SiC Single Crystal Dislocation Region Control
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Solution Overview
Problem
Existing SiC single crystals contain various dislocations that affect device characteristics, and there is a lack of techniques to specifically reduce or group dislocations into specific types or Burgers vectors in specific regions, which hinders the improvement of SiC device performance.
Innovation Solution
A SiC single crystal is grown with regions (A) and (B) where edge dislocations and basal plane dislocations with specific Burgers vectors are unevenly distributed, and wafers or substrates are cut to predominantly contain one of these regions, optimizing the cutting direction and size to minimize specific dislocation types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional SiC single crystal growth techniques are used, then overall dislocation reduction is achieved, but specific dislocation types cannot be selectively reduced or grouped in specific regions
Solution Approach 1:
The patent applies local quality by creating specific regions (first region and second region) with different dislocation type distributions within the SiC single crystal. The first region predominantly contains edge dislocations while the second region predominantly contains basal plane dislocations, allowing different areas of the crystal to have tailored dislocation characteristics suitable for different device requirements.
Solution Approach 2:
The patent segments the SiC single crystal into distinct regions with different dislocation characteristics. By dividing the crystal into a first region with edge dislocations and a second region with basal plane dislocations, the patent enables selective use of different dislocation types in different device applications from the same crystal.
2Reliability
If basal plane dislocations are converted to edge dislocations during epitaxial growth, then device characteristics improve, but conversion efficiency is limited when basal plane dislocations have Burgers vectors parallel to offset direction
Solution Approach 1:
The patent creates a specific region (first region) where edge dislocations with Burgers vectors in a direction substantially perpendicular to the offset direction are predominantly distributed. This local arrangement optimizes the conditions for dislocation conversion during epitaxial growth, as edge dislocations with Burgers vectors perpendicular to the offset direction can be more efficiently converted to basal plane dislocations.
3Reliability
If SiC substrate is cut to mainly contain one specific dislocation type region, then device degradation from specific dislocation types is reduced, but overall dislocation density cannot be uniformly minimized
Solution Approach 1:
The patent enables selective cutting of SiC substrates that mainly contain either the first region with edge dislocations or the second region with basal plane dislocations. This allows device manufacturers to choose substrates with dislocation types that are less harmful to their specific device applications, thereby reducing device degradation while accepting non-uniform dislocation distribution.
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 results in SiC devices with reduced degradation due to specific dislocation types, allowing for improved device characteristics and efficient conversion of basal plane dislocations to edge dislocations during epitaxial growth.
Implementation Method 1
A SiC single crystal is grown with regions (A) and (B) where edge dislocations and basal plane dislocations with specific Burgers vectors are unevenly distributed
Data Source
AI summary
A SiC single crystal includes, in a plane substantially parallel to a c-plane thereof, a region (A) in which edge dislocations having a Burgers vector (A) in a specific direction are unevenly distributed, and a region (B) in which basal plane dislocations having a Burgers vector (B) in a specific direction are unevenly distributed. The region (A) is located in a <1-100> direction with respect to a facet portion, while the region (B) is located in a <11-20> direction with respect to the facet portion. A SiC substrate is produced by cutting a SiC wafer from the SiC single crystal in a direction substantially parallel to the c-plane, and cutting the SiC substrate from the SiC wafer such that the SiC substrate mainly contains one of the region (A) and the region (B). A SiC device is fabricated using the SiC substrate.