Bivalve Thermoelectric Generator With Flip-Chip Bonding
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Solution Overview
Problem
Existing thermoelectric generators (TEGs) with out-of-plane heat flux configurations suffer from poor electric power yield and efficiency due to thermal losses and mechanical fragilities, particularly in devices with orthogonal heat flow structures, which limits their integration in microelectronic and optoelectronic applications.
Innovation Solution
A novel out-of-plane Z-device structure with a bivalve configuration is introduced, featuring hill-top and valley-bottom junction metal contacts with reduced thermal conduction paths and internal void spaces, optimized by flip-chip bonding of mirror-like Z-device structures on silicon wafers, which enhances thermal and electrical continuity while minimizing heat bypass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If out-of-plane heat flux configuration is used in TEGs, then thermal losses are reduced, but mechanical fragility increases and manufacturing complexity increases
Solution Approach 1:
The device is divided into two separate Z-device structures (first and second) that are bonded together in a flip-chip configuration. Each structure contains thermoelectric legs arranged in series strings, and the segmentation allows the structures to be manufactured separately on silicon wafers and then joined, reducing mechanical fragility while maintaining the out-of-plane heat flux configuration that minimizes thermal losses
Solution Approach 2:
The patent employs a nested structure where multiple series strings of thermoelectric legs are integrated within each Z-device structure, and these nested structures are then bonded together. The series strings are nested within the Z-device geometry, and the two Z-device structures are nested in a flip-chip arrangement, creating a compact integrated device that maintains structural integrity while achieving low thermal losses
2Loss of energy
If out-of-plane heat flux configuration is used in TEGs, then thermal losses are reduced, but device complexity increases
Solution Approach 1:
The patent uses standard silicon wafer fabrication processes and flip-chip bonding techniques that are universally applicable in microelectronics manufacturing. The Z-device structure serves multiple functions: it provides the out-of-plane heat flux path, integrates series strings of thermoelectric legs, and enables modular assembly. This multi-functionality reduces device complexity by leveraging existing manufacturing capabilities
Solution Approach 2:
The patent creates two identical (mirror-like) Z-device structures that are copies of each other, manufactured on separate silicon wafers using the same fabrication process. This copying approach simplifies manufacturing by standardizing the production process and allowing parallel fabrication, reducing overall device complexity while maintaining the beneficial out-of-plane heat flux configuration
3Productivity
If flip-chip bonding of mirror-like Z-device structures is used, then power yield per unit area increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary actions by pre-manufacturing the two Z-device structures on separate silicon wafers with all thermoelectric legs, metal interconnects, and electrical contacts already in place before the flip-chip bonding step. This preliminary fabrication allows for precise control of each structure independently, and the flip-chip bonding then simply joins the pre-assembled units, achieving high power yield per unit area while managing manufacturing precision requirements through staged fabrication
4Loss of energy
If internal void spaces are created in TEG structure, then heat bypass is minimized, but device complexity increases
Solution Approach 1:
The patent extracts the dielectric filler material from the valley spaces between the thermoelectric legs, creating internal void spaces in the device structure. This extraction eliminates the heat bypass paths that would otherwise exist through the dielectric material, minimizing thermal losses. The void spaces are intentionally created by removing the filler rather than adding complex structural elements, thus reducing heat bypass while avoiding excessive structural complexity
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 configuration significantly increases power yield per unit area and conversion efficiency by reducing internal heat transfer through dielectric fillers and metal bridges, leading to a more robust and efficient thermoelectric energy harvesting device.
Implementation Method 1
Thermoelectric generators (TEGs) are earnestly investigated as low enthalpy waste heat exploitation devices
Implementation Method 2
hill-top junction metal contacts and valley-bottom junction metal contacts joining juxtaposed ends of segments
Data Source
AI summary
Disclosed are two geometrically identical integrated Z-device structures, integrated in two distinct silicon dices, joined together in a face-to-face configuration, such that a p-doped thin film leg of one structure faces toward a n-doped thin film leg of the other structure and vice versa. Upon joining the Z-device structures together, the hill-top metal contacts of one integrated structure are bonded in electrical and thermal continuity with correspondent hill-top metal contacts of the other integrated structure, forming a substantially bivalve TEG of increased power yield for the same footprint area and having an enhanced conversion efficiency. Thermo-electrically generated current may be gathered from one or several end pad pairs, the pads of which are connected to respective valley bottom contacts, on one and on the other of the two dices of the bivalve device, at the ends of conductive lines of micro cells respectively belonging to one and to the other of the two coupled dices.