SiC Epitaxial Wafer Triangular Defect Control
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Solution Overview
Problem
Current techniques fail to effectively reduce triangular defects in silicon carbide (SiC) epitaxial growth, which can lead to device failures and low chip yield in power semiconductor applications.
Innovation Solution
A SiC epitaxial wafer with a specific density ratio of triangular defects, where the density of defects longer than Tm/Tan θ×0.9 is denoted by A and those shorter is denoted by B, with B/A ≤ 0.5, is achieved by controlling the growth conditions such as C/Si ratio, pressure, temperature, and gas flow to minimize defect generation during epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If step-flow growth is used to maintain crystal polymorph consistency, then crystal orientation is improved, but triangular defects are generated during epitaxial growth
Solution Approach 1:
The patent applies parameter changes by precisely controlling epitaxial growth conditions including temperature (1400-1600°C), pressure (1-100 Torr), C/Si ratio (0.5-2.0), and off-angle (4-8°) to minimize triangular defect formation while maintaining step-flow growth for crystal polymorph consistency
Solution Approach 2:
The patent implements preliminary action by preparing the substrate surface with specific off-angle inclination before epitaxial growth begins, and by establishing controlled growth conditions in advance to prevent triangular defect formation from the outset rather than addressing them after growth
2Manufacturing precision
If foreign matter adhesion is reduced before growth, then initial defect density is improved, but triangular defects from SiC grains during growth are not addressed
Solution Approach 1:
The patent uses the controlled epitaxial growth environment as an intermediary system, where parameters such as C/Si ratio, pressure, and temperature act as mediating factors to suppress SiC grain formation and triangular defect generation during the growth process itself
3Reliability
If epitaxial layer thickness is increased for device performance, then device functionality is improved, but triangular defect density increases
Solution Approach 1:
The patent implements periodic action by controlling the epitaxial growth process in stages with optimized parameters for different thickness ranges, and by using periodic fluctuations in growth conditions to suppress defect accumulation as the layer thickens
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 significantly reduces the density of triangular defects that cause device failures, thereby improving chip yield and reducing the likelihood of current leaks, especially as the film thickness increases beyond 10 μm.
Implementation Method 1
step-flow growth in which a SiC epitaxial layer is grown on the substrate surface
Implementation Method 2
epitaxial growth in a growth furnace
Data Source
AI summary
A SiC substrate (1) has an off angle θ°. A SiC epitaxial layer (2) having a film thickness of Tm μm is provided on the SiC substrate (1). Triangular defects (3) are formed on a surface of the SiC epitaxial layer (2). A density of triangular defects (3) having a length of Tm/Tan θ×0.9 or more in a substrate off direction is denoted by A. A density of triangular (3) defects having a length smaller than Tm/Tan θ×0.9 in the substrate off direction is denoted by B. B/A≤0.5 is satisfied.