SiC Single Crystal Quality Evaluation via X-ray Rocking Curve
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Solution Overview
Problem
Current methods for evaluating the quality of SiC single crystals, such as chemical etching and X-ray diffraction, are either destructive or time-consuming, making it difficult to assess dislocation density and internal stress effectively, which affects device fabrication and reproducibility.
Innovation Solution
A non-destructive method involving X-ray rocking curve measurements to obtain peak shift values, which are used to create polynomial equations to evaluate the quality of SiC single crystals, allowing for the identification of dislocation distribution and stress patterns without damaging the crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemical etching method is used to evaluate dislocation density, then measurement precision is improved, but the SiC single crystal is destroyed making it unusable for device fabrication
Solution Approach 1:
The patent replaces the chemical etching method with X-ray diffraction-based rocking curve measurement. This substitution uses physical X-ray diffraction principles instead of chemical reactions to evaluate dislocation density, achieving non-destructive measurement that preserves the crystal for subsequent device fabrication while maintaining measurement capability.
Solution Approach 2:
The patent introduces X-ray diffraction as an intermediary measurement technique. Instead of directly chemically etching the crystal surface, X-rays serve as a mediator to probe the crystal structure and dislocation characteristics through non-contact diffraction patterns, enabling evaluation without material destruction.
2Reliability
If conventional X-ray diffraction methods are used, then non-destructive evaluation is achieved, but measurement time is excessive reducing productivity
Solution Approach 1:
The patent extracts only the essential measurement information needed for quality evaluation from the complete X-ray diffraction pattern. By focusing specifically on rocking curve measurements at critical diffraction conditions rather than comprehensive pattern analysis, the method achieves rapid non-destructive evaluation suitable for production environments.
Solution Approach 2:
The patent performs a partial measurement approach by conducting rocking curve measurements at specific, pre-determined diffraction angles and conditions rather than exhaustive scanning. This selective measurement strategy provides sufficient quality assessment information while dramatically reducing measurement time compared to conventional comprehensive X-ray diffraction analysis.
3Manufacturing precision
If comprehensive quality evaluation is performed to reduce dislocations, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The patent performs preliminary quality evaluation of seed crystals using the rapid rocking curve method before initiating crystal growth. By identifying and selecting high-quality seed crystals with low dislocation density in advance, the method simplifies the overall manufacturing process while ensuring high manufacturing precision of the final product through proactive quality control.
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 the evaluation of SiC single crystal quality in a simple and non-destructive manner, facilitating the production of high-quality SiC single crystal ingots with reduced dislocations for improved device manufacturing and increased reproducibility.
Implementation Method 1
measuring an X-ray rocking curve on a main surface of the SiC single crystal body on a predetermined diffraction surface; obtaining an angle Ω at a plurality of measurement points Pn on a diameter of the main surface when a diffraction peak is exhibited
Data Source
AI summary
A method for evaluating the quality of a SiC single crystal by a non-destructive and simple method; and a method for producing a SiC single crystal ingot with less dislocation and high quality with good reproducibility utilizing the same. The method for evaluating the quality of a SiC single crystal body is based on the graph of a second polynomial equation obtained by differentiating a first polynomial equation, the first polynomial equation approximating the relation between a peak shift value and a position of the measurement point and the peak shift value being obtained by an X-ray rocking curve measurement. The method for producing a SiC single crystal ingot manufactures a SiC single crystal ingot by a sublimation recrystallization method using, as a seed crystal, the SiC single crystal body evaluated by the evaluation method.