JPH11186616A - Thermoelectric transducer and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of a thermoelectric transducer at the time of electrode bonding and current flowing after electrode bonding, by forming an alloy layer for preventing deterioration of performance on thermoelectric semiconductor. SOLUTION: On Bi-Te-Se based alloy or Bi-Sb-Te based alloy which form thermoelectric semiconductor A, an alloy layer B of at least one kind of element out of trivalent or tetravalent elements (B, Ga, In, T, C, Si, Ge, Sn) and at least one kind of metal out of Bi, Sb, Te, Se or Bi-Te-Se based alloy or Bi-Sb- Te based alloy is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and a method of manufacturing a thermoelectric conversion element, and more particularly to a thermoelectric conversion element capable of preventing performance degradation of a thermoelectric semiconductor and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional method for manufacturing a thermoelectric conversion element is based on a Bi-Sb-Te alloy or Bi-T
When joining the e-Se alloy and the electrode, Ni is directly formed on the thermoelectric semiconductor as a diffusion preventing layer to a thickness of 5 μm or more,
The bonding is performed using Sn-Pb solder material (for example, Japanese Patent Application Laid-Open No. 4-249385).

[0003]

However, in the conventional electrode bonding technique, the performance of the element may be deteriorated due to oxidation of the bonding surface of the thermoelectric semiconductor at the time of electrode bonding and generation of voids and minute voids. In addition, the heat generated due to the heat generated at the time of energization after electrode bonding, the thermal stress due to the temperature difference between the upper and lower surfaces, the generation of repeated stress due to the thermal cycle and dew condensation, etc., oxidize and deform the vicinity of the thermoelectric semiconductor bonding surface, and May decrease.

[0004] The present invention has been made in view of the above points, and by forming an alloy layer on a thermoelectric semiconductor so as not to deteriorate the performance, the thermoelectric conversion element can be formed at the time of electrode joining and at the time of energization after electrode joining. An object of the present invention is to provide a thermoelectric conversion element capable of preventing deterioration and a method for manufacturing the thermoelectric conversion element.

[0005]

In order to solve the above-mentioned problems, a thermoelectric conversion element and a method for manufacturing a thermoelectric conversion element according to the present invention are provided.
When the thermoelectric semiconductor and the electrode material are joined, an alloy layer for preventing the performance of the thermoelectric semiconductor from being deteriorated is formed on the joining surface of the thermoelectric semiconductor.

The thermoelectric conversion element according to claim 1 of the present invention comprises: a. Thermoelectric semiconductor Bi-Te-Se alloy (commonly referred to as n-type) b. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) and an alloy layer of at least one metal of Bi, Te, Se or a Bi-Te-Se-based alloy. , B. Characterized by comprising:

That is, as shown in FIG. 1, an alloy layer B is integrally formed on both opposing surfaces of a thermoelectric semiconductor A. The thermoelectric semiconductor A is a Bi-Te-Se alloy. Alloy layer B is 3
Or tetravalent element (B, Ga, In, Tl, C, S
i, Ge, Sn) and at least one type of element and B
It is an alloy layer with at least one kind of metal among i, Te, and Se or a Bi-Te-Se-based alloy.

When the trivalent or tetravalent element is present as an alloy in the n-type thermoelectric semiconductor as in the first aspect, it has an effect of reducing the carrier concentration. In general,
When the n-type thermoelectric conversion element is slightly oxidized, oxygen acts as a dopant to increase the carrier concentration and decrease the Seebeck coefficient, so that the figure of merit Z decreases. Therefore, the trivalent and tetravalent alloy layers B are converted to thermoelectric semiconductors A.
By suppressing the increase in the carrier concentration due to the oxidation, the decrease in the Seebeck coefficient can be suppressed, and the decrease in the performance can be suppressed. In addition, due to the stress generated when cutting the thermoelectric semiconductor A, bonding the electrodes, or energizing the thermoelectric semiconductor A,
It is considered that a large number of fine cracks, lattice defects due to crystal distortion, vacancies after Te release, and the like exist near the thermoelectric semiconductor junction interface. By filling these voids or voids with trivalent and tetravalent elements, the contact resistance is reduced, and there is a great effect on preventing performance degradation.

According to a second aspect of the present invention, there is provided a thermoelectric conversion element comprising: a '. Thermoelectric semiconductor Bi-Sb-Te alloy (commonly called p-type) b '. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) and an alloy layer of at least one metal of Bi, Sb, Te or a Bi-Sb-Te alloy. , B '. Characterized by comprising:

That is, as shown in FIG. 2, the thermoelectric semiconductor A '
Alloy layers B 'are integrally formed on both surfaces of the substrate. The thermoelectric semiconductor A 'is a Bi-Sb-Te alloy. Alloy layer B 'is 3
Or tetravalent element (B, Ga, In, Tl, C, S
i, Ge, Sn) and at least one type of element and B
It is an alloy layer of at least one kind of metal among i, Sb, and Te or a Bi-Sb-Te-based alloy.

The trivalent or tetravalent element present as an alloy in the p-type thermoelectric semiconductor has an effect of increasing the carrier concentration. In general,
When the p-type thermoelectric conversion element is oxidized, the carrier concentration decreases,
Since the conductivity decreases, the value of Z, which is a figure of merit, may decrease. Therefore, by forming a trivalent and tetravalent element alloy layer on the surface of the thermoelectric semiconductor, it is possible to suppress a decrease in the carrier concentration due to oxidation, and thus to suppress a decrease in conductivity and a decrease in performance. In addition, due to stresses generated during cutting of the thermoelectric semiconductor A ′, bonding of electrodes, energization, etc., many cracks, lattice defects due to crystal distortion, vacancies after Te release, etc. are present near the thermoelectric semiconductor bonding interface. it seems to do. By filling these voids or voids with trivalent and tetravalent elements, the contact resistance is reduced, and there is a great effect on preventing performance degradation.

According to a third aspect of the present invention, there is provided a thermoelectric conversion element comprising: a ″.
Type thermoelectric semiconductor b ″. Trivalent or tetravalent element (B, Ga, In, Tl,
(C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se, Bi-Te-Se alloy or Bi-S
Alloy layer with b-Te alloy c. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) at least one of the above elements a ″., B ″. , C. Characterized by comprising:

That is, as shown in FIG. 3, the thermoelectric semiconductor A ″
Alloy layers B "are integrally formed on both surfaces of the
A layer C of a trivalent or tetravalent element is integrally formed thereon. The thermoelectric semiconductor A ″ is a Bi—Te—Se alloy (n
Mold) or Bi-Sb-Te alloy. Alloy layer B "
Is a trivalent or tetravalent element (B, Ga, In, Tl, C,
Si, Ge, Sn) and at least one element thereof and B
i, Sb, Te, Se, at least one kind of metal, Bi-Te-Se alloy, or Bi-Sb-T
An alloy layer with an e-based alloy. The element layer C is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si, Ge, S
n) is a layer made of at least one kind of element.

According to a third aspect of the present invention, when crystal distortion occurs or a minute crack occurs in the thermoelectric semiconductor A ″ or alloy layer B ″ near the alloy layer B ″, trivalent to fill the voids and voids. Alternatively, it is possible to supply a tetravalent element, and since the layer C is a layer of the same kind of element as a part of the elements constituting the alloy layer B ″, good bonding resistance and good contact resistance and bonding strength can be obtained.

According to a fourth aspect of the present invention, there is provided a thermoelectric conversion element comprising: a ″.
Type thermoelectric semiconductor b ″. Trivalent or tetravalent element (B, Ga, In, Tl,
(C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se, Bi-Te-Se alloy or Bi-S
Alloy layer with b-Te alloy c. Trivalent or tetravalent elements (B, Ga, In, Tl,
A layer composed of at least one element of C, Si, Ge, and Sn) d. Metals having a diffusion preventing effect (Ti, Cr, Co, N
i, Nb, Mo, W) at least one element from the group consisting of: e. Electrode material (solder material, electrode) a "., B". , C. , D. , E. Or a ″., B ″. , D. , E. Characterized by comprising:

That is, as shown in FIG. 4, the thermoelectric semiconductor A ″
Alloy layers B "are integrally formed on both surfaces of the
A layer C of a trivalent or tetravalent element is formed integrally thereon as necessary, and a diffusion prevention layer D is formed integrally thereon,
The electrode material E is integrally formed on the diffusion prevention layer D. The thermoelectric semiconductor A ″ is a Bi—Te—Se alloy (n-type) or a Bi—Sb—Te alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si). , G
e, Sn) and at least one element of Bi, S
It is an alloy layer with at least one kind of metal among b, Te, and Se, or a Bi-Te-Se-based alloy or a Bi-Sb-Te-based alloy. The element layer C is a layer made of at least one of trivalent or tetravalent elements (B, Ga, In, Tl, C, Si, Ge, and Sn). The diffusion prevention layer D is made of a metal (Ti, Cr, C) having a diffusion prevention effect.
o, Ni, Nb, Mo, W). The electrode material E is the electrode E ₁ and the solder material E
₂

According to the fourth aspect, it is possible to conduct electricity from the electrode material E, and to prevent the diffusion of the electrode material E into the thermoelectric semiconductor A ″ by the diffusion preventing layer D, and the element layer C or the alloy layer B ″. The performance degradation due to oxidation or generation of pores or voids on the surface of the thermoelectric semiconductor A ″ can be suppressed.
A trivalent or tetravalent element (B,
Ga, In, Tl, C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se or a Bi-Te-Se-based alloy or Bi-Sb- A step of forming an alloy layer with a Te-based alloy.

That is, as shown in FIG. 5, the thermoelectric semiconductor A ″
The thermoelectric semiconductor A ″ is a Bi—Te—Se-based alloy (n-type) or a Bi—Sb—Te-based alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si, G
e, Sn) and at least one element of Bi, S
It is an alloy layer with at least one kind of metal among b, Te, and Se, or a Bi-Te-Se-based alloy or a Bi-Sb-Te-based alloy.

According to the fifth aspect of the present invention, it is possible to manufacture a thermoelectric conversion element capable of suppressing a decrease in performance due to oxidation as described in the first and second aspects. Claim 6 of the present invention
The method of manufacturing a thermoelectric conversion element according to claim 5 is characterized in that the method includes a step of forming a layer of an alloyed trivalent or tetravalent element on the surface of the alloy layer.

That is, as shown in FIG. 6, the thermoelectric semiconductor A ″
The alloy layer B ″ is integrally formed on both surfaces of the substrate, and a layer C of a trivalent or tetravalent element is integrally formed on the alloy layer B ″. The thermoelectric semiconductor A ″ is a Bi—Te—Se alloy (n-type) or a Bi—Sb—Te alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, Ga, In, T).
1, C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se or a Bi-Te-Se-based alloy or Bi-
An alloy layer with an Sb-Te alloy. The element layer C is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si,
Ge, Sn) is a layer made of at least one element.

According to the sixth aspect of the present invention, it is possible to manufacture a thermoelectric conversion element capable of maintaining the suppression of performance deterioration due to oxidation as in the third aspect. The method for producing a thermoelectric conversion element according to claim 7 of the present invention is the method according to claim 5, wherein
Forming a valence element layer on the thermoelectric semiconductor surface by a vacuum film forming method,
The method is characterized by including a step of forming an alloy layer by heating during film formation or heating after film formation.

That is, as shown in FIG. 7, the thermoelectric semiconductor A ″
The alloy layer B ″ is formed by forming a trivalent or tetravalent element layer by a vacuum film formation method and heating the film during or after film formation to form an alloy layer B ″. Bi-
It is a Te-Se-based alloy (n-type) or a Bi-Sb-Te-based alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, G
a, In, Tl, C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se, Bi-Te-Se-based alloy or Bi-Sb-Te An alloy layer with a base alloy.

Here, the vacuum film forming method includes sputtering (ion plating), vapor deposition, CVD, thermal spraying, etc., and uses an ion beam alone as in ion beam assisted film formation, or forms a film with an ion beam. Including assisting. The alloy layer B ″ is manufactured as in claim 7.
Can be effectively formed and oxidation can be prevented. Further, all of the alloy layer forming steps can be performed in a dry manner.

[0024] In the method for manufacturing a thermoelectric conversion element according to claim 8 of the present invention, in claim 6, a trivalent or tetravalent element layer is formed on the surface of the thermoelectric semiconductor by a vacuum film forming method. A step of forming an alloy layer and a trivalent or tetravalent element layer by heating after the film is formed. That is, as shown in FIG. 8, a trivalent or tetravalent element layer is formed on the thermoelectric semiconductor A ″ by a vacuum film forming method, and the alloy layer B ″ and the trivalent Alternatively, it is manufactured so as to form a layer C of a tetravalent element.

Here, the vacuum film forming method includes sputtering (ion plating), vapor deposition, CVD, thermal spraying, etc., and uses an ion beam alone as in ion beam assisted film formation, or forms a film with an ion beam. Including assisting. By manufacturing as in claim 8, the alloy layer B ″
And a layer C of a trivalent or tetravalent element can be formed at the same time, and oxidation can be prevented. Also, all the steps of forming the alloy layer B ″ and the layer C of a trivalent or tetravalent element can be performed in a dry manner.

According to a ninth aspect of the present invention, there is provided a method for manufacturing a thermoelectric conversion element according to the fifth or sixth aspect, wherein the metal (Ti, Cr, Co, N) having a diffusion preventing effect after the alloy layer is formed.
i, Nb, Mo, W) to form a layer made of at least one element; 1. Step of soldering Cu electrode 2. Step of thickening solder Step of Cu plating , 2. , 3. Forming an electrode by any one of the above methods.

That is, as shown in FIG. 9A, an alloy layer B "is integrally formed on the thermoelectric semiconductor A", and if necessary, as shown in FIG. 9C, a diffusion prevention layer D is integrally formed on the element layer C or the alloy layer B ″ as shown in FIG. 9C. As shown in FIG. 9D, FIG. 9E or FIG. 9F, the electrode material E is manufactured so as to be integrally formed. The thermoelectric semiconductor A ″ is a Bi—Te—Se alloy (n-type) or a Bi—Sb—Te alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, Ga, In, T).
1, C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se or a Bi-Te-Se-based alloy or Bi-
An alloy layer with an Sb-Te alloy. The element layer C is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si,
Ge, Sn) is a layer made of at least one element. The diffusion preventing layer D is made of a metal (T
i, Cr, Co, Ni, Nb, Mo, W). Electrode material E is electrode E
₁ or solder material is E _2. When the electrode material E is integrally laminated, the Cu electrode E ₁ is soldered with a solder material E _{2 as} shown in FIG. 9D, or the solder material E is soldered as shown in FIG. 9D.
_{This is performed} by thickly embossing _{No. 2} or by forming the electrode E1 by Cu plating as shown in FIG. 9 (f).

By manufacturing as in claim 9, claim 4
As described above, a thermoelectric conversion element that can be energized and that can prevent the electrode material E from diffusing into the thermoelectric semiconductor A ″ and thereby suppress performance degradation due to oxidation and generation of pores and voids on the surface of the thermoelectric semiconductor A ″. Can be manufactured. According to a tenth aspect of the present invention, in the method for manufacturing a thermoelectric conversion element according to the ninth aspect, a Ni layer is formed on the surface of the diffusion preventing layer.

That is, as shown in FIG. 10A, an alloy layer B "is integrally formed on a thermoelectric semiconductor A", and a trivalent or tetravalent element A layer C is integrally formed, a diffusion prevention layer D is integrally formed on the element layer C or the alloy layer B ″, and a Ni layer is formed on the diffusion prevention layer D as shown in FIG. F is integrally formed, and the electrode material E is integrally formed on the Ni layer F. Thermoelectric semiconductor A ″ is Bi-Te-Se alloy (n-type)
Or it is a Bi-Sb-Te alloy. Alloy layer B ″ is 3
Or tetravalent element (B, Ga, In, Tl, C, S
i, Ge, Sn) and at least one type of element and B
i, Sb, Te, Se, at least one kind of metal, Bi-Te-Se alloy, or Bi-Sb-T
An alloy layer with an e-based alloy. The element layer C is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si, Ge, S
n) is a layer made of at least one kind of element.
The diffusion prevention layer D is made of a metal (Ti, C) having a diffusion prevention effect.
r, Co, Nb, Mo, W).

By manufacturing according to claim 10,
The wettability of the solder material E ₂ can be secured. Claim 11 of the present invention
The method for manufacturing a thermoelectric conversion element according to claim 10, wherein
Metal layer (Cu, S) for improving solder wettability on the surface of the i-layer
n, Au, Bi-Sn at least one metal)
Is formed. That is, as shown in FIG. 11A, an alloy layer B "is integrally formed on the thermoelectric semiconductor A", and a layer C of a trivalent or tetravalent element is formed on the alloy layer B "as necessary. The diffusion prevention layer D is integrally formed on the element layer C or the alloy layer B ″, and the Ni layer F is integrally formed on the diffusion prevention layer D, as shown in FIG. Ni layer solder wettability improving layer G is formed integrally on the F, formed integrally with the solder material E ₂ by soldering on the solder wettability improving layer G as shown in FIG. 11 (c) as , it is prepared as integrally formed with Cu electrodes E ₁ as on the solder material E ₂ shown in FIG. 11 (d). Thermoelectric semiconductor A ″ is Bi-Te-
It is a Se-based alloy (n-type) or a Bi-Sb-Te-based alloy. The alloy layer B is made of a trivalent or tetravalent element (B, Ga, I
n, Tl, C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se or a Bi-Te-Se alloy or a Bi-Sb-Te alloy And an alloy layer. Elemental layer C
Is a trivalent or tetravalent element (B, Ga, In, Tl, C,
It is a layer made of at least one element among Si, Ge, and Sn). The diffusion preventing layer D is a layer made of at least one element among metals (Ti, Cr, Co, Ni, Nb, Mo, W) having a diffusion preventing effect. The solder wetting improving layer G is a metal layer (Cu, Sn,
Au, Bi-Sn).

By manufacturing according to claim 11,
The wettability of the soldering material E ₂ can be further ensured. The method for manufacturing a thermoelectric conversion element according to claim 12 of the present invention is the method according to claim 9 or claim 10 or claim 11, wherein
Forming a layer and a solder wettability improving layer by a vacuum film forming method.

That is, as shown in FIG. 12 (a), an alloy layer B "is integrally formed on the thermoelectric semiconductor A", and a trivalent or tetravalent element The layer C is integrally formed, and the diffusion prevention layer D is integrally formed on the element layer C or the alloy layer B ″ by a vacuum film forming method.
2 (b), a Ni layer F is integrally formed on the diffusion preventing layer D by a vacuum film forming method, and a solder wettability improving layer G is formed on the Ni layer F as shown in FIG. Are integrally formed by a vacuum film forming method, and the electrode material E is integrally formed on the solder wettability improving layer G. Thermoelectric semiconductor A ″ is a Bi—Te—Se alloy (n-type) or Bi—S
It is a b-Te alloy. The alloy layer B ″ is a trivalent or tetravalent element (B, Ga, In, Tl, C, Si, Ge, Sn)
And at least one element of Bi, Sb, Te, S
at least one kind of metal or Bi-Te-
This is an alloy layer with a Se-based alloy or a Bi-Sb-Te-based alloy. The element layer C is a trivalent or tetravalent element (B, G
a, In, Tl, C, Si, Ge, Sn). The diffusion prevention layer D is made of a metal (Ti, Cr, Co, Ni, N) having a diffusion prevention effect.
b, Mo, W). The solder wetting improving layer G is a metal layer (at least one kind of metal among Cu, Sn, Au, and Bi-Sn) for improving the solder wettability.

Here, the vacuum film forming method includes sputtering (ion plating), vapor deposition, CVD, thermal spraying, etc., and uses an ion beam alone as in an ion beam assisted film forming, or forms a film with an ion beam. Including assisting. By manufacturing as described in claim 12, all of the oxidation prevention and film formation processes can be performed by a dry method.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermoelectric conversion element is manufactured, for example, as follows. The thermoelectric semiconductor A ″ is a Bi—Te—Se-based alloy (n-type) or a Bi—Sb—Te-based alloy (p-type), and the junction surface of the thermoelectric semiconductor A ″ is wet-polished with sandpaper. Ultrasonic cleaning is performed with pure water. Next, the surface of the thermoelectric semiconductor A ″ is subjected to, for example, Ar plasma etching (reverse sputtering). Then, a trivalent or tetravalent element (B, Ga,
In, Tl, C, Si, Ge, Sn), at least one element is formed on the surface of the thermoelectric semiconductor A ″ by a vacuum film forming method as shown in FIG. By heating, an alloy layer B ″ is formed. For example, S
n is sputtered on the surface of the thermoelectric semiconductor A ", and an alloy layer B" in which Sn is diffused into the thermoelectric semiconductor A "is formed by heating at the time of sputtering. At this time, a vacuum film forming method such as sputtering is used as shown in FIG. As described above, the alloy layer B ″ and the layer C of a trivalent or tetravalent element may be formed. On the alloy layer B ″ or the element layer C, a metal having a diffusion preventing effect (Ti, Cr, Co, Ni, Nb, Mo,
W), a diffusion prevention layer D made of at least one element is formed by a vacuum forming film method as shown in FIG. For example, Mo is sputtered to form a diffusion prevention layer D on the element layer C or the alloy layer B ″. Then, a Ni layer F is formed on the diffusion prevention layer D by vacuum deposition as shown in FIG. For example, it is formed by sputtering Ni on the surface, and then a metal (C) for improving solder wettability is formed on the diffusion prevention layer D.
The solder wettability improving layer G made of u, Sn, Au, or Bi-Sn) is formed by a vacuum film forming method as shown in FIG. By doing so, the solder wettability improving layer G is formed. Then the electrode member E on the solder wettability improving layer G is being formed, for example, by soldering material E ₂ is soldered as shown in FIG. 9 (d), Cu electrodes E ₁ are soldered Joined. The thermoelectric conversion element is formed as described above, and the deterioration of the thermoelectric semiconductor can be prevented at the time of electrode joining and at the time of energization after electrode joining.

Hereinafter, the present invention will be described in more detail with reference to specific examples. (Example) The thermoelectric semiconductor used in the example of the present invention is p
Both the mold and the n-type are powder extruded sintered materials, and the components are Bi0.5, Sb1.5, Te3 for the p-type and Bi2, Te for the n-type.
2.85, Se 0.15. On the surface of this thermoelectric semiconductor, Sn, Mo, Ni, and Cu were sequentially formed as follows.

The conditions for forming Sn, Mo, Ni, and Cu and the method for forming the alloy layer are as follows. 1). The thermoelectric semiconductor is wet polished with a No. 400 sandpaper. 2). Perform ultrasonic cleaning with pure water and dry. 3). RF plasma is generated for 60 s at Ar, 6.6 Pa and 300 W, and the surface of the thermoelectric semiconductor is reverse-sputtered.

4). Ar, 0.4 Pa, 2 at 1500 W
A 0.5 μm thin film is formed by generating DC plasma for 0 s and sputtering an Sn target. At this time, the heating by the sputtered particles caused the pressure to be 0.1.
An alloy layer having a thickness of 1 to 0.5 μm is formed, and a Sn specular film (a dense film is formed, that is, a mirror film is not formed in the case of a porous film) is formed.

5). Ar, 1.0 Pa, 3 at 3000 W
A 0.5 μm diffusion prevention layer is formed by generating DC plasma for 0 s and sputtering a Mo target. 6). A DC plasma is generated for 30 s at Ar, 0.2 Pa and 3000 W for 30 s, and a 0.6 μm Ni layer is formed by sputtering a Ni target.

7). Ar, 4.0 Pa, 4 at 3000 W
By generating DC plasma for 0 s and sputtering a Cu target, a Cu layer of 1.0 μm is formed. 8). Perform soldering. 9). The performance index Z of the thermoelectric conversion element manufactured as described above, in which the Cu electrode was joined, was measured, and further the performance index Z after heating under the following conditions was measured. Table 1 shows the results of the heating test of the n-type thermoelectric conversion element, and Table 2 shows the results of the heating test of the p-type thermoelectric conversion element. It can be seen from these results that no performance degradation was observed in any case.

[0040]

[Table 1]

[0041]

[Table 2]

A thermoelectric conversion module was manufactured by connecting the p-type and n-type thermoelectric conversion elements in series, and a thermal cycle test was performed. In the heat cycle test, the module was fixed at 15 kgf with a heat exchange board so that both sides of the module were not deformed, and the other side was kept at 30 ° C or less while the temperature of one side was always kept at 30 ° C or less.
To 80 ° C. Temperature turns on current (5A) /
Changed by turning off. Table 3 shows the measurement results of the electrical resistance of the module before and after the heat cycle test.
This clearly shows that deterioration with time when the module of the present invention is used is small.

[0043]

[Table 3]

[0044]

The invention of claim 1 of the present invention has the effect of reducing the carrier concentration when the trivalent or tetravalent element is present as an alloy in the n-type thermoelectric semiconductor. In general, when an n-type thermoelectric conversion element is slightly oxidized, oxygen acts as a dopant to increase the carrier concentration and decrease the Seebeck coefficient, so that the figure of merit Z decreases. Therefore, by forming an alloy layer of trivalent and tetravalent elements on the surface of the thermoelectric semiconductor, it is possible to suppress an increase in the carrier concentration due to oxidation, and to thereby suppress a decrease in the Seebeck coefficient.
Performance degradation can be suppressed.

The invention of claim 2 of the present invention has an effect of increasing the carrier concentration when the trivalent or tetravalent element is present as an alloy in the p-type thermoelectric semiconductor. Generally, when a p-type thermoelectric conversion element is oxidized, the carrier concentration decreases and the conductivity decreases, so that the coefficient of performance Z may decrease. Therefore, by forming a trivalent and tetravalent element alloy layer on the surface of the thermoelectric semiconductor, it is possible to suppress a decrease in the carrier concentration due to oxidation, and thus to suppress a decrease in conductivity and a decrease in performance.

The invention of claim 3 of the present invention has a great effect in preventing a decrease in performance due to a reduction in contact resistance. In other words, it is thought that there are many fine cracks, crystal distortion, and many holes after Te release near the thermoelectric semiconductor junction interface due to the stress generated at the time of cutting the thermoelectric semiconductor, bonding the electrodes, energizing, and the like. Can be Therefore, the presence of a trivalent or tetravalent element film on the surface of the alloy layer fills these voids or voids with trivalent and tetravalent elements, thereby reducing contact resistance and greatly preventing performance degradation. There is.

According to the invention of claim 4 of the present invention, it is possible to conduct electricity, to prevent the electrode material from diffusing into the thermoelectric semiconductor, and to suppress a decrease in performance due to oxidation or generation of pores or voids on the thermoelectric semiconductor surface. . According to the invention of claim 5 of the present invention, it is possible to manufacture a thermoelectric conversion element capable of suppressing a decrease in performance due to oxidation as in the invention of claim 1 or 2.

According to the invention of claim 6 of the present invention, it is possible to manufacture a thermoelectric conversion element capable of sustaining the suppression of deterioration in performance due to oxidation as in the invention of claim 3. The invention of claim 7 of the present invention provides:
The alloy layer can be formed thinly and effectively, and oxidation can be prevented. Further, all of the alloy layer forming steps can be performed in a dry manner. According to the invention of claim 8 of the present invention, an alloy layer and a layer of a trivalent or tetravalent element can be simultaneously formed, and oxidation can be prevented. Further, all the steps of forming the alloy layer and the layer of a trivalent or tetravalent element can be performed by a dry method.

According to a ninth aspect of the present invention, an electric current can be supplied as described in the fourth aspect, the diffusion of the electrode material into the thermoelectric semiconductor can be prevented, and the oxidization and the pores or voids on the thermoelectric semiconductor surface can be prevented. A thermoelectric conversion element capable of suppressing a decrease in performance due to the generation of the heat can be manufactured. According to the tenth aspect of the present invention, the wettability of the solder can be ensured by the Ni layer. According to the eleventh aspect of the present invention, the solder wettability can be improved by at least one kind of metal layer among Cu, Sn, and Au.

According to the twelfth aspect of the present invention, oxidation can be prevented by performing the film formation of the ninth to eleventh aspects in a vacuum. In addition, all of the film forming steps can be performed by a dry method.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a state in which an alloy layer is formed on an n-type thermoelectric semiconductor, and FIG. 1B is an enlarged view of a part X in FIG.

2A is a cross-sectional view showing a state in which an alloy layer is formed on a p-type thermoelectric semiconductor, and FIG. 2B is an enlarged view of a portion X in FIG.

FIG. 3A is a cross-sectional view showing a state in which an alloy layer and a layer of a trivalent or tetravalent element are formed on a thermoelectric semiconductor, and FIG. 3B is an enlarged view of a part X in FIG.

FIG. 4 (a) shows an alloy layer, trivalent or tetravalent layer on a thermoelectric semiconductor.
FIG. 3B is a cross-sectional view showing a state in which a layer of a valence element, a diffusion prevention layer, and an electrode material are formed, and FIG.

FIG. 5 is a cross-sectional view illustrating a state in which an alloy layer is formed on a thermoelectric semiconductor.

6A is a cross-sectional view showing a state in which an alloy layer and a layer of a trivalent or tetravalent element are formed on a thermoelectric semiconductor, and FIG. 6B is an enlarged view of a part X in FIG.

FIG. 7 is a cross-sectional view illustrating a state in which an alloy layer is formed on a thermoelectric semiconductor by a vacuum film forming method.

FIG. 8 is a cross-sectional view illustrating a state in which an alloy layer and a layer of a trivalent or tetravalent element are formed on a thermoelectric semiconductor by a vacuum film formation method.

FIG. 9 is a cross-sectional view illustrating a state in which an alloy layer, a trivalent or tetravalent element layer, a diffusion prevention layer, and an electrode material are formed on a thermoelectric semiconductor.

FIG. 10 is a cross-sectional view illustrating a state in which a Ni layer is formed as a diffusion prevention layer.

FIG. 11 is a cross-sectional view illustrating a state in which a Ni layer, a solder wettability improving layer, and an electrode material are formed on a diffusion prevention layer.

12A is a cross-sectional view illustrating a state in which a diffusion prevention layer is formed, FIG. 12B is a cross-sectional view illustrating a state in which a Ni layer is formed, and FIG. 12C is a state in which a solder wettability improving layer is formed. It is sectional drawing explaining.

[Explanation of symbols]

 An n-type thermoelectric semiconductor A ′ p-type thermoelectric semiconductor A ″ n-type or p-type thermoelectric semiconductor B alloy layer B ′ alloy layer B ″ alloy layer C layer of trivalent or tetravalent element D diffusion prevention layer E electrode material F Ni Layer G Solder wettability improving layer

Claims (12)

[Claims] 1. A method according to claim 1, Thermoelectric semiconductor Bi-Te-Se alloy (n-type) b. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) and an alloy layer of at least one metal of Bi, Te, Se or a Bi-Te-Se-based alloy. , B. A thermoelectric conversion element characterized by comprising: A '. Thermoelectric semiconductor Bi-Sb-Te alloy (p-type) b '. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) and an alloy layer of at least one metal of Bi, Sb, Te or a Bi-Sb-Te alloy. , B '. A thermoelectric conversion element characterized by comprising: 3. a ''. N in claim 1 or 2
-Type or p-type thermoelectric semiconductor b ". Trivalent or tetravalent element (B, Ga, In, Tl,
(C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se, Bi-Te-Se alloy or Bi-S
Alloy layer with b-Te alloy c. Trivalent or tetravalent elements (B, Ga, In, Tl,
C, Si, Ge, Sn) at least one of the above elements a ″., B ″. , C. A thermoelectric conversion element characterized by comprising: (4) a ". N in claim 1 or 2;
-Type or p-type thermoelectric semiconductor b ". Trivalent or tetravalent element (B, Ga, In, Tl,
(C, Si, Ge, Sn) and at least one metal of Bi, Sb, Te, Se, Bi-Te-Se alloy or Bi-S
Alloy layer with b-Te alloy c. Trivalent or tetravalent elements (B, Ga, In, Tl,
A layer composed of at least one element of C, Si, Ge, and Sn) d. Metals having a diffusion preventing effect (Ti, Cr, Co, N
i, Nb, Mo, W) at least one element from the group consisting of: e. Electrode material (solder material, electrode) a "., B". , C. , D. , E. Or a ″., B ″. , D. , E. A thermoelectric conversion element comprising: 5. The thermoelectric semiconductor Bi—Te—Se-based alloy or Bi—Sb—Te-based alloy has at least one of trivalent or tetravalent elements (B, Ga, In, Tl, C, Si, Ge, Sn). One kind of element, Bi, Sb, Te, Se
At least one kind of metal or Bi-Te-S
A method for manufacturing a thermoelectric conversion element, comprising a step of forming an alloy layer with an e-based alloy or a Bi-Sb-Te-based alloy. 6. The method for manufacturing a thermoelectric conversion element according to claim 5, further comprising the step of forming a layer of an alloyed trivalent or tetravalent element on the surface of the alloy layer. 7. The method according to claim 5, wherein a step of forming a trivalent or tetravalent element on the surface of the thermoelectric semiconductor by a vacuum film forming method and heating the film during or after film formation to form an alloy layer. A method for manufacturing a thermoelectric conversion element, comprising: 8. The alloy layer and the trivalent or tetravalent element layer according to claim 6, wherein the trivalent or tetravalent element layer is formed on the surface of the thermoelectric semiconductor by a vacuum film forming method, and heat is applied during or after the film formation.
A method for manufacturing a thermoelectric conversion element, comprising a step of forming a valence or tetravalent element layer. 9. A metal (Ti, Cr, C) having an effect of preventing diffusion after forming an alloy layer according to claim 5 or claim 6.
o, Ni, Nb, Mo, W) to form a layer made of at least one element; 1. Step of soldering Cu electrode 2. Step of thickening solder Step of Cu plating , 2. , 3. Forming the electrode by any one of the above methods. 10. The method for manufacturing a thermoelectric conversion element according to claim 9, wherein a Ni layer is formed on the surface of the diffusion preventing layer. 11. The metal layer (Cu, Sn, Au, Bi) for improving solder wettability on the surface of a Ni layer according to claim 10.
-A method for producing a thermoelectric conversion element, wherein at least one kind of metal (Sn solder) is formed. 12. The thermoelectric conversion element according to claim 9, further comprising a step of forming a diffusion prevention layer, a Ni layer, and a solder wettability improving layer by a vacuum film forming method. Production method.