KR20110014786A - The thermoelectric device having improved thermoelectric efficiency and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A thermoelectric device having improved thermoelectric efficiency and manufacturing a method thereof are provided to increase thermoelectric efficiency by using a thermal insulating film having low thermoelectric efficiency. CONSTITUTION: A heat absorbing film(230) is formed on a substrate(210) and absorbs an outer heat source. A leg(240) transfers the heat absorbed through the heat absorbing film to the heat radiation film. A heat radiation film(250) emits the heat which it is transmitted from the leg to outside. Thermal isolation films(220,260) reduce the heat transfer rate at the leg. The thermal isolation film is formed in at least one of the leg lower part and upper part.

Description

The thermoelectric device having improved thermoelectric efficiency and manufacturing method

The present invention relates to a thermoelectric device having improved thermoelectric efficiency and a method of manufacturing the same, and more particularly, a thermoelectric device having a low thermal conductivity formed at a lower leg or an upper leg thereof to which heat is slowly transferred from the leg to improve thermoelectric efficiency. The manufacturing method is related.

Due to population growth and industrial development, humans face energy shortages and environmental pollution. In order to solve this problem, many scientists are conducting a lot of research to find a new energy source to replace the existing fossil fuel.

As a result of this research, a thermoelectric device capable of converting radiant heat such as solar heat, geothermal heat, body heat and waste heat into electric energy has been developed.

1 is a view showing a thermoelectric device commonly used.

Referring to FIG. 1, the thermoelectric element 100 includes a heat absorption film 130, a leg 140, and a heat sink film 150. It consists of p-type leg 140p and n-type leg 140n.

The heat absorbing layer 130 serves to absorb an external heat source, and the leg 140 transfers the heat absorbed through the heat absorbing layer 130 to the heat dissipating layer 150. The heat dissipation film 150 serves to discharge heat received from the leg 140 to the outside.

Due to the temperature difference between the heat absorbing layer 130 and the heat dissipating layer 150, holes move from the heat absorbing layer 130 toward the heat dissipating layer 150 in the p-type leg 140p. In the n-type leg 140n, electrons move from the heat absorbing film 130 toward the heat emission film 150, and current flows in the counterclockwise direction according to the movement of the holes and the electrons.

In order for the thermoelectric element 100 to have a high thermoelectric efficiency, the heat absorbing layer 130 must transfer all of the heat absorbed by absorbing as much of an external heat source as possible to the leg 140, and the leg 140 absorbs heat. Heat received from the membrane 130 should be transferred to the heat dissipating membrane 150 as slowly as possible. In addition, the heat dissipation film 150 should emit as much heat as possible from the leg 140 without absorbing any external heat source.

That is, a high thermoelectric efficiency may be obtained only when the temperature difference between the heat absorbing film 130 and the heat emitting film 150 is large, and for this purpose, the thermal conductivity of the leg 140 should have a small value as possible.

The ZT value is used as an indicator of the thermoelectric efficiency (figure of merit) of the thermoelectric element.

The ZT value is proportional to the square of the Seebeck coefficient and the electrical conductivity and inversely proportional to the thermal conductivity value.

However, in the case of a thermoelectric element using a metal, the Seebeck coefficient value is very low, such as several kW / K, and the electrical conductivity and the thermal conductivity are proportional to each other according to the Wiedemann-Franz law. The thermoelectric element used cannot have a high ZT value.

Recently, a thermoelectric device using a semiconductor material has been developed. As a representative thermoelectric material, Bi ₂ having a ZT value of at least 0.7 at room temperature and a ZT value of 0.9 at a maximum of 120 ^° C. Te ₃ can be mentioned.

However, in view of the recent trend of development and mass production of products using thermoelectric devices, Bi ₂ Te ₃ is expected to be depleted soon, which is a material that can replace Bi ₂ Te ₃ , that is, room temperature. Research is underway on materials with ZT values of at least 0.7 levels.

In view of this, silicon has been recognized as difficult to use in thermoelectric elements because of its high thermal conductivity of about 150 W / m · K and a ZT value of about 0.01. However, recently, silicon nanowires grown by CVD (chemical vapor deposition) have been reported to have a ZT value close to 1, as the thermal conductivity can be reduced to 0.01 times or less. It is expected to be fully utilized.

However, the silicon nanowire has a problem that the manufacturing method is difficult and complicated, which can be a big obstacle to mass production in the actual product production stage.

An object of the present invention is to implement a thermoelectric element having a high thermoelectric efficiency in a simple manufacturing process.

Thermoelectric device according to an embodiment of the present invention to achieve the above object, the substrate; A heat absorption film formed on the substrate to absorb an external heat source; A leg transferring heat absorbed through the heat absorbing film to a heat emitting film; A heat dissipation film for dissipating heat transferred from the leg to the outside; And a thermal insulating layer formed on at least one of the lower and upper legs to reduce the heat transfer rate in the legs.

The thermal insulating film is preferably formed of any one of an oxide film, a nitride film, a polymer film, and a mixed film thereof having a thermal conductivity of 10 W / m · K or less at room temperature, and the oxide film and the nitride film are porous and meso. It is preferable to use a low density oxide film and a low density nitride film including a mesoporous state.

On the other hand, to achieve the above object, a method of manufacturing a thermoelectric device according to an embodiment of the present invention, (a) forming a first thermal insulating film for reducing the heat transfer rate in the leg on the substrate; And (b) a heat absorbing film absorbing an external heat source over the first heat insulating film, a leg transferring heat absorbed through the heat absorbing film to a heat emitting film, and a heat emission emitting heat transmitted from the leg to the outside. Forming a film.

According to another aspect of the present invention, there is provided a method of manufacturing a thermoelectric device, including: (a) a heat absorbing film that absorbs an external heat source on the insulating film after forming an insulating film on the substrate, and dissipates heat absorbed through the heat absorbing film. Forming a leg for transferring the film and a heat dissipation film for dissipating heat transferred from the leg to the outside; And (b) etching the insulating film formed under the leg to form a first thermal insulating film in the etched portion to reduce the heat transfer rate in the leg.

It is preferable to form a second thermal insulating film on the leg to reduce the heat transfer rate in the leg, wherein the first and second thermal insulating films are oxide films having a thermal conductivity value of 10 W / m · K or less at room temperature, It is preferable to form using any one of a nitride film, a polymer film, and these mixed films. Here, it is preferable to use a low density oxide film and a low density nitride film including a porous and mesoporous state as the oxide film and the nitride film.

In the thermoelectric element according to the present invention, since the heat transferred from the heat absorbing film in the leg is slowly transferred to the heat emitting film by a heat insulating film having a low thermal conductivity formed on or under the leg, the heat absorbing film and the heat emitting film The temperature difference between them is increased, the thermoelectric efficiency can be improved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In describing a preferred embodiment of the present invention, when a part is said to "include" a certain component, unless otherwise stated, it may not include other components, but may further include other components. Means that. In addition, in the drawings, the thicknesses of layers and regions are exaggerated for clarity, and in the case where the layers are said to be "on" another layer or substrate, they may be formed directly on another layer or substrate or Or a third layer may be interposed therebetween.

2 is a cross-sectional view of the thermoelectric element 200 according to the first embodiment of the present invention.

Referring to FIG. 2, the thermoelectric device 200 according to the first exemplary embodiment of the present invention may include a first thermal insulating film 220 formed on the substrate 210 and a column formed on the first thermal insulating film 220. The absorption film 230, the legs 240, and the heat dissipation film 250, and the second heat insulating film 260 formed on the heat absorption film 230, the legs 240, and the heat dissipation film 250 are included. do.

The substrate 210 may be any one of a silicon substrate, a glass substrate, a plastic substrate, a metal substrate, a silicon on insulator (SOI) substrate, and a substrate having a multilayer structure in which these substrates are combined.

The heat absorption film 230 serves to absorb an external heat source, the leg 240 transfers the heat absorbed through the heat absorption film 230 to the heat release film 250, the heat release The membrane 250 dissipates heat transferred from the leg 240 to the outside.

The first and second thermal insulating films 220 and 260 may have a low thermal conductivity of 10 W / m · K or less at room temperature, for example, oxide films such as SiO, SiON, TiO, TiON, AlO, AlON, SiN, and the like. It can be formed using any one of a nitride film, a polymer film such as PDMS (Polydimethylsiloxane), PR (Photo resist), polyimide (Polyimide), and a mixed film thereof.

Here, as the oxide film and the nitride film, a low density oxide film and a low density nitride film including a porous and mesoporous state may be used. In other words, if the optical refractive index of the general oxide film or the general nitride film is assumed to be 100%, the low density oxide film and the low density nitride film have an optical refractive index of 20 to 90%.

The leg 240 includes at least one element of Si, Ge, C, Sn, and Pb, which are elements of the Group 4 of the periodic table, or at least one element of Sb, As, Bi, P, and N, which are elements of the Group 5 of the periodic table. Or, at least one element of Te, Se, Po, S and O of the periodic table group 6 elements, the thickness is preferably 10nm ~ 1cm.

That is, the first and second column insulating layers 220 and 260 are formed at the lower and upper portions of the leg 240, respectively, and serve to reduce the speed at which heat is transferred from the leg 240.

Therefore, since the heat transferred from the heat absorbing film 230 in the leg 240 by the first and second thermal insulating films 220 and 260 is slowly transferred to the heat dissipating film 250, the heat absorbing film A temperature difference between the heat dissipation layer 230 and the heat dissipation layer 250 may be increased, thereby improving thermoelectric efficiency.

In this case, in order to sufficiently reduce the heat transfer rate in the leg 240, the first and second thermal insulating layers 220 and 260 preferably have a thermal conductivity value of 10 W / m · K or less at room temperature.

Meanwhile, in the present exemplary embodiment, the first and second column insulating layers 220 and 260 are formed on the lower and upper portions of the legs 240, but only one of the two may be formed in some cases.

3A to 3C are cross-sectional views illustrating a method of manufacturing the thermoelectric element 200 according to the first embodiment of the present invention.

First, as shown in FIG. 3A, a first thermal insulating layer 220 is formed on the substrate 210.

The first thermal insulating film 220 is a film having a low thermal conductivity of 10 W / mK or less at room temperature, for example, an oxide film such as SiO, SiON, TiO, TiON, AlO, AlON, a nitride film such as SiN, PDMS ( It can be formed using any one of a polymer film, such as a polydimethylsiloxane, a PR (Photo resist), a polyimide (Polyimide), and a mixed film thereof.

Here, as the oxide film and the nitride film, a low density oxide film and a low density nitride film including a porous and mesoporous state may be used.

The first thermal insulating layer 220 may be formed by thermal oxidation, chemical vapor deposition (CVD), sputtering, atomic layer deposition (ALD), a sol-gel method, and spin coating. Etc. can be used.

Next, as illustrated in FIG. 3B, a heat absorbing film 230, a leg 240, and a heat dissipating film 250 are formed on the first heat insulating film 220.

Finally, as shown in FIG. 3C, a second thermal insulating layer 260 is formed on the leg 240.

The second thermal insulating layer 260 may have a low thermal conductivity of 10 W / m · K or less at room temperature, for example, an oxide film such as SiO, SiON, TiO, TiON, AlO, AlON, a nitride film such as SiN, or PDMS ( It can be formed using any one of a polymer film, such as a polydimethylsiloxane, a PR (Photo resist), a polyimide (Polyimide), and a mixed film thereof.

Here, as the oxide film and the nitride film, a low density oxide film and a low density nitride film including a porous and mesoporous state may be used.

4 is a cross-sectional view of a thermoelectric element 200 ′ according to a second embodiment of the present invention.

Referring to FIG. 4, the thermoelectric element 200 ′ according to the second embodiment of the present invention includes an insulating film 210a formed on the substrate 210 and a first thermal insulating film 220 formed on the insulating film 210a. ), A heat absorbing film 230, a leg 240, and a heat dissipating film 250 formed on the first heat insulating film 220, the heat absorbing film 230, a leg 240, and a heat dissipating film. A second thermal insulating layer 260 formed on the upper portion 250 is included.

Here, the first thermal insulating layer 220 is formed in the lower region of the leg 240, or includes the lower region of the leg 240, the heat absorption film 230 and the heat release film 250 It may be formed over the lower portion or the entire area of the.

That is, the thermoelectric element 200 ′ according to the second embodiment of the present invention may have a first thermal insulation layer 220 on the insulation layer 210a on the substrate 210 as compared with the thermoelectric element 200 shown in FIG. 2. The other components are the same except that () is formed.

5A through 5D are cross-sectional views illustrating a method of manufacturing a thermoelectric device 200 ′ according to a second embodiment of the present invention.

First, as shown in FIG. 5A, an insulating film 210a is formed on the substrate 210, and then the heat absorbing film 230, the leg 240, and the heat dissipating film 250 are formed on the insulating film 210a. Form.

Next, as illustrated in FIG. 5B, the insulating layer 210a formed under the leg 240 is etched.

Here, when the insulating layer 210a is etched, the lower region of the leg 240 is etched, or the heat absorbing layer 230 and the heat dissipation layer 250 are included, including the lower region of the leg 240. The insulating layer 210a may be etched over the lower portion or the entire area of the substrate.

Next, as shown in FIG. 5C, the first thermal insulating layer 220 is formed on the etched portion of the insulating layer 210a.

The first thermal insulating film 220 is a film having a low thermal conductivity of 10 W / mK or less at room temperature, for example, an oxide film such as SiO, SiON, TiO, TiON, AlO, AlON, a nitride film such as SiN, PDMS ( It can be formed using any one of a polymer film, such as a polydimethylsiloxane, a PR (Photo resist), a polyimide (Polyimide), and a mixed film thereof.

Here, as the oxide film and the nitride film, a low density oxide film and a low density nitride film including a porous and mesoporous state may be used.

The first thermal insulating layer 220 may be formed by thermal oxidation, chemical vapor deposition (CVD), sputtering, atomic layer deposition (ALD), a sol-gel method, and spin coating. Etc. can be used.

Next, as shown in FIG. 5D, a second thermal insulating layer 260 is formed on the leg 240.

The second thermal insulating layer 260 may have a low thermal conductivity of 10 W / m · K or less at room temperature, for example, an oxide film such as SiO, SiON, TiO, TiON, AlO, AlON, a nitride film such as SiN, or PDMS ( It can be formed using any one of a polymer film, such as a polydimethylsiloxane, a PR (Photo resist), a polyimide (Polyimide), and a mixed film thereof.

Here, as the oxide film and the nitride film, a low density oxide film and a low density nitride film including a porous and mesoporous state may be used.

The second thermal insulating layer 260 may be formed by thermal oxidation, chemical vapor deposition (CVD), sputtering, atomic layer deposition (ALD), a sol-gel method, and spin coating. Etc. can be used.

As described above, the thermoelectric elements 200 and 200 ′ according to the present invention have the low thermal conductivity and the legs 240 by the first and second thermal insulating layers 220 and 260 contacting the legs 240. Because of the slow heat transfer in the thermoelectric efficiency is improved.

So far, the present invention has been described based on the preferred embodiments. However, embodiments of the present invention is provided to more fully describe the present invention to those skilled in the art, the scope of the present invention is not limited to the above embodiments, various other Of course, the shape can be modified.

1 is a view showing a thermoelectric device commonly used.

2 is a cross-sectional view of a thermoelectric device according to a first exemplary embodiment of the present invention.

3A to 3C are cross-sectional views illustrating a method of manufacturing a thermoelectric device according to a first embodiment of the present invention.

4 is a cross-sectional view of a thermoelectric device according to a second exemplary embodiment of the present invention.

5A to 5D are cross-sectional views illustrating a method of manufacturing a thermoelectric device according to a second exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: conventional thermoelectric element 130: heat absorption film

140, 140p, 140n: Leg, p-type leg, n-type leg

150: heat release film

200, 200 ': thermoelectric element 210 of the present invention: substrate

210a: insulating film 220: first thermal insulating film

230: heat absorption film 240: leg

250: heat release film 260: second heat insulating film

Claims (12)

Board; A heat absorption film formed on the substrate to absorb an external heat source; A leg transferring heat absorbed through the heat absorbing film to a heat emitting film; A heat dissipation film for dissipating heat transferred from the leg to the outside; And And a thermal insulating layer formed on at least one of the lower and upper portions of the leg to reduce a heat transfer rate in the leg. The thermoelectric device of claim 1, wherein the thermal insulating film is formed of any one of an oxide film, a nitride film, a polymer film, and a mixed film thereof having a thermal conductivity of 10 W / m · K or less at room temperature. The thermoelectric device of claim 2, wherein the thermal insulating layer is formed of a low density oxide film in a porous and mesoporous state or a low density nitride film in a porous and mesoporous state. The method of claim 1, And when the thermal insulating film is formed under the leg, the thermal insulating film is formed over the lower portion or the entire portion of the heat absorbing film and the heat dissipating film including the lower leg. The thermoelectric device of claim 1, wherein the substrate is any one of a silicon substrate, a glass substrate, a plastic substrate, a metal substrate, a silicon on insulator (SOI) substrate, and a substrate having a multilayer structure in which these substrates are combined. The method of claim 1 The leg includes at least one element of Si, Ge, C, Sn, and Pb, which are Group 4 elements of the periodic table, or includes at least one element of Sb, As, Bi, P, and N, which are Periodic Group 5 elements, or A thermoelectric device comprising at least one of Te, Se, Po, S, and O, which are Group 6 elements. (a) forming a first thermal insulating film over the substrate to reduce the rate of heat transfer in the legs; And (b) a heat absorbing film absorbing an external heat source on the first heat insulating film, a leg transferring heat absorbed through the heat absorbing film to a heat emitting film, and a heat emitting film emitting heat transmitted from the leg to the outside; Method for producing a thermoelectric element comprising the step of forming. (a) forming an insulating film on the substrate and then absorbing an external heat source on the insulating film; Forming a heat dissipating film to emit; And and (b) etching the insulating film formed under the leg to form a first thermal insulating film in the etched portion to reduce a heat transfer rate in the leg. The method of claim 7 or 8, wherein after step (b), And forming a second thermal insulating layer on the leg to reduce a rate of heat transfer in the leg. 10. The method of claim 9, wherein the first and second thermal insulating films are formed using any one of an oxide film, a nitride film, a polymer film, and a mixed film thereof having a thermal conductivity of 10 W / m · K or less at room temperature. Method of manufacturing a thermoelectric element. The method of claim 10, wherein the first and second thermal insulating films are formed by using a low density oxide film in a porous and mesoporous state or a low density nitride film in a porous and mesoporous state. The manufacturing method of the thermoelectric element. The method of claim 8, wherein in step (b), And etching the lower region of the leg when the insulating layer is etched, or etching the insulating layer over a portion or the entire region of the heat absorbing layer and the heat dissipating layer, including the lower region of the leg. Manufacturing method.

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