cost
Solution Approach 1:
The patent extracts only the essential information needed for groove shape measurement from the two-dimensional images, specifically focusing on extracting profile data along the groove extending direction rather than assembling complete three-dimensional image data. This selective extraction approach obtains the necessary measurement information while significantly reducing data storage and processing requirements.
Solution Approach 2:
The patent segments the image processing into specific functional steps: detecting the groove extending direction, aligning images along this direction, and extracting profile information at different Z positions. This segmentation allows efficient processing of individual image components rather than handling the entire three-dimensional data set, reducing overall system complexity.
2Measurement precision
If camera focuses on wall surfaces of groove during image pickup, then groove shape information can be obtained, but data loss occurs when inclined surfaces are steep making accurate three-dimensional shape generation difficult
Solution Approach 1:
The patent performs preliminary alignment of the camera imaging direction with the groove extending direction before actually capturing the groove wall surface images. By pre-aligning the imaging system so that the pixel array direction matches the groove orientation, the subsequent image acquisition is optimized to capture wall surface data without data loss, even on steep inclined surfaces.
Solution Approach 2:
The patent employs asymmetric alignment where the pixel array direction is specifically oriented to match the groove extending direction rather than using symmetric or arbitrary imaging angles. This asymmetric alignment ensures that the camera captures the groove walls at the optimal angle, preventing data loss on steep surfaces while maintaining measurement accuracy.
Data Source
AI summary
The alignment method includes detecting an extending direction of a groove formed on a wafer, based on an image of the wafer picked up by a camera, and performing alignment so as to adjust the extending direction of the groove to be parallel to an array direction of pixels of the camera by relatively rotating the wafer and the camera.