SiC Step-Flow Epitaxy Using Carbon Chemical Potential Control
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Solution Overview
Problem
The challenge in producing large-size 4H-SiC epitaxial layers with uniformity and low defect density is exacerbated by high-speed growth processes that lead to step aggregation, and existing methods lack effective guidance for step growth mechanisms, particularly for 150 mm wafers where doping concentration and thickness uniformity are difficult to ensure, resulting in increased costs and lower productivity.
Innovation Solution
A method for SiC step flow growth by regulating growth monomers using chemical potential under non-equilibrium conditions, involving in-situ etching and epitaxial growth in a C-rich environment, where the chemical potential of carbon is controlled within a specific range to achieve rapid growth with reduced dislocations and improved surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed growth process is used to improve productivity, then growth speed is improved, but step aggregation occurs and manufacturing precision deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the chemical potential of carbon within a specific range (μCbulk - 0.5 eV ≤ μC ≤ μCbulk) during epitaxial growth. This parameter control enables the system to achieve high growth speeds while preventing step aggregation and maintaining low defect densities, thereby resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The patent implements dynamics by creating a non-equilibrium growth condition through dynamic control of chemical potential. The system transitions from traditional equilibrium-based growth to a dynamically controlled non-equilibrium state, allowing simultaneous achievement of high growth speed and high uniformity by regulating the chemical potential of carbon during the growth process
2Productivity
If chemical potential of carbon is increased to accelerate growth, then growth speed is improved, but dislocation defects increase
Solution Approach 1:
The patent precisely controls the chemical potential of carbon within a narrow optimal range (μCbulk - 0.5 eV ≤ μC ≤ μCbulk). This parameter optimization allows the system to achieve accelerated growth speed while simultaneously suppressing dislocation defect formation, resolving the contradiction between productivity and reliability
3Productivity
If C/Si ratio is increased to improve growth speed, then productivity is improved, but surface roughness deteriorates
Solution Approach 1:
The patent controls the chemical potential of carbon rather than simply increasing C/Si ratio. This refined parameter control within the range (μCbulk - 0.5 eV ≤ μC ≤ μCbulk) enables high growth speed while maintaining smooth surface morphology, resolving the contradiction between productivity and manufacturing precision regarding surface roughness
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 enables faster epitaxial growth with reduced dislocations, better surface roughness, and efficient doping, achieving a growth speed of 30 μm/hour while preventing step aggregation, thus addressing the challenges of uniformity and productivity in large-size 4H-SiC epitaxy.
Implementation Method 1
Compared to other epitaxy methods, chemical vapor deposition (CVD) involves performing a chemical reaction by introducing a source gas into a reaction chamber, and finally epitaxially growing an SiC layer on a substrate surface
Implementation Method 2
Common SiC epitaxy methods mainly comprise Chemical Vapor Phase Epitaxy (CVPE), Liquid Phase Epitaxy (LPE), Sublimation Epitaxy (PVT), and Molecular Beam Epitaxy (MBE)
Data Source
AI summary
A method for SiC high-speed growth by regulating growth monomers using chemical potential under a non-equilibrium condition. The method uses a C-rich process (Si/H2=0.97‰, C/Si=1.55) to achieve a rapid growth of an epitaxial layer. When a relative chemical potential μC of the C source in a growth atmosphere is high, growth monomers adsorbed in advance are SiC molecules in an epitaxial growth, and a height of a growth step is maintained at 1/2 c or 1 c. A rapid growth of the epitaxial growth is achieved, and a better surface roughness and a lower ionized doping concentration are obtained at the same time.