Thermoelectric conversion element and method for manufacturing the same

Abstract

To provide a thermoelectric conversion element including thermoelectric conversion cells connected in series and miniaturized easily, and a manufacturing method for the thermoelectric conversion element.SOLUTION: Thermoelectric conversion cells 30A to 30C of a thermoelectric conversion element 100 include a thermoelectric conversion layer 40 formed on a main surface 12 of a substrate 10, an insulating layer 50 covering the thermoelectric conversion layer 40, a first electrode 60 including a first layer 62 and a second layer 66, and a second electrode 70. The first layer 62 connects to a main surface 42 of the thermoelectric conversion layer 40 through a first contact hole 52, and the second layer 66 covers the first layer 62. The second electrode 70 connects to the main surface 42 of the thermoelectric conversion layer 40 through a second contact hole 54. The second layer 66 and the second electrode 70 and the first layer 62 are formed of materials with different work functions. In the adjacent thermoelectric conversion cells 30A to 30C, the second layer 66 of thermoelectric conversion cells 30B and 30C and the second electrode 70 of the other thermoelectric conversion cells 30A and 30B are formed integrally. The thermoelectric conversion cells 30A to 30C are connected in series.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a thermoelectric conversion element and a method for manufacturing a thermoelectric conversion element. [Background technology]

[0002] Thermoelectric conversion elements that generate thermoelectric power between two electrodes due to a temperature difference are known. For example, Patent Document 1 discloses a thermoelectric conversion element that includes a thin-film thermoelectric conversion material layer, a first electrode provided on one main surface of the thermoelectric conversion material layer, and a second electrode provided at a different location from the first electrode in the in-plane direction of the one main surface of the thermoelectric conversion material layer. In Patent Document 1, the work function of the material constituting the first electrode is different from the work function of the material constituting the second electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6513476 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses that the open-circuit voltage of the thermoelectric conversion element is 0.38 mV when a temperature difference of 70°C is applied. This open-circuit voltage is approximately 1 / 10 of the open-circuit voltage of a commercially available Peltier-type heat flux sensor with series-connected cells under the same conditions. Therefore, when using the thermoelectric conversion element of Patent Document 1 as a heat flux sensor, it is preferable to connect the thermoelectric conversion elements of Patent Document 1 in series to ensure the signal-to-noise ratio of the heat flux sensor. In this case, miniaturization of the thermoelectric conversion elements is desirable to increase the number of thermoelectric conversion elements per unit area. Furthermore, in the thermoelectric conversion element of Patent Document 1, the short-circuit current can be increased by narrowing the gap between the first and second electrodes, so miniaturization of the thermoelectric conversion elements is also desirable from this perspective.

[0005] On the other hand, when the thermoelectric conversion element of Patent Document 1 is miniaturized by photolithography and etching, several problems may arise. For example, when a first electrode is formed on one main surface of a thermoelectric conversion material layer, the thermoelectric conversion material layer and the first electrode are made of different materials, and the thermoelectric conversion material layer and the first electrode, which have different electrode potentials, are in a conductive state. Therefore, a battery is formed between the thermoelectric conversion material layer and the first electrode in the etching solution. As a result, a potential difference (difference in electrode potentials) between the thermoelectric conversion material layer and the first electrode causes a current to flow between the thermoelectric conversion material layer and the first electrode, which may result in dissolution of the thermoelectric conversion material layer or abnormal dissolution of the material that constitutes the first electrode. Similarly, when a second electrode is formed on one main surface of the thermoelectric conversion material layer on which the first electrode is formed, a current may flow between the thermoelectric conversion material layer and the first and second electrodes due to battery action in the etching solution, which may result in dissolution of the thermoelectric conversion material layer and the first electrode or abnormal dissolution of the material that constitutes the second electrode.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a thermoelectric conversion element having thermoelectric conversion cells connected in series and that can be easily miniaturized, and a method for manufacturing a thermoelectric conversion element. [Means for solving the problem]

[0007] In order to achieve the above object, a thermoelectric conversion element according to a first aspect comprises: A substrate; a plurality of thermoelectric conversion cells provided on the main surface of the substrate, Each of the thermoelectric conversion cells is a thermoelectric conversion layer formed on the main surface of the substrate; an insulating layer covering the thermoelectric conversion layer; a first electrode including a first layer formed on the insulating layer and connected to a main surface of the thermoelectric conversion layer through a first contact hole in the insulating layer, and a second layer formed on the insulating layer and covering the first layer; a second electrode formed on the insulating layer and connected to the main surface of the thermoelectric conversion layer through a second contact hole in the insulating layer, the second layer covers the first layer without the first layer being exposed from the second layer; the second layer and the second electrode are formed from the same material having a work function different from the work function of the material forming the first layer; In the adjacent thermoelectric conversion cells, the second layer of one of the thermoelectric conversion cells and the second electrode of the other of the thermoelectric conversion cells are integrally formed, the first electrodes and the second electrodes are connected one-to-one, and the plurality of thermoelectric conversion cells are connected in series. 、 the first layer covers the opening of the first contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer; The second electrode covers the opening of the second contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer. .

[0008] A method for manufacturing a thermoelectric conversion element according to a second aspect includes the steps of: forming a plurality of thermoelectric conversion layers on a substrate; forming an insulating layer on the plurality of thermoelectric conversion layers; forming a plurality of first contact holes in the insulating layer, the first contact holes corresponding to the thermoelectric conversion layers and exposing the main surfaces of the thermoelectric conversion layers; forming a first layer of a plurality of first electrodes on the insulating layer, the first layers corresponding to the thermoelectric conversion layers and connected to the main surfaces of the thermoelectric conversion layers via the first contact holes; forming a plurality of second contact holes in the insulating layer on which the first layer of the first electrode is formed, the second contact holes corresponding to the thermoelectric conversion layers and exposing the main surfaces of the thermoelectric conversion layers; forming, on the insulating layer, a plurality of second electrodes corresponding to each of the thermoelectric conversion layers and connected to the main surface of each of the thermoelectric conversion layers via the second contact holes, and a plurality of second layers of the first electrodes covering each of the first layers of the first electrodes, from a material having a work function different from a work function of a material forming the first layers of the first electrodes, to form a plurality of thermoelectric conversion cells each including the thermoelectric conversion layers, the insulating layer, the first electrodes, and the second electrodes; In the step of forming the plurality of thermoelectric conversion cells, forming the second layer of the first electrode in a state in which the first layer of the first electrode is not exposed from the second layer of the first electrode; In adjacent thermoelectric conversion cells, the second layer of the first electrode of one of the thermoelectric conversion cells and the second electrode of the other thermoelectric conversion cell are integrally formed, and the first electrodes and the second electrodes are connected one-to-one, thereby connecting the multiple thermoelectric conversion cells in series. [Effects of the Invention]

[0009] According to the present disclosure, when the first layer is formed by etching, the thermoelectric conversion layer is not exposed to the etching solution. Furthermore, when the second layer and the second electrode are formed by etching, the thermoelectric conversion layer and the first layer are not exposed to the etching solution. As a result, battery action between the thermoelectric conversion layer and the first layer via the etching solution and battery action between the thermoelectric conversion layer, the first layer, and the second electrode via the etching solution do not occur. Furthermore, in adjacent thermoelectric conversion cells, the second layer of one thermoelectric conversion cell and the second electrode of the other thermoelectric conversion cell are integrally formed, thereby connecting multiple thermoelectric conversion cells in series. Therefore, when the first layer, the second layer, and the second electrode are formed by etching, excessive dissolution of the thermoelectric conversion layer, the first layer, the second layer, and the second electrode caused by battery action is suppressed, and a thermoelectric conversion element having thermoelectric conversion cells connected in series can be easily miniaturized. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a top view showing a thermoelectric conversion element according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the thermoelectric conversion element shown in FIG. 1 taken along line AA. [Figure 3] FIG. 2 is a top view showing an insulating layer according to the first embodiment. [Figure 4] 1 is a flowchart showing a method for manufacturing a thermoelectric conversion element according to the first embodiment. [Figure 5] FIG. 2 is a cross-sectional view showing an underlayer according to the first embodiment. [Figure 6] FIG. 1 is a top view showing a thermoelectric conversion layer according to a first embodiment. [Figure 7] FIG. 2 is a top view showing an insulating layer and a thermoelectric conversion layer according to the first embodiment. [Figure 8] 8 is a cross-sectional view of the insulating layer and the thermoelectric conversion layer shown in FIG. 7, taken along line BB. [Figure 9] FIG. 2 is a top view showing a first contact hole according to the first embodiment. [Figure 10] FIG. 2 is a top view showing a first layer of a first electrode according to the first embodiment. [Figure 11] 11 is a cross-sectional view of the first layer of the first electrode shown in FIG. 10 taken along line CC. [Figure 12] FIG. 2 is a schematic diagram illustrating the formation of a first layer of a first electrode according to the first embodiment. [Figure 13] FIG. 3 is a top view showing a second contact hole according to the first embodiment. [Figure 14] FIG. 3 is a top view showing a second electrode and a second layer of a first electrode according to the first embodiment. [Figure 15] 15 is a cross-sectional view of the second electrode and the second layer of the first electrode shown in FIG. 14, taken along the line DD. [Figure 16] 3A and 3B are schematic views for explaining the formation of a second electrode and a second layer of a first electrode according to the first embodiment. [Figure 17] FIG. 10 is a top view showing a thermoelectric conversion element according to a second embodiment. [Figure 18] FIG. 10 is a top view showing a thermoelectric conversion element according to a third embodiment. [Figure 19] 19 is a cross-sectional view of the thermoelectric conversion element shown in FIG. 18 taken along line EE. [Figure 20] FIG. 10 is a top view showing a thermoelectric conversion element according to a modified example. [Figure 21] FIG. 10 is a top view showing a thermoelectric conversion element according to a modified example. [Figure 22] FIG. 10 is a top view showing a thermoelectric conversion element according to a modified example. [Figure 23] FIG. 10 is a schematic diagram showing connections of thermoelectric conversion elements according to a modified example. [Figure 24] FIG. 10 is a cross-sectional view showing a first electrode in a terminal opening according to a modified example. [Figure 25]FIG. 10 is a cross-sectional view showing a second electrode in a terminal opening according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a thermoelectric conversion element according to an embodiment will be described with reference to the drawings.

[0012] <Embodiment 1> A thermoelectric conversion element 100 according to this embodiment will be described with reference to FIGS. 1 to 16. As shown in FIGS. 1 and 2, the thermoelectric conversion element 100 includes a substrate 10, a base layer 20, three thermoelectric conversion cells 30A to 30C, and a protective layer 80. The thermoelectric conversion cells 30A to 30C are connected in series in a row. Each of the thermoelectric conversion cells 30A to 30C includes a thermoelectric conversion layer 40, an insulating layer 50, a first electrode 60, and a second electrode 70. The first electrode 60 includes a first layer 62 and a second layer 66. The second layer 66 and the second electrode 70 are formed from the same material, but have a work function different from that of the material forming the first layer 62. For ease of understanding, the base layer 20, the insulating layer 50, the first contact hole 52, and the second contact hole 54 are omitted from FIG. 1.

[0013] The thermoelectric conversion element 100 (thermoelectric conversion cells 30A to 30C) generates a thermoelectromotive force due to a temperature difference in the thickness direction of the thermoelectric conversion layer 40. That is, the thermoelectric conversion element 100 (thermoelectric conversion cells 30A to 30C) converts thermal energy into electrical energy. The thermoelectric conversion element 100 is used, for example, as a sensor that detects heat flux. For ease of understanding, in this specification, the right direction of the thermoelectric conversion element 100 in FIG. 1 (to the right on the paper) is defined as the +X direction, the upward direction (upward on the paper) is defined as the +Y direction, and the direction perpendicular to the +X and +Y directions (toward the viewer on the paper) is defined as the +Z direction (thickness direction).

[0014] The substrate 10 of the thermoelectric conversion element 100 is, for example, a flat glass substrate. The substrate 10 is preferably made of a material with high thermal conductivity in order to reduce the thermal resistance in the thickness direction (+Z direction).

[0015] The underlayer 20 of the thermoelectric conversion element 100 is provided on the first main surface 12 of the substrate 10. In this embodiment, the underlayer 20 is provided on the entire first main surface 12. The underlayer 20 is made of, for example, silicon oxide (SiO X ) is formed from

[0016] The thermoelectric conversion cells 30A to 30C of the thermoelectric conversion element 100 are formed on the first main surface 12 of the substrate 10. The thermoelectric conversion cells 30A to 30C are connected in series in a row. Since the thermoelectric conversion cells 30A to 30C are connected in series, the open circuit voltage of the thermoelectric conversion element 100 can be increased.

[0017] First, the configurations of the thermoelectric conversion cells 30A to 30C will be described using the thermoelectric conversion cell 30B as an example. The thermoelectric conversion cells 30A and 30C have the same configuration as the thermoelectric conversion cell 30B.

[0018] 2, the thermoelectric conversion cell 30B includes a thermoelectric conversion layer 40, an insulating layer 50, a first electrode 60, and a second electrode 70. The first electrode 60 has a first layer 62 and a second layer 66.

[0019] The thermoelectric conversion layer 40 of the thermoelectric conversion cell 30B is provided in a rectangular shape on the base layer 20. The thermoelectric conversion layer 40 is formed of an n-type or p-type thermoelectric conversion material. An example of an n-type thermoelectric conversion material is indium gallium zinc oxide (InGaZnO). An example of a p-type thermoelectric conversion material is magnesium silicide (MgSi) doped with silver (Ag). In this embodiment, the thermoelectric conversion layer 40 is formed of indium gallium zinc oxide.

[0020] On a first main surface 42 of the thermoelectric conversion layer 40 (the main surface opposite to the substrate 10), the thermoelectric conversion layer 40 is connected to a first electrode 60 (first layer 62), and the thermoelectric conversion layer 40 is connected to a second electrode 70. The first electrode 60 (first layer 62) and the second electrode 70 are connected to the thermoelectric conversion layer 40 at different locations on the first main surface 42.

[0021] The insulating layer 50 of the thermoelectric conversion cell 30B covers the thermoelectric conversion layer 40 and the base layer 20. As shown in FIG. 3, the insulating layer 50 has comb-shaped first contact holes 52 formed therein to connect the first electrode 60 (first layer 62) and the thermoelectric conversion layer 40. The insulating layer 50 also has comb-shaped second contact holes 54 formed therein to connect the second electrode 70 and the thermoelectric conversion layer 40. The insulating layer 50 is made of, for example, silicon oxide (SiO X ) The underlayer 20 is omitted in FIG. 3. In the following top views, the underlayer 20 may be omitted.

[0022] 2, the first electrode 60 of the thermoelectric conversion cell 30B is formed on the insulating layer 50 and is connected to the first main surface 42 of the thermoelectric conversion layer 40 through a first contact hole 52 in the insulating layer 50. The first electrode 60 has a first layer 62 and a second layer 66.

[0023] The first layer 62 of the first electrode 60 is connected to the first main surface 42 of the thermoelectric conversion layer 40 via the first contact hole 52 in the insulating layer 50. The first layer 62 covers the opening of the first contact hole 52 so that the thermoelectric conversion layer 40 exposed from the insulating layer 50 at the bottom of the first contact hole 52 is not exposed from the first layer 62.

[0024] 1, the first layer 62 has a first base portion 62a extending in the Y direction and a plurality of first comb teeth 62b extending from the first base portion 62a in the +X direction, and is formed in a comb shape. The first comb teeth 62b and second comb teeth 70b of a second electrode 70 (described later) are alternately arranged opposite each other on the first main surface 42 of the thermoelectric conversion layer 40. In this embodiment, the first comb teeth 62b, second comb teeth 70b, first comb teeth 62b, second comb teeth 70b, first comb teeth 62b, and second comb teeth 70b are arranged in this order from the +Y side. The first layer 62 is formed of, for example, titanium (Ti) having a small work function.

[0025] In this embodiment, the insulating layer 50 covers the thermoelectric conversion layer 40. Furthermore, the first layer 62 of the first electrode 60 formed on the insulating layer 50 is connected via the first contact hole 52 in the insulating layer 50. As a result, when the first layer 62 is formed by etching, the thermoelectric conversion layer 40 is not exposed from the insulating layer 50 and is not exposed to the etching solution. Because the thermoelectric conversion layer 40 is not exposed to the etching solution, a battery is not formed by the first layer 62, the etching solution, and the thermoelectric conversion layer 40 in the thermoelectric conversion cell 30B (thermoelectric conversion element 100). This allows the first layer 62 to be formed by etching without causing damage (e.g., excessive dissolution) to the first layer 62 and the thermoelectric conversion layer 40 due to battery action.

[0026] As shown in FIGS. 1 and 2, the second layer 66 of the first electrode 60 covers the first layer 62 without exposing it from the second layer 66. The second layer 66 is formed together with the second electrode 70 from the same material as that of the second electrode 70. As a result, when the second layer 66 is formed by etching, the first layer 62 is not exposed to the etching solution. Because the first layer 62 is not exposed to the etching solution, a battery is not formed between the second layer 66, the etching solution, and the first layer 62 in the thermoelectric conversion cell 30B (thermoelectric conversion element 100). This allows the second electrode 70 to be formed by etching without causing damage to the first layer 62 and the second layer 66 due to battery action. The materials for forming the second layer 66 and the second electrode 70 will be described later.

[0027] The second electrode 70 of the thermoelectric conversion cell 30B is formed on the insulating layer 50 and is connected to the first main surface 42 of the thermoelectric conversion layer 40 via the second contact hole 54 in the insulating layer 50. The second electrode 70 and the first electrode 60 (first layer 62) are not connected, and the second electrode 70 is connected to the first main surface 42 at a location different from the location of the first electrode 60 on the first main surface 42. The second electrode 70 covers the opening of the second contact hole 54 so that the thermoelectric conversion layer 40 exposed from the insulating layer 50 at the bottom of the second contact hole 54 is not exposed from the second electrode 70.

[0028] 1, the second electrode 70 has a second base portion 70a extending in the Y direction and a plurality of second comb-teeth portions 70b extending from the second base portion 70a in the −X direction, and is formed in a comb-teeth shape. The second comb-teeth portions 70b and the first comb-teeth portions 62b of the first layer 62 of the first electrode 60 are arranged alternately and opposite to each other on the first main surface 42 of the thermoelectric conversion layer 40.

[0029] The second electrode 70 and the second layer 66 of the first electrode 60 are both formed from the same material, which has a work function different from the work function of the material forming the first layer 62 of the first electrode 60. For example, the second electrode 70 and the second layer 66 of the first electrode 60 are formed from copper (Cu), which has a large work function.

[0030] In this embodiment, the insulating layer 50 covers the thermoelectric conversion layer 40, and the second electrode 70 formed on the insulating layer 50 is connected to the insulating layer 50 via the second contact hole 54 in the insulating layer 50. Therefore, when the second electrode 70 is formed by etching, the thermoelectric conversion layer 40 is not exposed to the etching solution. Furthermore, the first layer 62 of the first electrode 60 is covered by the second layer 66 formed together with the second electrode 70. Therefore, when the second electrode 70 (second layer 66) is formed by etching, the first layer 62 is not exposed to the etching solution. Because the thermoelectric conversion layer 40 and the first layer 62 are not exposed to the etching solution, a battery formed by the second electrode 70, the etching solution, and the thermoelectric conversion layer 40, and a battery formed by the second electrode 70, the etching solution, and the first layer 62 are not formed. As a result, in the thermoelectric conversion element 100, the second electrode 70 can be formed by etching without causing damage to the thermoelectric conversion layer 40, the first layer 62, the second layer 66, and the second electrode 70 due to battery action.

[0031] Next, the arrangement and connection of the thermoelectric conversion cells 30A to 30C will be described. The thermoelectric conversion cells 30A to 30C are arranged in the same direction and orientation in a plan view, with the first comb-tooth portions 62b facing the +X direction and the second comb-tooth portions 70b facing the -X direction, as shown in Fig. 1. The thermoelectric conversion cells 30A to 30C are also arranged in a row in the Y direction.

[0032] In the adjacent thermoelectric conversion cell 30A and thermoelectric conversion cell 30B, the second electrode 70 of the thermoelectric conversion cell 30A and the second layer 66 of the thermoelectric conversion cell 30B are integrally formed, and the second electrode 70 of the thermoelectric conversion cell 30A and the first electrode 60 of the thermoelectric conversion cell 30B are connected in a one-to-one relationship. In addition, in the adjacent thermoelectric conversion cell 30B and thermoelectric conversion cell 30C, the second electrode 70 of the thermoelectric conversion cell 30B and the second layer 66 of the thermoelectric conversion cell 30C are integrally formed, and the second electrode 70 of the thermoelectric conversion cell 30B and the first electrode 60 of the thermoelectric conversion cell 30C are connected in a one-to-one relationship. As a result, the thermoelectric conversion cells 30A to 30C are connected in series in a row. In this embodiment, the multiple thermoelectric conversion cells 30A to 30C are connected by integrally forming the second electrode 70 of one of the adjacent thermoelectric conversion cells (thermoelectric conversion cell 30A and thermoelectric conversion cell 30B, thermoelectric conversion cell 30B and thermoelectric conversion cell 30C) and the second layer 66 of the other of the adjacent thermoelectric conversion cells, so that the multiple thermoelectric conversion cells 30A to 30C can be easily connected in series.

[0033] In the thermoelectric conversion element 100, the thermoelectric conversion cells 30A to 30C are connected in series in a row, and the first layer 62 of the first electrode 60 and the second electrode 70 are made of materials with different work functions. The first layer 62 and the second electrode 70 are connected to the first main surface 42 of the thermoelectric conversion layer 40, and a thermoelectromotive force is generated due to a temperature difference in the thickness direction (Z direction) of the thermoelectric conversion layer 40. Because the thermoelectric conversion cells 30A to 30C are connected in series, the thermoelectromotive forces of the thermoelectric conversion cells 30A to 30C are added together, thereby increasing the open-circuit voltage of the entire thermoelectric conversion element 100. Furthermore, in the thermoelectric conversion element 100, forming the first layer 62 of the first electrode 60 by etching does not damage the thermoelectric conversion layer 40 and the first layer 62, and forming the second layer 66 and the second electrode 70 of the first electrode 60 by etching does not damage the thermoelectric conversion layer 40, the first layer 62, the second layer 66, and the second electrode 70. Therefore, the thermoelectric conversion element 100 having the thermoelectric conversion cells 30A to 30C connected in series in a row can be easily miniaturized by photolithography and etching.

[0034] The protective layer 80 of the thermoelectric conversion element 100 protects the first electrode 60, the second electrode 70, etc. The protective layer 80 is formed of, for example, photosensitive polyimide. As shown in FIG. 1 , the protective layer 80 is provided with terminal openings 85 for connecting the first electrode 60 of the thermoelectric conversion cell 30A and the second electrode 70 of the thermoelectric conversion cell 30C to an external device.

[0035] Next, a method for manufacturing the thermoelectric conversion element 100 will be described with reference to Fig. 4 to Fig. 16. Fig. 4 is a flowchart showing a method for manufacturing the thermoelectric conversion element 100. The method for manufacturing the thermoelectric conversion element 100 includes the steps of: forming an underlayer 20 on the first main surface 12 of the substrate 10 (step S10); forming a plurality of thermoelectric conversion layers 40 on the underlayer 20 (on the first main surface 12 of the substrate 10) (step S20); forming an insulating layer 50 on the plurality of thermoelectric conversion layers 40 (step S30); forming first contact holes 52 in the insulating layer 50 corresponding to each of the thermoelectric conversion layers 40 (step S40); and forming first layers 62 of a plurality of first electrodes 60 on the insulating layer 50 corresponding to each of the thermoelectric conversion layers 40 and connected to the first main surfaces 42 of the thermoelectric conversion layers 40 via the first contact holes 52 (step S50).

[0036] The manufacturing method of the thermoelectric conversion element 100 further includes a step (step S60) of forming second contact holes 54 corresponding to each of the thermoelectric conversion layers 40 in the insulating layer 50 on which the first layer 62 of the first electrode 60 has been formed, a step (step S70) of forming on the insulating layer 50 a plurality of second electrodes 70 corresponding to each of the thermoelectric conversion layers 40 and connected to the first main surface 42 of each of the thermoelectric conversion layers 40 via the second contact holes 54, and a plurality of second layers 66 of the first electrode 60 covering each of the first layers 62 of the first electrode 60, all from a material having a work function different from the work function of the material forming the first layer 62 of the first electrode 60, thereby forming a plurality of thermoelectric conversion cells 30A to 30C each comprising a thermoelectric conversion layer 40, an insulating layer 50, a first electrode 60, and a second electrode 70, and a step (step S80) of forming a protective layer 80.

[0037] In step S10, first, the substrate 10 is prepared. Next, as shown in Fig. 5, the base layer 20 is formed on the first main surface 12 of the substrate 10. The base layer 20 is formed from silicon oxide on the entire first main surface 12 by sputtering, for example.

[0038] 6, three rectangular thermoelectric conversion layers 40 are formed on the base layer 20. Specifically, first, a thermoelectric conversion film is formed from indium gallium zinc oxide by sputtering on the entire surface of the base layer 20. Next, the thermoelectric conversion layer 40 is formed from the thermoelectric conversion film by photolithography and etching.

[0039] 7 and 8, in step S30, an insulating layer 50 is formed on the plurality of thermoelectric conversion layers 40 and on the base layer 20. Specifically, the insulating layer 50 is formed from silicon oxide by CVD (Chemical Vapor Deposition) on the entire surfaces of the base layer 20 and the thermoelectric conversion layers 40. Here, the thermoelectric conversion layers 40 are covered with the insulating layer 50 in a state where they are not exposed from the insulating layer 50.

[0040] In step S40, first contact holes 52 corresponding to the thermoelectric conversion layers 40 are formed in the insulating layer 50 by photolithography and etching. In this embodiment, as shown in Fig. 9, the first contact holes 52 are formed in a comb-teeth shape so as to match the shape of the first layer 62 of the first electrode 60. As a result, the first main surface 42 of the thermoelectric conversion layer 40 is exposed from the insulating layer 50 in a comb-teeth shape.

[0041] 10 and 11, in step S50, first layers 62 of first electrodes 60 corresponding to the thermoelectric conversion layers 40 are formed on the insulating layer 50. The first layers 62 are connected to the first main surfaces 42 of the thermoelectric conversion layers 40 via the first contact holes 52. The first layers 62 also cover the openings of the first contact holes 52 so that the thermoelectric conversion layers 40 exposed from the insulating layer 50 at the bottoms of the first contact holes 52 are not exposed from the first layers 62.

[0042] Specifically, first, a titanium thin film is formed on the insulating layer 50 by sputtering, filling the first contact holes 52. Next, a first layer 62 is formed in a comb-like shape from the titanium thin film by photolithography and etching. In this embodiment, when etching the titanium thin film, as shown in FIG. 12, the thermoelectric conversion layer 40 is covered with the insulating layer 50 and the first layer 62 (titanium thin film), and further, the portion of the titanium thin film that will become the first layer 62 of the first electrode 60 is covered with photoresist. Therefore, the first layer 62 can be formed without exposing the thermoelectric conversion layer 40 to an etching solution.

[0043] In step S60, second contact holes 54 corresponding to the thermoelectric conversion layers 40 are formed in the insulating layer 50 by photolithography and etching. In this embodiment, as shown in FIG. 13 , the second contact holes 54 are formed in a comb-teeth shape so as to match the shape of the second electrodes 70. As a result, the first main surfaces 42 of the thermoelectric conversion layers 40 are exposed from the insulating layer 50 in a comb-teeth shape.

[0044] In step S70, as shown in FIGS. 14 and 15 , a plurality of second electrodes 70 corresponding to the thermoelectric conversion layers 40 and a plurality of second layers 66 of the first electrode 60 covering the first layers 62 of the first electrode 60 are formed on the insulating layer 50 to form the thermoelectric conversion cells 30A to 30C. The second electrodes 70 are connected to the first main surfaces 42 of the thermoelectric conversion layers 40 via the second contact holes 54. The second electrodes 70 cover the openings of the second contact holes 54 so that the thermoelectric conversion layers 40 exposed from the insulating layer 50 at the bottoms of the second contact holes 54 are not exposed through the second electrodes 70. The second layers 66 of the first electrodes 60 cover the first layers 62 of the first electrodes 60 so that the first layers 62 are not exposed through the second layers 66. The second electrodes 70 and the second layers 66 are formed from a material (copper) having a work function different from that of the material (titanium) forming the first layers 62 of the first electrodes 60. In FIG. 14, the first contact holes 52 are omitted for ease of understanding.

[0045] Furthermore, in the adjacent thermoelectric conversion cells 30A and 30B, the second electrode 70 of the thermoelectric conversion cell 30A and the second layer 66 of the first electrode 60 of the thermoelectric conversion cell 30B are integrally formed. 2 electrode 70 and the first thermoelectric conversion cell 30B 1 electrode 60 are connected one-to-one, and the thermoelectric conversion cells 30A and 30B are connected in series in a row. In the adjacent thermoelectric conversion cells 30B and 30C, the second electrode 70 of the thermoelectric conversion cell 30B and the second layer 66 of the first electrode 60 of the thermoelectric conversion cell 30C are also formed integrally, and the thermoelectric conversion cells 30B and 30C are connected in series. In this way, the thermoelectric conversion cells 30A to 30C are connected in series in a row.

[0046] Specifically, first, a copper thin film is formed on the insulating layer 50 and the first layer 62 by sputtering, filling the second contact hole 54. Next, the second electrode 70 and the second layer 66 are each formed into a comb-like shape from the copper thin film by photolithography and etching. In this case, the second electrode 70 on one side and the second layer 66 on the other side of adjacent thermoelectric conversion cells (thermoelectric conversion cell 30A and thermoelectric conversion cell 30B, thermoelectric conversion cell 30B and thermoelectric conversion cell 30C) are formed integrally. In this embodiment, when etching the copper thin film, as shown in Figure 16, the thermoelectric conversion layer 40 is covered with the insulating layer 50, the first layer 62, and the second electrode 70 (copper thin film), the first layer 62 is covered with the second layer 66 (copper thin film), and further, the portions of the copper thin film that will become the second layer 66 of the first electrode 60 and the second electrode 70 are covered with photoresist, so the second electrode 70 can be formed without exposing the thermoelectric conversion layer 40 and the first layer 62 to the etching solution.

[0047] In step S80, the protective layer 80 is formed from, for example, photosensitive polyimide. Specifically, the photosensitive polyimide is applied, and the applied photosensitive polyimide is exposed to light and developed. The developed photosensitive polyimide is then baked to form the protective layer 80. In this manner, the thermoelectric conversion element 100 can be manufactured.

[0048] As described above, in the thermoelectric conversion element 100, the thermoelectric conversion cells 30A to 30C are connected in series in a row by integrally forming the second electrode 70 on one side and the second layer 66 on the other side of adjacent thermoelectric conversion cells (thermoelectric conversion cells 30A and 30B, and thermoelectric conversion cells 30B and 30C). Since the thermoelectric conversion cells 30A to 30C are connected in series, the open circuit voltage of the thermoelectric conversion element 100 can be increased.

[0049] In the thermoelectric conversion element 100, the first layer 62 can be formed by etching without damaging the thermoelectric conversion layer 40 and the first layer 62, and the second layer 66 and the second electrode 70 can be formed without damaging the thermoelectric conversion layer 40, the first layer 62, the second layer 66, and the second electrode 70. Therefore, the thermoelectric conversion element 100 can be easily miniaturized by photolithography and etching. Furthermore, the external shapes of the thermoelectric conversion cells 30A to 30C can be freely set by photolithography and etching. For example, since the thermoelectric conversion cells 30A to 30C have opposing first electrodes 60 and second electrodes 70, by making the outer shapes of the thermoelectric conversion cells 30A to 30C rectangular as in this embodiment, the thermoelectric conversion cells 30A to 30C can be efficiently arranged on the first main surface 12 of the substrate 10, eliminating wasted area on the first main surface 12 of the substrate 10 and increasing the area ratio of the thermoelectric conversion cells 30A to 30C to the first main surface 12 of the substrate 10. Furthermore, by miniaturizing the comb-tooth-shaped first electrode 60 (first layer 62) and second electrode 70, the distance between the first electrode 60 and the second electrode 70 can be narrowed and the perimeter of the first electrode 60 and the second electrode 70 can be increased, thereby increasing the short-circuit current of the thermoelectric conversion element 100.

[0050] In the thermoelectric conversion element 100, the selection of the material forming the first layer 62 of the first electrode 60 and the material forming the second layer 66 of the first electrode 60 and the second electrode 70 based on the work function greatly affects the characteristics of the thermoelectric conversion element 100. On the other hand, in the case of conventional thermoelectric conversion elements (for example, the thermoelectric conversion element described in Japanese Patent No. 6513476), when the thermoelectric conversion element is manufactured by photolithography and etching, the material forming the electrodes must be selected taking into consideration not only the work function but also the cell action during etching.

[0051] In this embodiment, when forming the first layer 62 of the first electrode 60, the second layer 66 of the first electrode 60, and the second electrode 70, only one of the materials (titanium or copper) forming each is exposed and etched, so the material forming the first layer 62 of the first electrode 60 and the materials forming the second layer 66 of the first electrode 60 and the second electrode 70 can be selected based on their work functions without considering the galvanic action during etching. In other words, there is a high degree of freedom in selecting the material forming the first layer 62 of the first electrode 60 and the material forming the second layer 66 of the first electrode 60 and the second electrode 70, and the characteristics of the thermoelectric conversion element 100 can be easily improved.

[0052] <Embodiment 2> In the first embodiment, the thermoelectric conversion cells 30A to 30C are arranged in a row. The thermoelectric conversion cells may also be arranged in a matrix.

[0053] As shown in Fig. 17, the thermoelectric conversion element 100 of this embodiment includes a substrate 10, a base layer 20, nine thermoelectric conversion cells 30A to 30I, and a protective layer 80. The configurations of the substrate 10, base layer 20, and protective layer 80 of this embodiment are the same as those of embodiment 1. Note that in Fig. 17, the base layer 20, protective layer 80, and some of the reference numerals are omitted for ease of understanding.

[0054] The configuration of each of the thermoelectric conversion cells 30A to 30C and 30G to 30I is similar to that of the thermoelectric conversion cells 30A to 30C of embodiment 1. The configuration of each of the thermoelectric conversion cells 30D to 30F is similar to that of the thermoelectric conversion cells 30A to 30C of embodiment 1, except that the first comb teeth 62b of the first layer 62 and the second comb teeth 70b of the second electrode 70 are arranged in the following order from the +Y side: second comb teeth 70b, first comb teeth 62b, second comb teeth 70b, first comb teeth 62b, second comb teeth 70b, first comb teeth 62b. Here, the arrangement and connection of the thermoelectric conversion cells 30A to 30I will be described.

[0055] As shown in Fig. 17, the thermoelectric conversion cells 30A to 30I are arranged in a matrix of 3 rows and 3 columns on the first main surface 12 of the substrate 10. Specifically, the thermoelectric conversion cells 30A to 30C form the first column, the thermoelectric conversion cells 30D to 30F form the second column, and the thermoelectric conversion cells 30G to 30I form the third column. In the first column, the thermoelectric conversion cells 30A to 30C are arranged in the same direction and orientation in a plan view, with the first comb-tooth portions 62b facing the +X direction and the second comb-tooth portions 70b facing the -X direction, as in the first embodiment. In the second and third columns, the thermoelectric conversion cells 30D to 30I are also arranged in the same direction and orientation in a plan view, with the first comb-tooth portions 62b facing the +X direction and the second comb-tooth portions 70b facing the -X direction.

[0056] The thermoelectric conversion cells 30A to 30C in the first row are connected in series in a row, similar to the thermoelectric conversion cells 30A to 30C in embodiment 1, by integrally forming the second electrode 70 of the thermoelectric conversion cell 30A and the second layer 66 of the thermoelectric conversion cell 30B, and the second electrode 70 of the thermoelectric conversion cell 30B and the second layer 66 of the thermoelectric conversion cell 30C.

[0057] The thermoelectric conversion cells 30D to 30F in the second row are connected in series in a row by integrally forming the second layer 66 of the thermoelectric conversion cell 30D and the second electrode 70 of the thermoelectric conversion cell 30E, and the second layer 66 of the thermoelectric conversion cell 30E and the second electrode 70 of the thermoelectric conversion cell 30F. The thermoelectric conversion cells 30G to 30I in the third row are connected in series in a row by integrally forming the second electrode 70 of the thermoelectric conversion cell 30G and the second layer 66 of the thermoelectric conversion cell 30H, and the second electrode 70 of the thermoelectric conversion cell 30H and the second layer 66 of the thermoelectric conversion cell 30I.

[0058] In this embodiment, the second electrode 70 of the thermoelectric conversion cell 30C in the first row and the second layer 66 of the thermoelectric conversion cell 30F in the second row adjacent to the thermoelectric conversion cell 30C are integrally formed, thereby connecting the thermoelectric conversion cells 30A to 30C in the first row in series with the thermoelectric conversion cells 30D to 30F in the second row. Also, the second electrode 70 of the thermoelectric conversion cell 30D in the second row in series with the second layer 66 of the thermoelectric conversion cell 30G in the third row adjacent to the thermoelectric conversion cell 30D are integrally formed, thereby connecting the thermoelectric conversion cells 30D to 30F in the second row in series with the thermoelectric conversion cells 30G to 30I in the third row. As a result, the thermoelectric conversion cells 30A to 30I are connected in series.

[0059] In the thermoelectric conversion element 100 of this embodiment, similarly to the thermoelectric conversion element 100 of embodiment 1, the thermoelectric conversion cells 30A to 30I are connected in series by integrally forming the second electrode 70 of one of the adjacent thermoelectric conversion cells and the second layer 66 of the other. Since the thermoelectric conversion cells 30A to 30I are connected in series, the open circuit voltage of the thermoelectric conversion element 100 can be increased.

[0060] Furthermore, similar to embodiment 1, the thermoelectric conversion element 100 of this embodiment can be easily miniaturized by photolithography and etching. Furthermore, the area ratio of the thermoelectric conversion cells 30A to 30I to the first main surface 12 of the substrate 10 can be increased. The short-circuit current of the thermoelectric conversion element 100 of this embodiment can be increased by narrowing the gap between the first electrode 60 and the second electrode 70 and lengthening the perimeter of the first electrode 60 and the second electrode 70.

[0061] Furthermore, as in embodiment 1, there is greater freedom in selecting the material for forming the first layer 62 of the first electrode 60 and the material for forming the second layer 66 of the first electrode 60 and the second electrode 70, making it possible to easily improve the characteristics of the thermoelectric conversion element 100 of this embodiment.

[0062] <Embodiment 3> In the first and second embodiments, the first layer 62 of the first electrode 60 and the second electrode 70 have a comb-like shape. The first layer 62 of the first electrode 60 and the second electrode 70 may have other shapes.

[0063] The thermoelectric conversion element 100 of this embodiment includes a substrate 10, an underlayer 20, nine thermoelectric conversion cells 32A to 32I, and a protective layer 80. The configurations of the substrate 10, underlayer 20, and protective layer 80 of this embodiment are the same as those of the first embodiment.

[0064] Like the thermoelectric conversion cells 30A to 30C of embodiment 1, each of the thermoelectric conversion cells 32A to 32I includes a thermoelectric conversion layer 40, an insulating layer 50, a first electrode 60, and a second electrode 70. The first electrode 60 has a first layer 62 and a second layer 66. As shown in FIGS. 18 and 19, the configuration of the thermoelectric conversion cells 32A to 32I is similar to that of the thermoelectric conversion cells 30A to 30C of embodiment 1, except that the first layer 62 of the first electrode 60 and the second electrode 70 have a rectangular shape that is elongated in the X direction.

[0065] In the thermoelectric conversion cells 32A to 32C and 32G to 32I, the first electrode 60 is located on the +Y side, and the second electrode 70 is located on the -Y side. In the thermoelectric conversion cells 32D to 32F, the first electrode 60 is located on the -Y side, and the second electrode 70 is located on the +Y side. In addition, in Fig. 18, the protective layer 80 and some of the reference numerals are omitted for ease of understanding. Fig. 19 shows a cross section of the thermoelectric conversion cell 32B as an example of the thermoelectric conversion cells 32A to 32I.

[0066] The thermoelectric conversion cells 32A to 32I are arranged in a matrix of 3 rows and 3 columns, and connected in series, similarly to the thermoelectric conversion cells 30A to 30I of the second embodiment.

[0067] The thermoelectric conversion cells 32A to 32C in the first row are connected in series in a single row by integrally forming the second electrode 70 of the thermoelectric conversion cell 32A with the second layer 66 of the thermoelectric conversion cell 32B, and the second electrode 70 of the thermoelectric conversion cell 32B with the second layer 66 of the thermoelectric conversion cell 32C. The thermoelectric conversion cells 32D to 32F in the second row are connected in series in a single row by integrally forming the second layer 66 of the thermoelectric conversion cell 32D with the second electrode 70 of the thermoelectric conversion cell 32E, and the second layer 66 of the thermoelectric conversion cell 32E with the second electrode 70 of the thermoelectric conversion cell 32F. In addition, the thermoelectric conversion cells 32G to 32I in the third row are connected in series in a row by integrally forming the second electrode 70 of the thermoelectric conversion cell 32G and the second layer 66 of the thermoelectric conversion cell 32H, and the second electrode 70 of the thermoelectric conversion cell 32H and the second layer 66 of the thermoelectric conversion cell 32I.

[0068] Furthermore, by integrally forming the second electrode 70 of the thermoelectric conversion cell 32C in the first row and the second layer 66 of the thermoelectric conversion cell 32F in the second row adjacent to the thermoelectric conversion cell 32C, the thermoelectric conversion cells 32A to 32C in the first row are connected in series with the thermoelectric conversion cells 32D to 32F in the second row. By integrally forming the second electrode 70 of the thermoelectric conversion cell 32D in the second row and the second layer 66 of the thermoelectric conversion cell 32G in the third row adjacent to the thermoelectric conversion cell 32D, the thermoelectric conversion cells 32D to 32F in the second row are connected in series with the thermoelectric conversion cells 32G to 32I in the third row. As a result, the thermoelectric conversion cells 32A to 32I are connected in series.

[0069] In this embodiment, the first layer 62 of the first electrode 60 and the second electrode 70 have a rectangular shape. Therefore, when the design is performed according to the same rules as in the first and second embodiments, the area occupied by the thermoelectric conversion cells 32A to 32I on the first main surface 12 of the substrate 10 can be easily reduced. In this embodiment, nine thermoelectric conversion cells 32A to 32I are arranged in a 3-row, 3-column matrix. However, by reducing the area occupied by the thermoelectric conversion cells on the first main surface 12 of the substrate 10, it becomes possible to increase the number of thermoelectric conversion cells connected in series, thereby increasing the open-circuit voltage of the thermoelectric conversion element 100. When the thermoelectric conversion element 100 is used in a sensor application such as a heat flux sensor, it is preferable to increase the open-circuit voltage in order to increase the output voltage.

[0070] <Modification> Although the embodiments have been described above, various modifications can be made to the present disclosure without departing from the spirit and scope of the present disclosure.

[0071] For example, the substrate 10 is not limited to a glass substrate, and may be formed from an insulating film (for example, a polyimide film).

[0072] Furthermore, although the thermoelectric conversion elements 100 of the first to third embodiments include the base layer 20, the thermoelectric conversion elements 100 do not necessarily have to include the base layer 20. The thermoelectric conversion layer 40 may be formed directly on the first main surface 12 of the insulating substrate 10. Furthermore, the thermoelectric conversion elements 100 do not necessarily have to include the protective layer 80.

[0073] In the first to third embodiments, the first layer 62 of the first electrode 60 is formed from a material having a small work function, and the second layer 66 of the first electrode 60 and the second electrode 70 are formed from a material having a large work function. In the thermoelectric conversion element 100, it is only necessary that the work function of the material forming the first layer 62 of the first electrode 60 differs from the work function of the material forming the second layer 66 of the first electrode 60 and the second electrode 70.

[0074] The materials forming the first layer 62 of the first electrode 60, the second layer 66 of the first electrode 60, and the second electrode 70 may be materials having a small work function, such as cesium (Cs) or aluminum (Al), or materials having a large work function, such as nickel (Ni).

[0075] In the first to third embodiments, the surfaces of the first electrode 60 (second layer 66) and the second electrode 70 that are exposed from the terminal opening 85 of the protective layer 80 may be subjected to protective plating.

[0076] In the thermoelectric conversion cells 30A to 30C of embodiment 1 and the thermoelectric conversion cells 30A to 30I of embodiment 2, the first comb teeth 62b and the second comb teeth 70b extend in the X direction. As shown in Fig. 20, the first comb teeth 62b and the second comb teeth 70b may extend in the Y direction. In Fig. 20, the insulating layer 50, some of the reference numerals, etc. are omitted for ease of understanding.

[0077] In the thermoelectric conversion cells 30A to 30I of the third embodiment, the first layer 62 of the first electrode 60 and the second electrode 70 have a rectangular shape that is long in the X direction. As shown in Fig. 21 , the first layer 62 of the first electrode 60 and the second electrode 70 may have a rectangular shape that is long in the Y direction. In Fig. 21 , the insulating layer 50, some of the reference numerals, etc. are omitted for ease of understanding.

[0078] In the thermoelectric conversion element 100 of the second embodiment, the heat flux of the entire region in which the thermoelectric conversion cells 30A to 30I are arranged can be detected by measuring the output voltages of the thermoelectric conversion cells 30A to 30I connected in series. As shown in FIG. 22 , the thermoelectric conversion element 100 may detect the heat flux of each region in which the thermoelectric conversion cells 30A to 30D are arranged by measuring the output voltage of each second electrode 70 of the thermoelectric conversion cells 30A to 30D connected in series via wiring 92. This allows the thermoelectric conversion element 100 to detect the heat flux of the entire region in which the thermoelectric conversion cells 30A to 30D are arranged and to detect the distribution of the heat flux within the region in which the thermoelectric conversion cells 30A to 30D are arranged. For ease of understanding, the first layer 62 of the first electrode 60, the protective layer 80, and some of the reference numerals are omitted in FIG. 22 .

[0079] In the thermoelectric conversion element 100, as shown in Fig. 23, cell groups 94 in which thermoelectric conversion cells 30A to 30C are connected in series may be connected in parallel via wiring 92. This allows the thermoelectric conversion element 100 to detect heat flux even if some of the thermoelectric conversion cells 30A to 30C are disconnected. For ease of understanding, Fig. 23 shows the thermoelectric conversion cells 30A to 30C in a simplified manner, and omits the substrate 10, protective layer 80, etc.

[0080] In the first electrode 60 exposed from the terminal opening 85 of the first embodiment, a first layer 62 and a second layer 66 are laminated. The first electrode 60 exposed from the terminal opening 85 may be formed from only the second layer 66, as shown in Fig. 24. Furthermore, a thin film 64 for forming the first layer 62 of the first electrode 60 may remain under the second electrode 70 exposed from the terminal opening 85, as shown in Fig. 25.

[0081] In the first embodiment, the terminal openings 85 for connecting the thermoelectric conversion element 100 to an external device are arranged on different sides of the thermoelectric conversion element 100, but the positions, shapes, etc. of the terminal openings 85 are arbitrary. The connection form, connection positions, etc. between the thermoelectric conversion element 100 and the external device are also arbitrary. Furthermore, the number, arrangement, connection paths, etc. of the thermoelectric conversion cells in the thermoelectric conversion element 100 are also arbitrary and may be set depending on the application and installation location of the thermoelectric conversion element 100.

[0082] Although the preferred embodiments have been described above, the present disclosure is not limited to the specific embodiments, and the present disclosure includes the inventions described in the claims and their equivalents. [Explanation of symbols]

[0083] 10 substrate, 12 first principal surface, 20 underlayer, 30A to 30I, 32A to 32I thermoelectric conversion cell, 40 thermoelectric conversion layer, 42 first principal surface, 50 insulating layer, 52 first contact hole, 54 second contact hole, 60 first electrode, 62 first layer, 62a first base portion, 62b first comb tooth portion, 64 thin film, 66 second layer, 70 second electrode, 70a second base portion, 70b second comb tooth portion, 80 protective layer, 85 terminal opening, 92 wiring, 94 cell group, 100 thermoelectric conversion element

Claims

1. A substrate; a plurality of thermoelectric conversion cells provided on the main surface of the substrate, Each of the thermoelectric conversion cells is a thermoelectric conversion layer formed on the main surface of the substrate; an insulating layer covering the thermoelectric conversion layer; a first electrode including a first layer formed on the insulating layer and connected to a main surface of the thermoelectric conversion layer through a first contact hole in the insulating layer, and a second layer formed on the insulating layer and covering the first layer; a second electrode formed on the insulating layer and connected to the main surface of the thermoelectric conversion layer through a second contact hole in the insulating layer, the second layer covers the first layer in a state where the first layer is not exposed from the second layer; the second layer and the second electrode are formed from the same material having a work function different from the work function of the material forming the first layer; In the adjacent thermoelectric conversion cells, the second layer of one of the thermoelectric conversion cells and the second electrode of the other of the thermoelectric conversion cells are integrally formed, the first electrodes and the second electrodes are connected one-to-one, and the plurality of thermoelectric conversion cells are connected in series, the first layer covers the opening of the first contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer; the second electrode covers the opening of the second contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer; Thermoelectric conversion element.

2. the first layer has a first base portion and a plurality of first comb teeth extending from the first base portion; the second electrode has a second base portion and a plurality of second comb teeth extending from the second base portion; the first comb-tooth portions and the second comb-tooth portions are alternately arranged opposite to each other on the main surface of the thermoelectric conversion layer, The thermoelectric conversion element according to claim 1 .

3. The plurality of thermoelectric conversion cells are arranged in a matrix. The thermoelectric conversion element according to claim 1 or 2.

4. forming a plurality of thermoelectric conversion layers on a substrate; forming an insulating layer on the plurality of thermoelectric conversion layers; forming a plurality of first contact holes in the insulating layer, the first contact holes corresponding to the thermoelectric conversion layers and exposing the main surfaces of the thermoelectric conversion layers; forming a first layer of a plurality of first electrodes on the insulating layer, the first layers corresponding to the thermoelectric conversion layers and connected to the main surfaces of the thermoelectric conversion layers via the first contact holes; forming a plurality of second contact holes in the insulating layer on which the first layer of the first electrode is formed, the second contact holes corresponding to the thermoelectric conversion layers and exposing the main surfaces of the thermoelectric conversion layers; forming, on the insulating layer, a plurality of second electrodes corresponding to each of the thermoelectric conversion layers and connected to the main surface of each of the thermoelectric conversion layers via the second contact holes, and a plurality of second layers of the first electrodes covering each of the first layers of the first electrodes, from a material having a work function different from a work function of a material forming the first layers of the first electrodes, to form a plurality of thermoelectric conversion cells each including the thermoelectric conversion layers, the insulating layer, the first electrodes, and the second electrodes; In the step of forming the plurality of thermoelectric conversion cells, forming the second layer of the first electrode in a state in which the first layer of the first electrode is not exposed from the second layer of the first electrode; In the adjacent thermoelectric conversion cells, the second layer of the first electrode of one of the thermoelectric conversion cells and the second electrode of the other of the thermoelectric conversion cells are integrally formed, and the first electrodes and the second electrodes are connected one-to-one to connect the plurality of thermoelectric conversion cells in series. A method for manufacturing a thermoelectric conversion element.

5. the first layer of the first electrode covers the opening of the first contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer; the second electrode covers the opening of the second contact hole in a state in which the thermoelectric conversion layer is not exposed from the insulating layer; The method for manufacturing the thermoelectric conversion element according to claim 4 .

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