GaN-on-Handle Substrate Thermal Management via Wafer Bonding
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Solution Overview
Problem
Current methods for fabricating gallium nitride (GaN) on-insulator substrates face challenges in achieving high-quality, thermally conductive substrates with matched thermal expansion coefficients, leading to inefficiencies in device processing and performance.
Innovation Solution
A method involving wafer-bonded gallium and nitrogen containing materials with a handle substrate and adhesion layers, where the gallium and nitrogen containing region has a coefficient of thermal expansion similar to the handle substrate, allowing for epitaxial growth and optimized device design, including a core region and interface regions for improved thermal management and device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sapphire substrates are used for GaN-on-insulator fabrication, then substrate availability and ease of handling are improved, but thermal conductivity and thermal expansion matching deteriorate
Solution Approach 1:
The patent introduces an intermediate handle substrate layer between the GaN layer and the final application. This handle substrate serves as a mediator that provides mechanical support and handling ease while allowing for subsequent removal or replacement with a thermally optimized substrate, thus decoupling the handling requirements from the thermal performance requirements
Solution Approach 2:
The substrate structure is segmented into multiple functional layers: a handle substrate for handling, an insulator layer for electrical isolation, and a GaN layer for device functionality. This segmentation allows each layer to be optimized independently for its specific function, with the handle substrate optimized for handling and the GaN layer optimized for thermal and electrical performance
2Ease of manufacture
If standard silicon substrates are used, then cost and availability are improved, but thermal expansion mismatch and processing compatibility deteriorate
Solution Approach 1:
The patent changes the thermal and mechanical parameters of the substrate system by introducing a handle substrate with specific thermal expansion properties that better match GaN. This parameter optimization allows for reduced thermal stress and improved device reliability while maintaining manufacturing feasibility
3Adaptability or versatility
If transferred GaN layers are used, then substrate flexibility is improved, but crystalline quality and dislocation density deteriorate
Solution Approach 1:
The patent performs preliminary actions by growing the GaN layer on a carefully selected handle substrate with matched thermal and mechanical properties before transfer. This preliminary optimization of the growth substrate reduces the introduction of dislocations and maintains higher crystalline quality throughout the subsequent processing and transfer steps
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 approach results in high-quality GaN substrates and devices with enhanced thermal conductivity and reduced dislocation density, improving the efficiency and manufacturability of optoelectronic devices like LEDs, while optimizing thermal expansion matching for better device performance.
Implementation Method 1
wafer-bonded gallium and nitrogen containing materials with a handle substrate and adhesion layers
Implementation Method 2
The gallium and nitrogen containing region is characterized by a second coefficient of thermal expansion parallel to the surface. The second coefficient of thermal expansion is substantially similar to the first coefficient of thermal expansion.
Implementation Method 3
improving the efficiency and manufacturability of optoelectronic devices like LEDs, while optimizing thermal expansion matching for better device performance
Implementation Method 4
at least one p-type region formed epitaxially overlying the active region
Data Source
AI summary
A gallium and nitrogen containing substrate structure includes a handle substrate member having a first surface and a second surface and a transferred thickness of gallium and nitrogen material. The structure has a gallium and nitrogen containing active region grown overlying the transferred thickness and a recessed region formed within a portion of the handle substrate member. The substrate structure has a conductive material formed within the recessed region configured to transfer thermal energy from at least the transferred thickness of gallium and nitrogen material.