4H-SiC Semiconductor Substrate Bonding for Low-Defect Ohmic Contact
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Solution Overview
Problem
The production process of semiconductor substrates is complex and costly due to the need for high-quality 4H-SiC wafers, which often result in poor ohmic contact characteristics between the 4H-SiC layer and the base material, primarily due to lattice mismatch and heterojunctions.
Innovation Solution
A semiconductor substrate is created using a monocrystalline silicon carbide base with a lower quality indicator than the 4H-SiC layer, both materials being 4H-SiC, to minimize material differences and heterojunctions, with N-type doping and plasma bombardment processing to improve ohmic contact characteristics without additional surface processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-quality 4H-SiC wafers are used, then the quality of the semiconductor substrate is improved, but the cost increases and the yield decreases
Solution Approach 1:
The patent divides the semiconductor substrate into two distinct parts: a base layer and a 4H-SiC layer. The base layer can be made of lower-quality, lower-cost material while the 4H-SiC layer provides the necessary high-quality surface. This segmentation allows different quality standards for different functional regions, improving overall yield while maintaining device performance.
Solution Approach 2:
The patent applies local quality by requiring high-quality 4H-SiC only at the surface layer where the semiconductor device is actually fabricated, while the base layer can tolerate lower quality. This localized quality requirement reduces the overall cost and increases yield without compromising the critical device performance areas.
2Ease of manufacture
If a base with different material is used to reduce costs, then the cost of the semiconductor substrate is reduced, but the ohmic contact characteristic deteriorates due to lattice mismatch
Solution Approach 1:
The patent changes the material parameter of the base layer to match the 4H-SiC layer, specifically using silicon carbide for both layers. This parameter matching eliminates lattice mismatch and ensures good ohmic contact characteristics while still allowing cost reduction through selective use of high-quality material only where necessary.
3Reliability
If N-type doping is performed on both surfaces to improve ohmic contact, then the ohmic contact characteristic is improved, but the production process becomes complex
Solution Approach 1:
The patent extracts the need for complex surface doping processes by ensuring material compatibility at the interface through proper material selection. By using silicon carbide for both the base and 4H-SiC layers, the interface naturally provides good ohmic contact without requiring additional N-type doping steps, thereby simplifying the production 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 simplifies the production process, reduces costs, and ensures effective ohmic contact characteristics by reducing heterojunctions and improving conductive performance, allowing for the use of lower-quality 4H-SiC materials while maintaining high-quality 4H-SiC performance.
Implementation Method 1
A semiconductor substrate is created using a monocrystalline silicon carbide base with a lower quality indicator than the 4H-SiC layer, both materials being 4H-SiC, to minimize material differences and heterojunctions
Implementation Method 2
N-type doping is performed on both the surface that is of the base and that is used for binding and the surface that is of the 4H-SiC layer and that is used for binding, to improve the ohmic contact characteristic of the binding surface
Implementation Method 3
plasma bombardment processing to improve ohmic contact characteristics
Data Source
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AI summary
A semiconductor substrate (10), a production method thereof, and a semiconductor device are provided, and belong to the field of semiconductor technologies. The semiconductor substrate (10) includes a monocrystalline silicon carbide base (101) and a monocrystalline silicon carbide layer (102) stacked on a side of the monocrystalline silicon carbide base (101). A quality indicator of the monocrystalline silicon carbide base (101) is lower than a quality indicator of the monocrystalline silicon carbide layer (102). In the production method for the semiconductor substrate (10), a probability that a heterojunction occurs on a binding surface is reduced, and an ohmic contact characteristic between the monocrystalline silicon carbide base (101) and the monocrystalline silicon carbide layer (102) can be ensured without a need to perform additional processing on the binding surface in a production process, so that the production process of the semiconductor substrate (10) is simplified. The production method is used to produce the semiconductor substrate (10) and the semiconductor device.