JP2005277343A - Thermoelectric conversion element and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoelectric conversion element constituted by using an Fe<SB>2</SB>VAl series thermoelectric material formed into a thin film shape, and having sufficiently high thermoelectric capability, and to provide a manufacturing method for that. <P>SOLUTION: The thermoelectric conversion element 1 has a structure in which a thin film shaped n-type thermoelectric member 11 with a thickness of 5μm and a thin film shaped p-type thermoelectric member 12 with a thickness of 5μm are formed on the surface of a substrate 10. The n-type thermoelectric member 11 is formed of Fe<SB>50</SB>V<SB>25</SB>Al<SB>23.5</SB>Si<SB>1.5</SB>, and the p-type thermoelectric member 12 of Fe<SB>49.3</SB>V<SB>24.7</SB>Al<SB>26</SB>, and both are formed onto the surface of the substrate 10, heated up to 500°C or more and 1,000°C or less, by using sputtering, one of the physical vapor disposition techniques. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoelectric conversion element and a manufacturing method thereof.

  A thermoelectric conversion element is an element used to perform thermoelectric power generation by the Seebeck effect and thermoelectric cooling (electronic cooling) by the Peltier effect, and in general, alternately a plurality of p-type thermoelectric materials and a plurality of n-type thermoelectric materials. The structure is connected in series.

  In manufacturing this type of thermoelectric conversion element, conventionally, a raw material composition having the same composition as that of a p-type thermoelectric material or an n-type thermoelectric material is heated, melted or sintered, and then mechanically processed (cutting). Then, the block-shaped molded bodies were cut out, arranged on the substrate, and connected in series.

  However, since many thermoelectric materials have low mechanical strength, fine precision processing is difficult, and it has been difficult to reduce the size and thickness. Moreover, in the cutting process of the molded body, there is a problem that the yield is lowered.

  In response to such problems, the present inventors have already proposed a technique for manufacturing a thermoelectric conversion member by forming a thin film of a thermoelectric material by a physical vapor deposition technique such as sputtering (see Patent Document 1 below). .

According to such a manufacturing method, since a thin film-like thermoelectric material can be formed, a thin film of a thermoelectric material having a fine and complicated pattern can be formed, and an extremely small and thin thermoelectric conversion element can be obtained. Therefore, the thermoelectric conversion element could be arranged in a narrow space that was difficult to mount with the thermoelectric conversion element manufactured from the block-shaped molded body.
JP 2003-133660 A

By the way, in recent years, an Fe ₂ VAl thermoelectric material has attracted attention as one of thermoelectric materials, but this Fe ₂ VAl thermoelectric material is also a material that is difficult to finely process because of its low strength and poor workability.

Accordingly, the present inventors have made the Fe ₂ VAl thermoelectric material into a thin film by the technique described in Patent Document 1, thereby reducing the size and thickness of the thermoelectric conversion element using the Fe ₂ VAl thermoelectric material. I thought that could be achieved.

However, when a Fe ₂ VAl thermoelectric material was actually sputtered to form a thin film on the substrate, a thermoelectric conversion element was constructed, and a temperature difference was given to the thermoelectric conversion element, only a small voltage was generated. It was not possible to obtain a thermoelectric power generation device that could be put into practical use.

In order to solve such problems, the present inventors have further studied, and as a result, if the Fe ₂ VAl-based thermoelectric material thinned under a specific condition, the thermoelectric performance to the extent that it can be used as a thermoelectric power generation element. Found that would be higher.

The present invention has been completed on the basis of the above knowledge, and its purpose is a thermoelectric conversion element configured using a Fe ₂ VAl thermoelectric material formed in a thin film, and its thermoelectric performance is It is to provide a sufficiently high thermoelectric conversion element and a method for manufacturing the same.

The characteristic configuration employed in the present invention will be described below.
The thermoelectric conversion element of the present invention is
A thermoelectric conversion element having a structure in which a p-type thermoelectric material and an n-type thermoelectric material are connected in series,
At least one of the p-type thermoelectric material and the n-type thermoelectric material is an Fe ₂ VAl-based thermoelectric material, and the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less of the Fe ₂ VAl-based thermoelectric material It is characterized by being formed into a thin film by physical vapor deposition technology.

In this thermoelectric conversion element, the Fe ₂ VAl-based thermoelectric material is formed into a thin film by physical vapor deposition technology, and its thickness is not limited as long as sufficient thermoelectric performance can be obtained. However, it is desirable that the film is formed in the form of a thin film having a thickness of 0.1 to 100 μm because sufficiently satisfactory thermoelectric performance can be obtained and a sufficiently space-saving element can be configured. If the thickness is less than 0.1 μm, it will be difficult to achieve sufficiently satisfactory thermoelectric performance. On the other hand, even if the thickness is 100 μm or more, it cannot be expected that significant improvement in thermoelectric performance can be expected.

Further, the Fe ₂ VAl-based thermoelectric material can be a p-type thermoelectric material or an n-type thermoelectric material by controlling the composition ratio of its constituent elements or adding a small amount of a fourth element. More specifically, for example, when the Fe ₂ VAl thermoelectric material is to be a p-type thermoelectric material, the composition ratio is controlled to replace some Fe sites or V sites with Al, or as the fourth element. By adding a small amount of Ti, Ni, Mo or the like, it is preferable to replace some V sites with these fourth elements. If the Fe ₂ VAl-based thermoelectric material is to be an n-type thermoelectric material, a small amount of Si, Ni, Ge, rare earth (eg, Y), etc. is added as the fourth element, so that a part of Al is added to the fourth element. Replace the site.

  Further, the material of the base material is not particularly limited as long as the shape can be maintained even when heated to 500 ° C. or more and 1000 ° C. or less, and the alteration is not caused. However, for example, it is preferable to use a ceramic material or the like. It is. Examples of ceramic materials include zirconia, alumina, silica, silicon carbide, silicon nitride, aluminum nitride, mullite, steatite, cordierite, sapphire, titania, and forsterite. The ceramic material can be used.

  Furthermore, examples of the physical vapor deposition technique that can be used in the present invention include sputtering, ion beam sputtering, ion plating, vacuum vapor deposition, laser vapor deposition, and electron beam epitaxial growth (MBE).

In the present invention, it is important that the Fe ₂ VAl thermoelectric material as described above is formed into a thin film by a physical vapor deposition technique on the surface of a substrate heated to 500 ° C. or more and 1000 ° C. or less. It is. That is, even if the Fe ₂ VAl-based thermoelectric material is a thin film formed by physical vapor deposition technology on the surface of the base material, when the base material is only heated to less than 500 ° C. when the thin film is formed, Alternatively, when it is heated to over 1000 ° C., it becomes a thin film different from the thin film of the Fe ₂ VAl-based thermoelectric material employed in the present invention, and it tends to be difficult to obtain practically satisfactory thermoelectric performance. This fact was discovered by the inventors during repeated trial manufacture of thermoelectric conversion elements.

The reason why the Fe ₂ VAl thermoelectric material formed in a thin film on the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less by physical vapor deposition technology is high may be due to various factors overlapping. However, it is difficult to specify all of these factors. For example, by setting the temperature to 500 ° C. or higher, the regularity, crystallinity, or denseness of the constituent elements contained in the Fe ₂ VAl-based thermoelectric material is as described above. It is presumed that there are factors that are optimized under temperature conditions and that adverse effects from the substrate side can be suppressed by setting the temperature to 1000 ° C. or lower.

As a result, even a thin film of Fe ₂ VAl thermoelectric material formed by physical vapor deposition technology, a thin film formed on the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less, and 500 ° C. In the thin film formed on the surface of the base material that has been heated to less than or less than 1000 ° C., the regularity, crystallinity, and compactness of the constituent elements in the thin film It is speculated that there will be a difference in thermoelectric performance due to thin films with different microscopic structures.

In addition, although there may be factors other than the above, in any case, the Fe ₂ VAl system formed into a thin film by a physical vapor deposition technique on the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less. If it is a thermoelectric material, practically sufficiently satisfactory thermoelectric performance can be obtained.

Therefore, according to the present invention, at least one of the p-type thermoelectric material and the n-type thermoelectric material is an Fe ₂ VAl-based thermoelectric material, and this Fe ₂ VAl-based thermoelectric material is thinned on the surface of the substrate by physical vapor deposition technology. The thermoelectric performance of a thermoelectric conversion element having a structure formed in a shape can be sufficiently increased, and a thermoelectric conversion element having a small and thin structure using an Fe ₂ VAl-based thermoelectric material can be put into practical use. it can. In addition, if a thermoelectric conversion element having the same size as that of a conventional product can be configured, more Fe ₂ VAl-based thermoelectric material thin films can be integrated, so that higher output can be achieved. You can also.

Incidentally, when a Bi-Te-based thermoelectric material, which is one of the representative thermoelectric materials, is thinned by the technique described in Patent Document 1, a good thermoelectric performance can be obtained by using a thin film of about 30 μm. However, in the case of an Fe ₂ VAl thermoelectric material formed into a thin film by a physical vapor deposition technique on the surface of a substrate heated to 500 ° C. or more and 1000 ° C. or less, it is ½ or less of Bi—Te thermoelectric material ( A good thermoelectric performance can be obtained even with a film thickness of, for example, about 5 μm. Therefore, a thermoelectric conversion element having a smaller and thinner structure can be formed than a thin Bi-Te thermoelectric material.

In addition, the thermoelectric conversion element of this invention may be further comprised as follows.
First, in the thermoelectric conversion element of the present invention, both the p-type thermoelectric material and the n-type thermoelectric material may be Fe ₂ VAl-based thermoelectric materials, or one of the p-type thermoelectric material and the n-type thermoelectric material is Fe. ₂ VAl-based thermoelectric material, and the other may be a heterogeneous thermoelectric material having different constituent elements from the Fe ₂ VAl-based thermoelectric material.

When both the p-type thermoelectric material and the n-type thermoelectric material are Fe ₂ VAl-based thermoelectric materials, they do not contain harmful components, unlike Bi-Te-based thermoelectric materials that are one of the typical thermoelectric materials. Therefore, the use of the thermoelectric conversion element is expanded, and the problem of polluting the environment at the time of disposal is eliminated.

In addition, when one is Fe ₂ VAl thermoelectric material and the other is heterogeneous thermoelectric material, the performance of the thermoelectric conversion element can be improved by using different thermoelectric material with higher thermoelectric performance than Fe ₂ VAl thermoelectric material. In addition, it is possible to improve the productivity of the thermoelectric conversion element by using a dissimilar thermoelectric material having higher workability than the Fe ₂ VAl-based thermoelectric material. In the case of such a configuration, it is desirable that the dissimilar thermoelectric material is also formed into a thin film on the surface of the substrate by a physical vapor deposition technique in order to reduce the size and thickness of the thermoelectric conversion element.

  Bi-Te based thermoelectric materials, Mg—Si based thermoelectric materials, Mn—Si based thermoelectric materials, Fe—Si based thermoelectric materials, Si—Ge based thermoelectric materials, Pb—Te based thermoelectric materials, chalcogenite based materials Any of a thermoelectric material, a skutterudite thermoelectric material, a filled skutterudite thermoelectric material, or a boron carbide thermoelectric material can be used.

Also, the thermoelectric conversion element of the present invention, among the p-type thermoelectric material and the n-type thermoelectric material, one Fe ₂ VAl-based thermoelectric material, if the other is different thermoelectric materials, Fe ₂ VAl-based thermoelectric material and dissimilar thermoelectric materials Of these, the one with the higher melting temperature is first formed into a thin film by the physical vapor deposition technique on the surface of the substrate, and the one with the lower melting temperature is later formed into a thin film on the surface of the base material by the physical vapor deposition technique. The structure should be good. In this way, when the lower melting temperature is formed on the surface of the base material by a physical vapor deposition technique, the thin film is formed by the physical vapor deposition technique under a temperature condition that does not melt the higher melting temperature. Thus, a thin film having a low melting temperature can be formed without adversely affecting the thin film having a high melting temperature which has been previously formed into a thin film by a physical vapor deposition technique.

In the present invention, when forming a thin film of Fe ₂ VAl thermoelectric material, it is essential to form a thin film by physical vapor deposition on the surface of a substrate heated to 500 ° C. or more and 1000 ° C. or less. In the case of a dissimilar thermoelectric material having a melting temperature exceeding 1000 ° C., the film may be formed before the Fe ₂ VAl thermoelectric material, and in the case of a dissimilar thermoelectric material having a melting temperature lower than 500 ° C., the Fe ₂ VAl thermoelectric material may be used. The film may be formed later than the material. Any one of the different thermoelectric materials having a melting temperature of 500 ° C. to 1000 ° C. may be formed first, but a better order may be determined by appropriately performing trial manufacture or the like.

  The thermoelectric conversion element of the present invention may have a structure in which a p-type thermoelectric material and an n-type thermoelectric material are connected in series via a conductive material. In this case, the conductive material is a surface of a base material. In addition, it may be formed into a thin film by a physical vapor deposition technique.

  As the conductive material, for example, a metal such as gold, silver, copper, or aluminum can be used. As a condition of the conductive material, any material may be used as long as the material has a low electrical resistivity. By using such a conductive material, even when the bonding property between the p-type thermoelectric material and the n-type thermoelectric material is low, the conductive material having a high bonding property with the p-type thermoelectric material and the n-type thermoelectric material is interposed. The p-type thermoelectric material and the n-type thermoelectric material can be more reliably electrically connected.

  The order in which the thermoelectric material and the conductive material are provided is not particularly limited. By forming in the order of p-type thermoelectric material → conductive material → n-type thermoelectric material or n-type thermoelectric material → conductive material → p-type thermoelectric material. In addition, a conductive material may be sandwiched between a p-type thermoelectric material and an n-type thermoelectric material that are stacked by physical vapor deposition technology, or the p-type thermoelectric material is not overlapped with the p-type thermoelectric material and the n-type thermoelectric material. The conductive material may be deposited by physical vapor deposition technology so as to span between the material and the n-type thermoelectric material. When a conductive material is deposited by physical vapor deposition technology so as to span between the p-type thermoelectric material and the n-type thermoelectric material, the physical vapor deposition of the p-type thermoelectric material, the n-type thermoelectric material, and the conductive material in any order. Even if the film is formed by a technique, the conductive material can be provided so as to be bridged between the p-type thermoelectric material and the n-type thermoelectric material.

As described above, according to the present invention, it is possible to provide a thermoelectric conversion element that is configured using an Fe ₂ VAl-based thermoelectric material formed in a thin film and has sufficiently high thermoelectric performance. Moreover, the manufacturing method of such a thermoelectric conversion element can be provided.

Next, an embodiment of the present invention will be described with an example.
[Example 1]
First, Example 1 will be described.

As shown in FIG. 1A, the thermoelectric conversion element 1 of Example 1 has a structure in which an n-type thermoelectric material portion 11 and a p-type thermoelectric material portion 12 are formed on the surface of a substrate 10.
The substrate 10 is a ceramic (zirconia) single-layer substrate having a length of 30 mm × width of 5 mm × thickness of 200 μm.

The n-type thermoelectric material portion 11 is a thin film layer having a thickness of about 5 μm formed of an n-type thermoelectric material. In this embodiment, a small amount of Si is added to Fe—V—Al as an n-type thermoelectric material. N-type thermoelectric materials (composition ratio Fe ₅₀ V ₂₅ Al _23.5 Si _1.5 ) are used.

The p-type thermoelectric material portion 12 is a thin film layer having a thickness of about 5 μm formed of the p-type thermoelectric material. In this embodiment, as the p-type thermoelectric material, the Al compounding ratio of Fe—V—Al is increased. A p-type thermoelectric material (composition ratio Fe _49.3 V _24.7 Al ₂₆ ) is used.

  The n-type thermoelectric material part 11 and the p-type thermoelectric material part 12 are both formed by sputtering, which is one of physical vapor deposition techniques, and specifically manufactured by the following procedure. is there.

  First, a first masking jig having an opening having the same shape as the pattern of the n-type thermoelectric material portion 11 is placed on the substrate 10 to perform the first masking, and this is performed using a known sputtering apparatus. And the first sputtering is performed.

More specifically, in this embodiment, an RF sputtering apparatus is used, and the above-described Fe ₅₀ V ₂₅ Al _23.5 Si _1.5 is used as a target. Then, after the pressure in the chamber is reduced to 3.0 × 10 ⁻³ Pa or less by vacuum, a lamp heater under the substrate 10 is inserted in order to raise the substrate temperature to 600 ° C. After the heater is turned on, it is waited for the degree of vacuum to be reduced to 3.0 × 10 ⁻³ Pa or less, and after reducing the pressure, Ar gas is introduced as a sputtering gas. Then, the first sputtering is performed under the sputtering conditions of output: 300 W and Ar gas pressure: 1.0 × 10 ⁻¹ Pa. When the first sputtering is finished, the first masking jig is removed from the substrate 10. By performing such processing, an n-type thermoelectric material portion 11 is formed on the surface of the substrate 10 as shown in FIG.

  Next, a second masking jig having an opening having the same shape as the pattern of the p-type thermoelectric material portion 12 is placed on the substrate 10 (on the surface on which the n-type thermoelectric material portion 11 is formed). Then, the second masking is performed, and it is again put in the sputtering apparatus, and the second sputtering is performed.

More specifically, in this embodiment, an RF sputtering apparatus is used, and the above-described Fe _49.3 V _24.7 Al ₂₆ is used as a target. Then, after the pressure in the chamber is reduced to 3.0 × 10 ⁻³ Pa or less by vacuum, a lamp heater under the substrate 10 is inserted in order to raise the substrate temperature to 600 ° C. After the heater is turned on, it is waited for the degree of vacuum to be reduced to 3.0 × 10 ⁻³ Pa or less, and after reducing the pressure, Ar gas is introduced as a sputtering gas. Then, the second sputtering is performed under the sputtering conditions of output: 300 W, Ar gas pressure: 1.0 × 10 ⁻¹ Pa. When the second sputtering is finished, the second masking jig is removed from the substrate 10. By performing such processing, the p-type thermoelectric material portion 12 is formed on the surface of the substrate 10 in addition to the n-type thermoelectric material portion 11 previously formed as shown in FIG. Will be formed.

  The opening of the second masking jig is opened in such a shape that the end of the n-type thermoelectric material portion 11 is exposed, and the exposed portion of the n-type thermoelectric material portion 11 has a second sputtering. As shown in FIG. 1C, the p-type thermoelectric material portion 12 is formed so as to overlap. In this overlapping portion, the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 are electrically connected, and the eight substantially strip-shaped n-type thermoelectric material portions 11 and the eight approximately strip-shaped p-type thermoelectric material portions 12. However, it becomes the structure connected in series alternately.

  As described above, the connection between the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 is sputtered so that the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 are overlapped. Thus, an electrically connected structure may be formed, but another conductive material may be interposed.

  As a specific example, for example, as shown in FIG. 2A, an n-type thermoelectric material portion 11 and a p-type thermoelectric material portion 12 are formed on the surface of the substrate 10 by sputtering so that they do not overlap. Thereafter, a conductive portion 13 that contacts both the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 is formed by sputtering a metal having higher conductivity (for example, gold, silver, copper, aluminum, etc.). . With such a structure, the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 can be electrically connected via the conductive portion 13. In this case, the number of steps for forming the conductive portion 13 by sputtering increases, but the n-type thermoelectric material is used even when the adhesion when the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 are directly bonded is low. By forming the conductive part 13 with a conductive substance having high adhesion to both the part 11 and the p-type thermoelectric material part 12, the adhesion between the joints can be increased.

  The order in the case of providing the n-type thermoelectric material part 11, the p-type thermoelectric material part 12, and the conductive part 13 is not particularly limited. In addition to forming the conductive part 13 last as described above, for example, FIG. As shown in b), after one thermoelectric material part (for example, p-type thermoelectric material part 12) is formed, conductive part 13 is formed, and then the other thermoelectric material part (for example, n-type thermoelectric material part 11) is formed. It may be formed. Alternatively, as shown in FIG. 2C, the conductive portion 13 may be formed first, and then the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 may be formed.

  However, if there is a difference in the melting temperatures of the forming materials of the n-type thermoelectric material part 11, the p-type thermoelectric material part 12, and the conductive part 13, sputtering is performed in descending order of the melting temperature, and melting is performed in each sputtering step. The substrate 10 is preferably heated to about the temperature. If it carries out like this, a thin film with high crystallinity can be obtained in each sputtering process, and it can prevent melting the thin film by a previous sputtering process by the heating in a later sputtering process.

  Further, as shown in FIG. 1C, even when sputtering is performed so that the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 are formed to overlap each other, as shown in FIG. Thus, it is possible to interpose the conductive part 13 between the n-type thermoelectric material part 11 and the p-type thermoelectric material part 12. Also in this case, even when the adhesion when the n-type thermoelectric material part 11 and the p-type thermoelectric material part 12 are directly bonded is low, both the n-type thermoelectric material part 11 and the p-type thermoelectric material part 12 By forming the conductive portion 13 with a conductive material having high adhesiveness, it is possible to increase the adhesiveness between the joint portions.

  The desired thermoelectric conversion element 1 can be obtained by the above processes. A circular soldering land having a slightly larger area than other portions is formed at both ends of the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 that are alternately connected in series. Thus, the lead wire can be soldered. Depending on the purpose of use of the thermoelectric conversion element 1, a product obtained by soldering a lead wire to the soldering land may be shipped as a product.

[Example 2]
Next, Example 2 will be described. In addition, the thermoelectric conversion element of Example 2 is a p-type thermoelectric material used for forming the p-type thermoelectric material part, and the processing conditions thereof are different from those of Example 1 above. Since the shape and the like are the same as those of the thermoelectric conversion element of the first embodiment, those used in the description of the first embodiment are used as they are for the drawings.

The thermoelectric conversion element of Example 2 also has a structure in which an n-type thermoelectric material portion 11 and a p-type thermoelectric material portion 12 are formed on the surface of a substrate 10 as shown in FIG.
Among these, the substrate 10 and the n-type thermoelectric material portion 11 are configured in exactly the same manner as in the first embodiment.

The p-type thermoelectric material portion 12 is a thin film layer having a thickness of about 30 μm formed of a p-type thermoelectric material. In this embodiment, as the p-type thermoelectric material, Sb is added to Bi-Te to form a p-type thermoelectric material. A material (composition ratio (Bi ₂ Te ₃ ) _0.25 (Sb ₂ Te ₃ ) _0.75 )) is used.

  The n-type thermoelectric material part 11 and the p-type thermoelectric material part 12 are both formed by sputtering, which is one of physical vapor deposition techniques, and specifically manufactured by the following procedure. is there.

  First, a first masking jig having an opening having the same shape as the pattern of the n-type thermoelectric material portion 11 is placed on the substrate 10 to perform the first masking, and this is performed using a known sputtering apparatus. And the first sputtering is performed. Since this process is exactly the same as in the first embodiment, detailed description thereof is omitted here.

  Next, a second masking jig having an opening having the same shape as the pattern of the p-type thermoelectric material portion 12 is placed on the substrate 10 (on the surface on which the n-type thermoelectric material portion 11 is formed). Then, the second masking is performed, and it is again put in the sputtering apparatus, and the second sputtering is performed.

More specifically, in this embodiment, an RF sputtering apparatus is used, and (Bi ₂ Te ₃ ) _0.25 (Sb ₂ Te ₃ ) _0.75 described above is used as a target. Then, after reducing the pressure in the chamber to 3.0 × 10 ⁻³ Pa or less by vacuum, a lamp heater under the substrate 10 is put in order to raise the substrate temperature to 340 ° C. After the heater is turned on, it is waited for the degree of vacuum to be reduced to 3.0 × 10 ⁻³ Pa or less, and after reducing the pressure, Ar gas is introduced as a sputtering gas. Then, the second sputtering is performed under the sputtering conditions of output: 40 W, Ar gas pressure: 1.0 × 10 ⁻¹ Pa, and sputtering time of 90 minutes. When the second sputtering is finished, the second masking jig is removed from the substrate 10. By performing such processing, the p-type thermoelectric material portion 12 is formed on the surface of the substrate 10 in addition to the n-type thermoelectric material portion 11 previously formed as shown in FIG. Will be formed.

  When the n-type thermoelectric material portion 11 is formed, the substrate temperature is raised to 600 ° C., but when the p-type thermoelectric material portion 12 is formed, the substrate temperature is raised only to 340 ° C. Therefore, in the step of forming the p-type thermoelectric material portion 12, the thin film of the n-type thermoelectric material portion 11 is not melted, and the form and physical properties of the n-type thermoelectric material portion 11 are not adversely affected.

  Note that the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 are formed so as to overlap each other depending on the shape of the opening of the first and second masking jigs. The n-type thermoelectric material portions 11 and the eight substantially strip-shaped p-type thermoelectric material portions 12 are alternately connected in series, and the n-type thermoelectric material portions 11 and p-type alternately connected in series. The point that solder lands are formed at both ends of the thermoelectric material portion 12 is the same as in the first embodiment.

[Comparative example]
In Example 1 above, the lamp heater under the substrate 10 was put in order to raise the substrate temperature to 600 ° C. when performing the first and second sputtering, but this heater was not put in. Sputtering was performed at room temperature, and the n-type thermoelectric material part 11 and the p-type were formed on the surface of the substrate 10 as shown in FIG. A thermoelectric conversion element having a structure in which the thermoelectric material portion 12 was formed was produced.

[performance test]
In order to test the thermoelectric performance of each of the thermoelectric conversion elements of Example 1, Example 2, and Comparative Example, a voltmeter was connected to each of the thermoelectric conversion elements as shown in FIG. The pattern of the n-type thermoelectric material portion 11 and the p-type thermoelectric material portion 12 of each thermoelectric conversion element is a pattern in which the joint portions thereof are alternately included in the high temperature portion and the low temperature portion shown in FIG. When the high temperature part is heated and the low temperature part is cooled, a voltage is generated according to the temperature difference ΔT between the high temperature part and the low temperature part, and this voltage is measured by the voltmeter. In this test, a stainless steel block heated to 100 ° C. was applied to the high temperature portion side, and an aluminum plate was applied to the low temperature portion side, so that a voltage difference of 30 ° C. or higher was given. Measurements were made. Thermovision was used for temperature measurement. The results are shown in Table 1 below.

  From the comparison between Example 1 and the comparative example, the voltage obtained when the substrate temperature is raised to 600 ° C. and when the substrate temperature is not raised greatly increases when the same temperature difference is given. I understand that. In addition, when this substrate temperature is less than 500 degreeC, since the said voltage tends to fall, it is thought that it is desirable that the substrate temperature at the time of sputtering shall be 500 degreeC or more. In addition, when the substrate temperature at the time of sputtering exceeded 1000 ° C., there was a tendency for the voltage to decrease.

Further, even if the Fe ₂ VAl-based thermoelectric material and the Fe ₂ VAl-based thermoelectric material are used in combination with different thermoelectric materials (Bi-Te-based thermoelectric material in the present embodiment) from Example 2 above, thermoelectric conversion is possible. It can be seen that the element can be configured. Comparing Example 1 and Example 2 described above, Example 2 generates a larger voltage with a smaller temperature difference. This is an effect obtained by combining different types of thermoelectric materials with higher performance in the p-type thermoelectric material portion 12. Among the various thermoelectric materials, high performance as a p-type thermoelectric material and n-type thermoelectric material are used. By selecting and combining materials having high performance, it can be expected that the thermoelectric performance of the thermoelectric conversion element, one of which is an Fe ₂ VAl-based thermoelectric material, can be improved.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.
For example, in the above-described embodiment, a specific composition ratio is shown for the Fe ₂ VAl-based thermoelectric material. However, this composition ratio is an example, and the composition is appropriately selected within a range in which performance as a p-type or n-type thermoelectric material can be maintained. The ratio may be changed. Further, in the above embodiment, an example in which Si is added as the fourth element to the Fe ₂ VAl-based thermoelectric material has been described. However, this may be performed as long as the performance as the p-type or n-type thermoelectric material can be maintained. Four elements can be added.

In the above embodiment, the Bi-Te thermoelectric material is exemplified as the dissimilar thermoelectric material combined with the Fe ₂ VAl thermoelectric material. However, this thermoelectric material can also improve performance by combining with the Fe ₂ VAl thermoelectric material. As long as it is a material, it may be a thermoelectric material other than Bi-Te. As such thermoelectric materials, for example, Mg—Si based thermoelectric materials, Mn—Si based thermoelectric materials, Fe—Si based thermoelectric materials, Si—Ge based thermoelectric materials, Pb—Te based thermoelectric materials, chalcogenite based thermoelectric materials, Examples include skutterudite-based thermoelectric materials, filled skutterudite-based thermoelectric materials, and boron carbide-based thermoelectric materials. Any of these may be used.

  Furthermore, in the above embodiment, sputtering, which is one of physical vapor deposition techniques, was used to form the thin film n-type thermoelectric material part 11 and p-type thermoelectric material part 12, but in the present invention, Other physical vapor deposition techniques can also be used. Examples of other physical vapor deposition techniques include ion beam sputtering, ion plating, vacuum vapor deposition, laser vapor deposition, and electron beam epitaxial growth (MBE). Among these, ion plating and electron beam epitaxial growth (MBE) are physical vapor deposition techniques that can form a thin film with high crystallinity, and are therefore suitable for producing a thermoelectric conversion element with high thermoelectric performance.

1 is a structural diagram of a thermoelectric conversion element exemplified as an embodiment of the present invention. Sectional drawing which shows the structure which electrically connected the n-type thermoelectric material part and the p-type thermoelectric material part through the electroconductive part. Explanatory drawing for demonstrating the method of a performance test.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... n-type thermoelectric material part, 12 ... p-type thermoelectric material part, 13 ... Conductive part.

Claims (8)

A thermoelectric conversion element having a structure in which a p-type thermoelectric material and an n-type thermoelectric material are connected in series,
At least one of the p-type thermoelectric material and the n-type thermoelectric material is an Fe ₂ VAl-based thermoelectric material, and the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less of the Fe ₂ VAl-based thermoelectric material A thermoelectric conversion element characterized in that it is formed into a thin film by physical vapor deposition technology. The thermoelectric conversion element according to claim 1, wherein the Fe ₂ VAl-based thermoelectric material is formed in a thin film shape having a thickness of 0.1 to 100 μm. The thermoelectric conversion element according to claim 1, wherein both the p-type thermoelectric material and the n-type thermoelectric material are Fe ₂ VAl-based thermoelectric materials. Of the p-type thermoelectric material and the n-type thermoelectric material, one is the Fe ₂ VAl-based thermoelectric material, and the other is a different-type thermoelectric material having different constituent elements from the Fe ₂ VAl-based thermoelectric material, The thermoelectric conversion element according to claim 1 or 2, wherein the thermoelectric conversion element is formed on the surface of the base material in a thin film shape by a physical vapor deposition technique. The dissimilar thermoelectric material is a Bi—Te based thermoelectric material, an Mg—Si based thermoelectric material, an Mn—Si based thermoelectric material, an Fe—Si based thermoelectric material, an Si—Ge based thermoelectric material, a Pb—Te based thermoelectric material, or a chalcogenite based material. The thermoelectric conversion element according to claim 4, wherein the thermoelectric conversion element is any one of a thermoelectric material, a skutterudite thermoelectric material, a filled skutterudite thermoelectric material, or a boron carbide thermoelectric material. Of the Fe ₂ VAl-based thermoelectric material and the dissimilar thermoelectric material, the one with the higher melting temperature is first formed into a thin film by a physical vapor deposition technique on the surface of the substrate, and the one with the lower melting temperature is the one of the substrate. The thermoelectric conversion element according to claim 5, wherein the thermoelectric conversion element has a structure formed on the surface in a thin film by a physical vapor deposition technique later. The p-type thermoelectric material and the n-type thermoelectric material are connected in series via a conductive material, and the conductive material is formed into a thin film on the surface of the substrate by physical vapor deposition technology. The thermoelectric conversion element according to any one of claims 1 to 6, wherein: A method of manufacturing a thermoelectric conversion element having a structure in which a p-type thermoelectric material and an n-type thermoelectric material are connected in series,
At least one of the p-type thermoelectric material and the n-type thermoelectric material is an Fe ₂ VAl thermoelectric material, and the surface of the substrate heated to 500 ° C. or more and 1000 ° C. or less of the Fe ₂ VAl thermoelectric material A method for manufacturing a thermoelectric conversion element, characterized in that the thin film is formed by physical vapor deposition technology.

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