Graphene-Assisted SiC Substrate Fabrication Without Bonding Defects
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Solution Overview
Problem
The conventional method of bonding a single-crystal SiC semiconductor substrate to a polycrystal SiC substrate for forming SiC semiconductor substrates is costly due to the need for a polishing process to ensure surface roughness and often results in film defects at the bonding interface, leading to decreased yield.
Innovation Solution
A semiconductor substrate and fabrication method involving the formation of a graphene layer on an SiC single crystal substrate, followed by an SiC epitaxial growth layer, and a polycrystalline layer, where the SiC single crystal substrate is reused by removing it from the epitaxial growth layer, allowing for direct epitaxial growth on a provisional substrate without the need for substrate bonding, thus avoiding costly polishing processes and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-crystal SiC substrate is bonded to a polycrystal SiC substrate to form SiC semiconductor substrates, then the substrate can be formed with required structural properties, but the process becomes costly due to polishing requirements and substrate bonding defects occur
Solution Approach 1:
The invention extracts and removes the single-crystal SiC substrate after the epitaxial growth layer is formed on it. By using the single-crystal substrate only as a temporary support for high-quality epitaxial growth, then removing and reusing it, the method avoids the need for costly bonding processes while eliminating the source of bonding defects. The provisional substrate serves only as a temporary carrier during fabrication.
Solution Approach 2:
The invention performs preliminary epitaxial growth on the single-crystal SiC substrate before removing it. The high-quality crystalline structure is established in advance on the single-crystal substrate, which then serves as a template for subsequent transfer to the provisional substrate. This preliminary action ensures high substrate quality without requiring final bonding operations.
2Reliability
If substrate bonding is performed to form SiC semiconductor substrates, then the required substrate structure is achieved, but film defects occur at the bonding interface leading to decreased yield
Solution Approach 1:
The invention removes the single-crystal SiC substrate after completing the epitaxial growth, eliminating the bonding interface that causes film defects. By extracting the potential defect source (the bonding interface between single-crystal and polycrystal substrates), the method achieves high substrate structure integrity without compromising production yield.
Solution Approach 2:
The invention uses a provisional substrate as an intermediary carrier. The epitaxial growth layer is first formed on the single-crystal substrate, then transferred to the provisional substrate which serves as the final support. This intermediary approach allows the high-quality growth to occur on a perfect single-crystal surface while the final substrate can be a more practical polycrystal or semi-insulating material.
3Manufacturing precision
If polishing processes are applied to ensure surface roughness for substrate bonding, then bonding quality improves, but manufacturing costs increase
Solution Approach 1:
The invention removes the need for polishing processes by eliminating the substrate bonding step entirely. Since the single-crystal substrate is removed after epitaxial growth and not bonded to the final substrate, the costly polishing operations required to achieve precise surface roughness for bonding become unnecessary, significantly reducing manufacturing costs while maintaining high manufacturing precision through the epitaxial growth process itself.
4Reliability
If conventional substrate bonding methods are used, then SiC semiconductor substrates can be formed, but the process complexity increases due to multiple processing steps
Solution Approach 1:
The invention simplifies the device fabrication process by removing the substrate bonding step. The single-crystal SiC substrate is used only temporarily for epitaxial growth and then extracted, eliminating the need for subsequent bonding operations, surface preparation, and interface treatment steps. This reduces processing steps while maintaining reliable substrate formation through the epitaxial growth and transfer 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 reduces costs and improves yield by simplifying the processing steps, eliminating substrate bonding defects, and enabling high-throughput production of high-quality SiC semiconductor substrates with reduced crystallinity degradation.
Implementation Method 1
a method of forming an SiC epitaxial growth layer by a Chemical Vapor Deposition (CVD) method on an SiC single crystal substrate
Implementation Method 2
a method of forming an SiC wafer by a sublimation method
Data Source
AI summary
A semiconductor substrate (1) disclosed herein includes: an SiC single crystal substrate (10SB); a graphene layer (11GR) disposed on an Si plane of the SiC single crystal substrate (10SB); an SiC epitaxial growth layer (12RE) disposed above the SiC single crystal substrate (10SB) via the graphene layer (11GR); and a polycrystalline Si layer (15PS) disposed on an Si plane of the SiC epitaxial growth layer (12RE). The semiconductor substrate may include a graphite substrate or an silicon substrate disposed on a polycrystalline Si layer (15PS). The semiconductor substrate may further include an SiC polycrystalline growth layer (18PC) disposed on a C plane of the SiC epitaxial growth layer (12RE). Consequently, the present disclosure provides a low-cost and high-quality semiconductor substrate and a fabrication method thereof.