Diamond-BeO-GaN Substrate Structure for GaN Heat Dissipation
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Solution Overview
Problem
Gallium nitride (GaN) semiconductor devices face limitations in operational ratings due to excess heat generated during operation, and existing thermal management solutions are inadequate for high-power or high-frequency applications.
Innovation Solution
A semiconductor substrate is manufactured using a single-crystal diamond base layer, a single-crystal beryllium oxide (BeO) layer epitaxially grown over the diamond, and a single-crystal gallium nitride (GaN) layer grown over the BeO layer, enhancing thermal conductivity and reducing heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional substrates are used for GaN semiconductor devices, then manufacturing is simpler, but thermal management capabilities are insufficient leading to heat buildup and limited operational ratings
Solution Approach 1:
The patent employs a composite substrate structure consisting of multiple layers: a diamond base layer providing superior thermal conductivity, a buffer layer for lattice matching, and a GaN active layer. This composite approach combines the thermal management advantages of diamond with the semiconductor functionality of GaN, resolving the contradiction between thermal performance and manufacturing simplicity.
Solution Approach 2:
The substrate is segmented into distinct functional layers: the diamond base layer for thermal management, the buffer layer for crystal structure compatibility, and the GaN layer for semiconductor activity. This segmentation allows each layer to optimize its specific function while collectively solving the thermal management problem without overwhelming complexity.
2Temperature
If diamond base layer is made thinner to improve heat dissipation efficiency, then thermal management improves, but mechanical strength and handling ease deteriorate
Solution Approach 1:
The patent optimizes the diamond base layer thickness to a specific range (50-1100 microns) that balances thermal performance and mechanical strength. This parameter optimization ensures sufficient thermal conductivity while maintaining adequate mechanical integrity for handling and processing, resolving the contradiction between heat dissipation efficiency and mechanical strength.
3Power
If GaN layer is grown thicker to achieve desired device performance, then power rating improves, but defect density increases reducing reliability
Solution Approach 1:
The buffer layer is grown preliminarily on the diamond substrate before depositing the GaN active layer. This preliminary action prepares a crystal structure that promotes low-defect GaN growth, enabling thicker GaN layers to be grown with controlled defect densities, thus achieving higher power ratings while maintaining reliability.
Solution Approach 2:
The composite structure of diamond base layer plus buffer layer creates an optimized growth environment for the GaN layer. The diamond provides thermal management while the buffer layer provides crystal structure compatibility, enabling high-quality thick GaN growth that achieves high power ratings with controlled defect densities.
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 proposed solution effectively increases the thermal management capabilities of GaN semiconductor devices, allowing for higher power ratings and frequency operations while maintaining device reliability and reducing the risk of overheating.
Implementation Method 1
A single-crystal beryllium oxide (BeO) layer is epitaxially grown over the single-crystal diamond base layer
Implementation Method 2
A single-crystal gallium nitride (GaN) layer is epitaxially grown over the BeO layer
Implementation Method 3
One way to dissipate heat is to use highly thermally conductive substrates
Data Source
AI summary
A method for manufacturing a semiconductor substrate. The method provides a single-crystal diamond base layer. The method then forms a beryllium oxide (BeO) layer over the single-crystal diamond base layer. The method then forms a gallium nitride (GaN) layer over the BeO layer. In some embodiments, the method forms surfactants over the single-crystal diamond base layer and the BeO layer.