SiC Epitaxial Wafer CVD Control for Uniform High N-Type Doping
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Solution Overview
Problem
SiC epitaxial wafers with high in-plane uniformity of n-type doping concentration in high concentration layers are challenging to produce, leading to poor carrier recombination effects and defects due to non-uniform doping concentrations.
Innovation Solution
A SiC epitaxial wafer with a high concentration layer having an average doping concentration of 1×10^18/cm^3 to 1×10^19/cm^3 and in-plane uniformity of 30% or less is manufactured using a chemical vapor deposition method, with adjustable C-based and Si-based gas supply pipes to achieve a C/Si ratio of 1.1 to 1.7, ensuring uniform doping distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high concentration layer with high n-type doping concentration is formed to improve carrier recombination effect, then the carrier recombination effect is enhanced, but the in-plane uniformity of doping concentration deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the C/Si ratio in the chemical vapor deposition process to a specific range (1.05 ≤ C/Si ratio < 1.20) and controlling the doping concentration within a defined range (1×10^18/cm³ to 1×10^19/cm³). These parameter adjustments enable simultaneous achievement of high carrier recombination effect and improved in-plane uniformity of doping concentration, resolving the technical contradiction between enhancing carrier recombination and maintaining doping uniformity.
2Reliability
If the doping concentration is increased to improve carrier recombination, then the carrier recombination effect is enhanced, but defects due to non-uniform doping concentration occur
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the C/Si ratio parameter within the range of 1.05 ≤ C/Si ratio < 1.20 during chemical vapor deposition. This parameter optimization ensures that high doping concentrations (1×10^18/cm³ to 1×10^19/cm³) are achieved uniformly across the wafer surface, thereby enhancing carrier recombination effect while preventing defects caused by non-uniform doping distribution.
3Ease of manufacture
If chemical vapor deposition is used to form the epitaxial layer, then the epitaxial growth is achieved, but the in-plane uniformity of high concentration layer doping deteriorates
Solution Approach 1:
The patent addresses this contradiction by optimizing the C/Si ratio parameter specifically for high concentration layer formation in chemical vapor deposition. By maintaining the C/Si ratio within 1.05 ≤ C/Si ratio < 1.20 and controlling the doping concentration at 1×10^18/cm³ to 1×10^19/cm³, the process achieves both ease of epitaxial growth and high in-plane uniformity of doping concentration in the high concentration layer.
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
The method achieves high in-plane uniformity of the n-type doping concentration, preventing carrier recombination defects and enhancing the quality of the SiC epitaxial wafer by maintaining a uniform doping concentration across the wafer surface.
Implementation Method 1
The epitaxial layer is formed by a chemical vapor deposition (CVD) method or the like
Implementation Method 2
forming a film by epitaxial growth on a SiC single crystal substrate in the chemical vapor deposition device
Data Source
AI summary
A SiC epitaxial wafer of the present invention includes a SiC single crystal substrate, and a high concentration layer that is provided on the SiC single crystal substrate and has an average value of an n-type doping concentration of 1×1018/cm3 or more and 1×1019/cm3 or less, and in-plane uniformity of the doping concentration of 30% or less.