Composite SiC Substrate Bonding for Lower-Cost Power Devices
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Solution Overview
Problem
The high costs and limited yield of silicon carbide (SiC) power devices due to defects in the crystal growth process and inefficient utilization of low-quality SiC ingots and wafers, which restrict their application in various fields.
Innovation Solution
A composite substrate is created by bonding a high-quality monocrystalline silicon carbide layer with a low-quality silicon carbide layer, utilizing hydrogen ion implantation and annealing to form a defect layer, allowing for the reuse of high-quality ingots and effective utilization of low-quality materials, thereby improving electrical and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monocrystalline silicon carbide ingot is used to prepare a substrate, then the electrical conductivity and thermal conductivity are good, but the cost is high
Solution Approach 1:
The patent uses a composite substrate structure consisting of a monocrystalline silicon carbide layer and a polycrystalline silicon carbide layer. The monocrystalline layer provides good electrical and thermal conductivity where needed, while the polycrystalline layer reduces overall cost. This composite approach allows the substrate to achieve required performance characteristics without using entirely expensive monocrystalline material.
Solution Approach 2:
The patent applies different material qualities to different regions of the substrate. The monocrystalline silicon carbide layer is positioned where high electrical and thermal conductivity is critical, while the polycrystalline silicon carbide layer is used in regions where lower cost is prioritized. This local differentiation optimizes both performance and cost effectiveness.
2Productivity
If a silicon carbide crystal grows using PVT method, then the crystal can be produced, but process condition fluctuation causes large quantity of defects
Solution Approach 1:
The patent takes low-quality silicon carbide material that would normally be discarded due to defects and transforms it into useful polycrystalline silicon carbide for the substrate structure. Instead of wasting defective material, the invention utilizes it in applications where its properties are still adequate, thereby improving overall yield and reducing waste.
Solution Approach 2:
The patent changes the material parameter from monocrystalline to polycrystalline silicon carbide for specific substrate regions. This parameter change allows the use of material with broader process condition tolerances, reducing the impact of process fluctuations and improving overall manufacturing yield.
3Ease of manufacture
If low-quality silicon carbide is utilized, then the cost is reduced, but the electrical conductivity and thermal conductivity deteriorate
Solution Approach 1:
The patent creates a composite substrate combining monocrystalline and polycrystalline silicon carbide layers. This composite structure allows the substrate to achieve cost reduction through polycrystalline material while maintaining adequate electrical and thermal conductivity through the monocrystalline component.
Solution Approach 2:
The patent applies high-quality monocrystalline material locally where electrical and thermal conductivity are critical, while using lower-cost polycrystalline material in other regions. This local quality differentiation ensures that cost reduction does not compromise the conductivity where it matters most.
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 manufacturing costs, enhances the utilization of SiC materials, and improves the efficiency of SiC power devices, making them more viable for applications in fields like aeronautics and energy power generation.
Implementation Method 1
performing hydrogen ion implantation on a monocrystalline silicon carbide ingot from a back surface of the monocrystalline silicon carbide ingot, so that an implanted ion reaches a preset depth and forms a defect layer at the preset depth
Implementation Method 2
performing second annealing treatment on the third composite structure to repair a defect caused by hydrogen ion implantation in the first silicon carbide layer
Data Source
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AI summary
Embodiments of this application relate to the field of semiconductor technologies, and provide a composite substrate, a composite substrate preparation method, a semiconductor device, and an electronic device, to resolve a problem of high costs of SiC power devices due to high costs of SiC substrates. The composite substrate includes a first silicon carbide layer and a second silicon carbide layer. A material of the first silicon carbide layer includes monocrystalline silicon carbide. The second silicon carbide layer is bonded to the first silicon carbide layer. Defect density of at least a part of the second silicon carbide layer is greater than defect density of the first silicon carbide layer.