KR102198213B1 - Thermoelectric module manufacturing method equipped with thermoelectric legs with diffusion barrier layer, oxidation barrier layer, and oxide layer formed, and thermoelectric module thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed, and to a thermoelectric module thereby, and more particularly, to mutual diffusion of an electrode material and a component element of a thermoelectric leg installed at a high temperature. It relates to a thermoelectric leg in which a protective film is formed to prevent volatilization or oxidation of the thermoelectric leg due to exposure to an external environment.
In order to achieve the problem of the present invention, in a plurality of thermoelectric legs connected between an upper substrate electrode installed on a substrate in a high temperature region and a lower substrate electrode installed on a substrate in a low temperature region, the thermoelectric leg is formed on the upper surface of the thermoelectric leg. A method of manufacturing a thermoelectric module having a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg having an oxide layer, characterized in that it comprises a diffusion barrier layer and an oxidation barrier layer formed on the upper surface of the diffusion barrier layer and the outer surface of the thermoelectric leg to prevent oxidation. And it provides a thermoelectric module thereby.

Description

Thermoelectric module manufacturing method equipped with thermoelectric legs with diffusion barrier layer, oxidation barrier layer, and oxide layer formed, and thermoelectric module thereby }

The present invention relates to a method for manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed, and to a thermoelectric module thereby, and more particularly, to mutual diffusion of an electrode material and a component element of a thermoelectric leg installed at a high temperature. It relates to a thermoelectric leg in which a protective film is formed to prevent volatilization or oxidation of the thermoelectric leg due to exposure to an external environment.

Thermoelectric module is a generic term for various effects that appear from the interaction of heat and electricity.Thermistors used for stabilization of circuits and detection of heat, power, and light, and devices using the Seebeck effect used to measure temperature, There are Peltier devices used to manufacture refrigerators and thermostats.

In particular, modules using the Seebeck effect, which is a phenomenon in which electromotive force is generated due to a temperature difference, has been actively researched as an alternative energy as environmental pollution and energy depletion problems have recently emerged worldwide. have. In the thermoelectric module for power generation, which is composed of an alternative energy source using such thermoelectric modules, electrons and holes in the n-type thermoelectric leg and p-type thermoelectric leg, respectively, are transferred from the high-temperature part to the low-temperature part due to the temperature difference at both ends. By moving to the low temperature part, electrical energy is generated.

In addition, the efficiency of the thermoelectric module for power generation is determined by the number of thermoelectric module couples and thermoelectric characteristics such as thermoelectric power, thermal conductivity and electrical resistivity of the n-type thermoelectric leg and the p-type thermoelectric leg. Thermoelectric power generation, which requires no maintenance and repair due to noise-free and vibration-free, high reliability, was initially developed for application to special small power devices including military power supplies, but power generation is possible only by giving a temperature difference, so a low heat source of less than 100℃ Since there are various types of heat sources that can be used over a high heat source of about 1000℃, economical uses are greatly expanded in fields such as thermoelectric generators using industrial waste heat and alternative independent power sources.

As a conventional thermoelectric module for power generation, Korean Patent Office No. 10-2011-0077492 has been known in which a diffusion barrier layer is formed to reduce internal resistance to improve power generation efficiency and to prevent diffusion between the thermoelectric leg and the electrode. However, since the diffusion barrier layer has a protective film formed only on the upper and lower portions in contact with the electrode, volatilization occurs in thermoelectric legs used at high temperatures, resulting in deterioration of performance and low reliability.

In addition, Korean Patent Office No. 10-1772392 has been known, which is a thermoelectric leg that suppresses oxidation and volatilization by forming a first oxide film on the thermoelectric leg and a second oxide film on the first oxide film. However, there was a problem that volatilization or oxidation occurred in the side exposed to the external environment except for the upper surface.

Accordingly, there is a need for a technical method in which the process of forming two types of coating films is combined with the thermoelectric module manufacturing process.

KR 10-2011-0077492 A KR 10-1772392 B1

The present invention is to solve the above problems, and a method for manufacturing a thermoelectric module including a diffusion barrier layer and an oxidation barrier layer, and a thermoelectric leg with an oxide layer to prevent mutual diffusion between the constituent elements of the thermoelectric leg used at high temperature and the electrode material. The purpose is to provide a thermoelectric module.

In addition, an object of the present invention is to provide a method of manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed, and a thermoelectric module thereby.

In order to achieve such a problem of the present invention, the present invention provides a first step of synthesizing an ingot of magnesium silicide (Mg ₂ Si); A second step of forming a diffusion barrier layer 20 by depositing a diffusion barrier material on an upper surface of the ingot of the magnesium silicide (Mg ₂ Si) by a sputtering technique; A third step of cutting the ingot to form a cuboid-shaped thermoelectric leg (10); A fourth step of forming an antioxidant film 30 by sputtering deposition of Al or Cr on the remaining 5 surfaces of the thermoelectric leg 10 except for the front surface (6 surfaces) or the lower surface at the low temperature side; A fifth step of forming a thermoelectric module by bonding the upper surface of the thermoelectric leg 10 to the upper substrate electrode 200 and the lower substrate electrode 300 so that the upper surface of the thermoelectric leg 10 is positioned on the high temperature side; An aluminum oxide film (Al ₂ O ₃ ) or A sixth step of forming an oxide film 31 of a chromium oxide film (Cr ₂ O ₃ ); A method of manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed is a technical gist.

In addition, the diffusion barrier layer is a metal such as nickel, cobalt, titanium, molybdenum, chromium, iron, stainless steel, etc., or a material of any one of TaN, TiN, TaSiN, TiSiN, MoSi ₂ , TiSi ₂ , and TaSi ₂ It is preferable to use a method of manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed.

The present invention also includes a diffusion barrier layer formed on an upper surface of the thermoelectric module manufactured by the method of manufacturing a thermoelectric module including the diffusion barrier layer, the oxidation barrier layer, and the thermoelectric leg on which the oxide layer is formed; An oxidation prevention film formed on an upper surface of the diffusion prevention layer; An oxide film formed on the outer surface; A diffusion barrier layer, characterized in that the thermoelectric leg is connected in contact with the upper substrate electrode between the upper substrate electrode installed on the substrate in the high temperature region and the lower substrate electrode installed on the substrate in the low temperature region. Another technical gist is a thermoelectric module provided with an antioxidant film and a thermoelectric leg on which an oxide film is formed.

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A method of manufacturing a thermoelectric module having a diffusion barrier layer, an oxidation barrier, and a thermoelectric leg with an oxide film according to the present invention by means of solving the above problems, and the thermoelectric module has the effect of preventing diffusion between the thermoelectric leg and the electrode by the diffusion barrier layer. There is.

In addition, it prevents further oxidation from proceeding by the antioxidant film and also serves to prevent volatilization of the thermoelectric leg.

1 is a diagram illustrating a configuration of a general thermoelectric module.
2 is a diagram showing an ingot of a thermoelectric material according to an embodiment of the present invention.
3 is a diagram illustrating a diffusion barrier layer formed on an upper surface of an ingot made of a thermoelectric material according to an embodiment of the present invention.
4 is a diagram illustrating a thermoelectric leg formed by cutting an ingot of a thermoelectric material according to an embodiment of the present invention.
5 is a view showing an oxidation barrier formed on the top and side surfaces of the thermoelectric leg according to an embodiment of the present invention.
6 is a diagram illustrating a thermoelectric module in which a thermoelectric leg is bonded to an electrode according to an embodiment of the present invention.
7 is a view showing a result of thermal weight analysis for testing the protection ability of a Cr ₂ O ₃ coating film according to an embodiment of the present invention.

Hereinafter, a method of manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed according to an embodiment of the present invention, and a thermoelectric module therefrom, will be described in detail with reference to the drawings.

1 is a diagram for explaining the configuration of a general thermoelectric module, FIG. 2 is a view showing an ingot of a thermoelectric material according to an embodiment of the present invention, and FIG. 3 is a view illustrating an ingot of a thermoelectric material according to an embodiment of the present invention. A diagram showing a diffusion barrier layer formed on the upper surface, FIG. 4 is a view showing a thermoelectric leg formed by cutting an ingot of a thermoelectric material according to an embodiment of the present invention, and FIG. 5 is a thermoelectric leg according to an embodiment of the present invention. Fig. 5-(a) perspective view and Fig. 5-(b) are cross-sectional views of Fig. 5-(a), and Fig. 6 shows a thermoelectric leg according to an embodiment of the present invention. It is a diagram showing a thermoelectric module bonded to an electrode.

As shown in FIG. 1, the thermoelectric module includes a module substrate 100, an upper substrate electrode 200, a lower substrate electrode 300, and a thermoelectric leg. Hereinafter, an upper portion of the thermoelectric module to be described is designated as a high temperature portion and a lower portion thereof is designated as a low temperature portion. The thermoelectric module is composed of a plurality of thermoelectric legs connected between the upper substrate electrode 200 installed on the module substrate 100 in the high temperature part and the lower substrate electrode 300 installed on the module substrate 100 in the low temperature part do. In addition, the plurality of thermoelectric legs are alternately arranged in p-type and n-type and are electrically connected to each other by electrodes provided at both ends.

Referring to FIG. 6, the thermoelectric leg and the thermoelectric leg on which the diffusion barrier layer and the oxidation barrier layer are formed according to the present invention are composed of a thermoelectric leg 10, a diffusion barrier layer 20, and an oxidation barrier layer 30, each of which will be described in detail below. As follows.

The thermoelectric leg 10 is connected between the upper substrate electrode 200 installed on the substrate in the high temperature region and the lower substrate electrode 300 installed on the substrate in the low temperature region.

In addition, when forming a thermoelectric module with the thermoelectric leg 10 according to a preferred embodiment to be described later, the description will be made based on the fact that the upper surface is located in the high temperature part and the lower surface is located in the low temperature part.

In addition, the diffusion barrier layer 20 to be described later cuts the ingot of the thermoelectric material formed on the thermoelectric leg 10 in the Z-axis direction to form the thermoelectric leg 10 having a rectangular parallelepiped shape.

In addition, the thermoelectric leg 10 may have a different shape such as a cylinder other than a rectangular parallelepiped, and the shape is not limited.

The ingot of the thermoelectric material forming the thermoelectric leg 10 is synthesized using a sintering technique under high temperature and high pressure by charging raw material powder into a mold.

The diffusion barrier layer 20 is formed only on the upper surface of the thermoelectric leg 10 and the other surface is cut so that the thermoelectric leg 10 is exposed. In addition, technologies such as wire sawing and plasma discharge processing may be used for cutting thermoelectric materials.

The diffusion barrier layer 20 may be positioned on the high temperature side to prevent mutual diffusion of constituent elements of the thermoelectric leg 10 and the electrode material.

Further, the diffusion barrier layer 20 may be selected from a material according to a material constituting the thermoelectric leg 10.

When using magnesium silicide (Mg ₂ Si) as the material of the thermoelectric leg 10, it is a metal such as nickel, cobalt, titanium, molybdenum, chromium, iron, stainless steel, or TaN, TiN, TaSiN, TiSiN, MoSi ₂ , TiSi Any one of ₂ and TaSi ₂ may be selected. In addition, the diffusion barrier layer 20 may be formed by depositing on the thermoelectric leg using a sputtering technique.

The antioxidant layer 30 is formed on the upper surface of the diffusion barrier layer 20 and the outer surface of the thermoelectric leg 10 to serve as a protective layer so that volatilization or oxidation of the thermoelectric leg does not occur.

The antioxidant layer 30 may be formed only on the remaining 5 surfaces except for the lower surface of the low temperature part according to the formation method, and all may be formed on all 6 surfaces.

The antioxidant film 30 can also be deposited using a sputtering technique, and there are various methods that can be formed by other vapor deposition, plating, and the like, and the present invention is not limited by the technique.

In addition, it is preferable that the anti-oxidation film 30 is a metal capable of protecting the inside by forming a dense and hard oxide film when oxidized. Typically, Al and Cr are used, and a thermoelectric module is manufactured after depositing on the thermoelectric leg 10.

By raising the temperature of the thermoelectric module in the air or in an oxygen atmosphere, the oxidation preventing film 30 formed on the side of the thermoelectric leg 10 is oxidized due to exposure to the atmosphere, thereby forming the oxide film 31.

At this time, the oxide film 31 is formed on the side exposed to the outside, but the oxidation preventing film 30 formed on the upper surface of the thermoelectric leg 10 on the side of the high-temperature portion bonded to the upper substrate electrode 200 does not occur. So it remains as it is.

That is, between the upper surface of the thermoelectric leg 10 and the upper substrate electrode 200, the anti-oxidation layer 30 is formed on the upper surface of the diffusion barrier layer 20 and the diffusion barrier layer 20.

A process of forming the diffusion barrier layer and the oxidation barrier layer of the thermoelectric leg according to an embodiment of the present invention is as follows.

In one embodiment, magnesium silicide (Mg ₂ Si), one of the thermoelectric materials, will be described as an example.

Step 1: As shown in Fig. 2, in this embodiment, a spark plasma sintering technique is used, and the sintering temperature is 750°C, and the pressure during sintering is 12.7 mm in diameter and about 15 mm in height under 50 MPa conditions. An ingot of magnesium silicide (Mg ₂ Si) is synthesized.

Step 2: As shown in Fig. 3, a TiN film having a thickness of about 3 μm is sputtered under the condition of a substrate temperature of 100°C, a process pressure of 5 mTorr, and an Ar/N ₂ flow ratio = 4, and an ingot of magnesium silicide (Mg ₂ Si). The diffusion barrier layer 20 made of TiN is formed on the upper surface of the ingot made of thermoelectric material by depositing on the upper surface.

Step 3: As shown in FIG. 4, the thermoelectric leg 10 is formed by cutting the ingot of the thermoelectric material in the z direction (see FIG. 3) by wire sawing, plasma discharge processing, or the like. Here, the diffusion barrier layer 20 is present only on the upper surface of the thermoelectric leg 10, and the thermoelectric leg 10 is exposed on the other surface.

Step 4: As shown in FIG. 5, if all of the remaining 5 or 6 surfaces are possible except for the lower surface of the low-temperature part of the thermoelectric leg 10, the magnesium silicide (Mg ₂ Si) on which the diffusion barrier layer 20 is formed. Cr is deposited on all surfaces using a sputtering technique to a thickness of about 100 nm.

Step 5: As shown in FIG. 6, a thermoelectric module is fabricated using the diffusion barrier layer 20 and the thermoelectric leg 10 on which the oxidation barrier layer 30 is formed.

At this time, as described above, the thermoelectric leg is bonded to the upper substrate electrode 200 and the lower substrate electrode 300, taking care that the upper surface of the thermoelectric leg 10 is positioned on the high temperature side.

Step 6: Thereafter, the temperature of the thermoelectric module is raised in the atmosphere or in an oxygen atmosphere to oxidize the oxidation preventing film 30 formed on the side of the thermoelectric leg 10 to form the oxide film 31 of Cr ₂ O ₃ . The temperature required to form the oxide layer 31 is preferably in the range of 400 to 600° C., which is the use temperature of the medium temperature thermoelectric module, and varies depending on the heat resistance of the thermoelectric leg 10 and the material and thickness of the oxidation barrier 30 .

In one embodiment, oxidation is performed for 1 hour at 500°C in an oxygen atmosphere at 1 atmosphere.

Here, the oxide film 31 is formed on the side exposed to the outside, but oxidation does not occur on the upper surface of the high temperature portion bonded to the upper substrate electrode 200 so that the original anti-oxidation film 30 remains.

As shown in FIG. 7, in order to examine the protection ability of the Cr ₂ O ₃ coating film formed on the surface, a thermogravimetric analysis (TGA) was performed in the air. While magnesium silicide (Mg ₂ Si) without a coating film shows a large change in weight due to the volatilization of Mg, a Cr ₂ O ₃ coating film is formed. Magnesium silicide (Mg ₂ Si) shows significant improvement. This means that Cr ₂ O ₃ effectively prevents oxidation and volatilization.

The method for manufacturing a thermoelectric module including a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer is formed and the thermoelectric module according to the diffusion barrier layer described above have been described in detail with reference to a preferred embodiment of the present invention. It is not limited to, and various modifications may be made by those of ordinary skill in the art within the scope of the technical idea of the present invention.

100: module substrate
200: upper substrate electrode
300: lower substrate electrode
10: thermoelectric leg
20: diffusion barrier layer
30: antioxidant film
31: oxide film

Claims (5)

A first step of synthesizing an ingot of magnesium silicide (Mg ₂ Si);
A second step of forming a diffusion barrier layer 20 by depositing a diffusion barrier material on an upper surface of the ingot of the magnesium silicide (Mg ₂ Si) by a sputtering technique;
A third step of cutting the ingot to form a cuboid-shaped thermoelectric leg (10);
A fourth step of forming an antioxidant film 30 by sputtering deposition of Al or Cr on the remaining 5 surfaces of the thermoelectric leg 10 except for the front surface (6 surfaces) or the lower surface at the low temperature side;
A fifth step of forming a thermoelectric module by bonding the upper surface of the thermoelectric leg 10 to the upper substrate electrode 200 and the lower substrate electrode 300 so that the upper surface of the thermoelectric leg 10 is positioned on the high temperature side;
An aluminum oxide film (Al ₂ O ₃ ) or A sixth step of forming an oxide film 31 of a chromium oxide film (Cr ₂ O ₃ );
A method of manufacturing a thermoelectric module having a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg having an oxide layer formed thereon. The method of claim 1,
The diffusion barrier layer is a metal such as nickel, cobalt, titanium, molybdenum, chromium, iron, stainless steel, etc., or a material of any one of TaN, TiN, TaSiN, TiSiN, MoSi ₂ , TiSi ₂ , TaSi ₂ A method of manufacturing a thermoelectric module provided with a thermoelectric leg on which an anti-oxidation layer, an antioxidant layer, and an oxide layer are formed. It is manufactured by a thermoelectric module manufacturing method provided with a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg on which an oxide layer of claim 1 or 2 is formed.
A diffusion barrier layer formed on the upper surface;
An oxidation prevention film formed on an upper surface of the diffusion prevention layer;
An oxide film formed on the outer surface;
The formed thermoelectric leg
A thermoelectric with a diffusion barrier layer, an oxidation barrier layer, and a thermoelectric leg with an oxide layer, characterized in that the upper surface is connected in contact with the upper substrate electrode between an upper substrate electrode installed on a substrate in a high temperature region and a lower substrate electrode installed on a substrate in a low temperature region. module.
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