Dual-Camera 3D Measurement for Crystal Growth Melt Elevation
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Solution Overview
Problem
Existing crystal growth systems using the Czochralski process face challenges in accurately determining melt elevation and crystal diameter, leading to potential dislocations and quality issues in silicon ingots due to limited accuracy in measurement methods.
Innovation Solution
A dual-camera system captures images from different angles to generate a mathematical model of the growing crystal, allowing for three-dimensional measurement of crystal features and hotzone components, thereby improving the accuracy of melt elevation and diameter determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-camera systems are used for crystal diameter measurement, then device complexity is reduced, but measurement precision deteriorates due to limited accuracy in determining melt elevation and crystal diameter
Solution Approach 1:
The patent transitions from single-camera two-dimensional imaging to multi-camera three-dimensional measurement. By adding spatial dimensions through multiple cameras positioned at different angles, the system achieves accurate melt elevation determination and crystal diameter measurement simultaneously, resolving the trade-off between measurement precision and device complexity
Solution Approach 2:
The measurement task is segmented into multiple camera views, each capturing specific geometric features from different angles. The processing system segments the three-dimensional space into measurable components by projecting crystal features onto multiple image planes, enabling precise melt elevation and diameter determination through coordinated multi-view geometry
2Manufacturing precision
If dipstick methods are used to determine melt elevation, then device complexity is minimized, but manufacturing precision deteriorates due to dipstick etching affecting measurement accuracy
Solution Approach 1:
The patent replaces the mechanical dipstick contact method with an optical measurement system. Cameras capture images of the melt surface and crystal interface without physical contact, eliminating dipstick etching and its detrimental effects on measurement accuracy and crystal quality while maintaining relatively simple device architecture
Solution Approach 2:
The patent introduces optical images as an intermediary between the measurement system and the melt surface. Instead of direct mechanical contact with the reactive silicon melt, the system uses light reflection and camera imaging to determine melt elevation, thereby preventing chemical interaction and measurement degradation
3Measurement precision
If laser reflection methods are used for melt elevation determination, then measurement speed is improved, but measurement precision deteriorates due to limited accuracy in determining reflection elevation
Solution Approach 1:
The patent merges multiple measurement functions into a single multi-camera system. Instead of using separate laser reflection methods for speed and other methods for precision, the system combines multi-view imaging capabilities to simultaneously achieve both accurate melt elevation determination and real-time measurement updates during crystal growth
Solution Approach 2:
The system implements real-time feedback through continuous multi-camera imaging during crystal growth. The processing system continuously updates the three-dimensional crystal model and melt elevation measurements, providing immediate feedback for process control while maintaining high measurement precision through coordinated multi-view geometry
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 approach enhances the control over the crystal growth process, reducing dislocations and improving the quality of silicon ingots by providing more precise measurements of crystal dimensions and hotzone features.
Implementation Method 1
The camera generates a video image of the crystal including an image of the meniscus at the melt-solid interface
Data Source
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AI summary
Three-dimensional measurement of a crystal being pulled from a crucible is described. A first camera captures a first image of the crystal on a first image plane and a second camera captures a second image of the crystal on a second image plane. A mathematical model of a crystal during crystal growth is generated. The model includes a plurality of model sample points. A crystal growth feature is detected within the first image and the second image. A first error value is determined by comparing the model to the at least one crystal growth feature within the first image and a second error value is determined by comparing the model to the at least one crystal growth feature within the second image. An estimated 3-D metrology value associated with the at least one crystal growth feature is generated by adjusting the mathematical model to minimize the determined first error value and the determined second error value.