Composite Substrate with Nitride Barrier for Heat Dissipation
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Solution Overview
Problem
Current semiconductor device fabrication technologies face challenges in heat dissipation due to silicon substrates' low thermal conductivity and dielectric properties, and existing composite substrates suffer from contamination issues and high costs, particularly with sapphire and sintered ceramic bodies.
Innovation Solution
A composite substrate comprising an inorganic insulating sintered body with high heat conductivity and low frequency loss, made from materials like silicon nitride, covered with a thin nitride film to prevent metal impurity contamination, and a single crystal semiconductor film, which is cost-effective and suitable for power and RF devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sapphire substrate is used for heat dissipation and low frequency loss, then heat conductivity and high-frequency performance are improved, but cost increases and optical detection becomes impossible
Solution Approach 1:
The patent replaces expensive sapphire substrates with inexpensive silicon nitride sintered bodies. The silicon nitride substrate, while not as expensive as sapphire, provides sufficient heat conductivity for the application and maintains optical opacity for fabrication process detection, effectively solving the cost issue without sacrificing essential performance
Solution Approach 2:
The patent changes the material parameter from sapphire to silicon nitride sintered body, which has different but sufficient heat conductivity properties. This parameter change allows achieving the required heat dissipation performance while reducing cost and maintaining optical detection capability during fabrication
2Temperature
If sintered ceramic bodies like silicon nitride are used for heat dissipation and optical opacity, then heat conductivity and cost are improved, but metal impurity contamination occurs
Solution Approach 1:
The patent introduces an intermediate layer of single crystal silicon film between the silicon nitride sintered body substrate and the device active layer. This intermediate layer acts as a barrier that prevents metal impurities (Fe, Al) from the sintered body from contaminating the device fabrication process, while still allowing heat to be conducted effectively from the active layer through the silicon film to the substrate
3Temperature
If silicon substrate is thinned for heat dissipation, then heat sump effect is reduced, but manufacturing complexity increases and heat dissipation efficiency remains insufficient
Solution Approach 1:
The patent changes the substrate material parameter from silicon to silicon nitride sintered body, which has inherently higher heat conductivity. This material parameter change eliminates the need for extensive substrate thinning processes, as the silicon nitride substrate itself provides superior heat dissipation capability while maintaining structural integrity and reducing manufacturing complexity
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 solution provides a cost-effective composite substrate with high heat conductivity and low frequency loss, minimizing metal impurity contamination and enabling efficient heat dissipation, suitable for power and RF devices, while being compatible with device fabrication processes.
Implementation Method 1
a first nitride film covering the entire surface of the inorganic insulating sintered body substrate
Implementation Method 2
an inorganic insulating sintered body substrate which is opaque to visible light, has high heat conductivity
Implementation Method 3
a single crystal semiconductor film formed on a surface of the first nitride film
Data Source
Figure 1
AI summary
Disclosed is a composite substrate, which is provided with an inorganic insulating sintered substrate, which has a heat conductivity of 5 W/m·K or more, and a volume resistivity of 1×108 Ω·cm or more, and a single crystal semiconductor film, or a composite substrate, which is provided with the inorganic insulating sintered substrate, a single crystal semiconductor film, and a thin layer configured of at least one kind of material selected from among an oxide, a nitride, and an oxynitride, said thin layer being provided between the inorganic insulating sintered substrate and the single crystal semiconductor film. According to the present invention, a low-cost composite substrate with suppressed metal impurity contamination can be provided using an inorganic insulating sintered body, which is opaque to visible light, and which has excellent heat conductivity, and furthermore, a small loss in a high frequency region.