Method for manufacturing a thermoelectric conversion element

Abstract

The present invention provides a method for manufacturing a thermoelectric conversion element that has a thermoelectric element layer with excellent shape controllability and that can be highly integrated. The method for manufacturing a thermoelectric conversion element includes a thermoelectric element layer (4a, 4b) made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate (1), and includes the steps of providing a pattern frame (2) having an opening (3) on the substrate, filling the opening with the thermoelectric semiconductor composition, drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and peeling the pattern frame off the substrate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a thermoelectric conversion element.

Background Art

[0002] Conventionally, as one means for effectively using energy, there has been an apparatus that directly converts thermal energy and electrical energy with a thermoelectric conversion module having a thermoelectric effect such as the Seebeck effect or the Peltier effect. Among these, as the thermoelectric conversion element, the use of a so-called π-type thermoelectric conversion element is known. The π-type usually has a pair of electrodes spaced apart from each other provided on a substrate. For example, a P-type thermoelectric element is provided on one electrode, and an N-type thermoelectric element is provided on the other electrode, also spaced apart from each other, and the upper surfaces of both thermoelectric elements are connected to the electrodes of the opposing substrate. Further, the use of a so-called in-plane type thermoelectric conversion element is known. The in-plane type is usually configured by arranging a plurality of thermoelectric elements so that N-type thermoelectric elements and P-type thermoelectric elements are alternately arranged, and connecting the electrodes at the lower portions of the thermoelectric elements in series, for example.

[0003] In recent years, there have been demands such as improvement of thermoelectric performance including thinning and high integration of thermoelectric conversion elements. In Patent Document 1, as a thermoelectric element layer, a method of forming a pattern of a thermoelectric element layer directly by using a thermoelectric semiconductor composition containing a resin or the like from the viewpoint of thinning by thinning is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method of forming a thermoelectric element directly as a pattern layer on an electrode or a substrate by a screen printing method or the like using a thermoelectric semiconductor composition made of a thermoelectric semiconductor material, a heat-resistant resin, etc., as in Patent Document 1, the shape controllability of the obtained thermoelectric element layer is not sufficient, and bleeding occurs at the end of the thermoelectric element layer at the electrode interface or the substrate interface, or the shape of the thermoelectric element layer collapses and cannot be controlled to a desired shape. For example, when configuring the above-described π-type thermoelectric conversion element, sufficient electrical and physical bonding properties may not be obtained between the upper surface of the obtained thermoelectric element layer and the electrode surface on the opposing substrate. In this case, the thermoelectric performance originally possessed by the thermoelectric element layer, such as an increase in thermal resistance, cannot be sufficiently extracted, and it is necessary to increase the number of P-type thermoelectric element layer - N-type thermoelectric element layer pairs in order to obtain a predetermined power generation performance or cooling performance, etc. Furthermore, in the high integration of the π-type thermoelectric conversion element, the variation in the resistance values of a plurality of each P-type thermoelectric element layer - N-type thermoelectric element layer pair may increase, or adjacent thermoelectric element layers may come into contact with each other. Similarly, when highly integrating the configuration of the above-described in-plane type thermoelectric conversion element, the ends of the P-type thermoelectric element layer and the N-type thermoelectric element layer may penetrate each other and the interface may become unclear, and together with the variation in the resistance values of a plurality of each P-type thermoelectric element layer - N-type thermoelectric element layer pair, the occurrence or output of a temperature difference may vary between the joints of the adjacent P-type thermoelectric element layer and N-type thermoelectric element layer.

[0006] In view of the above, an object of the present invention is to provide a method for manufacturing a highly integrable thermoelectric conversion element having a thermoelectric element layer with excellent shape controllability.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the present inventors provided a pattern frame having spaced-apart openings on a substrate, filled a thermoelectric semiconductor composition containing a thermoelectric semiconductor material into the openings, dried it to form a thermoelectric element layer, and then peeled the pattern frame from the substrate, thereby finding a method for manufacturing a highly integrable thermoelectric conversion element having a thermoelectric element layer with excellent shape controllability and completing the present invention. That is, the present invention provides the following (1) to (13). (1) A method for manufacturing a thermoelectric conversion element including a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, the method including the steps of providing a pattern frame having an opening on the substrate, filling the opening with the thermoelectric semiconductor composition, drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and peeling the pattern frame from the substrate. (2) The method for manufacturing a thermoelectric conversion element according to (1) above, further including a step of annealing the thermoelectric element layer. (3) The method for manufacturing a thermoelectric conversion element according to (2) above, wherein the temperature of the annealing treatment is 250 to 600 °C. (4) The method for manufacturing a thermoelectric conversion element according to (2) or (3) above, including a step of peeling chips constituting the thermoelectric element layer after the annealing treatment. (5) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (4) above, wherein the substrate is a polyimide film, a polyamide film, a polyetherimide film, a polyaramide film, or a polyamideimide film. (6) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (5) above, wherein the pattern frame contains stainless steel, copper, aluminum, or iron. (7) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (6) above, wherein the pattern frame contains a ferromagnetic material. (8) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (7) above, wherein a release layer is included on the wall surface of the opening of the pattern frame. (9) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (8) above, including a step of fixing the pattern frame to the substrate using a magnet. (10) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (9) above, wherein the thermoelectric semiconductor composition further contains a heat-resistant resin and an ionic liquid and / or an inorganic ionic compound. (11) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (10) above, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material. (12) The method for manufacturing a thermoelectric conversion element according to (10) above, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin. (13) The method for manufacturing a thermoelectric conversion element according to any one of (1) to (12) above, wherein the shape of the opening is one or more shapes selected from the group consisting of an irregular shape, a polyhedral shape, a frustum of a cone shape, a frustum of an elliptical cone shape, a cylindrical shape, and an elliptical cylindrical shape.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a method for manufacturing a highly integrated thermoelectric conversion element having a thermoelectric element layer with excellent shape controllability.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] [Method for Manufacturing a Thermoelectric Conversion Element] The manufacturing method of the thermoelectric conversion element of the present invention is a method for manufacturing a thermoelectric conversion element including a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, the method including the steps of providing a pattern frame having an opening on the substrate, filling the opening with the thermoelectric semiconductor composition, drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and peeling the pattern frame from the substrate. In the manufacturing method of the thermoelectric conversion element of the present invention, a pattern frame having spaced openings is provided on a substrate, the openings are filled with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material, dried, and the pattern frame is peeled from the substrate, whereby a thermoelectric element layer having excellent shape controllability can be formed. The manufacturing method of the thermoelectric conversion element of the present invention is preferably used for the configurations of a π-type thermoelectric conversion element and an in-plane type thermoelectric conversion element. In the configuration of the π-type thermoelectric conversion element, sufficient electrical and physical bonding properties are obtained between the upper surface of the obtained thermoelectric element layer and the electrode surface on the opposing substrate, an increase in thermal resistance or the like is suppressed, and the thermoelectric performance originally possessed by the thermoelectric element layer can be sufficiently exhibited. In addition, when integrating the configuration of the π-type thermoelectric conversion element, since the shape controllability is excellent, variations in the resistance values of a plurality of each P-type thermoelectric element layer - N-type thermoelectric element layer pairs are suppressed, and since adjacent thermoelectric element layers do not come into contact with each other, high integration becomes possible. Also, when integrating the configuration of the in-plane type thermoelectric conversion element, since the shape controllability is excellent, the ends of adjacent P-type thermoelectric element layers and the ends of N-type thermoelectric element layers do not mutually penetrate and the interface does not become unclear, so variations in the resistance values of a plurality of each P-type thermoelectric element layer - N-type thermoelectric element layer pairs are suppressed, and also, since the occurrence or output of a temperature difference between the joints between adjacent P-type thermoelectric element layers and N-type thermoelectric element layers is stabilized, high integration becomes possible. On the one hand, even when the obtained thermoelectric element layer is transferred as it is to another substrate having electrodes to form a π-type thermoelectric conversion element or an in-plane type thermoelectric conversion element, or when, for example, each chip constituting the thermoelectric element layer is placed on the electrode of the substrate to form a π-type thermoelectric conversion element or an in-plane type thermoelectric conversion element, the bonding property with the electrode surface constituting the thermoelectric conversion element is improved, the decrease in thermoelectric performance due to an increase in thermal resistance or the like is suppressed, and the thermoelectric performance originally possessed by the thermoelectric element layer is exhibited. As a result, the number of thermoelectric element layers required to obtain a predetermined thermoelectric performance can be reduced, leading to a reduction in manufacturing cost. At the same time, in terms of cooling, it leads to lower power consumption, and in terms of power generation, it leads to higher output. Regarding integration, since a thermoelectric element layer with excellent shape controllability is used, high integration becomes possible.

[0011] In this specification, the "opening" is provided at a plurality of intervals inside the region of the entire pattern frame described later. The planar shape of each opening (when the pattern frame on the substrate is viewed from the upper surface side) extends to the substrate surface in the thickness (depth) direction of the pattern frame. For example, when the planar shape of the opening is rectangular, it varies depending on the method of forming or processing the pattern frame, etc., but the shape of the opening portion is usually substantially rectangular parallelepiped. Similarly, for example, when the planar shape of the opening is circular, the shape of the opening portion is usually substantially cylindrical. Note that the shape of the opening portion of the pattern frame is not particularly limited, and as described later, a desired shape can be used. Hereinafter, the manufacturing method of the thermoelectric conversion element of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is an explanatory diagram showing an example of the steps according to the manufacturing method of the thermoelectric conversion element of the present invention in the order of steps. (a) is a cross-sectional view showing a state where a pattern frame is opposed on a substrate, (b) is a cross-sectional view after forming the pattern frame on the substrate, (c) is a cross-sectional view after filling the opening of the pattern frame with a thermoelectric element layer, and (d) is a cross-sectional view showing a state where the pattern frame is peeled off from the filled thermoelectric element layer to obtain only the thermoelectric element layer.

[0013] FIG. 3 is a cross-sectional view showing an example of a π-type thermoelectric conversion element obtained by the steps according to the method for manufacturing a thermoelectric conversion element of the present invention. In FIG. 1(a), except that an electrode 12a is provided on a substrate (on the substrate 11a in FIG. 3), an N-type thermoelectric element layer 14a and a P-type thermoelectric element layer 14b are formed by the same steps as in FIGS. 1(b) to (d), and then the upper surfaces of the N-type thermoelectric element layer 14a and the P-type thermoelectric element layer 14b and the counter electrode 12b on the counter substrate 11b are joined to manufacture a π-type thermoelectric conversion element.

[0014] <Pattern frame forming step> The pattern frame forming step is a step of providing a pattern frame on a substrate. For example, in FIG. 1(a), the pattern frame 2 made of stainless steel 2' to be described later, having an opening 3s, an opening 3, and an opening depth (pattern frame thickness) 3d, is opposed to the substrate 1, and in (b), the pattern frame 2 is provided on the substrate 1. In the present invention, the pattern frame may be provided by directly forming it on the substrate, but from the viewpoint of peeling the pattern frame from the substrate in the pattern frame peeling step to be described later, it is usually preferable to place and fix a previously formed pattern frame on the substrate.

[0015] (Pattern frame) In the method for manufacturing a thermoelectric conversion element of the present invention, a pattern frame having an opening is provided on a substrate.

[0016] FIG. 2 is a configuration diagram for explaining an example of a pattern frame used in the method for manufacturing a thermoelectric conversion element of the present invention. (a) is a plan view of the pattern frame, and (b) is a cross-sectional view of the pattern frame when cut between A-A' in (a). The pattern frame 2 is made of stainless steel 2' and includes an opening 3s and an opening 3 with an opening depth (pattern frame thickness) 3d.

[0017] The arrangement, number, and dimensions of the openings and the opening included in the pattern frame, including the distance between the openings, are not particularly limited and are appropriately adjusted according to the shape and arrangement of the thermoelectric element layer. The shape of the opening is not particularly limited, and any desired shape can be used. Preferably, it is one or more shapes selected from the group consisting of an indefinite shape, a polyhedral shape, a frustum of a cone shape, a frustum of an elliptical cone shape, a columnar shape, and an elliptical columnar shape. Examples of the polyhedral shape include a cubic shape, a rectangular parallelepiped shape, and a frustum of a pyramid shape. A cubic shape, a rectangular parallelepiped shape, a frustum of a pyramid shape, and a columnar shape are more preferable because the formation or processing of the pattern frame is easy. Among these, from the viewpoints of the shape of the thermoelectric element layer and the thermoelectric performance, a rectangular parallelepiped shape and a cubic shape are even more preferable. In FIG. 2, the opening 3s is square, the opening 3 is substantially cubic (not shown), and there are a total of 4×4 openings and openings.

[0018] Examples of the material constituting the pattern frame include single metals such as copper, silver, iron, nickel, chromium, and aluminum, and alloys such as stainless steel and brass. Preferably, it preferably contains stainless steel, copper, aluminum, or iron. From the viewpoint of ease of forming the pattern frame, stainless steel and copper are more preferable. Note that stainless steel is denoted as SUS (Steel Special Use Stainless) in JIS and is defined as "an alloy steel containing Cr and Ni with iron as the main component for the purpose of improving corrosion resistance, generally an alloy steel with a C content of 1.2% or less and a Cr content of 10.5% or more". Examples of stainless steel include ferritic stainless steel (such as SUS430 series in JIS standards) and austenitic stainless steel (such as SUS304 series and SUS316 series in JIS standards).

[0019] It is also preferable that the pattern frame contains a ferromagnetic material. Thereby, when a magnet is disposed, for example, on the surface of the substrate opposite to the pattern frame, the pattern frame can be easily fixed with the substrate interposed therebetween. Examples of ferromagnetic materials include iron, nickel, cobalt, their alloys, and ferrite stainless steels. In addition, alloys of at least one element selected from iron, nickel, cobalt, manganese, and chromium and at least one element selected from platinum, palladium, iridium, ruthenium, and rhodium can be used. The properties of ferromagnetic materials can be changed by altering the composition, heat treatment, etc. Among these, ferrite stainless steels are preferred from the viewpoints of versatility, fixing strength, ease of attachment and detachment, damage to the substrate, and heat resistance. As the ferrite stainless steel, SUS430 is preferred. Also, the magnet is not particularly limited as long as there is no displacement of the pattern frame during the manufacture of the thermoelectric element layer, and a permanent magnet or an electromagnet can be used. For example, as the permanent magnet, a ferrite magnet (composition: BaO·6Fe2O3, SrO·6Fe2O3, magnetic flux density 0.4Wb / m 2 ), neodymium magnet (composition: Nd2Fe 14 B, magnetic flux density 1.2Wb / m 2 ), samarium magnet (composition: SmCo5, magnetic flux density 1.2Wb / m 2 ), praseodymium magnet (PrCo5), samarium iron nitride magnet, etc. can be used. Among these, ferrite magnets and neodymium magnets are more preferred from the viewpoints of versatility, fixing strength, damage to the substrate, and heat resistance.

[0020] The pattern frame is formed from the above materials. The method for forming the pattern frame is not particularly limited, and examples include a method of processing a sheet-like material into a predetermined pattern shape by using a known physical or chemical treatment mainly based on photolithography or a combination thereof, laser processing, electrical discharge machining, milling, computer numerical control machining, water jet machining, and punching. Alternatively, a layer made of the above material without a pattern formed thereon is processed into a predetermined pattern shape by a dry process such as PVD (physical vapor deposition method) such as vacuum evaporation method, sputtering method, ion plating method, or CVD (chemical vapor deposition method) such as thermal CVD, atomic layer deposition (ALD), or a wet process such as dip coating method, spin coating method, spray coating method, gravure coating method, die coating method, doctor blade method, electroplating method, etc., or a known physical or chemical treatment mainly using the above photolithography method, or a combination thereof. In the present invention, from the viewpoints of process simplicity and pattern accuracy, it is preferable to form a predetermined pattern by subjecting the sheet-like material to a known chemical treatment mainly using a photolithography method, for example, wet etching the patterned portion of a photoresist and removing the photoresist, or laser processing.

[0021] The thickness of the pattern frame depends on the thickness of the thermoelectric element layer and is appropriately adjusted. Preferably, it is 100 nm to 1000 μm, more preferably 1 to 600 μm, still more preferably 10 to 400 μm, and particularly preferably 10 to 300 μm. If the thickness of the pattern frame is within this range, it is easy to obtain a pattern frame having an opening shape with excellent pattern accuracy simply.

[0022] (Release layer) It is preferable that the wall surface of the opening of the pattern frame used in the present invention includes a release layer. The release layer has a function of easily peeling the formed thermoelectric element layer from the pattern frame. In this specification, the "wall surface of the opening of the pattern frame" means the wall surface of the pattern frame constituting each opening provided in the pattern frame.

[0023] The release agent constituting the release layer is not particularly limited, and examples thereof include fluorine-based release agents (fluorine atom-containing compounds; for example, fluorine oil, polytetrafluoroethylene, etc.), silicone-based release agents (silicone compounds; for example, silicone oil, silicone wax, silicone resin, polyorganosiloxane having polyoxyalkylene units, etc.), wax-based release agents (waxes; for example, vegetable waxes such as carnauba wax, animal waxes such as wool wax, paraffins such as paraffin wax, polyethylene wax, oxidized polyethylene wax, etc.), higher fatty acids or their salts (for example, metal salts, etc.), higher fatty acid esters, higher fatty acid amides, mineral oils, and the like. Among these, from the viewpoint of facilitating peeling after the formation of the thermoelectric element layer and after annealing treatment, and easily maintaining the shape controllability of the thermoelectric element layer after peeling, fluorine-based release agents and silicone-based release agents are preferable, and from the viewpoint of releasability, fluorine-based release agents are more preferable.

[0024] The thickness of the release layer is preferably 10 nm to 5 μm, more preferably 50 nm to 1 μm, and even more preferably 100 nm to 0.5 μm. When the thickness of the release layer is within this range, peeling after the formation of the thermoelectric element layer and after annealing treatment becomes easy, and the shape controllability of the thermoelectric element layer after peeling is easily maintained.

[0025] The formation of the release layer is performed using the above-described release agent. Examples of the method for forming the release layer include various coating methods such as dip coating method, spray coating method, gravure coating method, die coating method, and doctor blade method for the pattern frame. It is appropriately selected according to the shape of the pattern frame, the physical properties of the release agent, and the like.

[0026] 〈Pattern frame fixing step〉 In the method for manufacturing a thermoelectric conversion element of the present invention, it is preferable to include a step of fixing the pattern frame containing the ferromagnetic body to the substrate using the above-described permanent magnet. As a method for fixing the pattern frame, a known method can be used. For example, a pattern frame containing a ferromagnetic material is opposed to and fixed to a permanent magnet with a substrate interposed therebetween. The permanent magnet is appropriately adjusted according to the pattern frame made of a ferromagnetic material, the type of the substrate, and their thicknesses and the like.

[0027] (Substrate) In the thermoelectric conversion element of the present invention, as the substrate, a resin film that does not affect the decrease in the electrical conductivity and the increase in the thermal conductivity of the thermoelectric element layer can be used. Among them, from the viewpoints of excellent flexibility and the ability to maintain the performance of the thermoelectric element layer without thermal deformation of the substrate even when a thin film of the thermoelectric element layer made of a thermoelectric semiconductor composition is annealed, and high heat resistance and dimensional stability, a polyimide film, a polyamide film, a polyetherimide film, a polyaramide film, or a polyamideimide film is preferable, and further, from the viewpoint of high versatility, a polyimide film is particularly preferable.

[0028] From the viewpoints of flexibility, heat resistance, and dimensional stability, the thickness of the resin film is preferably 1 to 1000 μm, more preferably 5 to 500 μm, and still more preferably 10 to 100 μm. Further, the resin film preferably has a 5% weight loss temperature measured by thermogravimetric analysis of 300 °C or higher, more preferably 400 °C or higher. The heating dimensional change rate measured at 200 °C in accordance with JIS K7133 (1999) is preferably 0.5% or less, more preferably 0.3% or less. The linear expansion coefficient in the plane direction measured in accordance with JIS K7197 (2012) is 0.1 ppm·°C -1 ~50 ppm·°C -1 and is more preferably 0.1 ppm·°C -1 ~30 ppm·°C -1 and is more preferably this.

[0029] In addition, as the substrate used in the present invention, from the viewpoint of performing the annealing treatment at a high temperature, glass, silicon, ceramic, and metal can be mentioned. From the viewpoints of material cost and dimensional stability after heat treatment, it is more preferable to use glass, silicon, or ceramic. From the viewpoints of process and dimensional stability, the thickness of the substrate is preferably 100 to 1200 μm, more preferably 200 to 800 μm, and still more preferably 400 to 700 μm. In addition, electrodes described later may be formed on the substrate including the resin film.

[0030] In the manufacturing method of the present invention, as described later, when the obtained thermoelectric element layer is used as a chip constituting the thermoelectric element layer, it is preferable to use a transfer substrate as the substrate. By using the transfer substrate, the obtained thermoelectric element layer can be collectively transferred onto the electrodes of other substrates, for example, as a chip constituting the thermoelectric element layer. Examples of the transfer substrate include glass, silicon, ceramic, metal, or plastic having a sacrificial layer. From the viewpoint of performing the annealing treatment at a high temperature, glass, silicon, ceramic, and metal are preferable, and from the viewpoints of adhesion to the sacrificial layer, material cost, and dimensional stability after heat treatment, it is more preferable to use glass, silicon, or ceramic. From the viewpoints of process and dimensional stability, the thickness of the transfer substrate is preferably 100 to 1200 μm, more preferably 200 to 800 μm, and still more preferably 400 to 700 μm. The sacrificial layer is provided on the transfer substrate and has a function of easily peeling the obtained thermoelectric element layer from the transfer substrate as a chip constituting the thermoelectric element layer. As the material constituting the sacrificial layer, a resin or a release agent is preferable. The resin is not particularly limited, but a thermoplastic resin or a curable resin can be used. In addition, the release agent constituting the sacrificial layer is not particularly limited, but examples include fluorine-based release agents (fluorine atom-containing compounds; for example, polytetrafluoroethylene, etc.), silicone-based release agents (silicone compounds; for example, silicone resin, polyorganosiloxane having a polyoxyalkylene unit, etc.), higher fatty acids or their salts (for example, metal salts, etc.), higher fatty acid esters, higher fatty acid amides, etc. The thickness of the sacrificial layer is preferably from 10 nm to 10 μm, more preferably from 50 nm to 5 μm, and even more preferably from 200 nm to 2 μm. When the thickness of the sacrificial layer is within this range, peeling after the annealing treatment of the thermoelectric element layer becomes easy, and it is easy to maintain the thermoelectric performance of the chip of the thermoelectric element layer after peeling.

[0031] (Electrode formation step) The method for manufacturing the thermoelectric conversion element of the present invention may include an electrode formation step. The electrode formation step is a step of forming an electrode on a substrate. Examples of the metal material of the electrode of the thermoelectric conversion element include copper, gold, nickel, aluminum, rhodium, platinum, chromium, palladium, stainless steel, molybdenum, tin, or an alloy containing any of these metals. The thickness of the electrode layer is preferably from 10 nm to 200 μm, more preferably from 30 nm to 150 μm, and even more preferably from 50 nm to 120 μm. If the thickness of the electrode layer is within the above range, the electrical conductivity is high and the resistance is low, and sufficient strength as an electrode can be obtained.

[0032] The electrode is formed using the metal material described above. As a method for forming an electrode, after providing an electrode without a pattern formed on a substrate, a known physical treatment or chemical treatment mainly using a photolithography method, or a combination thereof, is used to process it into a predetermined pattern shape, or a method of directly forming an electrode pattern by a screen printing method, an inkjet method, or the like can be mentioned. Examples of the method for forming an electrode without a pattern include dry processes such as PVD (physical vapor deposition method) such as vacuum evaporation method, sputtering method, ion plating method, or CVD (chemical vapor deposition method) such as thermal CVD, atomic layer deposition (ALD), or various coating methods such as dip coating method, spin coating method, spray coating method, gravure coating method, die coating method, doctor blade method, and wet processes such as electrodeposition method, silver salt method, electrolytic plating method, electroless plating method, lamination of metal foil, etc., which are appropriately selected according to the material of the electrode. For the electrodes used in the present invention, from the viewpoint of maintaining thermoelectric performance, high conductivity and high thermal conductivity are required. Therefore, it is preferable to use electrodes formed by a plating method or a vacuum film forming method. Since high conductivity and high thermal conductivity can be easily realized, vacuum film forming methods such as vacuum evaporation method and sputtering method, and electrolytic plating method and electroless plating method are preferable. Depending on the requirements for the dimensions and dimensional accuracy of the formed pattern, a hard mask such as a metal mask can be interposed to easily form the pattern.

[0033] <Thermoelectric semiconductor composition filling step> The thermoelectric semiconductor composition filling step is a step of filling an opening of a pattern frame on a substrate, obtained in the pattern frame forming step, with a thermoelectric semiconductor composition containing the thermoelectric semiconductor material. For example, in FIG. 1(c), an opening 3 having an opening 3s of a pattern frame 2 made of stainless steel 2' prepared in (b) is filled with a thermoelectric semiconductor composition containing a P-type thermoelectric semiconductor material and a thermoelectric semiconductor composition containing an N-type thermoelectric semiconductor material in respective predetermined openings. As a method of filling the thermoelectric semiconductor composition into the opening of the pattern layer, known methods such as screen printing method, flexographic printing method, gravure printing method, spin coating method, die coating method, spray coating method, bar coating method, doctor blade method, and dispensing method can be mentioned. From the viewpoints of filling accuracy and manufacturing efficiency, it is preferable to use the screen printing method, stencil printing method, and dispensing method.

[0034] <Thermoelectric element layer forming step> The thermoelectric element layer forming step is a step of drying the thermoelectric semiconductor composition containing the thermoelectric semiconductor material filled in the thermoelectric semiconductor composition filling step to form a thermoelectric element layer. For example, in FIG. 1(c), the thermoelectric semiconductor composition containing the P-type thermoelectric semiconductor material and the thermoelectric semiconductor composition containing the N-type thermoelectric semiconductor material filled in the opening 3 are dried to form a P-type thermoelectric element layer 4b and an N-type thermoelectric element layer 4a. As drying methods, conventionally known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be adopted. The heating temperature is usually 80 to 150°C, and the heating time varies depending on the heating method, but is usually several seconds to several tens of minutes. When a solvent is used in the preparation of the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as it is within the temperature range capable of drying the used solvent.

[0035] (Thermoelectric element layer) The thermoelectric element layer used in the present invention (hereinafter sometimes referred to as "thin film of the thermoelectric element layer") is composed of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material. Preferably, it is composed of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material (hereinafter sometimes referred to as "thermoelectric semiconductor fine particles"), a heat-resistant resin, and an ionic liquid and / or an inorganic ionic compound.

[0036] (Thermoelectric semiconductor material) The thermoelectric semiconductor material used in the present invention, that is, the thermoelectric semiconductor material contained in the thermoelectric element layer, is not particularly limited as long as it can generate a thermoelectromotive force by applying a temperature difference. For example, bismuth-tellurium-based thermoelectric semiconductor materials such as P-type bismuth telluride and N-type bismuth telluride; telluride-based thermoelectric semiconductor materials such as GeTe and PbTe; antimony-tellurium-based thermoelectric semiconductor materials; ZnSb, Zn3Sb 2、 zinc-antimony-based thermoelectric semiconductor materials such as Zn4Sb3; silicon-germanium-based thermoelectric semiconductor materials such as SiGe; bismuth selenide-based thermoelectric semiconductor materials such as Bi2Se3; β-FeSi2, CrSi2, MnSi 1.73 , silicide-based thermoelectric semiconductor materials such as Mg2Si; oxide-based thermoelectric semiconductor materials; Heusler materials such as FeVAl, FeVAlSi, and FeVTiAl; sulfide-based thermoelectric semiconductor materials such as TiS2, etc. are used. Among these, bismuth-tellurium-based thermoelectric semiconductor materials, telluride-based thermoelectric semiconductor materials, antimony-tellurium-based thermoelectric semiconductor materials, or bismuth selenide-based thermoelectric semiconductor materials are preferred.

[0037] Furthermore, from the viewpoint of thermoelectric performance, it is more preferable that it is a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride. The P-type bismuth telluride has holes as carriers and a positive Seebeck coefficient. For example, Bi X Te3Sb 2-X represented by is preferably used. In this case, X is preferably 0 < X ≦ 0.8, more preferably 0.4 ≦ X ≦ 0.6. When X is greater than 0 and less than or equal to 0.8, the Seebeck coefficient and electrical conductivity increase, and the characteristics as a P-type thermoelectric element are maintained, which is preferable. Also, the N-type bismuth telluride has electrons as carriers and a negative Seebeck coefficient. For example, Bi2Te 3-Y Se Y represented by is preferably used. In this case, Y is preferably 0 ≦ Y ≦ 3 (when Y = 0: Bi2Te3), more preferably 0 < Y ≦ 2.7. When Y is 0 or more and 3 or less, the Seebeck coefficient and electrical conductivity increase, and the characteristics as an N-type thermoelectric element are maintained, which is preferable.

[0038] The thermoelectric semiconductor fine particles used in the thermoelectric semiconductor composition are obtained by pulverizing the above-described thermoelectric semiconductor material to a predetermined size using a pulverizer or the like.

[0039] The blending amount of the thermoelectric semiconductor fine particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass. More preferably, it is 50 to 96% by mass, and still more preferably, it is 70 to 95% by mass. When the blending amount of the thermoelectric semiconductor fine particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, the decrease in electrical conductivity is suppressed, and only the thermal conductivity decreases, so that high thermoelectric performance is exhibited, and a film having sufficient film strength and flexibility is obtained, which is preferable.

[0040] The average particle size of the thermoelectric semiconductor microparticles is preferably from 10 nm to 200 μm, more preferably from 10 nm to 30 μm, still more preferably from 50 nm to 10 μm, and particularly preferably from 1 to 6 μm. Within the above range, uniform dispersion becomes easy and the electrical conductivity can be increased. The method for obtaining thermoelectric semiconductor microparticles by pulverizing the thermoelectric semiconductor material is not particularly limited, and it may be pulverized to a predetermined size by a known fine pulverization device such as a jet mill, a ball mill, a bead mill, a colloid mill, a roller mill, etc. The average particle size of the thermoelectric semiconductor microparticles was obtained by measuring with a laser diffraction particle size analyzer (Master Sizer 3000, manufactured by Malvern), and used as the median of the particle size distribution.

[0041] Also, the thermoelectric semiconductor microparticles are preferably those that have been heat-treated beforehand (the "heat treatment" referred to here is different from the "annealing treatment" performed in the annealing treatment step of the present invention). By performing the heat treatment, the crystallinity of the thermoelectric semiconductor microparticles is improved, and furthermore, the surface oxide film of the thermoelectric semiconductor microparticles is removed, so that the Seebeck coefficient or the Peltier coefficient of the thermoelectric conversion material increases, and the thermoelectric performance index can be further improved. The heat treatment is not particularly limited, but before preparing the thermoelectric semiconductor composition, in an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere such as hydrogen, or under vacuum conditions, so as not to adversely affect the thermoelectric semiconductor microparticles, with the gas flow rate controlled. It is preferably carried out, and more preferably carried out in a mixed gas atmosphere of an inert gas and a reducing gas. The specific temperature conditions depend on the thermoelectric semiconductor microparticles used, but usually, it is preferably carried out at a temperature below the melting point of the microparticles and at 100 to 1500 °C for several minutes to several tens of hours.

[0042] (Heat-resistant resin) For the thermoelectric semiconductor composition used in the present invention, from the viewpoint of annealing the thermoelectric semiconductor material at a high temperature after forming the thermoelectric element layer, a heat-resistant resin is preferably used. It functions as a binder between thermoelectric semiconductor materials (thermoelectric semiconductor fine particles), can enhance the flexibility of the thermoelectric conversion module, and facilitates the formation of a thin film by coating or the like. The heat-resistant resin is not particularly limited, but when crystal growth of thermoelectric semiconductor fine particles is performed on a thin film made of a thermoelectric semiconductor composition by annealing or the like, a heat-resistant resin whose various physical properties such as mechanical strength and thermal conductivity as a resin are not impaired and are maintained is preferable. From the viewpoints of higher heat resistance and no adverse effect on the crystal growth of thermoelectric semiconductor fine particles in the thin film, polyamide resin, polyamideimide resin, polyimide resin, and epoxy resin are preferable for the heat-resistant resin. From the viewpoint of excellent flexibility, polyamide resin, polyamideimide resin, and polyimide resin are more preferable. When a polyimide film is used as a substrate described later, polyimide resin is more preferable as the heat-resistant resin from the viewpoint of adhesion to the polyimide film and the like. In the present invention, the polyimide resin is a general term for polyimide and its precursors.

[0043] The heat-resistant resin preferably has a decomposition temperature of 300 °C or higher. If the decomposition temperature is within the above range, as described later, even when a thin film made of a thermoelectric semiconductor composition is annealed, the function as a binder is not lost and the flexibility can be maintained.

[0044] Further, the heat-resistant resin preferably has a mass reduction rate at 300 °C by thermogravimetric measurement (TG) of 10% or less, more preferably 5% or less, and even more preferably 1% or less. If the mass reduction rate is within the above range, as described later, even when a thin film made of a thermoelectric semiconductor composition is annealed, the function as a binder is not lost and the flexibility of the thermoelectric element layer can be maintained.

[0045] The compounding amount of the heat-resistant resin in the thermoelectric semiconductor composition is 0.1 to 40% by mass, preferably 0.5 to 20% by mass, more preferably 1 to 20% by mass, and still more preferably 2 to 15% by mass. When the compounding amount of the heat-resistant resin is within the above range, it functions as a binder for the thermoelectric semiconductor material, facilitating the formation of a thin film, and a film with both high thermoelectric performance and film strength can be obtained.

[0046] (Ionic liquid) The ionic liquid used in the present invention is a molten salt formed by combining a cation and an anion, and refers to a salt that can exist as a liquid in any temperature range of -50 to 500 °C. The ionic liquid has characteristics such as an extremely low vapor pressure and being non-volatile, excellent thermal stability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, as a conductive auxiliary agent, it can effectively suppress the reduction of the electrical conductivity between thermoelectric semiconductor fine particles. In addition, the ionic liquid exhibits high polarity based on its aprotic ionic structure and has excellent compatibility with the heat-resistant resin, so it can make the electrical conductivity of the thermoelectric element layer uniform.

[0047] Known or commercially available ionic liquids can be used. For example, nitrogen-containing cyclic cation compounds such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, imidazolium and their derivatives; amine-based cations of tetraalkylammonium and their derivatives; phosphine-based cations such as phosphonium, trialkylsulfonium, tetraalkylphosphonium and their derivatives; lithium cation and its derivatives, etc. as cation components, and Cl - , AlCl4 - , Al2Cl7 - , ClO4 - and other chloride ions, Br - and other bromide ions, I - and other iodide ions, BF4 - , PF6 - and other fluoride ions, F(HF) n - and other halide anions, NO3 - , CH3COO- 、 CF3COO - 、 CH3SO3 - 、 CF3SO3 - 、 (FSO2)2N - 、 (CF3SO2)2N - 、 (CF3SO2)3C - 、 AsF6 - 、 SbF6 - 、 NbF6 - 、 TaF6 - 、 F(HF)n - 、 (CN)2N - 、 C4F9SO3 - 、 (C2F5SO2)2N - 、 C3F7COO - 、 (CF3SO2)(CF3CO)N - include those composed of anion components such as the following.

[0048] Among the above ionic liquids, from the viewpoints of high-temperature stability, compatibility with thermoelectric semiconductor fine particles and resin, suppression of the decrease in electrical conductivity in the gaps between thermoelectric semiconductor fine particles, etc., it is preferable that the cation component of the ionic liquid contains at least one selected from pyridinium cations and their derivatives, imidazolium cations and their derivatives. It is preferable that the anion component of the ionic liquid contains a halide anion, and it is more preferable to contain at least one selected from Cl - 、 Br - and I - .

[0049] Specific examples of ionic liquids in which the cation component includes pyridinium cations and their derivatives include 4-methyl-butylpyridinium chloride, 3-methyl-butylpyridinium chloride, 4-methyl-hexylpyridinium chloride, 3-methyl-hexylpyridinium chloride, 4-methyl-octylpyridinium chloride, 3-methyl-octylpyridinium chloride, 3,4-dimethyl-butylpyridinium chloride, 3,5-dimethyl-butylpyridinium chloride, 4-methyl-butylpyridinium tetrafluoroborate, 4-methyl-butylpyridinium hexafluorophosphate, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, 1-butyl-4-methylpyridinium iodide, and the like. Among these, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, and 1-butyl-4-methylpyridinium iodide are preferred.

[0050] In addition, specific examples of the ionic liquid in which the cation component includes an imidazolium cation and its derivatives include [1-butyl-3-(2-hydroxyethyl)imidazolium bromide], [1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate], 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium chloride, 1-decyl-3-methylimidazolium bromide, 1-dodecyl-3-methylimidazolium chloride, 1-tetradecyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-butylimidazolium methyl sulfate, 1,3-dibutylimidazolium methyl sulfate, and the like. Among these, [1-butyl-3-(2-hydroxyethyl)imidazolium bromide] and [1-butyl-3-(2-hydroxyethyl)imidazolium tetrafluoroborate] are preferred.

[0051] The above ionic liquid preferably has an electrical conductivity of 10 -7 S / cm or more, and more preferably 10 -6 S / cm or more. If the electrical conductivity is within the above range, as a conductive auxiliary agent, it is possible to effectively suppress a reduction in the electrical conductivity between the thermoelectric semiconductor fine particles.

[0052] In addition, the above ionic liquid preferably has a decomposition temperature of 300°C or higher. If the decomposition temperature is within the above range, as will be described later, even when a thin film of the thermoelectric element layer composed of the thermoelectric semiconductor composition is annealed, the effect as a conductive auxiliary agent can be maintained.

[0053] Further, it is preferable that the ionic liquid has a mass reduction rate of 10% or less, more preferably 5% or less, and even more preferably 1% or less at 300 °C as measured by thermogravimetry (TG). If the mass reduction rate is within the above range, as described later, even when a thin film of a thermoelectric element layer made of a thermoelectric semiconductor composition is annealed, the effect as a conductive auxiliary agent can be maintained.

[0054] The blending amount of the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and even more preferably 1.0 to 20% by mass. If the blending amount of the ionic liquid is within the above range, a decrease in electrical conductivity can be effectively suppressed, and a film having high thermoelectric performance can be obtained.

[0055] (Inorganic ionic compound) The inorganic ionic compound used in the present invention is a compound composed of at least a cation and an anion. Since the inorganic ionic compound is solid at room temperature, has a melting point at any temperature in the temperature range of 400 to 900 °C, and has characteristics such as high ionic conductivity, it can suppress a decrease in electrical conductivity between thermoelectric semiconductor fine particles as a conductive auxiliary agent.

[0056] As the cation, a metal cation is used. Examples of the metal cation include an alkali metal cation, an alkaline earth metal cation, a typical metal cation, and a transition metal cation, and an alkali metal cation or an alkaline earth metal cation is more preferable. Examples of the alkali metal cation include Li + , Na + , K + , Rb + , Cs + and Fr + and the like. Examples of the alkaline earth metal cation include Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ and the like.

[0057] Examples of anions include F - , Cl - , Br - , I - , OH - , CN - , NO3 - , NO2 - , ClO - , ClO2 - , ClO3 - , ClO4 - , CrO4 2- , HSO4 - , SCN - , BF4 - , PF6 - and so on.

[0058] Known or commercially available inorganic ionic compounds can be used. For example, cation components such as potassium cation, sodium cation, or lithium cation, and Cl - , AlCl4 - , Al2Cl7 - , ClO4 - and other chloride ions, Br - and other bromide ions, I - and other iodide ions, BF4 - , PF6 - and other fluoride ions, F(HF) n - and other halide anions, NO3 - , OH - , CN - and so on.

[0059] Among the above inorganic ionic compounds, from the viewpoints of high-temperature stability, compatibility between thermoelectric semiconductor fine particles and resin, and suppression of the decrease in electrical conductivity in the gaps between thermoelectric semiconductor fine particles, it is preferable that the cation component of the inorganic ionic compound contains at least one selected from potassium, sodium, and lithium. Further, it is preferable that the anion component of the inorganic ionic compound contains a halide anion, and Cl - , Br - , and I -It is more preferable to further contain at least one selected from the group consisting of

[0060] Specific examples of the inorganic ionic compound in which the cation component contains potassium cations include KBr, KI, KCl, KF, KOH, K2CO3, etc. Among these, KBr and KI are preferable. Specific examples of the inorganic ionic compound in which the cation component contains sodium cations include NaBr, NaI, NaOH, NaF, Na2CO3, etc. Among these, NaBr and NaI are preferable. Specific examples of the inorganic ionic compound in which the cation component contains lithium cations include LiF, LiOH, LiNO3, etc. Among these, LiF and LiOH are preferable.

[0061] The above inorganic ionic compound preferably has an electric conductivity of 10 -7 S / cm or more, and more preferably 10 -6 S / cm or more. If the electric conductivity is within the above range, as a conductive auxiliary agent, a reduction in the electric conductivity between the thermoelectric semiconductor fine particles can be effectively suppressed.

[0062] Further, the above inorganic ionic compound preferably has a decomposition temperature of 400 °C or higher. If the decomposition temperature is within the above range, as described later, even when the thin film of the thermoelectric element layer composed of the thermoelectric semiconductor composition is annealed, the effect as a conductive auxiliary agent can be maintained.

[0063] Further, the above inorganic ionic compound preferably has a mass reduction rate at 400 °C by thermogravimetric measurement (TG) of 10% or less, more preferably 5% or less, and even more preferably 1% or less. If the mass reduction rate is within the above range, as described later, even when the thin film of the thermoelectric element layer composed of the thermoelectric semiconductor composition is annealed, the effect as a conductive auxiliary agent can be maintained.

[0064] The compounding amount of the inorganic ionic compound in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and still more preferably 1.0 to 10% by mass. If the compounding amount of the inorganic ionic compound is within the above range, a decrease in electrical conductivity can be effectively suppressed, and as a result, a film with improved thermoelectric performance can be obtained. In addition, when an inorganic ionic compound and an ionic liquid are used in combination, the total content of the inorganic ionic compound and the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and still more preferably 1.0 to 10% by mass.

[0065] (Other additives) In addition to the components other than the above, the thermoelectric semiconductor composition used in the present invention may further contain other additives such as a dispersant, a film-forming aid, a light stabilizer, an antioxidant, a tackifier, a plasticizer, a colorant, a resin stabilizer, a filler, a pigment, a conductive filler, a conductive polymer, and a curing agent, as necessary. These additives can be used alone or in combination of two or more.

[0066] (Method for preparing thermoelectric semiconductor composition) The method for preparing the thermoelectric semiconductor composition used in the present invention is not particularly limited. By a known method such as an ultrasonic homogenizer, a spiral mixer, a planetary mixer, a disperser, or a hybrid mixer, the thermoelectric semiconductor fine particles, the heat-resistant resin, and the ionic liquid and / or inorganic ionic compound, and if necessary, the other additives, and further a solvent are added and mixed and dispersed to prepare the thermoelectric semiconductor composition. Examples of the solvent include solvents such as toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methylpyrrolidone, and ethyl cellosolve. These solvents may be used alone or in combination of two or more. The solid content concentration of the thermoelectric semiconductor composition is not particularly limited as long as the composition has a viscosity suitable for coating.

[0067] The thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition can be formed by filling and drying the thermoelectric semiconductor composition in the opening of the pattern frame used in the present invention. In this way, by forming the thermoelectric element layer, a thermoelectric element layer with excellent shape controllability reflecting the shape of the opening of the pattern layer can be obtained.

[0068] The thickness of the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is not particularly limited, but from the viewpoints of thermoelectric performance and film strength, it is preferably 100 nm to 1000 μm, more preferably 1 to 600 μm, still more preferably 10 to 400 μm, and particularly preferably 10 to 300 μm.

[0069] <Pattern Frame Peeling Step> The pattern frame peeling step is a step of peeling only the pattern frame from the substrate with respect to the pattern frame including the thermoelectric element layer formed in the thermoelectric element layer forming step. For example, in FIG. 1(d), the P-type thermoelectric element layer 4b and the N-type thermoelectric element layer 4a formed in the opening 3 are peeled from the substrate 1 with the pattern frame 2 made of stainless steel 2', and the P-type thermoelectric element layer 4b and the N-type thermoelectric element layer 4a are left on the substrate 1. As the peeling method, when peeling the pattern frame, there is no particular limitation as long as the shape of the thermoelectric element layer is not damaged, the damage to the surface of the thermoelectric element layer is slight, and there is no decrease in thermoelectric performance, and it can be performed by a known method. Further, the pattern frame peeling step may also be performed after the annealing treatment step described later, as long as the above is satisfied after peeling.

[0070] 〈Annealing Treatment Step〉 In the manufacturing method of the present invention, it is preferable to include a step of annealing the thermoelectric element layer. The annealing treatment step is a step of further heat-treating the thermoelectric element layer after drying the thermoelectric element layer in the thermoelectric semiconductor composition drying step. By performing the annealing treatment, the thermoelectric performance can be stabilized, and the thermoelectric semiconductor fine particles in the thermoelectric element layer (thin film) can be crystallized and grown, and the thermoelectric performance can be further improved.

[0071] The annealing treatment is not particularly limited, but is usually carried out in an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere, or under vacuum conditions with controlled gas flow. It depends on the heat-resistant resin, ionic liquid, inorganic ionic compound used, and the heat-resistant temperature of the substrate, etc. When using a substrate with high heat resistance such as the aforementioned glass, silicon, ceramic, or metal as the substrate, the annealing temperature is usually 250 to 650 °C for several minutes to several tens of hours, preferably 250 to 600 °C for several minutes to several tens of hours. Also, when using a resin film such as the aforementioned polyimide film, polyamide film, polyetherimide film, polyaramide film, or polyamideimide film as the substrate, it is usually carried out at 100 to 450 °C for several minutes to several tens of hours, preferably 150 to 400 °C for several minutes to several tens of hours, more preferably 200 to 375 °C for several minutes to several tens of hours, and even more preferably 250 to 350 °C for several minutes to several tens of hours.

[0072] 〈Thermoelectric element layer peeling step〉 In the manufacturing method of the present invention, a step of peeling the chips constituting the thermoelectric element layer after the annealing treatment may be included. The thermoelectric element layer peeling step is a step of peeling the thermoelectric element layer as chips constituting the thermoelectric element layer from the substrate after annealing the thermoelectric element layer.

[0073] In the thermoelectric element layer peeling step, the method of peeling the chips constituting the thermoelectric element layer from the substrate is not particularly limited as long as it is a peelable method, and it is carried out by a known method. It may be peeled directly from the substrate, or using the aforementioned transfer substrate, the chips constituting a plurality of thermoelectric element layers may be collectively transferred onto another substrate or on the electrodes of another substrate. It can be appropriately adjusted according to the configuration of the thermoelectric conversion element.

[0074] The chips constituting the thermoelectric element layer have excellent shape controllability. From the viewpoint of improving the thermoelectric performance, it is preferably configured to be used in a π-type or in-plane type thermoelectric conversion element and formed to be connected via electrodes. Here, when constructing a π-type thermoelectric conversion element, for example, a pair of electrodes spaced apart from each other are provided on a substrate, a chip constituting a P-type thermoelectric element layer is provided on one electrode, and a chip constituting an N-type thermoelectric element layer is provided on the other electrode, also spaced apart from each other. The upper surfaces of the chips constituting both thermoelectric element layers are electrically connected in series to the electrodes on the substrate facing each other. From the viewpoint of efficiently obtaining high thermoelectric performance, it is preferable to use a plurality of pairs of chips constituting a P-type thermoelectric element layer and a chip constituting an N-type thermoelectric element layer with an intervening electrode on the opposing substrate, and electrically connect them in series. Similarly, when constructing an in-plane type thermoelectric conversion element, for example, one electrode is provided on a substrate, a chip constituting a P-type thermoelectric element layer on the surface of the electrode, and a chip constituting an N-type thermoelectric element layer on the surface of the same electrode are provided such that the side surfaces of both chips (for example, the surfaces perpendicular to the substrate) are in contact with or spaced apart from each other, and are electrically connected in series (including a pair of extraction electrodes) with the electrode intervening in the in-plane direction of the substrate. From the viewpoint of efficiently obtaining high thermoelectric performance, in this configuration, it is preferable to use chips constituting a plurality of P-type thermoelectric element layers and chips constituting N-type thermoelectric element layers of the same number, alternately with an intervening electrode, and electrically connect them in series in the in-plane direction of the substrate.

[0075] According to the method for manufacturing a thermoelectric conversion element of the present invention, the shape controllability of the thermoelectric element layer can be improved by a simple method. As the configuration of the thermoelectric conversion element, it is preferable to use a configuration used for a π-type or in-plane type thermoelectric conversion element. In any configuration, high integration of the thermoelectric conversion element can be achieved.

[0076] [Thermoelectric conversion element] The thermoelectric conversion element obtained by the manufacturing method of the present invention includes a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, and is obtained through a process of providing a pattern frame having an opening on the substrate, a process of filling the opening with the thermoelectric semiconductor composition, a process of drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer, and a process of peeling the pattern frame from the substrate.

[0077] (Thermoelectric element layer) The thermoelectric element layer of the thermoelectric conversion element obtained by the manufacturing method of the present invention has a concave depression on its upper surface. Since the thermoelectric element layer is formed by filling the opening of the pattern frame with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material and then removing the volatile components in the thermoelectric semiconductor composition by drying, the surface of the thermoelectric element layer corresponding to the opening of the opening on the side opposite to the substrate side of the pattern frame is not flat but concave. For example, in FIG. 1(d), the upper surface portions of the N-type thermoelectric element layer 4a and the P-type thermoelectric element layer 4b may be concave. The shape and dimensions of the concave depression depend on the viscosity, volatile components, drying conditions, etc. of the thermoelectric semiconductor composition, and thus are not constant. Usually, the concave depression is a 1-30% depression with respect to the thickness of the thermoelectric element layer.

[0078] The thermoelectric element layer of the thermoelectric conversion element obtained by the manufacturing method of the present invention may have streak-like rubbing marks extending in a direction intersecting the substrate on its side surface. This is because the thermoelectric element layer is formed by filling the opening of the pattern frame with a thermoelectric semiconductor composition containing a thermoelectric semiconductor material, then becoming the thermoelectric element layer by drying, and then peeling the pattern frame from the substrate. Therefore, when peeling the pattern frame, physical interactions such as friction occur at the interfaces of both sides between the wall surface in the opening of the pattern frame and the side surface of the thermoelectric element layer. After peeling, it is presumed that streak-like rubbing marks extending in a direction intersecting the substrate are formed on the side surface of the thermoelectric element layer obtained on the substrate. For example, in FIG. 1(d), streak-like rubbing marks extending in a direction intersecting the substrate are generated on either side surface portions of the N-type thermoelectric element layer 4a and the P-type thermoelectric element layer 4b. The length, width, number, etc. of the streak-like rubbing marks depend on the surface hardness, surface roughness of the wall surface in the opening of the pattern frame, and peeling conditions (peeling direction, peeling speed, etc.), and thus are not constant. Usually, the length of the streak-like rubbing marks is 100 nm to 500 μm.

Industrial Applicability

[0079] According to the method for manufacturing a thermoelectric conversion element of the present invention, a highly integrated thermoelectric conversion element having a thermoelectric element layer with excellent shape controllability can be obtained by a simple manufacturing method. At the same time, since the variation in the resistance values of a plurality of each P-type thermoelectric element layer - N-type thermoelectric element layer pair can be suppressed, an improvement in the yield in manufacturing can be expected. Furthermore, the thermoelectric conversion element obtained by the method for manufacturing a thermoelectric conversion element of the present invention can be thinned (miniaturized and lightweight). By using the thermoelectric conversion element obtained by the above method for manufacturing a thermoelectric conversion element as a module, it can be applied to power generation applications for converting waste heat from various combustion furnaces such as factories, waste incinerators, and cement kilns, combustion gas waste heat from automobiles, and waste heat from electronic devices into electricity. As a cooling application, in the field of electronic devices, for example, it can be applied to temperature control of CPUs (Central Processing Units) used in smartphones, various computers, etc., image sensors such as CMOS (Complementary Metal Oxide Semiconductor Image Sensors) and CCDs (Charge Coupled Devices), and various sensors such as MEMS (Micro Electro Mechanical Systems) and other light-receiving elements.

Explanation of Signs

[0080] 1: Substrate 2: Pattern frame 2’: Stainless steel 3s: Opening 3d: Opening depth (pattern frame thickness) 3: Opening 4a: N-type thermoelectric element layer 4b: P-type thermoelectric element layer 11a: Substrate 11b: Opposing substrate 12a: Electrode 12b: Opposing electrode 14a: N-type thermoelectric element layer 14b: P-type thermoelectric element layer

Claims

1. A method for manufacturing a thermoelectric conversion element including a thermoelectric element layer made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate, comprising: a step of placing and fixing a pre-formed pattern frame having an opening on the substrate; a step of filling the opening with the thermoelectric semiconductor composition; a step of drying the thermoelectric semiconductor composition filled in the opening to form a thermoelectric element layer from which volatile components are removed; and a step of peeling the pattern frame from the substrate.

2. The method for manufacturing a thermoelectric conversion element according to claim 1, further comprising a step of annealing the thermoelectric element layer.

3. The method for manufacturing a thermoelectric conversion element according to claim 2, wherein the temperature of the annealing treatment is 250 to 600 °C.

4. The method for manufacturing a thermoelectric conversion element according to claim 2 or 3, further comprising a step of peeling chips constituting the thermoelectric element layer after the annealing treatment.

5. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 4, wherein the substrate is a polyimide film, a polyamide film, a polyetherimide film, a polyaramide film, or a polyamideimide film.

6. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 5, wherein the pattern frame contains stainless steel, copper, aluminum, or iron.

7. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 6, wherein the pattern frame contains a ferromagnetic material.

8. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 7, wherein a release layer is included on the wall surface of the opening of the pattern frame.

9. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 8, further comprising a step of fixing the pattern frame to the substrate using a magnet.

10. The method for manufacturing a thermoelectric conversion element of a substrate according to any one of claims 1 to 9, wherein the thermoelectric semiconductor composition further contains a heat-resistant resin and an ionic liquid and / or an inorganic ionic compound.

11. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 10, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material.

12. The method for manufacturing a thermoelectric conversion element according to claim 10, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamideimide resin, or an epoxy resin.

13. The method for manufacturing a thermoelectric conversion element according to any one of claims 1 to 12, wherein the shape of the opening portion is one or more shapes selected from the group consisting of an irregular shape, a polyhedron shape, a frustum of a cone shape, a frustum of an elliptical cone shape, a columnar shape, and an elliptical columnar shape.

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