Polycrystalline Silicon Rod Selection via X-Ray Diffraction
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Solution Overview
Problem
Current methods for selecting polycrystalline silicon as a raw material for monocrystalline silicon production are subjective and lack quantitativeness and repeatability, leading to high rejection rates and potential dislocation issues during crystal growth.
Innovation Solution
An X-ray diffraction method is used to evaluate the degree of crystalline orientation by forming polycrystalline silicon into plate-like samples, performing in-plane rotation, and determining diffraction intensity values to select suitable polycrystalline silicon rods based on specific criteria, ensuring uniform melting and reducing dislocation generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If visual determination under optical microscope is used to evaluate polycrystalline silicon, then the evaluation process is simple and quick, but the determination results show differences depending on etching degree and observer skills, lacking quantitativeness and repeatability
Solution Approach 1:
The patent replaces the mechanical/visual inspection system with an X-ray diffraction measurement system. Instead of using optical microscopes and human observers to evaluate polycrystalline silicon, the invention uses X-ray diffraction to obtain diffraction patterns and evaluate crystalline orientation objectively through diffraction intensity ratios, eliminating subjectivity and improving measurement precision and repeatability.
2Productivity
If acceptance criteria are set to higher level to reduce determination differences, then manufacturing yield of monocrystalline silicon increases, but rejection rate of polycrystalline silicon rods becomes higher
Solution Approach 1:
The patent changes the evaluation parameter from visual appearance (subjective) to crystalline orientation degree measured by X-ray diffraction (objective). By establishing quantitative acceptance criteria based on diffraction intensity ratios (e.g., I(200)/I(111) for FZ method), the invention enables precise selection of suitable polycrystalline silicon rods, reducing both false rejections and manufacturing defects, thereby optimizing both yield and rejection rate.
3Quantity of substance
If polycrystalline silicon with acicular crystal is used as raw material, then material availability increases, but unmelted crystallites pass through melt zone as solid particles causing defect formation
Solution Approach 1:
The patent performs preliminary evaluation of polycrystalline silicon rods using X-ray diffraction before they are used as raw materials for monocrystalline silicon growth. By measuring the diffraction intensity ratios and comparing them against established criteria, the invention identifies and selects rods with appropriate crystalline orientation that will melt uniformly during the growth process, preventing unmelted crystallites from causing defects in the final monocrystalline product.
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 allows for the stable production of monocrystalline silicon by selecting polycrystalline silicon rods with low crystalline orientation, preventing local unmelted residues and dislocation, thus enhancing manufacturing yield and consistency.
Implementation Method 1
evaluating the degree of crystalline orientation of polycrystalline silicon by an X-ray diffraction method
Implementation Method 2
disposing the plate-like sample in a position where Bragg reflection from a Miller index face (100), (110), (111) or (200) is detected
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
When the degree of crystalline orientation of polycrystalline silicon is evaluated by an X-ray diffraction method, each obtained disc-like sample 20 is disposed in a position where Bragg reflection from a Miller index face <hkl> is detected and in-plane rotated at a rotational angle φ with the center of the disc-like sample 20 as the center of rotation, so that an X-ray-radiated region defined by a slit φ-scans over the principal surface of the disc-like sample 20, to determine a chart representing the dependence of the intensity of Bragg reflection from the Miller index face <hkl> on the rotational angle (φ) of the disc-like sample 20, a baseline is determined from the chart, and the diffraction intensity value of the baseline is used as an estimative index of the degree of crystalline orientation.