Thermoelectric piece and process of making the same

Details Thermoelectric piece and process of making the same Thermoelectric piece and process of making the same

1998-11-10

2000-07-04

Bowers, Charles

Semiconductor device manufacturing: process

Making device or circuit responsive to nonelectrical signal

Thermally responsive

257467, 324451, H01L 2100, H01L 31058, G01N 2500

Patent

active

060837705

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention is directed to thermoelectric pieces of P-type and N-type thermoelectric semiconductors which are ready for immediate connection with electrodes to provide a module or circuit of a thermoelectric heater/cooler or thermoelectric generators and more particularly to such thermoelectric pieces with increased adhesive strength with the electrodes.


BACKGROUND ART

Japanese Patent Laid-open publication No. 4-249385 proposed a prior art thermoelectric piece which comprises a thermoelectric semiconductor coated on its opposed faces respectively with Ni-layers for soldering connection with corresponding electrodes. The Ni-layer is selected to block interdiffusion of one or more elements of the thermoelectric semiconductor and a soldering material into each other in order to avoid lowering of thermoelectric characteristics over a long time of use. However, the Ni layer is found to give only a reduced adhesive strength to the thermoelectric semiconductor, which may result in disconnection of the circuit and lower reliability of the thermoelectric device.


DISCLOSURE OF THE INVENTION

The above problem has been overcome by the present invention which provides a thermoelectric piece capable of giving an increased adhesive strength between a diffusion barrier layer and a semiconductor matrix, yet effectively blocking the diffusion of one or more elements of the thermoelectric semiconductor to maintain reliable thermoelectric characteristics over a long time of use.
The thermoelectric piece in accordance with the present invention comprises a thermoelectric semiconductor of Bi--Sb--Te or Bi--Te--Se having opposed faces, an Sn-alloy layer disposed on each of the opposed faces of the semiconductor, and a diffusion barrier layer disposed on each the Sn-alloy layer. The diffusion barrier layer is made of at least one element selected from the group consisting of Mo, W, Nb and Ni for blocking diffusion of the elements of the thermoelectric semiconductor and/or a soldering material utilized for electrical connection of said thermoelectric semiconductor to an external electric circuit. The Sn-alloy layer comprises Sn as an essential metal element which diffuses mutually with at least one element of the semiconductor to form at least one Sn-alloy selected from a group consisting of Sn--Bi alloy, Sn--Te alloy, Sn--Sb alloy, Sn--Se alloy, Sn--Bi--Te alloy, Sn--Bi--Sb alloy, Sn--Bi--Se alloy, Sn--Te--Se alloy, and Sn--Te--Sb alloy, in the form of either a solid solution, an intermetallic or combination of these. With the provision of the Sn-alloy layer between the thermoelectric semiconductor and the diffusion barrier layer, the diffusion barrier layer can have an increased adhesive strength to the semiconductor because of a diffusion bonding at the interface with the semiconductor matrix due-to the interdiffusion, and also because of an alloy bonding between the Sn-alloy layer and the diffusion barrier layer of the selected element. It is found that Sn will not lower the thermoelectric characteristic when diffusing into the semiconductor matrix and provides an sufficient adhesive strength to the metal elements of the diffusion barrier layer.
The alloy layer may be formed therein with a tin lamina replete with Sn contained in 90% or more based upon the atomic weight ratio. The tin lamina can give a good platform for enhanced bonding with the diffusion barrier layer of Mo, W, Nb, and Ni.
The Sn-alloy layer, which is defined to have 10% of more of Sn based upon the atomic weight ratio, is preferably made to have a thickness of 0.1 to 3.0 .mu.m. The tin lamina is preferred to have a thickness less than 2.0 .mu.m, while the diffusion barrier layer has a thickness of 0.1 to 5.0 .mu.m.
The present invention also discloses a process of making the thermoelectric piece which comprises the steps of: having opposed faces; thermoelectric semiconductor; thermoelectric semiconductor to form an Sn-alloy layer on the each of the opposed faces of the thermoelectric semiconductor; diffusion barrier layer bein

REFERENCES:
patent: 3045057 (1962-07-01), Cornish et al.
patent: 3444005 (1969-05-01), Avis et al.
patent: 3808670 (1974-05-01), Seetoo
patent: 3859143 (1975-01-01), Krebs
patent: 3930303 (1976-01-01), Alais
patent: 3988171 (1976-10-01), Miller
patent: 4180415 (1979-12-01), Hampl, Jr.
patent: 4489742 (1984-12-01), Moore
patent: 4650919 (1987-03-01), Benson
patent: 5241828 (1993-09-01), Kapitulnik
patent: 5429680 (1995-07-01), Fuschetti
patent: 5817188 (1996-09-01), Yahatz

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