Thermoelectric Interconnection Layer for Silicon-Based Devices
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Solution Overview
Problem
Existing thermoelectric devices based on silicon containing materials face instability and performance degradation due to metal diffusion and thermal stress at high temperatures, leading to limited operational lifetime and reduced conductivity.
Innovation Solution
A thermoelectric conversion device with an interconnection layer composed of a recrystallized phase of silicon, silicon composites, or metal-silicide elements and a selected interconnection metal that does not form silicides, melts below the thermoelectric elements' melting point, dissolves components, and solidifies with low solubility, creating a chemically inert and conductive interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a direct silicon containing material-metal interconnection is used, then the device structure is simple and manufacturing is easy, but metal diffusion into the thermoelectric material and silicon reaction with the metal interconnection form brittle metal silicides, degrading electrical properties and mechanical stability
Solution Approach 1:
An interconnection layer comprising a recrystallized material phase consisting of constituents of the silicon containing material is introduced between the silicon containing thermoelectric material and the metal interconnection. This intermediate layer acts as a diffusion barrier, preventing metal atoms from penetrating into the thermoelectric material and blocking silicon from reacting with the metal to form brittle silicides, thereby maintaining electrical properties and mechanical stability during high temperature operation.
2Temperature
If high temperature resistant metals such as nickel or copper are used for electrical interconnection, then the interconnection can withstand high operating temperatures, but these metals diffuse into the thermoelectric material and form brittle metal silicides, causing performance degradation
Solution Approach 1:
The recrystallized material phase layer serves as a protective intermediary that allows the use of high temperature resistant metals like nickel or copper for electrical interconnection while preventing these metals from diffusing into the thermoelectric material. The layer maintains the temperature resistance capability of the metal interconnection while preserving the electrical properties of the thermoelectric material by blocking diffusion pathways.
3Reliability
If silicon containing material-metal interconnects are used, then the interconnection provides good electrical conductivity, but differences in thermal expansion coefficient lead to thermal stress and crack formation during operation
Solution Approach 1:
The interconnection structure employs different materials with different functions in different locations: the recrystallized material phase layer (consisting of silicon containing constituents) provides thermal expansion matching and stress relief at the interface with the thermoelectric material, while the metal interconnection layer provides electrical conductivity. This local differentiation of material properties allows simultaneous achievement of good electrical conductivity and mechanical stability under thermal cycling.
4Reliability
If the interconnection layer uses a recrystallized phase of silicon containing material and interconnection metal, then chemical inertness and low electrical resistance are achieved, but the manufacturing process complexity increases
Solution Approach 1:
The interconnection layer merges two functional components into a single integrated structure: the recrystallized material phase providing chemical inertness and thermal expansion matching, and the interconnection metal providing electrical conductivity. This merged structure achieves multiple functions (chemical stability, thermal stress relief, and electrical conduction) simultaneously, reducing the need for separate functional layers and simplifying the overall device architecture despite the sophisticated material design.
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, low-resistance, and mechanically robust interconnection that maintains performance under high temperatures, overcoming the limitations of previous technologies by ensuring chemical inertness and high conductivity while minimizing mechanical strength reduction.
Implementation Method 1
In the molten state the interconnection metal will dissolve at least one of the components of the thermoelectric elements, preferably the silicon element, or all components of the thermoelectric elements in the composition as exists in the elements
Implementation Method 2
the interconnection metal will melt at a temperature below the melting point of any of the first or second thermoelectric elements
Implementation Method 3
As the voltage generated by the Seebeck effect over one thermoelectric element in such a thermoelectric conversion device is typically in the order of 100 mV
Data Source
AI summary
A thermoelectric device includes active elements containing thermoelectric materials of silicon, an alloy of silicon, a metal-silicide or silicon composite and an interconnection zone consisting of a metal interconnect and a re-crystallized phase consisting of material from the active thermoelectric elements. The metal interconnect is from a metal that does not form metal silicides in a solid state, has a certain solubility for components of the thermoelectric elements in the liquid phase and a low solubility of these components in the solid phase. The active thermoelectric elements are shaped with a first and a second contact interface. The interconnection between the different thermoelectric elements consists of at least two phases of material, one of which is mainly the metallic interconnection material, the other is formed by the re-crystallized components of the thermoelectric materials.