SiC Ingot Fabrication Filter for Impurity Control
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Solution Overview
Problem
The growth of high-quality single crystals of silicon carbide (SiC) is hindered by carbon impurities and defects introduced during the seeded growth sublimation process, leading to defective crystals and reduced product yield.
Innovation Solution
An apparatus with a crucible, a filter part positioned between the raw material and the seed, and an auxiliary filter part on the raw material to prevent impurities and control sublimation speed, ensuring homogeneous gas flow and trapping of carbon impurities, thereby growing a high-quality single crystal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter part is introduced to remove carbon impurities, then crystal quality is improved, but device complexity increases
Solution Approach 1:
A filter part is introduced as an intermediary component between the raw material and the seed crystal. This filter part selectively removes carbon impurities from the gas phase while allowing SiC species to pass through, thereby improving crystal quality without fundamentally changing the sublimation process itself
Solution Approach 2:
The filter part is designed with porous structure that allows selective permeation. The pores are sized to trap carbon impurities and larger particles while permitting smaller SiC-containing gas molecules to pass through, achieving purification through material selection rather than complex mechanical filtration
2Reliability
If the filter part is positioned close to the raw material to effectively trap impurities, then impurity removal is improved, but gas flow uniformity deteriorates
Solution Approach 1:
The filter part is positioned in the vertical dimension between the raw material and seed crystal, creating distinct gas flow zones. This spatial arrangement allows the filter to intercept impurities rising from the raw material while maintaining uniform horizontal gas flow distribution across the seed crystal surface
3Productivity
If the sublimation speed is increased to improve productivity, then crystal growth rate is improved, but crystal quality deteriorates due to impurity introduction
Solution Approach 1:
The filter part converts the harmful effect of rapid sublimation (which generates more impurities) into a benefit by actively removing these impurities. The increased sublimation rate produces more carbon impurities, but the filter part traps these impurities, allowing high productivity to be maintained without sacrificing crystal 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 apparatus enables the growth of homogeneous and less defective single crystals, preventing convex shape formation and increasing product yield by effectively blocking impurities and controlling sublimation speed, resulting in improved crystal quality and efficiency.
Implementation Method 1
The filter part can adsorb the carbon impurities or trap the carbon impurities. The pores of the filter part can adsorb micro-impurities
Implementation Method 2
The pores of the filter part can adsorb micro-impurities, and can block large-size impurities between the pores, so that the large-size impurities may be trapped
Implementation Method 3
In the second gas room, the gas sublimated from the surface of the raw material can be homogenously and widely condensed on a lower end of the filter
Implementation Method 4
Temperature gradient is formed between the raw material and the seed, so that the raw material in the crucible is dispersed to the seed, and re-crystallized to grow a single crystal
Data Source
AI summary
Disclosed is an apparatus for fabricating an ingot. The apparatus includes a crucible to receive a raw material, a holder disposed at an upper portion of the crucible to fix a seed, and a filter part in the crucible. The filter part is spaced apart from a surface of the raw material.