JP5987449B2 - Thermoelectric conversion element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thermoelectric conversion element that converts electrical energy into thermal energy and a method for manufacturing the same.

In recent years, thermoelectric conversion elements have attracted attention from the viewpoint of reducing carbon dioxide (CO ₂ ) and protecting the environment. By using the thermoelectric conversion element, it is possible to convert the thermal energy that has been discarded so far into electric energy and reuse it. In addition, thermoelectric conversion elements are attracting attention as devices for cooling heat generated locally in a CPU of a computer.

JP 2005-223307 A

  When the thermoelectric conversion element is used for cooling a CPU of a computer or the like, it is desirable to have high thermal conductivity. Moreover, in the thermoelectric conversion element using the thermoelectric conversion thin film, in order to obtain the high voltage, it is desired to connect the elements miniaturized in series. In order to manufacture this thermoelectric conversion element, a thermoelectric conversion thin film is first formed on a substrate, and then the non-conductive portion is formed by processing the thermoelectric conversion thin film by etching or the like. For this reason, the surface of the thermoelectric conversion thin film becomes uneven, which is a factor of reducing thermal conductivity.

  The present invention has been made in view of the above-described problems, and has a conductive portion and a non-conductive portion that are both flat on the surface (both have a substantially coplanar surface), and have excellent thermal conductivity. An object of the present invention is to provide a thermoelectric conversion element having a high temperature and a method for producing the same.

One aspect of the thermoelectric conversion element is a substrate, an insulating layer formed in a predetermined region on the substrate, a conductive portion having a thermoelectric conversion characteristic formed in a non-formation portion of the insulating layer on the substrate, look including an insulating portion formed on the insulating layer, the conductive portion and the insulating portion, the conductive portion is crystallized on the substrate, the same material that the insulating portion does not crystallize on the insulating layer , Both are formed flat on the surface .

One aspect of a method for manufacturing a thermoelectric conversion element includes a step of forming an insulating layer in a predetermined region on a substrate, and a step of forming a film made of a material having thermoelectric conversion characteristics on a substrate including the insulating layer. only containing the membrane is non-forming site of the insulating layer on the substrate is a conductive portion is crystallized, sites on the insulating layers are made an insulating portion which does not crystallize.

  According to the above aspects, the conductive portion and the non-conductive portion are both formed to be flat on the surface (both surfaces are substantially in the same plane), thereby realizing a highly reliable thermoelectric conversion element with excellent thermal conductivity. .

It is a schematic diagram which shows schematic structure of the thermoelectric conversion element by this embodiment. It is a schematic sectional drawing which shows the manufacturing method of the thermoelectric conversion element by this embodiment in process order. It is a characteristic view which shows the result measured by the XRD method about the thermoelectric conversion thin film.

Hereinafter, specific embodiments of the thermoelectric conversion element and the manufacturing method thereof will be described in detail with reference to the drawings.
1A and 1B are schematic views showing a schematic configuration of the thermoelectric conversion element according to the present embodiment, in which FIG. 1A is a plan view, FIG. 1B is a cross-sectional view taken along a broken line II ′ in FIG. FIG. 4 is a cross-sectional view taken along a broken line II-II ′ in FIG.

(Configuration of thermoelectric conversion element)
The thermoelectric conversion element includes a substrate 1, an insulating layer 2 formed in a predetermined region on the substrate 1, a conductive portion 3 formed on the substrate 1 at a portion where the insulating layer 2 is not formed, and an insulating layer 2. The non-conductive part (insulating part) 4 formed, an electrode 5 formed on the conductive part 3 and the insulating part 4, and heat sinks 11 and 12 are configured.

Substrate made of _{(SrAl 0.5 Ta 0.5 O 3)} 0.7 [LSAT], SrTiO 3 [STO], NaGaO 3, and one selected from DyScO ₃ - substrate _{1, LaAlO 3 [LAO], (} LaAlO 3) 0.3 It is. In the present embodiment, the substrate 1 is, for example, an LSAT substrate.

The insulating layer 2 is formed in a region where the insulating portion 4 is to be formed on the substrate 1, and includes magnesium oxide oxide (MgO), silicon oxide (SiO ₂ ), silicon nitride (SiN), and silicon oxynitride. It is formed from one kind selected from a material (SiON) or the like. In the present embodiment, the insulating layer 2 is formed using, for example, MgO.

  The conductive portion 3 and the insulating portion 4 constitute a thermoelectric conversion thin film formed on the substrate 1 including the insulating layer 2. The thermoelectric conversion thin film is a thin film formed of, for example, STO into which La or Nb is introduced on the substrate 1 including the insulating layer 2 by a sputtering method or a pulsed laser deposition (PLD) method. The thermoelectric conversion thin film is a thin film in which a conductive portion 3 which is a crystalline portion having thermoelectric conversion characteristics is formed on a portion of the substrate 1 where the insulating layer 2 is not formed, and an insulating portion 4 which is an amorphous portion is formed on the insulating layer 2. It is. Since the conductive portion 3 and the insulating portion 4 are formed of a single layer of thermoelectric conversion thin film, both are formed to have a flat surface (both have a substantially flush surface).

The electrode 5 is formed as a laminated film of a conductive material such as chromium (Cr) and gold (Au) on the conductive portion 3 and the insulating portion 4 so as to be electrically connected to the conductive portion 3.
The heat sinks 11 and 12 are formed of Cu or Al or the like on both sides of the upper surface of the substrate 1. In this embodiment, the heat sink 11 is on the high temperature side and the heat sink 12 is on the low temperature side, the electrode 5 connected to the heat sink 11 is the positive electrode, and the electrode 5 connected to the heat sink 12 is the negative electrode.

(Method for manufacturing thermoelectric conversion element)
FIG. 2 is a schematic cross-sectional view illustrating the manufacturing method of the thermoelectric conversion element according to the present embodiment in the order of steps. Each figure in FIG. 2 corresponds to a cross section taken along the broken line II-II ′ in FIG. 1, as in FIG.

First, as shown in FIG. 2A, the insulating layer 2 is formed in the region where the insulating portion is to be formed on the substrate 1.
For example, an LSAT substrate is prepared as the substrate 1.
For example, on the (100) plane of the substrate 1, a metal mask 21 having an opening 21 a that exposes a region where an insulating portion is to be formed on the surface of the substrate 1 is disposed.
Using the metal mask 21, for example, MgO as an insulating material is selectively formed in the opening 21a by sputtering. Thus, the insulating layer 2 made of MgO is formed in the region where the insulating portion is to be formed on the substrate 1. Thereafter, the metal mask 21 is removed.

Subsequently, as shown in FIG. 2B, a conductive part 3 and an insulating part 4 are formed by forming a thermoelectric conversion thin film.
The substrate 1 is heated to about 600 ° C. in the film formation chamber, and Ar gas, for example, is introduced into the film formation chamber. As a target of the thermoelectric conversion thin film, a polycrystalline target of STO ((La _0.02 , Sr _0.98 ) TiO ₃ ) containing 2 at% La, for example, is used. A thermoelectric conversion thin film is formed to a thickness of, for example, about 100 nm to 1 m on the substrate 1 including the insulating layer 2 by sputtering. At this time, the portion of the thermoelectric conversion thin film on the substrate 1 (that is, the portion where the insulating layer 2 is not formed) is crystallized to form the conductive portion 3. The conductive part 3 has thermoelectric conversion characteristics as well as conductivity. The insulating portion 4 is formed without crystallizing the portion of the thermoelectric conversion thin film on the insulating layer 2. As described above, since the conductive portion 3 and the insulating portion 4 are formed of a single layer of thermoelectric conversion thin film, both are formed to have a flat surface (both have a substantially flat surface).

The thermoelectric conversion thin film may be formed by the PLD method instead of the sputtering method. In this case, the polycrystalline target is placed in the film forming chamber, and the polycrystalline target is irradiated with laser light to peel off molecules from the polycrystalline target (ablation). 3 and the thermoelectric conversion thin film which consists of the insulation part 4 are formed.
Further, as a target of the thermoelectric conversion thin film, La or Nb or the like is introduced instead of STO, for example, (La _x Sr _1-x ) TiO _3-δ , Sr (Nb _x Ti _1-x ) O _3-δ Etc. may be used.

Subsequently, as shown in FIG. 2C, the electrode 5 is formed.
On the thermoelectric conversion thin film, a metal mask 22 having an opening 22a that exposes a region where an electrode is to be formed is disposed.
Using the metal mask 21, Cr and Au are selectively formed in the openings 22a by sputtering or vapor deposition as conductive materials. Thus, the electrode 5 having a Cr / Au laminated structure is formed in the electrode formation scheduled region on the conductive portion 3 and the insulating portion 4. Thereafter, the metal mask 22 is removed.

Thereafter, the heat sinks 11 and 12 made of Cu or Al are arranged so as to be electrically connected to the electrode 5, respectively.
Thus, the thermoelectric conversion elements shown in FIGS. 1A to 1C are formed.

  Here, the conductive part and the insulating part constituting the thermoelectric conversion thin film were measured by an X-ray diffraction (XRD) method. The measurement results are shown in FIG. Here, an STO substrate and an MgO substrate were used, and an STO film doped with La formed on the STO substrate and an STO film doped with La formed on the MgO substrate were measured. As shown in the figure, the former STO film has an intensity peak, which indicates that it is crystallized. On the other hand, in the latter STO film, no intensity peak is confirmed, and it can be seen that the latter is not crystallized (non-crystalline state).

  As described above, according to the present embodiment, both the conductive portion 3 and the insulating portion 4 are formed to be flat on the surface (both have a substantially coplanar surface), and have excellent thermal conductivity and high reliability. A thermoelectric conversion element is realized.

  Hereinafter, various aspects of the thermoelectric conversion element and the manufacturing method thereof are collectively described as supplementary notes.

(Appendix 1) a substrate;
An insulating layer formed in a predetermined region on the substrate;
A conductive part having thermoelectric conversion characteristics formed in a non-formation portion of the insulating layer on the substrate;
A thermoelectric conversion element comprising: an insulating portion formed on the insulating layer.

  (Supplementary note 2) The thermoelectric conversion element according to supplementary note 1, wherein the insulating layer is made of one selected from magnesium oxide oxide, silicon oxide, silicon nitride, and silicon oxynitride.

Appendix, characterized in that it consists of _{(SrAl 0.5 Ta 0.5 O 3)} 0.7, SrTiO 3, NaGaO 3, and one selected from DyScO ₃ - (Supplementary Note 3) The _{substrate, LaAlO 3, (LaAlO 3)} 0.3 The thermoelectric conversion element according to 1 or 2.

  (Additional remark 4) The said electroconductive part and the said insulating part are formed from the same material, The thermoelectric conversion element of any one of Additional remarks 1-3 characterized by the above-mentioned.

  (Additional remark 5) La or Nb is introduce | transduced into the said electroconductive part and the said insulating part, The thermoelectric conversion element of any one of Additional remark 1-4 characterized by the above-mentioned.

(Appendix 6) A step of forming an insulating layer in a predetermined region on the substrate;
A material having thermoelectric conversion characteristics is formed on a substrate including the insulating layer, and a conductive portion is formed on a portion of the substrate where the insulating layer is not formed, and an insulating portion is formed on the insulating layer. The process of manufacturing a thermoelectric conversion element characterized by including these processes.

  (Additional remark 7) The said insulating layer consists of 1 type chosen from magnesium oxide oxide, silicon oxide, silicon nitride, and silicon oxynitride, The manufacture of the thermoelectric conversion element of Additional remark 6 characterized by the above-mentioned. Method.

(Supplementary Note 8) The _{substrate, LaAlO 3, (LaAlO 3)} 0.3 - characterized in that it consists of _{(SrAl 0.5 Ta 0.5 O 3)} 0.7, SrTiO 3, NaGaO 3, and one selected from DyScO ₃ Appendix A method for producing a thermoelectric conversion element according to 6 or 7.

  (Additional remark 9) The said electroconductive part and the said insulating part are formed from the same material, The manufacturing method of the thermoelectric conversion element of any one of Additional remarks 6-8 characterized by the above-mentioned.

  (Additional remark 10) La or Nb is introduce | transduced into the said electroconductive part and the said insulating part, The manufacturing method of the thermoelectric conversion element of any one of Additional remark 6-9 characterized by the above-mentioned.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Insulating layer 3 Conducting part 4 Insulating part 5 Electrodes 11 and 12 Heat sinks 21 and 22 Metal masks 21a and 22a Opening

Claims (5)

A substrate,
An insulating layer formed in a predetermined region on the substrate;
A conductive part having thermoelectric conversion characteristics formed in a non-formation portion of the insulating layer on the substrate;
Look containing a formed on the insulating layer the insulating portion,
The conductive portion and the insulating portion are formed of the same material that the conductive portion is crystallized on the substrate and the insulating portion is not crystallized on the insulating layer, and both are formed to have a flat surface. Conversion element.   The thermoelectric conversion element according to claim 1, wherein the insulating layer is made of one selected from magnesium oxide oxide, silicon oxide, silicon nitride, and silicon oxynitride. The _{substrate, LaAlO 3, (LaAlO 3)} 0.3 - (SrAl 0.5 Ta 0.5 O 3) 0.7, SrTiO 3, NaGaO 3, and claim 1 or 2, characterized in that it consists of one selected from DyScO ₃ The thermoelectric conversion element according to 1. The thermoelectric conversion element according to any one of claims 1 to 3 , wherein La or Nb is introduced into the conductive portion and the insulating portion. Forming an insulating layer in a predetermined region on the substrate;
Wherein the substrate including on the insulating layer, seen including a step of forming a film made of a material having thermoelectric conversion properties,
A non-crystallized portion of the insulating layer on the substrate is crystallized to become a conductive portion, and a portion on the insulating layer is an insulating portion that is not crystallized. Method.

Images