SiC Epitaxial Growth on Low Off-Axis Substrates
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Solution Overview
Problem
Current methods for epitaxially growing SiC layers on single crystal SiC substrates result in significant waste due to the need to slice substrates off-axis, leading to increased costs and higher defect densities as wafer diameters increase.
Innovation Solution
A method involving heating a single-crystal SiC substrate to at least 1400°C at a rate of 30°C/minute with a surface inclined 1° to 3° relative to the basal plane, using a constant flow rate of carrier and precursor gases to epitaxially grow SiC layers, which reduces defect density and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If off-axis substrates are used for epitaxial growth, then defect density is reduced, but substrate waste increases significantly
Solution Approach 1:
The patent changes the off-axis angle parameter from the conventional range (typically >3°) to a specific optimized range of 0.5° to 2°, which maintains the defect reduction benefits while minimizing the waste of single-crystal boule material during slicing
Solution Approach 2:
The patent introduces dynamic control of heating rate (≥30°C/minute) and gas flow rates during epitaxial growth, allowing the process to adapt to the specific off-axis angle and achieve optimal defect reduction with minimal waste
2Manufacturing precision
If heating rate is increased to at least 30°C/minute, then epitaxial growth quality is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary high-rate heating to quickly reach the optimal growth temperature, reducing the total time spent in intermediate temperature zones where defects may form, thereby improving quality while controlling overall energy consumption
3Manufacturing precision
If constant gas flow rate is maintained during growth, then surface roughness is improved, but process complexity increases
Solution Approach 1:
The patent implements feedback control of gas flow rates, where the constant flow rate is maintained through active regulation based on process conditions, ensuring consistent surface quality while using standard equipment capabilities
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 reduces defect density and waste by optimizing growth conditions, achieving low defect counts and improved surface roughness, making the process more cost-effective and efficient.
Implementation Method 1
heating a single-crystal SiC substrate to a first temperature of at least 1400° C.
Implementation Method 2
introducing a carrier gas, a silicon containing gas and carbon containing gas into the chamber
Implementation Method 3
epitaxially growing a layer of SiC on a surface of the SiC substrate
Implementation Method 4
epitaxially growing a layer of SiC on a surface of the SiC substrate
Data Source
AI summary
A method of epitaxially growing a SiC layer on a single crystal SiC substrate is described. The method includes heating a single-crystal SiC substrate to a first temperature of at least 1400° C. in a chamber, introducing a carrier gas, a silicon containing gas and carbon containing gas into the chamber; and epitaxially growing a layer of SiC on a surface of the SiC substrate. The SiC substrate is heated to the first temperature at a rate of at least 30° C./minute. The surface of the SiC substrate is inclined at an angle of from 1° to 3° with respect to a basal plane of the substrate material.