Silicon Carbide Wafer Off-Angle Optimization
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Solution Overview
Problem
The existing methods for manufacturing silicon carbide single crystal wafers face challenges in maximizing the utilization rate of bulk silicon carbide, maintaining high element characteristics, and ensuring cleavability, particularly due to issues with surface dislocations and defects caused by large off-angles during epitaxial growth.
Innovation Solution
A method involving cutting silicon carbide wafers at an off-angle of 0.1° to 0.4° from the (0001)c plane, followed by surface treatment to remove machining damages, and epitaxial growth using a CVD process within a specific temperature range, ensuring a flat homoepitaxial growth surface with reduced surface roughness and dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If silicon carbide is grown at a temperature of 1700°C or higher, then planarity of the grown surface is improved, but electrical characteristics of the epitaxially grown film deteriorate due to impurities from exhausted members
Solution Approach 1:
The patent changes the growth temperature parameter to a specific range (1500-1700°C) that balances surface planarity and film quality, avoiding both the triangular-pit defects of lower temperatures and the impurity generation of higher temperatures. It also optimizes other parameters including C/Si ratio (0.5-2.0), pressure (10-1000 Pa), and growth rate (1-10 μm/h) to achieve the desired outcome
2Ease of manufacture
If a large off-angle is used during wafer cutting, then cleavability is improved, but utilization rate of bulk single crystal decreases and dislocation density increases
Solution Approach 1:
The patent optimizes the off-angle parameter to a specific range (0.5-5.0 degrees) that provides sufficient cleavability while minimizing the loss of bulk crystal and reducing dislocation density. This optimized angle range represents a compromise that balances manufacturing ease with material utilization efficiency
3Ease of manufacture
If a large off-angle is used during wafer cutting, then cleavability is improved, but surface dislocation density in grown crystal increases causing deterioration of element characteristics
Solution Approach 1:
The patent optimizes the off-angle parameter to a specific range (0.5-5.0 degrees) that provides sufficient cleavability while minimizing the propagation of surface dislocations to the epitaxial layer, thereby maintaining high element characteristics
4Loss of substance
If growth temperature is reduced below 1700°C, then exhaustion of members is reduced, but triangular-pit defects are generated impairing surface planarity
Solution Approach 1:
The patent sets the growth temperature to a specific range (1500-1700°C) that reduces member exhaustion compared to higher temperatures while avoiding the triangular-pit defects that occur at lower temperatures. This optimized temperature range, combined with optimized C/Si ratio and pressure, achieves both reduced material loss and maintained surface 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
This approach enhances the utilization rate of bulk silicon carbide, reduces surface defects, and improves the quality of the epitaxial growth surface, leading to high-quality silicon carbide wafers suitable for electronic and optical devices with improved electrical and optical characteristics.
Implementation Method 1
reacting the silicon source gas and carbon source gas to epitaxially grow the α(hexagonal) silicon carbide single crystal on the wafer
Implementation Method 2
feeding a silicon source gas and carbon source gas in the reaction vessel; and reacting the silicon source gas and carbon source gas
Data Source
AI summary
The invention provides a method for manufacturing the silicon carbide single crystal wafer capable of improving the utilization ratio of the bulk silicon carbide single crystal, capable of improving characteristics of the element and capable of improving cleavability, and the silicon carbide single crystal wafer obtained by the manufacturing method. An α(hexagonal)-silicon carbide single crystal wafer which has a flat homoepitaxial growth surface with a surface roughness of 2 nm or less and which has an off-angle from the (0001)c plane of 0.4° or less.