SiC Epitaxial Wafer Doping Uniformity for Reliable Power Devices
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Solution Overview
Problem
Existing SiC epitaxial wafers face issues with poor in-plane uniformity of n-type doping concentration in high concentration layers, leading to potential device reliability concerns due to basal plane dislocation expansion and stacking faults.
Innovation Solution
The development of 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, achieved through precise control of C/Si ratio and independent adjustment of C-based and Si-based gas supply positions during chemical vapor deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high concentration layer with n-type doping concentration of 1×10^18/cm^3 to 1×10^19/cm^3 is formed, then device reliability is improved by inhibiting basal plane dislocation expansion, but in-plane uniformity of doping concentration deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the C/Si ratio within 1.05 to 1.35 and adjusting gas supply positions independently. This resolves the contradiction by optimizing deposition parameters to achieve both high doping concentration (1×10^18 to 1×10^19/cm^3) and acceptable in-plane uniformity (30% or less), thereby improving device reliability while maintaining manufacturing precision
Solution Approach 2:
The patent applies local quality by independently adjusting the gas supply positions for C-based and Si-based gases. This allows different regions of the substrate to receive optimized gas distribution, achieving uniform doping concentration across the wafer surface while maintaining the required high concentration level to prevent basal plane dislocation expansion
2Manufacturing precision
If C/Si ratio is controlled within 1.05 to 1.35, then in-plane uniformity of doping concentration is improved to 30% or less, but manufacturing complexity increases due to precise gas supply control
Solution Approach 1:
The patent applies segmentation by separating the gas supply control into independent C-based gas supply and Si-based gas supply systems. This allows precise control of the C/Si ratio through independent adjustment of each gas flow, achieving the required in-plane uniformity (30% or less) while managing the complexity through modular control architecture
Solution Approach 2:
The patent implements feedback control by monitoring the doping concentration uniformity and adjusting gas supply parameters accordingly. The C/Si ratio is controlled within 1.05 to 1.35 based on feedback from process monitoring, ensuring in-plane uniformity of 30% or less while adapting to variations in the deposition process
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 a SiC epitaxial wafer with improved in-plane uniformity of n-type doping concentration, inhibiting basal plane dislocation expansion and enhancing device reliability, particularly for large-current power devices.
Implementation Method 1
The epitaxial layer is formed by a chemical vapor deposition (CVD) method or the like
Implementation Method 2
The SiC substrate is obtained by processing a bulk single crystal of SiC grown by a sublimation recrystallization method
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.