Chromium-Based Diamond Bonding for High Power Density Thermal Management
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Solution Overview
Problem
Current thermal management configurations for wide band gap electronic devices, such as GaN, SiC, and GaAs, face challenges with high thermal barrier resistance due to the difficulty in bonding diamond components, especially at high power densities where temperature changes are significant, limiting device performance and reliability.
Innovation Solution
A chromium-based metallization scheme is introduced, replacing the standard titanium-platinum based scheme, featuring a chromium layer bonded to the diamond heat spreader and a gold layer or other metals for improved bonding, which reduces thermal barrier resistance by minimizing intermetallic compound formation and enhancing phonon compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a three-layer metallization scheme (Ti/Pt/Au) is used for bonding diamond components, then adhesion and mechanical robustness are improved, but thermal barrier resistance increases
Solution Approach 1:
The patent removes the platinum diffusion barrier layer from the traditional Ti/Pt/Au three-layer metallization scheme, reducing it to a two-layer Ti/Au structure. This extraction of the harmful Pt layer eliminates the source of increased thermal resistance while maintaining the necessary adhesion and mechanical properties through the remaining Ti and Au layers.
Solution Approach 2:
The patent employs a composite metallization structure combining Ti and Au layers with specific thicknesses (Ti: 5-50 nm, Au: 50-500 nm). This composite approach leverages the carbide-forming capability of Ti for strong diamond bonding while using Au as a protective and conductive top layer, achieving both mechanical robustness and low thermal barrier resistance.
2Reliability
If conventional cooling techniques are used for wide band gap devices, then device performance is maintained, but thermal management capability is limited at high power densities
Solution Approach 1:
The patent changes the thermal conductivity parameter of the bonding interface by eliminating the Pt layer, which has lower thermal conductivity compared to the Ti-diamond interface. This parameter change in the metallization scheme enables effective heat dissipation at high power densities while maintaining device reliability.
Solution Approach 2:
The patent applies a thin Ti layer (5-50 nm) that forms a Ti carbide bonding layer at the diamond interface before final assembly. This preliminary carbide formation creates a thermally conductive pathway that prepares the interface for high power density operation, preventing thermal accumulation before it occurs.
3Strength
If a thin titanium layer is used to form a carbide bond with diamond, then adhesion is improved, but thermal resistance increases due to interface scattering
Solution Approach 1:
The patent optimizes the Ti layer thickness to a specific range (5-50 nm) that is sufficient to form a strong carbide bonding layer with diamond but thin enough to minimize thermal scattering at the interface. This precise parameter control achieves both strong adhesion and low thermal resistance.
Solution Approach 2:
The patent uses the Ti carbide interface as a model for achieving low thermal barrier resistance, demonstrating that this specific interface structure can be replicated and scaled for various high power density device applications requiring efficient heat dissipation.
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 chromium-based bonding scheme significantly reduces junction temperatures in high power density applications, offering a 25% reduction in channel temperature across devices, with improved thermal conductivity and mechanical robustness, outperforming the standard titanium-platinum bonding solution.
Implementation Method 1
a carbide forming metal layer which forms a carbide bonding to the diamond component
Implementation Method 2
heat transport is a non-trivial physics process, alternating between phonon and electron transport processes with different scattering mechanisms
Implementation Method 3
heat transport is a non-trivial physics process, alternating between phonon and electron transport processes with different scattering mechanisms
Data Source
Figure 1(a)~1(b)
Figure 2(a)~3
Figure 4~5
AI summary
A semiconductor device comprising: a semiconductor component; a diamond heat spreader; and a metal bond, wherein the semiconductor component is bonded to the diamond heat spreader via the metal bond, wherein the metal bond comprises a layer of chromium bonded to the diamond heat spreader and a further metal layer disposed between the layer of chromium and the semiconductor component, and wherein the semiconductor component is configured to operate at an areal power density of at least 1 kW/cm2 and/or a linear power density of at least 1 W/mm.