SiC Substrate Transfer Using Graphene for Low-Defect Epitaxy
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Solution Overview
Problem
The development of silicon carbide (SiC) semiconductor substrates for power devices faces challenges in achieving high-quality epitaxial growth and efficient manufacturing processes, particularly in forming low-defect graphene layers and SiC epitaxial layers with minimal substrate adhesion and defects, while maintaining cost-effectiveness and reusability of the SiC monocrystalline substrate.
Innovation Solution
A method involving thermal surface etching and decomposition using silicon fluoride gases to form high-quality graphene layers on SiC monocrystalline substrates, followed by van der Waals epitaxial growth of SiC layers with a stress layer and temporary graphite substrate for easy separation and reuse, reducing manufacturing costs and defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal surface etching and decomposition using silicon fluoride gases is employed to form graphene layers, then the quality of graphene layers and SiC epitaxial layers is improved with reduced defects, but the process complexity and manufacturing steps increase
Solution Approach 1:
A temporary graphite substrate is introduced as an intermediary carrier to support the SiC epitaxial layer during manufacturing. This mediator enables easy separation and transfer of the epitaxial layer to the final SiC monocrystalline substrate, reducing defects and improving quality while managing process complexity through a dedicated intermediate step
Solution Approach 2:
The manufacturing process is segmented into distinct stages: forming graphene layers on the SiC substrate, growing SiC epitaxial layers on a separate temporary graphite substrate, and then transferring the epitaxial layer to the final substrate. This segmentation allows each step to be optimized independently, improving overall quality
2Ease of repair
If van der Waals epitaxial growth is used to form SiC layers on temporary graphite substrate, then substrate reusability is improved and manufacturing costs are reduced, but the epitaxial growth process requires precise control conditions
Solution Approach 1:
The temporary graphite substrate is discarded after transferring the SiC epitaxial layer to the SiC monocrystalline substrate, while the SiC substrate itself is recovered and reused for subsequent epitaxial growth cycles. This approach improves substrate reusability and reduces manufacturing costs by eliminating the need to replace expensive SiC substrates
Solution Approach 2:
The temporary graphite substrate serves as a mediator that facilitates epitaxial growth under optimized conditions without requiring the expensive SiC substrate to be directly reused in each growth cycle, thereby protecting the valuable SiC substrate while enabling its recovery and reuse
3Manufacturing precision
If multiple layers are formed including stress layer and temporary graphite substrate, then defect reduction and substrate separation are improved, but the number of manufacturing steps and time increase
Solution Approach 1:
The structure is segmented into multiple functional layers (graphene layer, SiC epitaxial layer, stress layer, and temporary graphite substrate) that can be grown and processed separately, then assembled. This segmentation improves defect reduction by allowing each layer to be optimized independently, though it increases manufacturing time
4Ease of manufacture
If room temperature bonding or diffusion bonding is used to bond monocrystalline SiC to polycrystalline SiC, then manufacturing costs are reduced, but the bonding quality and reliability may be compromised
Solution Approach 1:
A graphene layer is introduced as an intermediary bonding interface between the SiC epitaxial layer and the SiC monocrystalline substrate. This mediator enables bonding at reduced temperatures while maintaining reliability, as the graphene layer facilitates atomic-level contact and bonding between the SiC layers without requiring high-temperature diffusion bonding
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 enables the formation of high-quality SiC epitaxial layers with reduced defects and improved substrate reusability, enhancing the efficiency and cost-effectiveness of SiC semiconductor substrate production.
Implementation Method 1
thermal surface etching and decomposition using silicon fluoride gases to form high-quality graphene layers on SiC monocrystalline substrates
Implementation Method 2
van der Waals epitaxial growth of SiC layers
Data Source
AI summary
The present disclosure provides a method of manufacturing a semiconductor substrate. The method includes: forming a graphene layer on a silicon plane of a silicon carbide monocrystalline substrate; forming a SiC epitaxial growth layer on the graphene layer; forming a stress layer on the SiC epitaxial growth layer; attaching a temporary substrate onto the stress layer; peeling off the graphene layer from the SiC epitaxial growth layer; forming a SiC polycrystalline growth layer on a carbon plane of the SiC epitaxial growth layer from which the graphene layer has been peeled off; and removing the temporary substrate. At least one of the forming of the graphene layer and the forming of the SiC epitaxial growth layer is under an atmosphere including fluorine.