WO2020045378A1

WO2020045378A1 - Semiconductor element

Info

Publication number: WO2020045378A1
Application number: PCT/JP2019/033407
Authority: WO
Inventors: 亘森田; 邦久加藤; 豪志武藤; 祐馬勝田
Original assignee: リンテック株式会社
Priority date: 2018-08-28
Filing date: 2019-08-27
Publication date: 2020-03-05
Also published as: JP7348192B2; TW202023073A; JPWO2020045378A1

Abstract

This semiconductor element contains a semiconductor element layer formed from a semiconductor composition containing a semiconductor material on a substrate; when the semiconductor element is used as a thermoelectric conversion element, the semiconductor element provides a thermoelectric conversion element provided with a thermoelectric element layer which has excellent thermoelectric performance and of which the sectional shape has been controlled. Defining S(μm²⁾as the area of the vertical section including the center part of the semiconductor element layer, Dmax(μm) as the maximum value of the thickness-direction thickness of the vertical section and Xmax (μm) as the maximum value of the width-direction length of the vertical section, the vertical section of the semiconductor element layer satisfies conditions (A) and (B) below. (A) 0.75 ≤ S / (Dmax×Xmax) ≤ 1.00 (B) Dmax ≥ 10 μm, or (Dmax/Xmax) ≥ 0.03

Description

Semiconductor element

<< The present invention relates to a semiconductor device.

Conventionally, by using a semiconductor element as a thermoelectric conversion element, as one of effective means of energy utilization, a thermoelectric conversion module having a thermoelectric effect such as a Seebeck effect or a Peltier effect allows direct mutual conversion between thermal energy and electric energy. There are devices designed to do this.
Among them, a configuration of a so-called π-type thermoelectric conversion element is known as the thermoelectric conversion element. In the π type, usually, a pair of electrodes which are separated from each other are provided on a substrate, and, for example, a P type thermoelectric element is placed on a negative electrode, an N type thermoelectric element is placed on the other electrode, and similarly separated from each other. And the upper surfaces of both thermoelectric elements are connected to the electrodes of the opposing substrate. Further, use of a so-called in-plane type thermoelectric conversion element is known. The in-plane type usually arranges a plurality of thermoelectric elements so that N-type thermoelectric elements and P-type thermoelectric elements are alternately arranged, and for example, connects the lower or upper electrodes of the thermoelectric elements in series. It is configured by connecting.

In recent years, there has been a demand for improvement of thermoelectric performance including thinning and high integration of thermoelectric conversion elements. Patent Document 1 discloses a method of directly forming a pattern of a thermoelectric element layer by a screen printing method or the like using a thermoelectric semiconductor composition containing a resin or the like, including a viewpoint of thinning by thinning, as a thermoelectric element layer. I have.

International Publication No. WO 2016/104615

However, as disclosed in Patent Document 1, a method of forming a thermoelectric element as a pattern layer directly on an electrode or a substrate by a screen printing method or the like using a thermoelectric semiconductor composition composed of a thermoelectric semiconductor material, a heat-resistant resin, or the like is obtained. In addition, the shape controllability of the thermoelectric element layer is not sufficient, and bleeding occurs at the edge of the thermoelectric element layer at the electrode interface or the substrate interface, whereby the shape of the thermoelectric element layer may be broken. For example, when the shape of the thermoelectric element layer is formed to be formed in a rectangular parallelepiped shape (including a cubic shape) from the viewpoint of thermoelectric performance and manufacturability, the actual cross-sectional shape is substantially semi-elliptical (described later). 3 (a)), it may not be possible to obtain a desired thickness, and it may not be possible to control the region of the upper surface of the thermoelectric element layer to be uniform and flat. Therefore, when the above-described π-type thermoelectric conversion element is configured, the area of the junction between the upper surface of the obtained thermoelectric element layer and the electrode facing the electrode cannot be sufficiently increased, and the interface resistance and the thermal resistance increase. In some cases, the thermoelectric performance is reduced, and the thermoelectric performance inherent in the thermoelectric element layer cannot be sufficiently obtained. Furthermore, when an in-plane thermoelectric element is configured, the cross-sectional area of the thermoelectric element layer is reduced, and the electric resistance is increased, which may lead to a decrease in thermoelectric performance. As described above, when forming the thermoelectric element layers, it is important to improve the shape controllability of each thermoelectric element layer from the viewpoint of improving the thermoelectric performance and increasing the degree of integration.

In view of the above, an object of the present invention is to provide a thermoelectric conversion element including a thermoelectric element layer having a controlled cross-sectional shape, having excellent thermoelectric performance when a semiconductor element is used as a thermoelectric conversion element.

In order to solve the above problems, the present invention provides the following (1) to (7).
(1) A semiconductor element including a semiconductor element layer made of a semiconductor composition containing a semiconductor material on a substrate, wherein an area of a vertical section including a central portion of the semiconductor element layer is S (μm ² ), and a thickness of the vertical section is When the maximum value of the thickness in the width direction is Dmax (μm) and the maximum value of the length in the width direction of the vertical section is Xmax (μm), the vertical section of the semiconductor element layer has the following condition (A). And (B).
(A) 0.75 ≦ S / (Dmax × Xmax) ≦ 1.00
(B) Dmax ≧ 10 μm or (Dmax / Xmax) ≧ 0.03
Here, the maximum value Dmax of the thickness in the thickness direction of the vertical section is the upper and lower ends of the thickness in the thickness direction of the vertical section when a vertical line is formed on the substrate in the vertical section of the semiconductor element layer. Means the maximum distance (thickness) between two intersections obtained when the vertical line intersects with the vertical line. The maximum value Xmax of the length in the width direction of the longitudinal section is obtained by drawing a parallel line parallel to the substrate. Sometimes it means the maximum distance (length) between two intersections obtained when the left and right ends of the length in the width direction of the vertical cross section and the parallel line intersect.
(2) The thermoelectric conversion element using the semiconductor element according to (1), wherein the semiconductor material is a thermoelectric semiconductor material, and the semiconductor element includes a thermoelectric element layer made of a thermoelectric semiconductor composition containing the thermoelectric semiconductor material. .
(3) The thermoelectric conversion element according to (2), wherein the thermoelectric semiconductor composition further contains a heat-resistant resin.
(4) The thermoelectric semiconductor material according to (2) or (3), wherein the thermoelectric semiconductor material is a bismuth-tellurium thermoelectric semiconductor material, a telluride thermoelectric semiconductor material, an antimony-tellurium thermoelectric semiconductor material, or a bismuth selenide thermoelectric semiconductor material. 3. The thermoelectric conversion element according to item 1.
(5) The thermoelectric conversion element according to any of (2) to (4), wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin.
(6) The thermoelectric conversion element according to any one of (2) to (5), wherein the thermoelectric semiconductor composition further contains an ionic liquid and / or an inorganic ionic compound.
(7) The condition (A) satisfies 0.83 ≦ S / (Dmax × Xmax) ≦ 1.00, and the condition (B) satisfies Dmax ≧ 50 μm or (Dmax / Xmax) ≧ 0.08. The thermoelectric conversion element according to any one of the above (1) to (6).

According to the present invention, it is possible to provide a thermoelectric conversion element having a thermoelectric element layer having a controlled cross-sectional shape and having excellent thermoelectric performance when a semiconductor element is used as a thermoelectric conversion element.

Equipped with a thermoelectric element layer whose longitudinal cross-section was controlled
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional configuration diagram illustrating an example of a thermoelectric conversion element including a thermoelectric element layer having a controlled longitudinal cross-section according to the present invention. It is a figure for explaining the definition of the longitudinal section of a thermoelectric element layer when the semiconductor element of the present invention is used for a thermoelectric conversion element. It is sectional drawing for demonstrating the longitudinal cross section of the thermoelectric element layer used for the thermoelectric conversion element of the Example of this invention, or a comparative example. It is explanatory drawing which shows an example of the manufacturing method of the thermoelectric element layer by the pattern frame arrangement / separation method used for this invention in order of a process. It is explanatory drawing which shows an example of the manufacturing method of the thermoelectric conversion element by the pattern layer arrangement method used for this invention in order of a process.

[Thermoelectric conversion element]
The semiconductor device of the present invention is a semiconductor device including a semiconductor device layer made of a semiconductor composition including a semiconductor material on a substrate, and has a vertical cross-sectional area including a central portion of the semiconductor device layer, S (μm ² ); When the maximum value of the thickness in the thickness direction of the vertical section is Dmax (μm) and the maximum value of the length in the width direction of the vertical section is Xmax (μm), the vertical section of the semiconductor element layer has the following It is characterized by satisfying the conditions (A) and (B).
(A) 0.75 ≦ S / (Dmax × Xmax) ≦ 1.00
(B) Dmax ≧ 10 μm or (Dmax / Xmax) ≧ 0.03
Here, the maximum value Dmax of the thickness in the thickness direction of the vertical section is the upper and lower ends of the thickness in the thickness direction of the vertical section when a vertical line is formed on the substrate in the vertical section of the semiconductor element layer. Means the maximum distance (thickness) between two intersections obtained when the vertical line intersects with the vertical line. The maximum value Xmax of the length in the width direction of the longitudinal section is obtained by drawing a parallel line parallel to the substrate. Sometimes it means the maximum distance (length) between two intersections obtained when the left and right ends of the length in the width direction of the vertical cross section and the parallel line intersect.
When the longitudinal section of the semiconductor element layer constituting the semiconductor element of the present invention satisfies the above conditions (A) and (B), the longitudinal section of the semiconductor element layer is likely to be substantially square, and the shape of the semiconductor element layer Is easily controlled into a substantially rectangular parallelepiped shape (including a substantially cubic shape), which is preferable from the viewpoints of performance improvement and high integration.
Preferably, the semiconductor material is a thermoelectric semiconductor material, and the semiconductor element is a thermoelectric conversion element using the semiconductor element, including a thermoelectric element layer made of a thermoelectric semiconductor composition containing the thermoelectric semiconductor material.
When the semiconductor element layer satisfying the above conditions (A) and (B) is used as a thermoelectric element layer, it is preferable from the viewpoint of thermoelectric performance and manufacturability. In addition to obtaining the desired thickness, the area of the upper surface of the thermoelectric element layer tends to be flat, and the area of the junction between the upper surface of the thermoelectric element layer and the opposing electrode is sufficient, and the interface resistance and thermal resistance When a π-type thermoelectric conversion element or an in-plane type thermoelectric conversion element is configured, particularly in the case of a π-type thermoelectric conversion element having a large joint area with an electrode, the thermoelectric element layer originally has a thermoelectric element. This leads to sufficient performance, resulting in improved thermoelectric performance. In addition, since the area of the longitudinal section becomes large, the electric resistance of the thermoelectric element layer decreases, so that when an in-plane thermoelectric conversion element is formed, the thermoelectric performance is improved.

In this specification, the definition of “longitudinal section including the central portion of the semiconductor element layer” will be described with reference to FIG. FIG. 2 is a view for explaining a longitudinal section of a thermoelectric element layer when the semiconductor element of the present invention is used for a thermoelectric conversion element, and FIG. 2 (a) is a plan view of the thermoelectric element layer 4, and FIG. The layer 4 has a length X in the width direction and a length Y in the depth direction. (B) is a vertical section of the thermoelectric element layer 4, and the vertical section includes the central portion C of (a). , A hatched portion (rectangle in the figure) having a length X and a thickness D obtained when cut between AA ′ in the width direction.
Further, in the present specification, "the longitudinal section of the thermoelectric element layer is likely to be substantially square" means that it is easy to become a rectangle such as a rectangle or a square including a trapezoid.

FIG. 1 is a cross-sectional configuration view showing an example of a thermoelectric conversion element provided with a thermoelectric element layer having a controlled vertical cross-sectional shape according to the present invention. The thermoelectric conversion element 1 has an N-type thermoelectric element on an electrode 3a of a substrate 2a. It has an element layer 4a and a P-type thermoelectric element layer 4b, and further has a counter electrode substrate having an electrode 3b on a substrate 2b on the upper surface of the N-type thermoelectric element layer 4a and the P-type thermoelectric element layer 4b. Adjacent N-type thermoelectric element layers 4a and P-type thermoelectric element layers 4b are arranged so as to be electrically connected in series with the electrodes 3b on the substrate 2b interposed therebetween, and are configured as π-type thermoelectric conversion elements.

(Thermoelectric element layer)
The thermoelectric element layer (hereinafter sometimes referred to as “thermoelectric element layer thin film”) constituting the thermoelectric conversion element of the present invention is made of a thermoelectric semiconductor composition containing a thermoelectric semiconductor material on a substrate. From the viewpoint of the shape stability of the thermoelectric element layer, the thermoelectric semiconductor material preferably contains a heat-resistant resin, and from the viewpoint of thermoelectric performance, more preferably, the thermoelectric semiconductor material (hereinafter sometimes referred to as “thermoelectric semiconductor fine particles”). ), A heat-resistant resin, and a thermoelectric semiconductor composition containing an ionic liquid and / or an inorganic ionic compound.

<Vertical cross section of thermoelectric element layer>
The longitudinal section of the thermoelectric element layer used in the present invention will be described with reference to the drawings.

FIG. 3 is a cross-sectional view for explaining a vertical cross section of a thermoelectric element layer used in a thermoelectric conversion element according to an example of the present invention or a comparative example, and (a) illustrates a thermoelectric element layer 4s used in Comparative Example 1. The thermoelectric element layer 4s has a vertical section (cross-sectional area S) having a maximum value Xmax of the length in the width direction and a maximum value Dmax of the thickness in the thickness direction, and the vertical section is approximately half. It is elliptical. (B) is a vertical cross section of the thermoelectric element layer 4t used in Example 1, and the vertical cross section of the thermoelectric element layer 4t has a maximum value Xmax in the width direction and a maximum thickness in the thickness direction. It has a vertical section (cross-sectional area S) having the value Dmax, and the vertical section is substantially quadrangular (generally trapezoidal). Further, (c) is a longitudinal section of the thermoelectric element layer 4u used in Example 2, which has a maximum value Xmax in the width direction and a maximum value Dmax in the thickness direction (cross-sectional area). S), and the longitudinal section is substantially square (rectangular).

In the vertical section including the center of the thermoelectric element layer constituting the thermoelectric conversion element included in the semiconductor element of the present invention, the area of the vertical section is S (μm ² ), and the maximum value of the thickness in the thickness direction of the vertical section is When Dmax (μm) and the maximum value of the length of the vertical section in the width direction are Xmax (μm), the vertical section of the thermoelectric element layer needs to satisfy the following conditions (A) and (B). .
(A) 0.75 ≦ S / (Dmax × Xmax) ≦ 1.00
(B) Tmax ≧ 10 μm or (Dmax / Xmax) ≧ 0.03

Condition (A) requires that S / (Dmax × Xmax) be 0.75 ≦ S / (Dmax × Xmax) ≦ 1.00. When S / (Dmax × Xmax) is less than 0.75, the vertical cross section of the thermoelectric element layer tends to be semi-elliptical, and is unlikely to be substantially square. In the shape of the thermoelectric element layer, it is difficult to have a substantially rectangular parallelepiped shape (including a substantially cubic shape), a desired constant thickness cannot be obtained, and a flat region on the upper surface of the thermoelectric element layer becomes small. . In addition, the area of the longitudinal section is reduced. S / (Dmax × Xmax) is preferably at least 0.78, more preferably at least 0.83, even more preferably at least 0.90, particularly preferably at least 0.95.

Condition (B) requires that Dmax ≧ 10 μm or (Dmax / Xmax) ≧ 0.03.
When Dmax is less than 10 μm or Dmax / Xmax is less than 0.03, the longitudinal section is less likely to be a semi-ellipse by a coating method such as screen printing and stencil printing, and the shape of the thermoelectric element layer In some cases, it may be easier to control the shape into a substantially rectangular parallelepiped shape, but when used as a thermoelectric element layer, problems such as a decrease in efficiency of thermoelectric performance and a decrease in integration may occur.
When Dmax is 10 μm or more, or Dmax / Xmax is 0.03 or more, in a coating method such as screen printing or stencil printing, the longitudinal section tends to be semi-elliptical, and the shape of the thermoelectric element layer is substantially rectangular parallelepiped. (Including a substantially cubic shape).
Dmax is preferably 50 μm or more, more preferably 100 μm or more, and still more preferably 150 μm or more. Further, Dmax / Xmax is preferably 0.05 or more, more preferably 0.08 or more, further preferably 0.08 to 3.00, particularly preferably 0.09 to 1.50, and most preferably 0.10 to 1. 1.00. When Dmax or Dmax / Xmax is within the above range, the longitudinal section tends to be substantially square, and the shape of the thermoelectric element layer can be easily controlled to be substantially rectangular (including substantially cubic). This leads to higher efficiency and higher integration of thermoelectric performance.

When the vertical cross section of the thermoelectric element layer constituting the thermoelectric conversion element is in the range of the above-described conditions (A) and (B), the vertical cross section of the thermoelectric element layer is likely to be substantially rectangular, and the shape of the thermoelectric element layer is reduced. In this case, the thermoelectric element layer can be easily controlled to have a substantially rectangular parallelepiped shape (including a substantially cubic shape), and a desired constant thickness can be obtained. In addition, the upper surface region of the thermoelectric element layer can easily become a flat surface. The area of the junction between the upper surface of the first electrode and the opposing electrode is sufficiently large, and an increase in interface resistance and thermal resistance is suppressed. In addition, since the area of the vertical section becomes large, the electric resistance of the thermoelectric element layer decreases. In any case, the thermoelectric performance is improved.

(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. P-type bismuth telluride, N-type bismuth telluride, etc. bismuth - telluride thermoelectric semiconductor material; GeTe, telluride based thermoelectric semiconductor materials such as PbTe; antimony - tellurium based thermoelectric semiconductor _{_{material; ZnSb, Zn 3 Sb 2,}} Zn 4 Sb 3 , etc. Zinc-antimony-based thermoelectric semiconductor material; silicon-germanium-based thermoelectric semiconductor material such as SiGe; bismuth selenide-based thermoelectric semiconductor material such as Bi ₂ Se ₃ ; β-FeSi ₂ , CrSi ₂ , MnSi _1.73 , Mg ₂ Si Etc .; oxide-based thermoelectric semiconductor materials; FeVAl, F VAlSi, Heusler materials such FeVTiAl, such sulfide-based thermoelectric semiconductor materials, such as TiS ₂ is used.
Among these, 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 is preferable.

Further, from the viewpoint of thermoelectric performance, a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride is more preferable.
As the P-type bismuth telluride, those having a carrier as a hole and a Seebeck coefficient as a positive value, for example, those represented by Bi _X Te ₃ Sb _2-X are preferably used. In this case, X is preferably 0 <X ≦ 0.8, and more preferably 0.4 ≦ X ≦ 0.6. When X is greater than 0 and 0.8 or less, the Seebeck coefficient and the electrical conductivity increase, which is preferable because characteristics as a P-type thermoelectric element are maintained.
The N-type bismuth telluride preferably has an electron carrier and a negative Seebeck coefficient and is preferably represented by, for example, Bi ₂ Te _3-Y Se _Y. In this case, Y is preferably 0 ≦ Y ≦ 3 (when Y = 0: Bi ₂ Te ₃ ), and more preferably 0 <Y ≦ 2.7. When Y is 0 or more and 3 or less, the Seebeck coefficient and the electric conductivity increase, and the characteristics as an N-type thermoelectric element are preferably maintained.

熱 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.

配合 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, still more preferably 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, and the decrease in electric conductivity is suppressed, and only the heat conductivity is reduced, so that high thermoelectric performance is exhibited. In addition, a film having sufficient film strength and flexibility is obtained, which is preferable.

The average particle size of the thermoelectric semiconductor fine particles is preferably 10 nm to 200 μm, more preferably 10 nm to 30 μm, further preferably 50 nm to 10 μm, and particularly preferably 1 to 6 μm. Within the above range, uniform dispersion is facilitated, and electric conductivity can be increased.
The method of pulverizing the thermoelectric semiconductor material to obtain thermoelectric semiconductor fine particles is not particularly limited, and may be pulverized to a predetermined size by a known pulverizer such as a jet mill, a ball mill, a bead mill, a colloid mill, and a roller mill. .
The average particle size of the thermoelectric semiconductor fine particles was obtained by measuring with a laser diffraction particle size analyzer (manufactured by Malvern, Mastersizer 3000), and was defined as the median value of the particle size distribution.

The thermoelectric semiconductor particles are preferably heat-treated in advance (the "heat treatment" here is different from the "annealing treatment" performed in the annealing step in the present invention). By performing the heat treatment, the thermoelectric semiconductor particles have improved crystallinity, and further, since the surface oxide film of the thermoelectric semiconductor particles is removed, the Seebeck coefficient or the Peltier coefficient of the thermoelectric conversion material increases, and the thermoelectric performance index further increases. Can be improved. The heat treatment is not particularly limited, but before preparing the thermoelectric semiconductor composition, the gas flow rate is controlled so as not to adversely affect the thermoelectric semiconductor particles, under an atmosphere of an inert gas such as nitrogen or argon. The reaction is preferably performed under a reducing gas atmosphere such as hydrogen or under vacuum conditions, and more preferably under a mixed gas atmosphere of an inert gas and a reducing gas. The specific temperature condition depends on the thermoelectric semiconductor fine particles to be used, but it is usually preferable that the temperature is lower than the melting point of the fine particles and at 100 to 1500 ° C. for several minutes to several tens of hours.

(Heat-resistant resin)
In the thermoelectric semiconductor composition used in the present invention, it is preferable to use a heat-resistant resin from the viewpoint of annealing the thermoelectric semiconductor material at a high temperature after forming the thermoelectric element layer. It acts as a binder between the thermoelectric semiconductor materials (thermoelectric semiconductor particles), can increase 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. However, when a thin film of the thermoelectric semiconductor composition is subjected to crystal growth of thermoelectric semiconductor particles by annealing or the like, various properties such as mechanical strength and thermal conductivity of the resin are used. A heat-resistant resin that maintains its physical properties without deterioration is preferred.
The heat-resistant resin is preferably a polyamide resin, a polyamide-imide resin, a polyimide resin, or an epoxy resin, which has higher heat resistance and does not adversely affect the crystal growth of the thermoelectric semiconductor particles in the thin film, and has excellent flexibility. In this respect, a polyamide resin, a polyamideimide resin, and a polyimide resin are more preferable. When a polyimide film is used as a substrate described later, a polyimide resin is more preferable as the heat-resistant resin from the viewpoint of adhesion to the polyimide film. In the present invention, the polyimide resin is a general term for polyimide and its precursor.

分解 The heat-resistant resin preferably has a decomposition temperature of 300 ° C or higher. When the decomposition temperature is in the above range, as described later, even when the thin film made of the thermoelectric semiconductor composition is annealed, the flexibility can be maintained without losing the function as a binder.

Further, the heat-resistant resin preferably has a mass reduction rate at 300 ° C. by thermogravimetry (TG) of 10% or less, more preferably 5% or less, and still more preferably 1% or less. . If the mass reduction rate is within the above range, as described later, even when the thin film made of the thermoelectric semiconductor composition is annealed, the flexibility of the thermoelectric element layer can be maintained without losing the function as a binder. .

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 further preferably 2 to 15% by mass. % By mass. When the compounding amount of the heat-resistant resin is within the above range, it functions as a binder of the thermoelectric semiconductor material, facilitates formation of a thin film, and obtains a film having both high thermoelectric performance and high film strength.

(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. Ionic liquids have features such as extremely low vapor pressure, non-volatility, excellent thermal stability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, as a conductive auxiliary agent, it is possible to effectively suppress a decrease in electric conductivity between the thermoelectric semiconductor particles. Further, the ionic liquid has a high polarity based on the aprotic ionic structure and has excellent compatibility with the heat-resistant resin, so that the electric conductivity of the thermoelectric element layer can be made uniform.

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 derivatives thereof; amine cations of tetraalkylammonium and derivatives thereof; phosphines such as phosphonium, trialkylsulfonium and tetraalkylphosphonium systems cations and their derivatives; and cationic components, such as lithium cations and derivatives ^{_{^{_{thereof, Cl -, AlCl 4 -,}}}} Al 2 Cl 7 -, ClO 4 - chloride or ion, Br ^-, etc. of bromide ion, I ^-, etc. Ion, BF ₄ ⁻ , fluoride ion such as PF ₆ ⁻ , halide anion such as F (HF) _n ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF _₃ SO ₃ ^-, _{_{^{_{FSO 2) 2 N -, (}}}} CF 3 SO 2) 2 N -, (CF 3 SO 2) 3 C -, AsF 6 -, SbF 6 -, NbF 6 -, TaF 6 -, F (HF) n -, Anions such as (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ⁻ And a component.

Among the above ionic liquids, the cation component of the ionic liquid is a pyridinium cation and a derivative thereof from the viewpoints of high-temperature stability, compatibility with the thermoelectric semiconductor fine particles and the resin, and suppression of a decrease in electric conductivity in the gap between the thermoelectric semiconductor fine particles. , And at least one selected from imidazolium cations and derivatives thereof. The anionic component of the ionic liquid preferably contains a halide anion, and more preferably contains at least one selected from Cl ⁻ , Br ⁻ and I ⁻ .

Specific examples of the ionic liquid in which the cation component contains a pyridinium cation and a derivative thereof include 4-methyl-butylpyridinium chloride, 3-methyl-butylpyridinium chloride, 4-methyl-hexylpyridinium chloride, and 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- Chill pyridinium iodide and the like. Of these, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate, and 1-butyl-4-methylpyridinium iodide are preferred.

Specific examples of the ionic liquid in which the cation component contains an imidazolium cation and a derivative thereof include [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] and [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-methylimida Lithium 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 methylsulfate, 1,3-dibutylimidazolium methylsulfate and the like. Among them, [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] and [1-butyl-3- (2-hydroxyethyl) imidazolium tetrafluoroborate] are preferable.

The above ionic liquid preferably has an electric conductivity of 10 ⁻⁷ S / cm or more, more preferably 10 ⁻⁶ S / cm or more. When the electric conductivity is in the above range, a decrease in electric conductivity between the thermoelectric semiconductor particles can be effectively suppressed as a conductive auxiliary agent.

The ionic liquid preferably has a decomposition temperature of 300 ° C or higher. When the decomposition temperature is in the above range, as described later, even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, the effect as the conductive auxiliary agent can be maintained.

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

配合 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 further preferably 1.0 to 20% by mass. When the blending amount of the ionic liquid is within the above range, a decrease in electric conductivity is effectively suppressed, and a film having high thermoelectric performance is obtained.

(Inorganic ionic compound)
The inorganic ionic compound used in the present invention is a compound composed of at least a cation and an anion. 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 is possible to suppress a decrease in the electric conductivity between the thermoelectric semiconductor particles.

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 ⁺ .
Examples of the alkaline earth metal cation include Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ .

Examples of the anion include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , OH ⁻ , CN ⁻ , NO ₃ ⁻ , NO ₂ ⁻ , ClO ⁻ , ClO ₂ ⁻ , ClO ₃ ⁻ , ClO ₄ ⁻ , and CrO ₄ ^{2. _{^{^{-, HSO 4 -, SCN -}}}} , BF 4 -, PF 6 - , and the like.

Known or commercially available inorganic ionic compounds can be used. For example, a cation component such as potassium cation, sodium cation, or lithium ^{_{^{_{cations, Cl -, AlCl 4 -,}}}} Al 2 Cl 7 -, ClO 4 - chloride or ion, Br ^-, etc. of bromide ion, I ^-, etc. And iodide ions, fluoride ions such as BF ₄ ⁻ and PF ₆ ⁻ , halide anions such as F (HF) _n ⁻ and anion components such as NO ₃ ⁻ , OH ⁻ and CN ^−. It is.

Among the above-mentioned inorganic ionic compounds, from the viewpoints of high-temperature stability, compatibility with the thermoelectric semiconductor fine particles and the resin, suppression of a decrease in electric conductivity between the thermoelectric semiconductor fine particles, the cation component of the inorganic ionic compound is potassium. , Sodium, and lithium. The anionic component of the inorganic ionic compound preferably contains a halide anion, and more preferably contains at least one selected from Cl ⁻ , Br ⁻ , and I ⁻ .

Specific examples of the inorganic ionic compound in which the cation component contains a potassium cation include KBr, KI, KCl, KF, KOH, and K ₂ CO ₃ . Among them, KBr and KI are preferable.
Specific examples of the inorganic ionic compound in which the cation component contains a sodium cation include NaBr, NaI, NaOH, NaF, and Na ₂ CO ₃ . Of these, NaBr and NaI are preferred.
Specific examples of the inorganic ionic compound whose cation component includes a lithium cation include LiF, LiOH, and LiNO ₃ . Among them, LiF and LiOH are preferable.

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

The inorganic ionic compound preferably has a decomposition temperature of 400 ° C or higher. When the decomposition temperature is in the above range, as described later, even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, the effect as the conductive auxiliary agent can be maintained.

In addition, the inorganic ionic compound preferably has a mass reduction rate at 400 ° C. by thermogravimetry (TG) of 10% or less, more preferably 5% or less, and more preferably 1% or less. More preferred. When the mass reduction rate is in the above range, as described later, even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is annealed, the effect as the conductive auxiliary agent can be maintained.

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 further preferably 1.0 to 10% by mass. . When the amount of the inorganic ionic compound is within the above range, a decrease in electric conductivity can be effectively suppressed, and as a result, a film having improved thermoelectric performance can be obtained.
When the inorganic ionic compound and the 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 from 0.01 to 50% by mass, Preferably it is 0.5 to 30% by mass, more preferably 1.0 to 10% by mass.

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

(Method of preparing thermoelectric semiconductor composition)
The method for preparing the thermoelectric semiconductor composition used in the present invention is not particularly limited, and the thermoelectric semiconductor particles and the heat-resistant resin can be obtained by a known method such as an ultrasonic homogenizer, a spiral mixer, a planetary mixer, a disperser, and a hybrid mixer. The thermoelectric semiconductor composition may be prepared by adding the ionic liquid and / or the inorganic ionic compound, the other additives as needed, and the solvent, and mixing and dispersing the mixture.
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 as a mixture 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.

<Method of manufacturing thermoelectric element layer>
In the present invention, the thermoelectric element layer is formed on a substrate or an electrode using a coating liquid or the like made of the thermoelectric semiconductor composition.
Examples of a method for producing a thermoelectric element layer satisfying the conditions (A) and (B) constituting the thermoelectric conversion element of the present invention include the following methods (P), (Q) and (R).
(P) Multilayer printing method (Q) Pattern frame arrangement / peeling method (R) Pattern layer arrangement method

(Multilayer printing method)
The multi-layer printing method, using a coating liquid or the like composed of a thermoelectric semiconductor composition, on the substrate, or at the same position on the electrode, using a screen plate having a desired pattern, a stencil plate, a screen printing method, a stencil This is a method in which printing is performed a plurality of times by a printing method or the like to form a thick thermoelectric element layer in which thin films of a plurality of thermoelectric element layers are stacked.
Specifically, first, a coating film to be a thin film of the first thermoelectric element layer is formed, and the obtained coating film is dried to form a thin film of the first thermoelectric element layer. Next, similarly to the first layer, a coating film to be a thin film of the second thermoelectric element layer is formed on the thin film of the thermoelectric element layer obtained in the first layer, and the obtained coating film is dried. Thereby, a thin film of the second thermoelectric element layer is formed. For the third and subsequent layers, similarly, a coating film to be a thin film of the third and subsequent thermoelectric element layers is formed on the thin film of the thermoelectric element layer obtained immediately before, and the obtained coating film is dried. Thus, a thin film of the third and subsequent thermoelectric element layers is formed. By repeating this process a desired number of times, a thick thermoelectric element layer in which a plurality of thin thermoelectric element layers are stacked can be obtained.
As a drying method, a conventionally known drying method such as a hot air drying method, a hot roll drying method, and an infrared irradiation method can be employed. 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 the used solvent can be dried.
By using the multilayer printing method, a thermoelectric element layer satisfying the above conditions (A) and (B) can be obtained.

(Pattern frame arrangement / peeling method)
The pattern frame arrangement / peeling method is to provide a pattern frame having an opening separated on a substrate, fill the opening with a thermoelectric semiconductor composition, dry, and peel the pattern frame from the substrate. This is a method for forming a thermoelectric element layer having excellent shape controllability reflecting the shape of the opening of the pattern frame.
As a manufacturing process, a step of providing a pattern frame having an opening on a substrate, a step of filling the opening with the thermoelectric semiconductor composition, drying the thermoelectric semiconductor composition filled in the opening, and a thermoelectric element Forming a layer, and separating the pattern frame from the substrate.
An example of a method for manufacturing a thermoelectric element layer using a pattern frame arrangement / peeling method will be specifically described with reference to the drawings.
FIG. 4 is an explanatory view showing an example of a method of manufacturing a thermoelectric element layer by a pattern frame arrangement / peeling method used in the present invention in the order of steps;
(A) is sectional drawing which shows the aspect which the pattern frame was made to oppose on the board | substrate, the pattern frame which consists of stainless steel 12 'and has opening 13s, opening 13, and opening part depth (pattern frame thickness) 13d. 12 is prepared and is made to face the substrate 11;
(B) is a cross-sectional view after the pattern frame is provided on the substrate, and the pattern frame 12 is provided on the substrate 11;
(C) is a cross-sectional view after filling the thermoelectric element layer into the opening of the pattern frame. The P-type is formed in the opening 13 having the opening 13s of the pattern frame 12 made of the stainless steel 12 'prepared in (b). A thermoelectric semiconductor composition containing a thermoelectric semiconductor material and a thermoelectric semiconductor composition containing an N-type thermoelectric semiconductor material are respectively filled in predetermined openings 13, and a thermoelectric semiconductor composition containing a P-type thermoelectric semiconductor material filled in the openings 13 Drying the thermoelectric semiconductor composition including the material and the N-type thermoelectric semiconductor material to form a P-type thermoelectric element layer 14b and an N-type thermoelectric element layer 14a;
(D) is a cross-sectional view showing an embodiment in which the pattern frame is peeled off from the filled thermoelectric element layer to obtain only the thermoelectric element layer, and the pattern frame 12 is formed by forming a P-type thermoelectric element layer 14b and an N-type thermoelectric element layer. The P-type thermoelectric element layer 14b and the N-type thermoelectric element layer 14a as self-supporting layers are obtained by peeling off from the layer 14a.
The drying method, the case where a solvent is used in the preparation of the thermoelectric semiconductor composition, and the like are the same as the above-described multilayer printing method.
As described above, a thermoelectric element layer used for a thermoelectric conversion element can be obtained.
As described above, by using the pattern frame arrangement / peeling method, a thermoelectric element layer satisfying the conditions (A) and (B) can be easily obtained.

(Pattern layer arrangement method)
The pattern layer disposing method is to provide a pattern layer made of a layer containing a resin having an opening which is spaced apart on an electrode of a substrate, fill the opening with a thermoelectric semiconductor composition, and dry it to form an opening in the pattern layer. This is a method for forming a thermoelectric element layer having excellent shape controllability in which the shape of a portion is reflected.
As a manufacturing process, for example, when forming a π-type thermoelectric conversion element, a step of forming a pattern layer having a separated opening on the electrode, a thermoelectric semiconductor composition including a P-type thermoelectric semiconductor material in the separated opening Filling a thermoelectric semiconductor composition containing an object and an N-type thermoelectric semiconductor material, the thermoelectric semiconductor composition containing the P-type thermoelectric semiconductor material and the N-type thermoelectric semiconductor material filled in the spaced openings. A step of drying the thermoelectric semiconductor composition to obtain a P-type thermoelectric element layer and an N-type thermoelectric element layer.
An example of a method for manufacturing a thermoelectric conversion element using the pattern layer arrangement method will be specifically described with reference to the drawings.
FIG. 5 is an explanatory view showing an example of a method for manufacturing a thermoelectric conversion element by a pattern layer arrangement method used in the present invention in the order of steps;
(A) is a sectional view after an electrode is formed on a substrate, and an electrode 23a is formed on a substrate 22a;
(B) is a cross-sectional view after forming a layer containing a resin on the electrode, and forming a layer 24 ′ containing a resin on the electrode 23a;
(C) is a plan view of the pattern layer after processing the layer containing the resin (electrodes are not shown), and (c ') is the pattern layer when cut between AA' in (c). Is a cross-sectional view of FIG. 1, processing a resin-containing layer 24 ′ to form a pattern layer 24 having openings 25 s and openings 25 separated on the electrodes;
(D) is a cross-sectional view after the opening of the pattern layer is filled with the thermoelectric element layer, and the opening 25 of the pattern layer 24 includes a thermoelectric semiconductor composition containing a P-type thermoelectric semiconductor material and an N-type thermoelectric semiconductor material. Each of the thermoelectric semiconductor compositions is filled and dried to form an N-type thermoelectric element layer 26a and a P-type thermoelectric element layer 26b;
(E) is a cross-sectional view showing a mode in which the upper surface of the thermoelectric element layer obtained in (d) is opposed to and bonded to an electrode on a substrate facing the thermoelectric element layer, and has an upper surface of the thermoelectric element layer and an electrode 23b. A counter electrode substrate made of the substrate 22b is joined.
The drying method, the case where a solvent is used in the preparation of the thermoelectric semiconductor composition, and the like are the same as those in the above-described multilayer printing method and pattern frame arrangement / peeling method.
As described above, a π-type thermoelectric conversion element can be obtained.
As described above, by using the pattern layer arrangement method, it is possible to easily obtain a π-type thermoelectric conversion element including a thermoelectric element layer satisfying the conditions (A) and (B).

Among the above, from the viewpoint of obtaining a high filling rate, it is more preferable to use the pattern frame arrangement / peeling method or the pattern layer arrangement method, and from the viewpoint that the longitudinal section can be easily controlled to a substantially rectangular parallelepiped shape, More preferably, a peeling method is used.

The viscosity of the coating liquid composed of the thermoelectric semiconductor composition is appropriately adjusted depending on the blending amount of the thermoelectric semiconductor material, the thickness of the thermoelectric element layer, and the dimensions of the pattern.From the viewpoint of shape controllability of the thermoelectric element layer, for example, 1 Pa · s to 1000 Pa · s, preferably 5 Pa · s to 500 Pa · s, more preferably 10 Pa · s to 300 Pa · s, and still more preferably 30 Pa · s to 200 Pa · s at 25 ° C. and 5 s ^−1. is there.
The thickness of the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition, when used as a π-type thermoelectric conversion element, from the viewpoint of using a screen printing method, a stencil printing method, etc., 50 μm or more, 1 mm or less, Preferably it is 80 μm or more and 1 mm or less, more preferably 100 μm or more and 700 μm or less, further preferably 150 μm or more and 500 μm or less.
On the other hand, when used as an in-plane type thermoelectric conversion element, the thickness of the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is 10 μm or more, 300 μm or less, preferably 10 μm or more from the viewpoint of flexibility. It is 200 μm or less, more preferably 10 μm or more and 100 μm or less.

(Annealing treatment)
In the present invention, it is preferable to perform an annealing treatment after the formation of the thermoelectric element layer. By performing the annealing treatment, the thermoelectric performance can be stabilized, and the thermoelectric semiconductor particles in the thermoelectric element layer can be crystal-grown, so that the thermoelectric performance can be further improved.
The annealing treatment is not particularly limited, but is usually performed under a controlled gas flow rate, under an inert gas atmosphere such as nitrogen or argon, under a reducing gas atmosphere, or under vacuum conditions. Although depending on the inorganic ionic compound and the like, the annealing temperature is usually 100 to 600 ° C. for several minutes to several tens of hours, preferably 150 to 600 ° C., for several minutes to several tens of hours, and more preferably 250 to tens of hours. The reaction is performed at 600 ° C. for several minutes to several tens of hours, more preferably at 250 to 550 ° C. for several minutes to tens of hours.

(substrate)
In the thermoelectric conversion element of the present invention, the substrate is not particularly limited, but from the viewpoint of thinness and flexibility, it is possible to use a resin film which does not affect the decrease in the electric conductivity of the thermoelectric element layer and the increase in the heat conductivity. it can. Above all, even when the thin film of the thermoelectric element layer made of the thermoelectric semiconductor composition is excellent in flexibility, the performance of the thermoelectric element layer can be maintained without thermally deforming the substrate, and the heat resistance and the dimensions can be maintained. From the viewpoint of high stability, a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film is preferable. Further, from the viewpoint of high versatility, a polyimide film is particularly preferable.

The thickness of the resin film is preferably from 1 to 1000 μm, more preferably from 5 to 500 μm, and still more preferably from 10 to 100 μm, from the viewpoints of flexibility, heat resistance and dimensional stability.
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 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 measured in accordance with JIS K7197 (2012) is 0.1 ppm · ° C. ^-1 to 50 ppm · ° C. ^-1 and 0.1 ppm · ° C. ^-1 to 30 ppm · ° C. ^-1 Is more preferred.

In addition, an insulating material such as glass or ceramic may be used as the substrate used in the present invention. The thickness of the substrate is preferably 100 to 1200 μm, more preferably 200 to 800 μm, and further preferably 400 to 700 μm, from the viewpoint of process and dimensional stability.

(electrode)
Examples of the metal material of the electrodes of the thermoelectric conversion element used in the present invention include copper, gold, nickel, aluminum, rhodium, platinum, chromium, palladium, stainless steel, molybdenum, tin, and alloys containing any of these metals. Can be
The thickness of the electrode layer is preferably 10 nm to 200 μm, more preferably 30 nm to 150 μm, and still more preferably 50 nm to 120 μm. When the thickness of the electrode layer is within the above range, the electric conductivity is high, the resistance is low, and sufficient strength as an electrode is obtained.

The electrodes are formed using the above-described metal material.
As a method of forming an electrode, after providing an electrode on which a pattern is not formed on a resin film, a predetermined physical or chemical treatment mainly using a photolithography method, or a combination thereof, or the like, is used. Or a method of directly forming an electrode pattern by a screen printing method, an ink jet method, or the like.
Examples of a method for forming an electrode on which no pattern is formed include PVD (physical vapor deposition) such as vacuum deposition, sputtering, and ion plating, or CVD (chemical vapor deposition) such as thermal CVD and atomic layer deposition (ALD). Dry processes such as vapor phase epitaxy), various coatings such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade, and wet processes such as electrodeposition, silver salt methods , An electrolytic plating method, an electroless plating method, lamination of a metal foil, and the like, which are appropriately selected according to the material of the electrode.
Since high conductivity and high thermal conductivity are required for the electrode used in the present invention from the viewpoint of maintaining thermoelectric performance, it is preferable to use an electrode formed by a plating method or a vacuum film forming method. Since high conductivity and high thermal conductivity can be easily realized, a vacuum film forming method such as a vacuum evaporation method and a sputtering method, an electrolytic plating method, and an electroless plating method are preferable. The pattern can be easily formed with a hard mask such as a metal mask interposed therebetween, depending on the size and dimensional accuracy requirements of the formed pattern.

(Joining material layer)
In the thermoelectric conversion element used in the present invention, a bonding material layer can be used for bonding the thermoelectric element layer and the electrode.
Examples of the bonding material used for the bonding material layer include a solder material, a conductive adhesive, a sintered bonding agent, and the like, and in this order, a solder layer, a conductive adhesive layer, a sintered bonding agent layer, and the like. It is preferably formed on. In this specification, “conductive” means that the electrical resistivity is less than 1 × 10 ⁶ Ω · m.

The solder material constituting the solder layer may be appropriately selected in consideration of the heat-resistant temperature of the material constituting the thermoelectric conversion element, and the conductivity and thermal conductivity of the solder layer. Sn, Sn / Pb Alloy, Sn / Ag alloy, Sn / Cu alloy, Sn / Sb alloy, Sn / In alloy, Sn / Zn alloy, Sn / In / Bi alloy, Sn / In / Bi / Zn alloy, Sn / Bi / Pb / Cd Alloy, Sn / Bi / Pb alloy, Sn / Bi / Cd alloy, Bi / Pb alloy, Sn / Bi / Zn alloy, Sn / Bi alloy, Sn / Bi / Pb alloy, Sn / Pb / Cd alloy, Sn / Cd Known materials such as alloys can be used. From the viewpoints of lead-free and / or cadmium-free, melting point, electrical conductivity and thermal conductivity, 43Sn / 57Bi alloy, 42Sn / 58Bi alloy, 40Sn / 56Bi / 4Zn alloy, 48Sn / 52In alloy, 39.8Sn / 52In / 7Bi / An alloy such as a 1.2 Zn alloy is preferred.
Commercially available solder materials include the following. For example, a 42Sn / 58Bi alloy (manufactured by Tamura Seisakusho Co., Ltd., product name: SAM10-401-27), a 41Sn / 58Bi / Ag alloy (manufactured by Nihon Handa Co., product name: PF141-LT7HO) and the like can be used.
The thickness (after heating and cooling) of the solder layer is preferably 10 to 200 μm, more preferably 20 to 150 μm, further preferably 30 to 130 μm, and particularly preferably 40 to 120 μm. When the thickness of the solder layer is in this range, it is easy to obtain the adhesion of the thermoelectric conversion material to the chip and the electrode.
As a method of applying the solder material, a known method such as stencil printing, screen printing, and dispensing method may be used. The heating temperature varies depending on the solder material, resin film, and the like used, but is usually at 150 to 280 ° C. for 3 to 20 minutes.

The conductive adhesive constituting the conductive adhesive layer is not particularly limited, and examples thereof include a conductive paste. Examples of the conductive paste include a copper paste, a silver paste, and a nickel paste. When a binder is used, an epoxy resin, an acrylic resin, a urethane resin, and the like are used.
As a method of applying the conductive adhesive, a known method such as a screen printing and a dispensing method may be used.
The thickness of the conductive adhesive layer is preferably from 10 to 200 μm, more preferably from 20 to 150 μm, further preferably from 30 to 130 μm, and particularly preferably from 40 to 120 μm.

The sintering bonding agent constituting the sintering bonding agent layer is not particularly limited, and examples thereof include a sintering paste and the like. The sintering paste is made of, for example, micron-sized metal powder and nano-sized metal particles, and is different from the conductive adhesive in that metal is directly bonded by sintering, and is an epoxy resin, an acrylic resin, a urethane. A binder such as a resin may be included.
Examples of the sintering paste include a silver sintering paste and a copper sintering paste.
As a method of applying the sintered bonding agent layer, a known method such as screen printing, stencil printing, or a dispensing method may be used. The sintering conditions vary depending on the metal material used and the like, but are usually at 100 to 300 ° C. for 30 to 120 minutes.
Commercially available sintered bonding agents include, for example, sintering paste (manufactured by Kyocera Corporation, product name: CT2700R7S) and sintered metal bonding material (manufactured by Nihon Handa, product name: MAX102) as silver sintering paste. Can be used.
The thickness of the sintered bonding agent layer is preferably 10 to 200 μm, more preferably 20 to 150 μm, further preferably 30 to 130 μm, and particularly preferably 40 to 120 μm.

When the semiconductor element of the present invention is used as a thermoelectric conversion element, a thermoelectric conversion element having excellent thermoelectric performance is obtained by satisfying the conditions (A) and (B) in the longitudinal section of the obtained thermoelectric element layer. be able to. Further, it is possible to realize high integration of the thermoelectric element layer.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The evaluation of the electric resistance value and the filling rate of the thermoelectric conversion elements produced in the examples and comparative examples were performed by the following methods.
(A) Evaluation of Electric Resistance Value The electric resistance value between the extraction electrode portions of the thermoelectric element layer of the obtained thermoelectric conversion element was measured at 25 ° C. × 50 by a digital hi-tester (manufactured by Hioki Electric Co., Ltd., model name: 3801-50). It was measured in an environment of% RH.
(B) Filling ratio evaluation A vertical section including the center of the thermoelectric element layer of the obtained thermoelectric conversion element was observed using a digital microscope (manufactured by Keyence Corporation, model name “VHX-5000”), and the area of the vertical section was observed. S (μm ² ), the maximum value Dmax (μm) of the thickness in the thickness direction of the vertical section, and the maximum value Xmax (μm) of the length in the width direction of the vertical section were measured, and the filling rate [S / (Dmax × Xmax)] was calculated and evaluated.

(Example 1)
The thermoelectric semiconductor material constituting the thermoelectric semiconductor composition is used as thermoelectric semiconductor particles.
(Preparation of thermoelectric semiconductor particles)
P-type bismuth telluride Bi _0.4 Te ₃ Sb _1.6 (manufactured by Kojundo Chemical Laboratory, particle size: 180 μm), which is a bismuth-tellurium-based thermoelectric semiconductor material, was mixed with a planetary ball mill (Premium line P, manufactured by Fritsch Japan KK). Using -7), the particles were pulverized in a nitrogen gas atmosphere to produce thermoelectric semiconductor particles T1 having an average particle size of 1.2 μm. The thermoelectric semiconductor particles obtained by the pulverization were subjected to particle size distribution measurement using a laser diffraction type particle size analyzer (manufactured by Malvern, Mastersizer 3000).
Further, N-type bismuth telluride Bi ₂ Te ₃ (manufactured by Kojundo Chemical Laboratory, particle size: 180 μm), which is a bismuth-tellurium-based thermoelectric semiconductor material, is pulverized in the same manner as described above, and thermoelectric semiconductor fine particles having an average particle size of 1.4 μm. T2 was produced.

(Preparation of coating liquid)
Coating liquid (P)
90 parts by mass of the obtained fine particles T1 of the P-type bismuth-tellurium-based thermoelectric semiconductor material, and a polyamic acid (poly (pyromellitic dianhydride-co-4,4, manufactured by Sigma-Aldrich Co.) '-Oxydianiline) amic acid solution, 5 parts by mass of a solvent: N-methylpyrrolidone, solid content concentration: 15% by mass), and [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] as an ionic liquid A coating liquid (P) comprising a thermoelectric semiconductor composition in which 5 parts by mass were mixed and dispersed was prepared. The viscosity of the coating liquid (P) was 170 Pa · s.
Coating liquid (N)
90 parts by mass of the obtained fine particles T2 of the N-type bismuth-tellurium-based thermoelectric semiconductor material, and a polyamic acid (poly (pyromellitic dianhydride-co-4,4, manufactured by Sigma-Aldrich Co.) '-Oxydianiline) amic acid solution, 5 parts by mass of a solvent: N-methylpyrrolidone, solid content concentration: 15% by mass), and [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] as an ionic liquid A coating liquid (N) composed of a thermoelectric semiconductor composition in which 5 parts by mass were mixed and dispersed was prepared. The viscosity of the coating liquid (N) was 190 Pa · s.

<Formation of thermoelectric element layer>
The above-mentioned coating is performed on an electrode (4.0 mm long × 1.5 mm wide × 10 μm thick) provided on a lower polyimide film substrate (manufactured by Dupont Toray, Kapton 200H, 100 mm × 100 mm, thickness: 50 μm). The liquid (P) was applied three times by a stencil printing method as follows (multilayer printing method).
First, using a coating liquid (P), printing was performed at a predetermined position with a first stencil plate having a plate thickness of 30 μm and dried. Next, a third stencil plate having a plate thickness of 80 μm was printed and dried on the printing layer formed with the first stencil plate having a plate thickness of 30 μm. Further, printing was performed with a fifth stencil plate having a plate thickness of 150 μm on the printing layer formed with the third stencil plate having a plate thickness of 80 μm, and dried. Thereafter, by annealing, 100 P-type thermoelectric element layers of the same size of 1.5 mm × 1.5 mm on which the P-type thermoelectric element layers obtained by three-layer printing were arranged were provided.
The drying after the application of the coating liquid was performed at a temperature of 150 ° C. for 10 minutes in an argon atmosphere, and the annealing of the obtained thin film of the thermoelectric element layer was performed using a mixed gas of hydrogen and argon (hydrogen: argon = 3 volumes). %: 97% by volume) In an atmosphere, the temperature was increased at a heating rate of 5 K / min, and the temperature was maintained at 325 ° C. for 1 hour to grow fine particles of the thermoelectric semiconductor material to form a P-type thermoelectric element layer.
Similarly, the upper polyimide film substrate (having the same specifications except for the arrangement of the electrodes of the lower polyimide film substrate, the arrangement of the electrodes is such that 100 pairs of P-type thermoelectric element layers and N-type thermoelectric element layers are alternately arranged in series, Then, the coating liquid (N) was used for printing and drying at a predetermined position with a second stencil plate having a plate thickness of 30 μm using a coating liquid (N). Next, printing was performed with a fourth stencil plate having a plate thickness of 80 μm on the printing layer formed with the second stencil plate having a plate thickness of 30 μm, followed by drying. Further, printing was performed with a sixth stencil plate having a plate thickness of 150 μm on the printing layer formed with the fourth stencil plate having a plate thickness of 80 μm, and dried. Thereafter, by annealing, 100 N-type thermoelectric element layers of the same size of 1.5 mm × 1.5 mm on which the N-type thermoelectric element layers obtained by three-layer printing were arranged were provided.
The thicknesses of the P-type thermoelectric element layer and the N-type thermoelectric element layer were all 160 μm.

Next, a solder material (PF141-LT7HOF = 10, manufactured by Nihon Solder Co., Ltd.) was provided on the upper surface of the P-type thermoelectric element layer and the electrodes of the lower polyimide film substrate. By providing the above-mentioned solder material on the upper surface portion of the and bonding the thermoelectric element layers and the electrodes, 100 pairs of P-type thermoelectric element layers and N-type thermoelectric element layers are alternately arranged in series, and electrically connected. A π-type thermoelectric conversion element (Peltier cooling element) connected in series was produced.
The distance between the centers of the P-type thermoelectric element layer and the N-type thermoelectric element layer formed on the electrodes of the lower polyimide film substrate was 2.5 mm, and the distance between the P-type thermoelectric element layers on the electrodes of the upper polyimide film substrate was 2.5 mm. The distance between each center and the N-type thermoelectric element layer was 2.5 mm.

(Example 2)
A thermoelectric conversion element of Example 2 (π-type thermoelectric conversion element) was produced in the same manner as in Example 1 except that the formation of the thermoelectric element layer was performed by the following pattern frame arrangement / peeling method. .
<Formation of thermoelectric element layer by pattern frame arrangement / peeling method>
The lower polyimide film substrate (manufactured by Du Pont-Toray Co., Ltd., Kapton 200H, 100 mm × 100 mm, thickness: 50 μm) was designed to have spaced openings (openings: 1.5 mm × 1.5 mm, Number of openings: 200, distance between centers of openings corresponding to formation of a pair of P-type thermoelectric element layers and N-type thermoelectric element layers: 2.5 mm) A pattern frame having a plate thickness of 200 μm was provided. Is filled with the above-mentioned coating liquids (P) and (N), dried, and the pattern frame is peeled off from the substrate to form a 1.5 mm × 1.5 mm P-type thermoelectric element layer and an N-type thermoelectric element. A total of 100 pairs of element layers were provided. The thicknesses of the thermoelectric element layers after the annealing treatment were all 160 μm.

(Example 3)
A thermoelectric conversion element of Example 3 (π-type thermoelectric conversion element) was produced in the same manner as in Example 1, except that the formation of the thermoelectric element layer was performed by the following pattern layer arrangement method.
<Formation of thermoelectric element layer by pattern layer arrangement method>
The lower polyimide film substrate (manufactured by Du Pont-Toray Co., Ltd., Kapton 200H, 100 mm × 100 mm, thickness: 50 μm) was designed to have spaced openings (openings: 1.5 mm × 1.5 mm, Number of openings: 200, distance between centers of openings corresponding to formation of a pair of P-type thermoelectric element layers and N-type thermoelectric element layers: 2.5 mm) Pattern layer made of a 250 μm-thick polyimide resin layer Is filled with the above-described coating liquids (P) and (N) in the openings, and dried to form a pair of a 1.5 mm × 1.5 mm P-type thermoelectric element layer and an N-type thermoelectric element layer. A total of 100 pairs were provided. The thicknesses of the thermoelectric element layers after the annealing treatment were all 160 μm.

(Example 4)
Except that the viscosities of the coating solution (P) and the coating solution (N) were adjusted to 70 Pa · s by adding N-methylpyrrolidone and used, A conversion element (π-type thermoelectric conversion element) was manufactured. The thicknesses of the thermoelectric element layers after the annealing treatment were all 160 μm.

(Example 5)
In Example 1, the thermoelectric element layer was formed in the same manner as in Example 1 except that the thermoelectric element layer was formed by the following pattern frame arrangement / peeling method, and the thermoelectric conversion element was formed into an in-plane type. A conversion element (in-plane type thermoelectric conversion element) was manufactured.
<Formation of thermoelectric element layer by pattern frame arrangement / peeling method>
A polyimide film substrate (manufactured by Toray DuPont, Kapton 200H, 100 mm × 100 mm, thickness: 50 μm) has an opening (aperture 1.0 mm × width 6.0 mm × thickness 10 μm) spaced apart (opening) : 1.0 mm × 1.0 mm, number of openings: 200, distance between centers of openings corresponding to formation of a pair of P-type thermoelectric element layers and N-type thermoelectric element layers: 2.0 mm) An 80 μm pattern frame is provided, the openings are filled with the above-mentioned coating liquids (P) and (N), dried, and the pattern frame is peeled off from the substrate to obtain a 1.0 mm × 1.0 mm. A total of 100 pairs of P-type thermoelectric element layers and N-type thermoelectric element layers were provided.
The drying after filling with the coating liquid was performed at a temperature of 150 ° C. for 10 minutes in an argon atmosphere, and the annealing of the obtained thin film of the thermoelectric element layer was performed using a mixed gas of hydrogen and argon (hydrogen: argon = 3 volumes). %: 97% by volume) In an atmosphere, the temperature was increased at a heating rate of 5 K / min, and the temperature was maintained at 325 ° C. for 1 hour to grow fine particles of a thermoelectric semiconductor material, thereby forming a P-type thermoelectric element layer and an N-type thermoelectric element layer. And The thicknesses of the thermoelectric element layers after the annealing were all 60 μm.

(Comparative Example 1)
A thermoelectric conversion element of Comparative Example 1 was produced in the same manner as in Example 1 except that only one thermoelectric element layer was formed using a stencil plate having a plate thickness of 235 μm when forming the thermoelectric element layer. The thicknesses of the thermoelectric element layers after the annealing treatment were all 160 μm.

(Comparative Example 2)
Comparative Example 2 was prepared in the same manner as in Comparative Example 1 except that the viscosity of the coating solutions (P) and (N) was adjusted to 70 Pa · s by adding N-methylpyrrolidone. Was manufactured.

(Comparative Example 3)
In Example 5, the thermoelectric element layer of Comparative Example 3 (in-plane type) was formed in the same manner as in Example 5 except that the thermoelectric element layer was formed by a one-layer printing method using a stencil plate having a plate thickness of 80 μm. Thermoelectric conversion element). The thicknesses of the thermoelectric element layers after the annealing were all 60 μm.

評価 Evaluation of the electric resistance value and the filling factor of the thermoelectric conversion elements obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were performed. Table 1 shows the evaluation results.

It is apparent from Table 1 that when comparing the configurations of the π-type thermoelectric conversion elements, the thermoelectric conversion elements of Examples 1 to 4 having the thermoelectric element layers having the vertical cross sections satisfying the conditions (A) and (B) are different. , Compared with the thermoelectric conversion elements of Comparative Examples 1 and 2 having a thermoelectric element layer having a longitudinal section that does not satisfy the condition (A), It can be seen that the resistance value is low and high thermoelectric performance can be obtained. Similarly, when comparing the configuration of the in-plane thermoelectric conversion element with the configuration of the in-plane type thermoelectric conversion element, when the example 5 is compared with the comparative example 3, the example 5 clearly has a lower electric resistance value between the electrode portions and can obtain a higher thermoelectric performance. You can see that.

According to the thermoelectric conversion element included in the semiconductor element of the present invention, the thermoelectric conversion element including the thermoelectric element layer having the vertical section satisfying the conditions (A) and (B) has a substantially rectangular parallelepiped shape. The thermoelectric element layer and the electrode can be easily controlled, and the electric resistance of the thermoelectric element layer can be controlled to be small. Therefore, improvement in thermoelectric performance can be expected. Furthermore, since the thermoelectric conversion element of the present invention has excellent controllability of the shape of the thermoelectric element layer, high integration can be expected.
By using the above-mentioned thermoelectric conversion element as a module, power generation that converts exhaust heat from various types of combustion furnaces such as factories, waste combustion furnaces, cement combustion furnaces, exhaust gas from automobiles and exhaust heat from electronic devices into electricity It is conceivable to apply to the application. As a cooling application, in the field of electronic devices, for example, a CPU (Central Processing Unit) used for a smart phone, various computers, and the like, a CMOS (Complementary Metal Oxide Semiconductor Image Sensor), a CCD (Charge Coupled Image) sensor of a CCD (Charge Coupled), and the like. Further, the present invention can be applied to temperature control of various sensors such as MEMS (Micro Electro Mechanical Systems) and other light receiving elements.

1: thermoelectric conversion element 2a: substrate 2b: substrate 3a: electrode 3b:

electrodes

4, 4s, 4t, 4u: thermoelectric element layer 4a: N-type thermoelectric element layer 4b: P-type thermoelectric element layer 11: substrate 12: pattern frame 12 ': Stainless steel 13s: Opening 13d: Opening depth (pattern frame thickness)
13: Opening 14a: N-type thermoelectric element layer 14b: P-type thermoelectric element layers 22a, 22b:

Substrates

23a, 23b: Electrode 24: Pattern layer 24 ': Layer containing resin 25: Opening 25s: Opening 26a: N-type Thermoelectric element layer 26b: P-type thermoelectric element layer X: Length (width direction)
Xmax: Maximum value of length in width direction (longitudinal section)
Y: Length (depth direction)
D: Thickness (thickness direction)
Dmax: maximum value of thickness in the thickness direction (longitudinal section)
S: Area of longitudinal section

Claims

A semiconductor element including a semiconductor element layer made of a semiconductor composition including a semiconductor material on a substrate,
The area of the vertical section including the central portion of the semiconductor element layer is S (μm 2 ), the maximum value of the thickness in the thickness direction of the vertical section is Dmax (μm), and the maximum value of the length of the vertical section in the width direction is A semiconductor device in which the vertical section of the semiconductor device layer satisfies the following conditions (A) and (B) when Xmax (μm).
(A) 0.75 ≦ S / (Dmax × Xmax) ≦ 1.00
(B) Dmax ≧ 10 μm or (Dmax / Xmax) ≧ 0.03
Here, the maximum value Dmax of the thickness in the thickness direction of the vertical section is the upper and lower ends of the thickness in the thickness direction of the vertical section when a vertical line is formed on the substrate in the vertical section of the semiconductor element layer. Means the maximum distance (thickness) between two intersections obtained when the vertical line intersects with the vertical line. The maximum value Xmax of the length in the width direction of the longitudinal section is obtained by drawing a parallel line parallel to the substrate. Sometimes it means the maximum distance (length) between two intersections obtained when the left and right ends of the length in the width direction of the vertical cross section and the parallel line intersect.
The thermoelectric conversion element using the semiconductor element according to claim 1, wherein the semiconductor material is a thermoelectric semiconductor material, and the semiconductor element includes a thermoelectric element layer made of a thermoelectric semiconductor composition containing the thermoelectric semiconductor material.
The thermoelectric conversion element according to claim 2, wherein the thermoelectric semiconductor composition further contains a heat-resistant resin.
4. The thermoelectric conversion element according to claim 2, 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. .
The thermoelectric conversion element according to any one of claims 2 to 4, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin.
The thermoelectric conversion element according to any one of claims 2 to 5, wherein the thermoelectric semiconductor composition further contains an ionic liquid and / or an inorganic ionic compound.
The condition (A) is 0.83 ≦ S / (Dmax × Xmax) ≦ 1.00, and the condition (B) is Dmax ≧ 50 μm or (Dmax / Xmax) ≧ 0.08. 7. The thermoelectric conversion element according to any one of 1 to 6.