Off-Angle SiC Epitaxy Using a PVD Nitride Mediator Layer
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Solution Overview
Problem
The existing methods for manufacturing epitaxial structures on silicon carbide substrates with off-angle silicon faces result in poor epitaxial quality due to the extension of substrate off-angle properties to the group III nitride layers, affecting the performance of components like HEMTs.
Innovation Solution
A method involving the deposition of a nitride angle adjustment layer with a thickness less than 50 nm on the SiC substrate using physical vapor deposition, followed by the growth of a first and second group III nitride layer, improves epitaxial quality by mitigating the off-angle effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aluminum nitride layer is grown on a SiC substrate with off-angle silicon face through MOCVD, then the nucleation layer can be formed, but the off-angle property extends to the nitride layer resulting in poor epitaxial quality
Solution Approach 1:
A thin nitride angle adjustment layer (5-50 nm) is deposited as an intermediary between the SiC substrate and the subsequent nitride layers through PVD. This intermediate layer acts as a mediator that prevents the off-angle property from extending to the epitaxial layers, thereby improving epitaxial quality while maintaining the nucleation function.
Solution Approach 2:
The patent changes the deposition method parameter from MOCVD to PVD for the angle adjustment layer, and controls the thickness parameter to be between 5-50 nm. This parameter change enables the layer to adjust the growth angle and prevent off-angle extension, resolving the contradiction between forming a nucleation layer and maintaining epitaxial quality.
2Ease of manufacture
If a silicon face with off-angle is used as growth face, then the substrate can be prepared, but the off-angle property extends to subsequent layers affecting component performance
Solution Approach 1:
The nitride angle adjustment layer serves as an intermediary that decouples the substrate orientation from the epitaxial layer orientation. It accepts the off-angle substrate and provides a corrected growth interface, allowing easy substrate preparation while achieving precise layer orientation.
Solution Approach 2:
The patent segments the growth process into distinct stages: first depositing the angle adjustment layer through PVD to correct the orientation, then growing the nitride layers through MOCVD. This segmentation allows independent optimization of each stage, maintaining ease of manufacture while achieving manufacturing precision.
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 enhances the epitaxial quality of both the first and second group III nitride layers, as evidenced by reduced RMS roughness and FWHM values, leading to improved performance in electronic components such as HEMTs.
Implementation Method 1
deposit a nitride angle adjustment layer having a thickness less than 50 nm on the growth face of the SiC substrate through physical vapor deposition (PVD)
Data Source
AI summary
A method of manufacturing an epitaxial structure includes steps of: A: provide a silicon carbide (SiC) substrate, wherein a silicon face (Si-face) of the SiC substrate is taken as a growth face having an off-angle relative to the Si-face of the SiC substrate; B: deposit a nitride angle adjustment layer having a thickness less than 50 nm on the growth face of the SiC substrate through physical vapor deposition (PVD); C: deposit a first group III nitride layer on the nitride angle adjustment layer; and D: deposit a second group III nitride layer on the first group III nitride layer. Through the method of manufacturing the epitaxial structure, when the silicon face of the silicon carbide substrate has the off-angle, the problem of a poor epitaxial quality of the first group III nitride layer and a poor epitaxial quality of the second group III nitride layer could be effectively relieved.