Epitaxial Wafer Defect Density Reduction via Segmented SiC Growth
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Solution Overview
Problem
Conventional electronic elements fabricated using sapphire or silicon substrates fail to meet performance requirements due to unsatisfactory wafer quality, particularly in silicon carbide-based elements which suffer from high defect densities.
Innovation Solution
An epitaxial wafer is developed with a substrate and epitaxial layers having a first semiconductor layer and a second semiconductor layer, where the second layer is grown at a higher thickness with a surface defect density of 0.1/cm² or less, using materials like 3C-SiC, 4H-SiC, or 6H-SiC, and optimized growth processes to minimize internal and surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional substrates (sapphire or silicon) are used for fabricating electronic elements, then the fabrication process is simple and well-established, but the wafer quality and performance requirements are not satisfied due to high defect densities
Solution Approach 1:
The epitaxial layer is divided into multiple semiconductor layers (first semiconductor layer and second semiconductor layer) with different thicknesses and defect densities. This segmentation allows the lower first layer to serve as a buffer that captures defects, while the upper second layer provides the high-quality region needed for electronic elements, thus resolving the contradiction between achieving high wafer quality and maintaining ease of manufacture
Solution Approach 2:
The first semiconductor layer is grown preliminarily as a buffer layer before growing the second semiconductor layer. This preliminary action allows defects to be generated and captured in the first layer, preventing them from propagating to the second layer, thereby achieving high wafer quality in the final product while using a manageable two-stage fabrication process
2Productivity
If the epitaxial layer is grown quickly to improve productivity, then production efficiency increases, but internal defects and surface defects increase
Solution Approach 1:
The growth process is segmented into two distinct stages: first growing the first semiconductor layer at a speed optimized for defect reduction, then growing the second semiconductor layer at a higher speed. This segmentation allows the system to achieve both low defect density in the critical second layer and high overall productivity by optimizing each stage independently
Solution Approach 2:
The first semiconductor layer is grown preliminarily at a controlled speed to establish a defect-capturing buffer before the high-speed growth of the second layer. This preliminary slow growth phase prepares the substrate to prevent defect propagation, enabling subsequent high-speed growth without compromising quality
3Reliability
If silicon carbide is used to meet performance requirements, then the electronic elements can achieve desired performance, but the wafer quality remains unsatisfactory due to high defect densities
Solution Approach 1:
The silicon carbide epitaxial layer is segmented into multiple layers with different functions: the first layer captures defects generated during growth, while the second layer provides the high-quality silicon carbide region needed for performance-critical electronic elements. This segmentation enables silicon carbide to achieve both its performance advantages and low defect density
Solution Approach 2:
The first semiconductor layer acts as an intermediary buffer between the substrate and the second semiconductor layer. It mediates the defect generation process by capturing defects before they can propagate to the second layer, thereby enabling the second layer to achieve the low defect density required for high-performance silicon carbide electronic elements
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 epitaxial wafer significantly reduces internal and surface defects, enhancing the quality of electronic elements such as power and light-emitting devices by ensuring lower defect densities and improved crystalline structure, thus meeting the performance criteria of silicon carbide-based electronic elements.
Implementation Method 1
an epitaxial layer disposed on the substrate. The epitaxial layer includes: a first semiconductor layer disposed on the substrate; and a second semiconductor layer disposed on the first semiconductor
Data Source
AI summary
An epitaxial wafer includes an epitaxial layer disposed on a substrate. The epitaxial layer includes a first semiconductor layer disposed on the substrate and a second semiconductor layer disposed on the first semiconductor layer and having a thickness that is thicker than that of the first semiconductor layer. A surface defect density of the second semiconductor layer is 0.1/cm2 or less.