Silicon Carbide Layer Growth Sequence for Defect Reduction
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Solution Overview
Problem
Existing silicon carbide substrate production methods fail to effectively reduce crystallographic defects, which impede the performance and reliability of silicon carbide semiconductors used in high-demand applications like aerospace and automotive industries, leading to increased costs due to necessary quality control measures.
Innovation Solution
A process involving multiple buffer and epitaxial layer growth stages using specific gas compositions and doping agents to minimize crystallographic defects, resulting in substrates with <1 ppm defects, enhancing the quality and reliability of silicon carbide substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single buffer layer is used in silicon carbide substrate production, then the manufacturing process is simple and cost-effective, but crystallographic defects remain at 1%-10% in the crystalline matrix
Solution Approach 1:
The single buffer layer is segmented into multiple buffer layers (first buffer layer, second buffer layer, third buffer layer) with distinct functions. Each layer addresses specific defect types: the first buffer layer closes dislocations, the second buffer layer eliminates stacking faults, and the third buffer layer prevents polytype inclusions. This segmentation allows systematic reduction of crystallographic defects while maintaining process control.
Solution Approach 2:
Multiple buffer layers are grown before the final epitaxial layer to preliminarily address and close crystallographic defects. The buffer layers perform preliminary defect closure actions (dislocation closure, stacking fault elimination) before the killer defects are formed in the final epitaxial layer, preventing defect propagation to the device-active region.
2Manufacturing precision
If multiple buffer and epitaxial layers are grown in sequence, then crystallographic defects are reduced to <1 ppm, but the manufacturing process complexity increases
Solution Approach 1:
Each buffer and epitaxial layer is assigned specific local quality characteristics: different thicknesses (0.1-10 μm for buffer layers, 1-100 μm for epitaxial layers), different doping concentrations, and different growth conditions. The first buffer layer has optimized parameters for dislocation closure, the second for stacking fault elimination, and the third for polytype inclusion prevention. This local quality differentiation enables precise defect control in each layer while maintaining overall manufacturing feasibility.
3Reliability
If strict quality control and burn-in tests are implemented, then device reliability is ensured, but production costs increase
Solution Approach 1:
The multiple buffer layers perform preliminary defect closure actions during the manufacturing process itself, eliminating killer defects before device fabrication. This preliminary defect elimination reduces or eliminates the need for post-production burn-in tests and quality control measures, thereby reducing production costs and improving productivity while maintaining high device reliability.
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 process significantly reduces crystallographic defects, improving the electrical and mechanical performance of silicon carbide substrates, thereby enhancing the reliability and cost-effectiveness of semiconductor devices.
Implementation Method 1
growing a first buffer layer B1 on a substrate S, growing a first epitaxial layer epi1 above said first buffer layer B1, growing a second buffer layer B2 above said first epitaxial layer epi1, growing a second epitaxial layer epi2 above said second buffer layer B2
Data Source
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AI summary
The present invention describes a process for producing silicon carbide substrates which reduces the crystallographic defects.