Silicon Carbide Substrate with Dual-Layer CVD Structure for Low Loss and Heat Dissipation
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Solution Overview
Problem
Conventional silicon carbide substrates used for high-frequency semiconductor elements face challenges due to high loss in the high-frequency region and inadequate thermal conductivity, making them unsuitable for applications requiring both excellent insulation and heat dissipation.
Innovation Solution
A two-layer silicon carbide substrate structure is developed, where a first layer with higher thermal conductivity and a second layer with reduced high-frequency loss are formed using CVD processes in different atmospheres, with the second layer having a thickness of 10 µm or more accounting for up to 20% of the total substrate thickness, achieving low high-frequency loss and high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a silicon carbide substrate with high thermal conductivity is used, then heat dissipation is improved, but high-frequency loss increases
Solution Approach 1:
The substrate is divided into two distinct layers: a first layer with high thermal conductivity for heat dissipation and a second layer with low high-frequency loss for signal transmission. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between thermal performance and electrical performance.
Solution Approach 2:
The invention uses a composite structure combining two different silicon carbide materials with complementary properties. The first layer uses silicon carbide optimized for thermal conductivity, while the second layer uses silicon carbide optimized for low dielectric loss, creating a composite substrate that achieves both high heat dissipation and low high-frequency loss simultaneously.
2Loss of energy
If a silicon carbide substrate with low high-frequency loss is used, then signal transmission is improved, but thermal conductivity decreases
Solution Approach 1:
The substrate is divided into two distinct layers: a first layer with high thermal conductivity for heat dissipation and a second layer with low high-frequency loss for signal transmission. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between thermal performance and electrical performance.
Solution Approach 2:
The invention uses a composite structure combining two different silicon carbide materials with complementary properties. The first layer uses silicon carbide optimized for thermal conductivity, while the second layer uses silicon carbide optimized for low dielectric loss, creating a composite substrate that achieves both high heat dissipation and low high-frequency loss simultaneously.
3Ease of manufacture
If a single-layer silicon carbide substrate is used, then manufacturing is simplified, but it cannot simultaneously achieve both high thermal conductivity and low high-frequency loss
Solution Approach 1:
The substrate is divided into two distinct layers: a first layer with high thermal conductivity for heat dissipation and a second layer with low high-frequency loss for signal transmission. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between thermal performance and electrical performance.
Solution Approach 2:
The invention uses a composite structure combining two different silicon carbide materials with complementary properties. The first layer uses silicon carbide optimized for thermal conductivity, while the second layer uses silicon carbide optimized for low dielectric loss, creating a composite substrate that achieves both high heat dissipation and low high-frequency loss simultaneously.
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 substrate exhibits low high-frequency loss and excellent heat dissipation characteristics, enabling reliable operation of semiconductor devices and SOI wafers in high-frequency applications with improved insulation and thermal management.
Implementation Method 1
the first layer can be formed by a CVD process in an atmosphere containing nitrogen and the second layer can be formed by the CVD process in an atmosphere containing no nitrogen
Data Source
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AI summary
Disclosed is a silicon carbide substrate which has less high frequency loss and excellent heat dissipating characteristics. The silicon carbide substrate (S) is provided with a first silicon carbide layer (1), which is composed of a polycrystalline silicon carbide, and a second silicon carbide layer (2), which is composed of a polycrystalline silicon carbide formed on the surface of the first silicon carbide layer. The second silicon carbide layer (2) has a high-frequency loss smaller than that of the first silicon carbide layer (1), the first silicon carbide layer (1) has a thermal conductivity higher than that of the second silicon carbide layer (2), and on the surface side of the second silicon carbide layer (2), the high-frequency loss at a frequency of 20 GHz is 2 dB/mm or less, and the thermal conductivity is 200 W/mK or more.