Patent Application
20250185512
The present disclosure relates to a thermoelectric conversion element and a method for manufacturing a thermoelectric conversion element.
Thermoelectric conversion is a technology of directly converting heat energy to electric energy using the Seebeck effect in which an electromotive force is generated in proportion to a temperature difference applied between both ends of a material. Alternatively, thermoelectric conversion is a technology of converting electric energy to heat energy using the Peltier effect in which a temperature difference arises between both ends of a material by current generated in the material.
The performance of a thermoelectric conversion element is evaluated by a performance index Z or a nondimensionalized performance index ZT which is a product of the performance index Z and an absolute temperature T. ZT is represented as ZT=S2T/ρκ, using a Seebeck coefficient S, an electrical resistivity ρ, and a thermal conductivity κ of a thermoelectric material used for the thermoelectric conversion element. Therefore, using a thermoelectric material of which the Seebeck coefficient S is high and the electrical resistivity ρ and the thermal conductivity κ are low is desirable in terms of enhancement in thermoelectric conversion performance.
As the thermoelectric conversion element, a TT-type thermoelectric conversion element is known. In the TT-type thermoelectric conversion element, a p-type thermoelectric member having a positive Seebeck coefficient and an n-type thermoelectric member having a negative Seebeck coefficient are connected electrically in series and connected thermally in parallel, whereby a thermocouple is formed.
As the thermoelectric conversion element, a uni-leg type thermoelectric conversion element is also known. In the uni-leg type thermoelectric conversion element, only one of a p-type thermoelectric member and an n-type thermoelectric member is used as a thermoelectric member, and by a metal plate, each thermoelectric member is connected electrically in series and connected thermally in parallel. For example, JP 2015-70217 and JP 2016-111309 describe uni-leg type thermoelectric conversion elements. In the TT-type thermoelectric conversion element, it is important to use a p-type thermoelectric member and an n-type thermoelectric member that are close to each other in properties such as an electrical resistivity, a thermal conductivity, and a Seebeck coefficient. On the other hand, in the uni-leg type thermoelectric conversion element, since only one of a p-type thermoelectric member and an n-type thermoelectric member is used as the thermoelectric member, there are fewer constraints on selection of the thermoelectric member.
In the above technologies, configuring a uni-leg type thermoelectric conversion element using a thin-film-shaped thermoelectric member is not assumed.
Accordingly, the present disclosure provides a technology that is advantageous in terms of thermoelectric conversion performance while using a thin-film-shaped thermoelectric member in a uni-leg type thermoelectric conversion element.
The present disclosure provides the following thermoelectric conversion element.
A thermoelectric conversion element including:
The thermoelectric conversion element of the present disclosure is configured as a uni-leg type thermoelectric conversion element including a thin-film-shaped thermoelectric member, and is advantageous in terms of thermoelectric conversion performance.
(Finding on which the Present Disclosure is Based)
In a uni-leg type thermoelectric conversion element, it is considered that a metal plate for electrically connecting a thermoelectric member has a high thermal conductance relative to the thermoelectric member. Therefore, in the uni-leg type thermoelectric conversion element, the thermal conductance of the entire element is likely to become higher than in a TT-type thermoelectric conversion element. This cannot be considered advantageous in terms of thermoelectric conversion performance.
In the uni-leg type thermoelectric conversion element, a thermal conductance Gt of the thermoelectric member is represented as Gt=κt×At/Lt, using a thermal conductivity κt of a material forming the thermoelectric member, an area At of an end surface forming one end in the heat flow direction of the thermoelectric member, and a dimension Lt in the heat flow direction of the thermoelectric member. A thermal conductance Gm of the metal plate which forms a thermocouple together with the thermoelectric member is represented as Gm=κm×Am/Lm, using a thermal conductivity κm of a material of the metal plate, an area Am of an end surface forming one end in the heat flow direction of the metal plate, and a dimension Lm in the heat flow direction of the metal plate. In the uni-leg type thermoelectric conversion element, the dimension Lt and the dimension Lm can be adjusted to values that are the same or close to each other. Therefore, by making the area Am of the metal plate smaller than the area At of the thermoelectric member, the thermal conductance of the electroconductive member which is a member forming a thermocouple together with the thermoelectric member in the uni-leg type thermoelectric conversion element is likely to become low.
In a thermoelectric conversion element including a thermoelectric member formed by a bulk obtained through a manufacturing process including cutting work, it is difficult to manufacture a metal plate which forms a thermocouple together with a thermoelectric member, so as to have a fine structure. Accordingly, it is conceivable to manufacture thermoelectric conversion elements including a thin-film-shaped thermoelectric member by using a semiconductor manufacturing process or the like. In this case, a fine structure is likely to be obtained by a method such as lithography. Accordingly, it is conceivable to electrically connect each thin-film-shaped thermoelectric member using, instead of the metal plate, an electroconductive member of which the area of an end surface at one end in the heat flow direction is small and which contains at least one selected from the group consisting of metal and a metal compound. Thus, the thermal conductance of the member electrically connecting each thermoelectric member in the uni-leg type thermoelectric conversion element can be reduced. On the other hand, in order to form an electroconductive member having a fine structure, a process with a process node involving high manufacturing cost is needed, depending on the degree of fineness of the structure. In addition, it is difficult to enlarge the dimension of the electroconductive member in a direction perpendicular to a principal surface of a substrate. Accordingly, the present inventors have studied intensively on a technology that can reduce the thermal conductance of a member for electrically connecting each thermoelectric member while reducing the manufacturing cost, using a thin-film-shaped thermoelectric member in a uni-leg type thermoelectric conversion element. As a result, the present inventors have finally completed the thermoelectric conversion element of the present disclosure.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions of the components, connection forms, process conditions, steps, order of the steps, etc., shown in the following embodiments are examples, and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, the components that are not described in the independent claims that represent broadest concepts are described as discretionary components. Each drawing is a schematic diagram, and is not necessarily exactly illustrated.
A material forming the thermoelectric member 10g is not limited to a specific material. The material may be a thermoelectric material having a positive Seebeck coefficient or a thermoelectric material having a negative Seebeck coefficient. The material forming the thermoelectric member 10g is desirably a semiconductor material in which carriers serving for electric conduction can be adjusted to either holes or electrons by doping, for example. Examples of such a semiconductor material are Si, SiGe, SiC, GaAs, InAs, InSb, InP, GaN, ZnO, and BiTe. The material forming the thermoelectric member 10g may be another material. The material forming the thermoelectric member 10g may be a single-crystal material, a polycrystal material, or an amorphous material.
The thickness of the thermoelectric member 10g in the direction perpendicular to the principal surface of the substrate 20 is not limited to a specific thickness. The thickness is 100 nm or more and 10 μm or smaller, for example. The carrier density of the thermoelectric member 10g is not limited to a specific value. The carrier density is in a range of 1×1019 cm−3 to 1×1021 cm−3, for example.
The metal or the metal compound contained in the electroconductive member 10m is not limited to specific metal or a specific metal compound. Examples of the metal and the metal compound are materials, such as Al, Cu, TIN, and TaN, used in a semiconductor manufacturing process.
The thermal conductivity of the electroconductive member 10m is not limited to a specific value as long as the thermal conductivity of the thermal insulator 11 is lower than the thermal conductivity of the electroconductive member 10m. The thermal conductivity of the electroconductive member 10m is 15 Wm−1K−1 or higher and 400 Wm−1K−1 or lower, for example.
The dimension of the electroconductive member 10m in the direction perpendicular to the principal surface of the substrate 20 is not limited to a specific value. The dimension can vary in accordance with the thickness of the thermoelectric member 10g. The dimension is 100 nm or greater and 10 μm or smaller, for example.
The maximum dimension of the electroconductive member 10m in a direction parallel to the principal surface of the substrate 20 is not limited to a specific value. The maximum dimension is 2 μm or greater and 50 μm or smaller, for example. With this configuration, the electroconductive member 10m can be formed without using a process with a process node involving high manufacturing cost, so that the manufacturing cost of the thermoelectric conversion element 1a is less likely to become high.
The thermal conductivity of the thermal insulator 11 is not limited to a specific value as long as the thermal conductivity thereof is lower than that of the electroconductive member 10m. The thermal conductivity of the thermal insulator 11 is 10 Wm−1K−1 or lower, for example. In this case, the thermal conductance of the structure including the electroconductive member 10m and the thermal insulator 11 is likely to become low, so that the thermal conductance of the entire thermoelectric conversion element 1a is likely to become low. Therefore, the thermoelectric conversion performance of the thermoelectric conversion element 1a is likely to become higher. The thermal conductivity of the thermal insulator 11 may be 20 Wm−1K−1 or lower, or 10 Wm−1K−1 or lower. The thermal conductivity of the thermal insulator 11 is 0.1 Wm−1K−1 or higher, for example.
The thermal insulator 11 contains an amorphous material, for example. In this case, the thermal conductivity of the thermal insulator 11 is likely to become low, so that the thermal conductance of the structure including the electroconductive member 10m and the thermal insulator 11 is likely to become low. The thermal insulator 11 may contain a polycrystal material. A material forming the thermal insulator 11 is not limited to a specific material as long as the thermal conductivity of the thermal insulator 11 is lower than the thermal conductivity of the electroconductive member 10m. Examples of the material forming the thermal insulator 11 are oxides such as SiO2 and Al2O3, and metal glass.
In the thermoelectric conversion element 1a, the ratio of the volume of the thermal insulator 11 to the sum of the volumes of the electroconductive member 10m and the thermal insulator 11 is not limited to a specific value. The ratio is 50% to 90%, for example. With this configuration, the thermal conductance of the structure including the electroconductive member 10m and the thermal insulator 11 is likely to become lower, so that the thermal conductance of the entire thermoelectric conversion element 1a is likely to become lower. In addition, the electroconductive member 10m is likely to have a desired electric conductivity.
As shown in
As shown in
The thermoelectric members 10g and the electroconductive members 10m are connected electrically in series via the first wiring 30a and the second wiring 30b. Thus, the thermocouples 10t are configured by the thermoelectric members 10g and the electroconductive members 10m.
As shown in
The thermoelectric conversion element 1a includes a plurality of plugs 53, for example. The plugs 53 extend through the second interlayer insulation film 42 in the direction perpendicular to the principal surface of the substrate 20. The plugs 53 are disposed on the second wiring 30b and are electrically connected to the second wiring 30b.
The thermoelectric conversion element 1a includes a first electrode pad 51 and a second electrode pad 52, for example. The first electrode pad 51 and the second electrode pad 52 are electrically connected to different plugs 53, respectively. Thus, between the first electrode pad 51 and the second electrode pad 52, the thermocouples 10t are electrically connected to the first electrode pad 51 and the second electrode pad 52.
The shape of the thermoelectric member 10g is not limited to a specific shape.
The arrangement of the thermal insulator 11 and the electroconductive member 10m is not limited to specific arrangement as long as the thermal insulator 11 is in contact with the electroconductive member 10m. The thermal insulator 11 is surrounded by the electroconductive member 10m, for example. With this configuration, the thermal conductance of the structure including the electroconductive member 10m and the thermal insulator 11 is likely to become low, and the electroconductive member 10m is likely to have a desired electric conductivity.
The electroconductive member 10m may be formed to have at least one selected from the group consisting of a hollow and a recess. In this case, the thermal insulator 11 can be disposed so as to fill at least a part of the hollow or at least a part of the recess.
In the examples shown in
The ratio of the volume of the hollow 10j and the recess 10k to the sum of the volume of the electroconductive member 10m and the volume of the hollow 10j and the recess 10k is not limited to a specific value. The ratio is 50% or greater and 90% or smaller, for example. With this configuration, the thermal conductance of the structure including the electroconductive member 10m and the thermal insulator 11 is likely to become lower, so that the thermal conductance of the entire thermoelectric conversion element 1a is likely to become lower. In addition, the electroconductive member 10m is likely to have a desired electric conductivity.
A material forming the base 20a is not limited to a specific material. The base 20a is an Si substrate, for example. The base 20a may be formed by a semiconductor other than Si or a material other than a semiconductor.
A material forming the foundation insulation film 20b is not limited to a specific material. The foundation insulation film 20b may contain an oxide insulator such as silicon oxide and aluminum oxide, or a nitride insulator such as silicon nitride and aluminum nitride. In a case where the base 20a has an electric insulation property, the foundation insulation film 20b may be omitted. The thickness of the foundation insulation film 20b is not limited to a specific value. The thickness may be 50 nm to 1 μm, for example.
Materials forming the first wiring 30a and the second wiring 30b are not limited to specific materials as long as the materials have a predetermined electric conductivity. The first wiring 30a and the second wiring 30b contain metal or a metal compound, for example. Examples of the metal and the metal compound are materials, such as Al, Cu, TiN, and TaN, used in a semiconductor manufacturing process. The thicknesses of the first wiring 30a and the second wiring 30b are not limited to specific values. The thicknesses are 100 nm to 1 μm, for example.
Materials forming the first interlayer insulation film 41 and the second interlayer insulation film 42 are not limited to specific materials. The first interlayer insulation film 41 and the second interlayer insulation film 42 may contain an oxide insulator such as silicon oxide and aluminum oxide, or a nitride insulator such as silicon nitride and aluminum nitride. Materials forming the first interlayer insulation film 41 and the second interlayer insulation film 42 may be a single-crystal material, a polycrystal material, or an amorphous material. Materials forming the first interlayer insulation film 41 and the second interlayer insulation film 42 may be the same kind of material or different kinds of materials. The thickness of the first interlayer insulation film 41 may vary in accordance with the thicknesses of the thermoelectric members 10g. The thickness of the first interlayer insulation film 41 is 100 nm to 10 μm, for example. The thickness of the second interlayer insulation film 42 is not limited to a specific value as long as the second interlayer insulation film 42 can cover the second wiring 30b. The thickness is 100 nm to 2 μm, for example.
Materials forming the plug 53, the first electrode pad 51, and the second electrode pad 52 are not limited to specific materials. The materials are metal or a metal compound, for example. The metal and the metal compound may be materials, such as Al, Cu, W, TiN, and TaN, used in a semiconductor manufacturing process, for example.
As shown in
In the thermoelectric conversion element of embodiment 1, when a temperature difference arises in the direction perpendicular to the principal surface of the substrate 20, an electromotive force is generated between the first electrode pad 51 and the second electrode pad 52 by the Seebeck effect. Through conductive wires connected to the first electrode pad 51 and the second electrode pad 52, the electromotive force is outputted to outside of the thermoelectric conversion element. Thus, the thermoelectric conversion element can be used as an electric generation device and a heat flow sensor.
In the thermoelectric conversion element of embodiment 1, when conductive wires are connected to the first electrode pad 51 and the second electrode pad 52 and a current is generated, a heat flow in the direction perpendicular to the principal surface of the substrate 20 can be generated by the Peltier effect. The direction of the heat flow can change depending on the direction of the current. Thus, the thermoelectric conversion element of embodiment 1 can be used as a temperature control device for cooling or heating.
An example of a method for manufacturing the thermoelectric conversion element of embodiment 1 will be described. The method for manufacturing the thermoelectric conversion element is not limited to the following method. The method for manufacturing the thermoelectric conversion element of embodiment 1 includes disposing the thermal insulator 11 in contact with the electroconductive member 10m which contains metal or a metal compound and is arranged together with the thin-film-shaped thermoelectric member 10g along the principal surface of the substrate 20. In a case where the electroconductive member 10m has at least one selected from the group consisting of a hollow and a recess, the thermal insulator 11 is disposed so as to fill the hollow or the recess.
As shown in
Next, as shown in
Next, as shown in
Next, as shown in
Next, at least parts of the hollows 10j are filled with the thermal insulators 11 made of an amorphous material such as SiO2 by a method such as sputtering and CVD from above the first interlayer insulation film 41. Next, as shown in
Next, as shown in
Next, as shown in
For example, the second wiring 30b and the electroconductive members 10m may contain the same kind of material. In this case, the second wiring 30b and the electroconductive members 10m having the hollows 10j may be formed in the same step, by photolithography and etching, or lift-off, after the metal thin film 13 is formed. Then, the second interlayer insulation film 42 containing an electric insulator such as SiO2 is formed, whereby formation of the second interlayer insulation film 42 and filling with the thermal insulators 11 into the hollows 10j of the electroconductive members 10m can be performed in the same step. In this case, the second interlayer insulation film 42 and the thermal insulators 11 can be formed by the same kind of material.
Next, as shown in
Next, a thin film of a material such as Al and TIN is formed by a method such as sputtering and CVD from above the second interlayer insulation film 42, so as to fill the recesses 53h. Next, as shown in
While the foundation insulation film 20b, the first interlayer insulation film 41, and the second interlayer insulation film 42 are formed of different materials, only the first interlayer insulation film 41 may be finally removed by etching. For example, the first interlayer insulation film 41 may be formed by SiO2, and the foundation insulation film 20b and the second interlayer insulation film 42 may be formed by Al2O3. Then, SiO2 may be etched by gas-phase hydrofluoric acid, to remove the first interlayer insulation film 41. Owing to removal of the first interlayer insulation film 41 around the thermoelectric member 10g and the electroconductive member 10m, a temperature difference arising between a one-end surface and an other-end surface of each of the thermoelectric member 10g and the electroconductive member 10m in the direction perpendicular to the principal surface of the substrate 20 is likely to become great. As a result, the performance of the thermoelectric conversion element is likely to become higher.
As shown in
Each thermoelectric member 10g may contain a p-type thermoelectric material having a positive Seebeck coefficient, or an n-type thermoelectric material having a negative Seebeck coefficient.
The electroconductive member 10m is disposed on the second portion 10r, for example. With this configuration, electric connection between the electroconductive member 10m and the thermoelectric member 10g can be ensured even if a configuration corresponding to the first wiring 30a of the thermoelectric conversion element of embodiment 1 is omitted.
The second portion 10r serves a role equivalent to the first wiring 30a in the thermoelectric conversion element of embodiment 1. The second thickness of the second portion 10r is not limited to a specific value as long as the second thickness is smaller than the first thickness. The second thickness is, for example, 10 nm or greater, and desirably 100 nm or greater.
As shown in
As shown in
An example of a method for manufacturing the thermoelectric conversion element of embodiment 2 will be described. The method for manufacturing the thermoelectric conversion element of embodiment 2 is not limited to the following method.
As shown in
Next, the thermoelectric material thin film 18 is doped with impurity ions and the carrier density of electrons or holes is adjusted into a range of 1×1019 cm−3 to 1×1021 cm−3. The doping is performed by a method such as ion implantation and thermal diffusion, for example. An annealing treatment may be additionally performed to adjust the carrier density to a desired value. The doping may be performed for the entire surface of the thermoelectric material thin film 18, or may be performed for a predetermined area thereof using photolithography.
Next, as shown in
Next, as shown in
Next, as shown in
Next, at least parts of the hollows 10j are filled with the thermal insulators 11 made of an amorphous material such as SiO2 by a method such as sputtering and CVD from above the first interlayer insulation film 41. Next, as shown in
Next, as shown in
Next, as shown in
For example, in a case where the wiring 30 and the electroconductive members 10m contain the same kind of material, the wiring 30 and the electroconductive members 10m having the hollows 10j may be formed in the same step by photolithography and etching, or lift-off, after the metal thin film 13 is formed. Then, the second interlayer insulation film 42 containing an electric insulator such as SiO2 is formed, whereby formation of the second interlayer insulation film 42 and filling with the thermal insulators 11 into the hollows 10j of the electroconductive members 10m can be performed in the same step. In this case, the second interlayer insulation film 42 and the thermal insulators 11 can be formed by the same kind of material.
Next, as shown in
Next, a thin film of a material such as Al and TiN is formed by a method such as sputtering and CVD from above the second interlayer insulation film 42, so as to fill the recesses 53h. Next, as shown in
From the above description, the following technologies are disclosed.
A thermoelectric conversion element comprising:
With this configuration, the thermal conductance of the electroconductive member is likely to become low while the manufacturing cost is reduced. Thus, the thermoelectric conversion performance of the uni-leg type thermoelectric conversion element including the thin-film-shaped thermoelectric member is likely to become high.
The thermoelectric conversion element according to technology 1, wherein the thermal insulator is surrounded by the electroconductive member in a plan view.
With this configuration, the thermal conductance of the structure including the electroconductive member and the thermal insulator is likely to become low and the electroconductive member is likely to have a desired electric conductivity. Thus, the thermoelectric conversion performance of the thermoelectric conversion element is likely to become higher.
The thermoelectric conversion element according to technology 1 or 2, wherein
With this configuration, the thermal conductance of the structure including the electroconductive member and the thermal insulator is likely to become lower. Thus, the thermoelectric conversion performance of the thermoelectric conversion element 1a is likely to become higher.
The thermoelectric conversion element according to any one of technologies 1 to 3, wherein
With this configuration, the thermal conductance of the structure including the electroconductive member and the thermal insulator is likely to become lower. Thus, the thermoelectric conversion performance of the thermoelectric conversion element is likely to become higher.
The thermoelectric conversion element according to any one of technologies 1 to 4, wherein
With this configuration, the thermal conductance of the structure including the electroconductive member and the thermal insulator is likely to become lower, so that the thermal conductance of the entire thermoelectric conversion element is likely to become lower. In addition, the electroconductive member is likely to have a desired electric conductivity. Thus, the thermoelectric conversion performance of the thermoelectric conversion element is likely to become higher.
The thermoelectric conversion element according to any one of technologies 1 to 5, wherein
With this configuration, a configuration corresponding to the first wiring 30a of the thermoelectric conversion element of embodiment 1 can be omitted. Thus, the configuration of the thermoelectric conversion elements is likely to be simplified.
The thermoelectric conversion element according to technology 6, wherein
With this configuration, electric connection between the electroconductive member and the thermoelectric member can be ensured even if a configuration corresponding to the first wiring 30a of the thermoelectric conversion element of embodiment 1 is omitted.
A method for manufacturing a thermoelectric conversion element, comprising disposing a thermal insulator in contact with an electroconductive member which contains at least one selected from the group consisting of metal and a metal compound and is arranged together with a thin-film-shaped thermoelectric member along a principal surface of a substrate, wherein
Whit this method, the thermal conductance of the electroconductive member can be reduced by the thermal insulator. Thus, the thermoelectric conversion performance of the thermoelectric conversion element is likely to be enhanced while the manufacturing cost is reduced.
Hereinafter, with reference to Examples, the present embodiment will be described in more detail. However, the thermoelectric conversion element of the present embodiment 1 is not limited to configurations described in the following Examples.
An Al thin film having a thickness of 100 nm was formed on an SiO2 thin film having a thickness of 100 nm formed on an Si substrate. Photolithography and etching were performed on the Al thin film, to form a pattern to be a first wiring. Next, an SiO2 film having a thickness of 1.1 μm was formed so as to cover the first wiring, thus obtaining a first interlayer insulation film. Photolithography and etching were performed on the first interlayer insulation film, to form a recess in the first interlayer insulation film. At this time, a part of the first wiring was exposed so as to form a bottom surface of the recess. Next, a thin film of polycrystal Si was formed and the polycrystal Si outside the recess was removed by CMP, whereby a thermoelectric material thin film was formed in the recess. Next, boron ions were implanted as impurities into the thermoelectric material thin film, with a dosage of 1×1016 cm−2, to obtain an Si thermoelectric member. A bottom surface of the Si thermoelectric member had a square shape with each side having a length of 100 μm, and the thickness of the Si thermoelectric member was 1 μm.
Next, a recess was formed in an area adjacent to the Si thermoelectric member in the first interlayer insulation film, by photolithography and etching. Next, an Al thin film was formed on the first interlayer insulation film. The Al thin film was formed so as to cover a bottom surface and a side surface of the recess. Next, while the Al thin film present in an area separated from the recess was removed by photolithography and etching, a part of the Al thin film around the recess and the Al thin film on the Si thermoelectric member were left, to obtain a second wiring. At this stage, an Al member having a hollow surrounded by the Al thin film was formed correspondingly to the recess in a plan view. A bottom surface of the Al member had a square shape with each side having a length of 100 μm, and a height of the Al member which was a dimension of the Al member in a direction perpendicular to a principal surface of the Si substrate was 1 μm. The ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow was 90%. Next, an SiO2 thin film was formed from above the hollow, to fill the entirety of the hollow with SiO2. Finally, SiO2 around the Si thermoelectric member and the Al member was removed by photolithography and etching, to expose parts of the second wiring. Thus, an element of a sample A-1 was obtained.
Elements of samples A-2 to A-10 were obtained in the same manner as the sample A-1 except that a formation condition of the Al thin film for creating the Al member was adjusted so that the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow became values shown in Table 1. In the sample A-10, the Al member was formed so as not to form the hollow.
Elements of samples B-1 to B-10 were manufactured in the same manner as the sample A-1 except for the following. In the samples B-1 to B-10, a bottom surface of the Al member had a square shape with each side having a length of 30 μm. In the samples B-1 to B-10, a formation condition of the Al thin film for creating the Al member was adjusted so that the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow became values shown in Table 2.
Elements of samples C-1 to C-10 were manufactured in the same manner as the sample A-1 except for the following. In the samples C-1 to C-10, a bottom surface of the Al member had a square shape with each side having a length of 20 μm. In the samples C-1 to C-10, a formation condition of the Al thin film for creating the Al member was adjusted so that the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow became values shown in Table 3.
The thermoelectric performance of the element of each sample was evaluated and the nondimensionalized performance index ZT thereof at 300 K was determined. The electric resistance of the element of each sample was measured in accordance with a four-terminal method via the first wiring. The thermal conductance of the element of each sample was measured in accordance with a thermoreflectance method. A sample including a polycrystal Si thin film and an Al thin film created on another substrate was separately manufactured, and the Seebeck coefficient of the Si thermoelectric member was determined using the sample and a measurement device ZEM3 manufactured by ULVAC-RIKO, Inc. The value of the Seebeck coefficient was used for determination of the nondimensionalized performance index ZT. Results of these are shown in Tables 1 to 3.
As shown in Table 1, the nondimensionalized performance index ZT of the element of the sample A-4 was equal to or greater than two times that of the element of the sample A-10 having no hollow in the Al member. In the sample A-4, the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow was 60%, and the hollow was filled with SiO2. The thermal conductivity of SiO2 is lower than the thermal conductivity of Al.
As shown in Table 2, the nondimensionalized performance index ZT of the element of the sample B-3 was equal to or greater than two times that of the element of the sample B-10 having no hollow in the Al member. In the sample B-3, the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow was 70%, and the hollow was filled with SiO2.
As shown in Table 3, the nondimensionalized performance index ZT of the element of the sample C-2 was equal to or greater than two times that of the element of the sample C-10 having no hollow in the Al member. In the sample C-2, the ratio of the volume of the hollow to the sum of the volume of the Al member and the volume of the hollow was 80%, and the hollow was filled with SiO2.
The thermoelectric conversion element of the present disclosure is applicable to various purposes including purposes of electric generation and temperature control, for example.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-138390 | Aug 2022 | JP | national |
This application is a continuation of PCT/JP2023/030824 filed on Aug. 25, 2023, which claims foreign priority of Japanese Patent Application No. 2022-138390 filed on Aug. 31, 2022, the entire contents of both of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/030824 | Aug 2023 | WO |
| Child | 19046241 | US |
