Laser Crucible Evaluation for Silicon Crystal Growth
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Solution Overview
Problem
Current methods for evaluating vitreous silica crucibles are limited as they cannot measure the three-dimensional shape of the inner surface, which is crucial for improving performance and quality control, especially for large crucibles used in monocrystalline silicon production, and often require destructive sampling.
Innovation Solution
A non-destructive method using a contactless internal ranging section that emits laser light obliquely to the inner surface, detecting reflected light to measure distances and obtain three-dimensional coordinates, allowing for the precise measurement of the inner surface shape and distribution of physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement devices are used to measure crucible dimensions, then height and outer diameter can be measured, but the three-dimensional shape of the inner surface cannot be measured
Solution Approach 1:
The patent replaces conventional mechanical contact measurement devices with a laser-based optical measurement system. The laser ranging section emits laser light that reflects off the crucible inner surface, and the reflected light is detected to calculate three-dimensional coordinates. This optical substitution enables comprehensive 3D shape measurement without mechanical contact, resolving the limitation of conventional devices that could only measure height and outer diameter.
Solution Approach 2:
The patent transitions from two-dimensional surface measurements to three-dimensional shape measurement by introducing angular positioning capabilities. The laser ranging section moves in radial and axial directions while the crucible rotates, collecting measurement data from multiple angles and positions to reconstruct the complete three-dimensional inner surface shape, including curvature radius information.
2Reliability
If contactless measurement is used, then contamination is prevented, but measurement capability is limited compared to contact methods
Solution Approach 1:
The patent uses laser light reflection instead of mechanical contact to measure the crucible inner surface. The laser ranging section emits laser light that reflects off the inner surface, and the reflected light intensity and position are detected to calculate precise three-dimensional coordinates. This contactless optical method prevents contamination while achieving high measurement precision through optical triangulation and intensity analysis.
Solution Approach 2:
The patent utilizes changes in light reflection characteristics to measure surface properties. By detecting the intensity and position of reflected laser light at different angles and positions, the system can determine three-dimensional coordinates and surface curvature without physical contact, maintaining both contamination prevention and measurement accuracy.
3Measurement precision
If destructive sampling is used for quality control, then inner surface properties can be measured, but manufacturing yield is reduced
Solution Approach 1:
The patent replaces destructive mechanical sampling with contactless laser optical measurement. The laser ranging section can measure the inner surface shape, curvature, and other properties of complete crucibles without cutting or damaging them. This enables quality control of every produced crucible rather than requiring destructive testing of samples, significantly improving manufacturing yield while maintaining measurement precision.
Solution Approach 2:
The patent creates a three-dimensional digital copy or map of the crucible inner surface through laser scanning. By collecting reflection data from multiple positions and angles, the system reconstructs the complete inner surface geometry without physical contact or damage to the original crucible, enabling comprehensive quality inspection of all produced items.
4Productivity
If large crucibles are manufactured, then production capacity increases, but measurement and quality control become more difficult
Solution Approach 1:
The patent employs dynamic measurement capabilities where the laser ranging section can move radially and axially, and the crucible can rotate during measurement. This dynamic approach allows the measurement system to adapt to large crucible sizes by adjusting measurement positions, angles, and scanning patterns, making it feasible to measure and control quality of large-diameter crucibles that would be difficult to inspect with static conventional devices.
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
Enables high-speed, accurate, and cost-effective measurement of the three-dimensional shape and physical properties of vitreous silica crucibles, preventing contamination and improving manufacturing yield and quality control, particularly for large crucibles used in high-purity monocrystalline silicon production.
Implementation Method 1
measuring a distance between an internal ranging section and an inner surface as a distance from the inner surface, by subjecting the inner surface of the crucible to irradiation with laser light and then detecting a reflected light from the inner surface
Implementation Method 2
the laser light being emitted from the internal ranging section in an oblique direction with respect to the inner surface, and the measurement being conducted at a plurality of measuring points along a course of a movement of the internal ranging section
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
The present invention provides a method for evaluating a vitreous silica crucible which can measure a three-dimensional shape of the inner surface of the crucible in a non-destructive manner. According to the present invention, A method for evaluating a vitreous silica crucible, including the steps of: moving an internal ranging section along an inner surface of the vitreous silica crucible in a contactless manner; measuring a distance between the internal ranging section and the inner surface as a distance from the inner surface, by subjecting the inner surface of the crucible to irradiation with laser light and then detecting a reflected light from the inner surface, the laser light being emitted from the internal ranging section in an oblique direction with respect to the inner surface, and the measurement being conducted at a plurality of measuring points along a course of a movement of the internal ranging section; and obtaining a three-dimensional shape of the inner surface of the crucible, by associating three-dimensional coordinates of each of the measuring points with the distance from the inner surface, is provided.