Semiconductor Substrate with Amorphous Buffer for Diamond Adhesion
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Solution Overview
Problem
The formation of a diamond layer on a nitride semiconductor layer often results in damage to the nitride semiconductor layer and weak adhesion between the layers, leading to potential cracking and low electrical conductivity, especially as the nitride semiconductor layer thickness increases.
Innovation Solution
A semiconductor substrate is designed with a nitride semiconductor layer, an amorphous semiconductor layer, a high-roughness layer with increased surface roughness, and a diamond layer, where the amorphous semiconductor layer and high-roughness layer act as intermediates to reduce damage and enhance adhesion, using materials like amorphous silicon and microcrystalline silicon to manage thermal expansion and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diamond layer is formed directly on nitride semiconductor layer, then heat dissipation performance is improved, but damage to nitride semiconductor layer occurs and adhesion is weak
Solution Approach 1:
An amorphous semiconductor layer is introduced as an intermediary between the nitride semiconductor layer and the diamond layer. This intermediate layer acts as a buffer that reduces thermal stress and mechanical damage during diamond layer formation, while also improving adhesion between the two layers. The amorphous layer absorbs stress and prevents direct contact between the hard diamond and the brittle nitride semiconductor, thereby protecting the underlying structure.
Solution Approach 2:
The interface between nitride semiconductor layer and diamond layer is segmented by introducing the amorphous semiconductor layer. This segmentation divides the direct interface into two separate interfaces (nitride-amorphous and amorphous-diamond), allowing each interface to be optimized independently and reducing the overall stress concentration at the boundary.
2Reliability
If nitride semiconductor layer thickness is increased, then electrical conductivity is improved, but crack occurrence increases
Solution Approach 1:
The amorphous semiconductor layer serves as a stress-absorbing intermediary that prevents crack propagation in thick nitride semiconductor layers. When the nitride layer becomes thick and prone to cracking, the amorphous layer acts as a compliant buffer that absorbs thermal expansion differences and mechanical stresses, preventing crack formation and allowing the nitride layer to achieve the necessary thickness for high electrical conductivity.
Solution Approach 2:
The introduction of the amorphous semiconductor layer changes the physical and mechanical parameters at the interface, including stress distribution, thermal expansion matching, and adhesion strength. These parameter changes enable the nitride semiconductor layer to be grown to greater thicknesses without cracking, thereby achieving the electrical conductivity required for high-power applications.
3Strength
If relaxation layer is used to reduce crack, then crack occurrence is reduced, but adhesion between nitride semiconductor layer and diamond layer becomes weak
Solution Approach 1:
The amorphous semiconductor layer functions as both a relaxation layer and an adhesion promoter simultaneously. It relaxes stress to prevent cracking while its amorphous structure and chemical composition enable strong bonding to both the nitride semiconductor layer below and the diamond layer above, thus maintaining adhesion while reducing cracks.
Solution Approach 2:
The structure forms a composite material system where the amorphous semiconductor layer combines the stress-relief properties of a relaxation layer with the adhesion properties of an interface layer. This composite approach allows the system to achieve both crack reduction and strong interlayer adhesion that cannot be achieved with a single-material relaxation layer.
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 configuration significantly reduces damage to the nitride semiconductor layer and enhances adhesion to the diamond layer, allowing for improved heat dissipation and higher power density applications while maintaining structural integrity.
Implementation Method 1
using materials like amorphous silicon and microcrystalline silicon to manage thermal expansion and surface roughness
Implementation Method 2
a high-roughness layer which is a semiconductor layer formed on the amorphous semiconductor layer and has a surface roughness larger than the amorphous semiconductor layer
Implementation Method 3
Since diamond has extremely high heat conductivity, a field-effect transistor provided on diamond is capable of a high-power operation
Data Source
AI summary
A semiconductor substrate according to the present invention includes a nitride semiconductor layer 203, an amorphous semiconductor layer 205 formed on one main surface side of the nitride semiconductor layer 203, a high-roughness layer 206 which is a semiconductor layer formed on the amorphous semiconductor layer 205 and has a surface roughness larger than the amorphous semiconductor layer 205, and a diamond layer 207 formed on the high-roughness layer 206. Damage to the nitride semiconductor layer can be reduced in forming the diamond layer on the nitride semiconductor layer and adhesion between the layers can be increased.