SiC Container Vapor-Phase Epitaxy for Uniform High-Purity Growth
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Solution Overview
Problem
Existing methods for forming SiC epitaxial layers, such as CVD and seed crystal addition, suffer from low growth velocity, non-uniformity, and potential impurity mixing, leading to high costs and purity issues, making them unsuitable for mass production.
Innovation Solution
A vapor-phase epitaxial growth method using a TaC container with a SiC container and a temperature gradient to sublimate C atoms, allowing high-purity SiC epitaxial layers to grow on an underlying substrate under Si vapor pressure, enabling uniform and efficient growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD method is used to form SiC epitaxial layer, then epitaxial layer can be formed, but growth velocity is low and process period is long
Solution Approach 1:
The invention changes the fundamental parameters of the epitaxial growth process by using vapor-phase epitaxy at temperatures of 1600-2000°C with Si vapor pressure control, compared to conventional CVD methods. This parameter change enables growth velocities of 10-100 μm/h, which is 10-100 times faster than CVD while maintaining high crystal quality and low defect density.
Solution Approach 2:
The invention utilizes phase transitions of silicon and carbon materials. Si vapor is generated by heating SiO2 or Si-containing materials, and C vapor is generated by heating carbon-containing materials. These phase transitions enable high-rate epitaxial growth while maintaining stoichiometric control and high purity, resolving the contradiction between growth speed and quality.
2Manufacturing precision
If CVD method is used, then epitaxial layer can be formed, but growth velocity is non-uniform depending on substrate height and position
Solution Approach 1:
The invention replaces the mechanical gas flow delivery system of CVD with a vapor-phase system where Si and C vapors are generated in-situ through heating. This substitution eliminates the non-uniform gas distribution problems of CVD and achieves uniform growth across the entire substrate surface, including areas at different heights and positions.
Solution Approach 2:
The vapor-phase epitaxy system can handle substrates at various positions and orientations uniformly. The Si and C vapors distribute evenly throughout the reaction chamber, enabling consistent growth velocity and quality regardless of substrate height or position, making the process universally applicable to different substrate configurations.
3Manufacturing precision
If seed crystal addition and sublimation technique is used, then epitaxial layer can be formed, but elements for increasing solubility might be unintentionally mixed in epitaxial crystal
Solution Approach 1:
The invention extracts and eliminates the problematic step of adding solubility-enhancing elements to the melt. Instead, it uses vapor-phase deposition where Si and C are supplied as vapors without requiring any melt additives. This extraction of the contamination source ensures high purity epitaxial layers free from unintentional element mixing.
Solution Approach 2:
The vapor-phase epitaxy process creates an inert vapor environment where Si and C vapors react on the substrate surface without requiring a liquid melt. This inert vapor atmosphere prevents unwanted chemical reactions and element mixing, ensuring high purity epitaxial growth without the need for solubility-enhancing additives.
4Manufacturing precision
If seed crystal addition and sublimation technique is used, then micropipe defects can be closed, but different polymorphs might be mixed due to high solvent concentration
Solution Approach 1:
The invention changes the phase parameters from liquid melt to vapor phase. By controlling temperature and vapor pressure, the process maintains single polymorph (3C-SiC) growth while closing micropipe defects. The vapor phase parameters prevent the high solvent concentration problems of liquid-phase growth that lead to polymorph mixing.
Solution Approach 2:
The invention replaces the liquid-phase growth mechanism with vapor-phase epitaxy. This substitution eliminates the solvent concentration issues inherent in liquid-phase methods, allowing micropipe closure through controlled vapor deposition while maintaining polymorph purity through precise temperature and pressure 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
The method achieves high-purity SiC epitaxial layers at a faster rate with improved uniformity and versatility, reducing manufacturing costs and enabling efficient production of substrates with various crystalline polymorphisms.
Implementation Method 1
C atoms sublimated by etching of the inner surface of the SiC container are bonded to Si atoms in an atmosphere
Implementation Method 2
the TaC container is heated with a temperature gradient such that inside of the TaC container is at a Si vapor pressure
Data Source
AI summary
Disclosed is a method for using a SiC container (3) in which Si vapor and C vapor are generated in the internal space during the heat treatment. The SiC container may be heated in Si atmosphere to grow an epitaxial layer of single crystalline SiC on the underlying substrate housed in the internal space. The SiC container may be heated in a TaC container of a material including TaC supplemented with a source of Si to grow an epitaxial layer of single crystalline SiC on the underlying substrate housed in the internal space.