Patterned Interface GaN-on-Silicon Structure for Lower Thermal Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon-based GaN microwave and millimeter-wave devices face high thermal resistance issues due to poor heat dissipation performance, primarily caused by the low thermal conductivity of silicon substrates and large lattice mismatch with GaN, leading to significant self-heating effects and reduced output power.
Innovation Solution
A material structure comprising a silicon substrate, a high thermal conductivity dielectric layer with an uneven patterned interface, a buffer layer, and a composite barrier layer is introduced, which reduces thermal boundary resistances and improves heat dissipation by increasing interface contact areas and reducing compressive stress between lattice layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silicon substrate is used for GaN device fabrication, then cost is reduced and substrate size is increased, but thermal conductivity deteriorates and thermal resistance increases
Solution Approach 1:
The patent introduces a thermal management layer as an intermediary between the silicon substrate and the GaN device. This layer has high thermal conductivity to facilitate heat dissipation from the device to the substrate, effectively bridging the thermal conductivity gap between GaN and silicon while maintaining the cost advantages of silicon substrates.
Solution Approach 2:
The patent employs composite material structures including the thermal management layer combined with the silicon substrate, and potentially multiple layers with different thermal and mechanical properties. This composite approach optimizes both thermal performance and mechanical compatibility, resolving the contradiction between cost-effective silicon substrates and adequate thermal management.
2Productivity
If a silicon substrate is used for GaN device fabrication, then production scalability is improved, but thermal boundary resistance increases and heat dissipation deteriorates
Solution Approach 1:
The thermal management layer serves as a mediator that improves heat dissipation from the GaN device to the silicon substrate without affecting the scalability advantages of using silicon substrates in existing production lines.
Solution Approach 2:
The patent modifies the thermal parameters of the substrate-device interface by introducing the thermal management layer with optimized thermal conductivity. This parameter change enhances heat dissipation while maintaining compatibility with scalable silicon-based manufacturing processes.
3Reliability
If there is a large lattice mismatch between silicon and GaN, then device performance can be maintained, but thermal boundary resistance increases and self-heating effect worsens
Solution Approach 1:
The thermal management layer acts as an intermediary that improves heat dissipation at the silicon-GaN interface without interfering with the lattice mismatch management. This allows the device to maintain performance while reducing the self-heating effect caused by thermal boundary resistance.
4Temperature
If SiC substrate is used for GaN device fabrication, then thermal conductivity is improved and thermal resistance is reduced, but cost increases and substrate size is limited
Solution Approach 1:
The thermal management layer provides a cost-effective solution to achieve thermal conductivity similar to SiC substrates while using inexpensive silicon substrates. This intermediary layer bridges the thermal performance gap without requiring expensive SiC materials.
Solution Approach 2:
The patent uses inexpensive silicon substrates with added thermal management layers as a substitute for expensive SiC substrates. This approach achieves comparable thermal performance at lower cost, making silicon-based GaN devices more economically viable.
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 effectively reduces thermal resistance and enhances heat dissipation performance, improving the maximum output power and efficiency of silicon-based GaN microwave and millimeter-wave devices while maintaining high bonding strength and compatibility with existing production lines.
Implementation Method 1
the thermal conductivity of the silicon substrate is relatively poor, and typically the thermal conductivity of the SiC substrate is 4.0 W/cm·K, while the thermal conductivity of the silicon substrate is only 1.5 W/cm·K
Implementation Method 2
The thermal boundary resistance mainly describes a heat conduction process occurred between material boundaries, and its value is a reciprocal of a thermal boundary conductivity
Data Source
AI summary
A material structure for silicon-based gallium nitride microwave and millimeter-wave devices and a manufacturing method thereof are provided. The material structure includes: a silicon substrate; a dielectric layer of high thermal conductivity, disposed on an upper surface of the silicon substrate, and an uneven first patterned interface being formed between the dielectric layer and the silicon substrate; a buffer layer, disposed on an upper surface of the dielectric layer, and an uneven second patterned interface being formed between the buffer layer and the dielectric layer; a channel layer, disposed on an upper surface of the buffer layer; and a composite barrier layer, disposed on an upper surface of the channel layer. In the material structure, the uneven patterned interfaces increase contact areas of the interfaces, a thermal boundary resistance and a thermal resistance of device are reduced, and a heat dissipation performance of device is improved.