SiC Polycrystal Growth Using α-Rich Seeds for Micropipe Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing SiC polycrystals do not effectively produce crystals with high thermal conductivity due to limitations in crystal structure and impurity management.
Innovation Solution
A sublimation recrystallization method using a SiC seed crystal with controlled impurities and a specialized manufacturing apparatus that includes a stress-buffering sheet and a projection on the lid to manage stress and impurity distribution, ensuring uniform growth and high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional graphite vessel without stress-buffering structure is used, then the manufacturing process is simple, but micropipes form and thermal conductivity is reduced
Solution Approach 1:
The graphite vessel is segmented into functional regions: a stress-buffering sheet region that deforms to absorb stress, a projection region on the lid that prevents micropipe formation, and a conventional graphite vessel body. This segmentation allows each region to address specific issues (stress management, micropipe prevention) while maintaining overall structural integrity and thermal conductivity.
Solution Approach 2:
The stress-buffering sheet is pre-installed in the graphite vessel before seed crystal attachment, and the projection is pre-formed on the lid. These preliminary structural preparations ensure that stress can be buffered and micropipes prevented from the outset during crystal growth, improving thermal conductivity without requiring post-processing modifications.
2Productivity
If the seed crystal is disposed close to the ceiling to reduce space, then manufacturing efficiency improves, but the rear surface of the seed crystal contacts the ceiling causing defects
Solution Approach 1:
The projection is pre-formed on the lid at a position that will contact the rear surface of the seed crystal during growth. This preliminary positioning ensures that when the seed crystal is disposed close to the ceiling for efficiency, the projection prevents contact between the seed rear surface and the ceiling, avoiding defects while maintaining manufacturing efficiency.
3Reliability
If impurities are not controlled in the seed crystal, then manufacturing is easier, but thermal conductivity is reduced due to impurity concentration
Solution Approach 1:
The projection on the lid creates a localized region with different properties (higher impurity concentration zone) that serves to trap and concentrate impurities away from the main crystal growth area. This local quality differentiation allows the main crystal to maintain high thermal conductivity while the projection region manages impurity distribution, balancing manufacturing ease with product quality.
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
The method produces SiC polycrystals with improved thermal conductivity and reduced micropipes, achieving higher thermal conductivity and product yield by controlling impurity concentrations and crystal orientation.
Implementation Method 1
a polycrystalline SiC substrate produced by a sublimation recrystallization method
Implementation Method 2
sublimation recrystallization method using a SiC seed crystal
Implementation Method 3
heating a furnace, and promoting gas phase transport from the Si and C atom sources to the seed crystal while making it unlikely that the rear surface of the seed will contact the ceiling by evacuating the induction furnace
Data Source
AI summary
Provided is a SiC polycrystal manufacturing method based on a sublimation recrystallization method using a SiC seed crystal. In the method, a polycrystalline SiC substrate that is a SiC polycrystal produced by a sublimation recrystallization method and contains a greater amount of α-SiC than β-SiC is used as the SiC seed crystal.