Heat Stable Intermetallic Junction for Semiconductor Devices
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Solution Overview
Problem
Existing methods for joining components, such as brazing and thermocompression bonding, face limitations in stability and durability at high temperatures, with brazing causing chemical degradation and thermocompression bonding leading to gold diffusion that degrades thermoelectric device performance.
Innovation Solution
A strong, heat-stable intermetallic bond formed between indium, tin, or their mixture, and nickel, with specific compositions like InxSn(1-x))3Ni2 or Ni3Sn2, which maintains mechanical integrity and low electrical resistance up to 750°C or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing is used to join components, then the components can be joined together, but chemical degradation occurs due to aggressive chemical interaction and interdiffusion between the braze and thermoelectric materials
Solution Approach 1:
The patent introduces an intermediate diffusion barrier layer between the braze and thermoelectric materials to prevent direct chemical interaction. This barrier layer acts as a mediator that allows the joint to maintain strength while preventing harmful chemical degradation and interdiffusion of components.
Solution Approach 2:
The patent employs a multi-layer composite structure consisting of adhesion layers, diffusion barriers, and fluxes in combination with the braze. This composite approach creates a complex material system where each layer performs a specific function, collectively providing both mechanical strength and chemical stability at the joint.
2Strength
If aluminum-silicon eutectic braze is used, then the components can be joined, but the useful temperature range is limited to about 660° C. due to stability constraints
Solution Approach 1:
The patent changes the compositional parameters of the braze material system by incorporating multiple metal elements in specific proportions. This parameter modification allows the joint to maintain structural integrity and stability at temperatures exceeding 660° C., thereby expanding the usable temperature range for high-temperature applications.
Solution Approach 2:
The patent develops a composite braze material comprising multiple metal elements rather than using a simple eutectic composition. This composite material structure provides enhanced thermal stability and mechanical strength at elevated temperatures, overcoming the temperature limitation of conventional aluminum-silicon eutectic brazes.
3Reliability
If thermocompression bonding with gold layers is used, then low resistance electrical contact is achieved, but gold rapidly diffuses along surfaces and deeply into thermoelectric materials causing performance degradation
Solution Approach 1:
The patent introduces diffusion barrier layers as intermediaries between the gold contact layers and thermoelectric materials. These barrier layers prevent rapid gold diffusion along surfaces and into the bulk material, thereby preserving the electrical contact quality while preventing performance degradation from gold contamination.
Solution Approach 2:
The patent applies diffusion barrier layers in advance before forming the electrical contact, preventing gold diffusion from occurring in the first place. This preliminary protective action ensures that when thermocompression bonding is performed, the gold remains confined to the contact layers without penetrating into the thermoelectric materials.
4Reliability
If multi-layer solutions with adhesion layers, diffusion barriers, and fluxes are used for brazing, then chemical degradation is prevented, but the device complexity increases
Solution Approach 1:
The patent combines multiple functional layers (adhesion layers, diffusion barriers, and fluxes) into an integrated multi-layer structure that works synergistically. By merging these functions into a unified junction design, the patent achieves chemical stability while managing the complexity through systematic integration rather than separate discrete components.
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 provides a stable and strong electrical junction with low resistivity, enhancing the functional stability and mechanical strength of semiconductor devices, outperforming traditional methods in retention of physical strength and performance over time.
Implementation Method 1
a strong, heat stable junction therebetween including an intermetallic bond formed of: substantially (a) indium (In), tin (Sn) or a mixture thereof, and (b) substantially nickel (Ni)
Implementation Method 2
heating the prospective junction which comprises a layer of substantially indium, tin, or a mixture thereof aligned against a layer of substantially nickel to a temperature of about 400° C. or more, thereby forming a strong, heat stable intermetallic bond between the layers
Implementation Method 3
The bond can comprise refractory intermetallic compounds between indium and/or tin and nickel including (InxSn(1-x))3Ni2 or any mixture of In3Ni2, Ni3Sn2 intermetallic phases, for instance. A strong bond obtains for the junction up to a temperature of about 750° C. or more
Data Source
AI summary
Provided among other things is an electrical device comprising: a first component that is a semiconductor or an electrical conductor; a second component that is an electrical conductor; and a strong, heat stable junction there between including an intermetallic bond formed of: substantially (a) tin (Sn) or a mixture of Sn and indium (In) thereof, and (b) substantially nickel (Ni). The junction can have an electrical contact resistance that is small compared to the resistance of the electrical device.