Dual-Camera Single Crystal Diameter Detection
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Solution Overview
Problem
Conventional methods for detecting the diameter of single crystals during the Czochralski process are prone to errors due to changes in the relative position of cameras and the melt surface, leading to variations in crystal diameter and reduced yield.
Innovation Solution
Using two cameras placed at a fixed distance from each other to capture both ends of the single crystal growth point, allowing for precise diameter detection based on captured images, independent of camera position changes, and controlling the crystal diameter accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera is used to capture the meniscus ring for diameter detection, then the device complexity is low, but the measurement precision deteriorates due to position changes of the camera or melt surface
Solution Approach 1:
The single camera system is segmented into two separate cameras positioned at different locations. Each camera captures the meniscus ring from its specific viewpoint, and the images are processed separately to calculate diameter values. This segmentation allows the system to maintain low individual camera complexity while achieving high measurement precision through multiple independent measurements.
Solution Approach 2:
The solution transitions from a single-point measurement (one camera) to a multi-point measurement system (two cameras at different positions). By adding the dimension of spatial distribution, the system compensates for position changes and provides more reliable diameter detection that is independent of camera or melt surface position variations.
2Ease of operation
If the camera position is adjusted to re-set the chamber after a batch, then the ease of operation is improved, but the measurement precision deteriorates due to relative position changes
Solution Approach 1:
By using two cameras positioned at different locations, the system segments the measurement task so that each camera provides an independent measurement. This allows the chamber to be re-set or adjusted without affecting the overall measurement accuracy, as the dual-camera system can compensate for position changes.
Solution Approach 2:
The system continuously monitors the meniscus ring position and diameter from two different viewpoints, providing feedback that allows for real-time compensation of camera or melt surface position changes. This feedback mechanism maintains measurement precision even when operational adjustments are made to the chamber.
3Productivity
If the melt surface position changes during crystal pulling, then the productivity is maintained, but the measurement precision deteriorates due to distance changes from the camera
Solution Approach 1:
The system uses two cameras positioned at different spatial locations to capture the meniscus ring. When the melt surface position changes during crystal pulling, the dual-camera configuration ensures that at least one camera maintains accurate focus and measurement capability, compensating for the position changes and maintaining measurement precision throughout the productivity-optimized pulling process.
Data Source
AI summary
A method for detecting a diameter of a single crystal at the time of pulling the single crystal from a silicon melt contained in a crucible according to the Czochralski method, the method including at least: using two cameras placed equidistant from each other as a target diameter upon forming a straight-body portion of the single crystal and face both ends of the diameter of the single crystal in a growth point of the single crystal respectively, to separately capture both of the ends of the growth point of the single crystal from an outside of a furnace, the growth point being a contact point between the single crystal and a melt surface; and detecting the diameter of the single crystal on the basis of the captured images. As a result, diameter detection precision is improved.