Thermoelectric element

Abstract

A thermoelectric element according to one embodiment of the present invention includes a first substrate, a first insulating layer disposed on the first substrate, a second insulating layer disposed on the first insulating layer, a first electrode disposed on the second insulating layer, and a semiconductor structure disposed on the first electrode, wherein the first insulating layer includes an uneven portion, a portion of the first electrode is embedded in the second insulating layer, and the second insulating layer includes a recess recessed in a direction from a side of the first electrode toward the first insulating layer, and the recess vertically overlaps the uneven portion.

Description

Technical Field

[0001] The present invention relates to a thermoelectric element, and more particularly to a substrate and an insulating layer of a thermoelectric element.

Background Art

[0002] The thermoelectric phenomenon is a phenomenon generated by the movement of electrons and holes inside a material, and means a direct energy conversion between heat and electricity.

[0003] A thermoelectric element is a general term for elements that utilize the thermoelectric phenomenon, and has a structure in which a P-type thermoelectric material and an N-type thermoelectric material are joined between metal electrodes to form a PN junction pair.

[0004] Thermoelectric elements can be classified into elements that utilize the temperature change of electrical resistance, elements that utilize the Seebeck effect, which is a phenomenon in which an electromotive force is generated due to a temperature difference, and elements that utilize the Peltier effect, which is a phenomenon in which heat absorption or heat generation occurs due to an electric current.

[0005] Thermoelectric elements are widely applied to home appliances, electronic components, communication components, etc. For example, thermoelectric elements can be applied to cooling devices, heating devices, power generation devices, etc. Along with this, the requirements for the thermoelectric performance of thermoelectric elements are becoming increasingly high.

[0006] A thermoelectric element includes a substrate, electrodes, and thermoelectric legs. A plurality of thermoelectric legs are arranged between an upper substrate and a lower substrate, a plurality of upper electrodes are arranged between the plurality of thermoelectric legs and the upper substrate, and a plurality of lower electrodes are arranged between the plurality of thermoelectric legs and the lower substrate.

[0007] In order to improve the heat transfer performance of thermoelectric elements, attempts to use metal substrates are increasing.

[0008] Generally, a thermoelectric element can be fabricated by sequentially laminating electrodes and thermoelectric legs on a pre-provided metal substrate. When a metal substrate is used, although an advantageous effect can be obtained in terms of heat conduction, there is a problem that the withstand voltage is low, resulting in low reliability during long-term use.

[0009] In order to solve such problems, there has been an attempt to anodize the surface of an aluminum substrate to increase the withstand voltage, but there is a problem that it is difficult to bond between the anodized metal substrate and the electrode.

[0010] Accordingly, there is a need for a thermoelectric element in which not only the heat conduction performance but also the withstand voltage performance and the bonding performance are all improved.

Summary of the Invention

Problems to be Solved by the Invention

[0011] The technical problem to be achieved by the present invention is to provide a structure of a substrate and an insulating layer of a thermoelectric element in which the heat conduction performance, the withstand voltage performance, and the bonding performance are all improved.

Means for Solving the Problems

[0012] A thermoelectric element according to an embodiment of the present invention includes a first substrate, a first insulating layer disposed on the first substrate, a second insulating layer disposed on the first insulating layer, a first electrode disposed on the second insulating layer, and a semiconductor structure disposed on the first electrode. The first insulating layer includes uneven portions, a partial region of the first electrode is embedded in the second insulating layer, the second insulating layer includes a recess recessed in a direction from a side surface of the first electrode toward the first insulating layer, and the recess overlaps perpendicularly with the uneven portions.

[0013] At least one of the composition and elasticity of the first insulating layer is different from at least one of the composition and elasticity of the second insulating layer. The withstand voltage of the first insulating layer is higher than the withstand voltage of the second insulating layer, and the thermal conductivity of the second insulating layer may be higher than the thermal conductivity of the first insulating layer.

[0014] The first insulating layer is made of a composite containing silicon and aluminum, and the second insulating layer can be a resin layer made of a resin composition containing at least one of an epoxy resin and a silicone resin and an inorganic filler.

[0015] The composite can contain at least one of Al-Si bonds, Al-O-Si bonds, Si-O bonds, Al-Si-O bonds, and Al-O bonds.

[0016] The uneven portions are formed on the surface of the first insulating layer that contacts the second insulating layer among both surfaces of the first insulating layer, and the surface roughness (Ra) of the uneven portions can be 0.1 μm or more.

[0017] The thickness of the first insulating layer can be 20 to 35 μm.

[0018] The thickness of the second insulating layer can be 20 to 70 μm.

[0019] The recesses are arranged between two adjacent first electrodes, and the thickness of the second insulating layer can decrease from the side surfaces of the two adjacent first electrodes toward the central region between the two adjacent first electrodes.

[0020] The thickness of the second insulating layer arranged on the side surface of the first electrode may be greater than the thickness of the second insulating layer arranged on the lower surface of the first electrode.

[0021] It further includes a second electrode arranged on the semiconductor structure, a third insulating layer arranged on the second electrode, and a second substrate arranged on the third insulating layer, and at least one of the first substrate and the second substrate can be made of at least one of aluminum, copper, an aluminum alloy, and a copper alloy.

Advantages of the Invention

[0022] According to an embodiment of the present invention, a thermoelectric element with excellent performance and high reliability can be obtained. In particular, according to an embodiment of the present invention, a thermoelectric element with improved not only in thermal conduction performance but also in withstand voltage performance and bonding performance can be obtained. According to an embodiment of the present invention, a thermoelectric element with high bonding force both between the substrate and the electrode and between the substrate and the heat sink can be obtained.

[0023] The thermoelectric element according to an embodiment of the present invention can be applied not only to applications embodied in a small size but also to applications embodied in a large size such as vehicles, ships, steel mills, incinerators, etc.

Brief Description of the Drawings

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Figure 1

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Figure 2

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Figure 3

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Figure 4

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Figure 5

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Figure 6

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Figure 7

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Figure 8(a)-8(c)

Figure 9(a)-9(c)

Embodiments for Carrying Out the Invention

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] However, the technical idea of the present invention is not limited to some of the described embodiments, and can be embodied in various different forms. Within the scope of the technical idea of the present invention, one or more of its components can be selectively combined or replaced between embodiments and used.

[0034] Also, the terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted in a meaning generally understood by those having ordinary knowledge in the technical field to which the present invention belongs, unless specifically defined and described otherwise. Terms generally used like those defined in a dictionary can have their meanings interpreted considering the meaning in the context of the related technology.

[0035] Also, the terms used in the embodiments of the present invention are for explaining the embodiments and are not intended to limit the present invention.

[0036] In this specification, the singular form can include the plural form unless specifically stated otherwise in the text. When described as "at least one (or one or more) of A and (or) B, C", it can include one or more of all combinations that can be combined with A, B, and C.

[0037] Also, in the description of the components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. can be used.

[0038] Such terms are merely for distinguishing the components from other components and are not limited to the essence, order, or sequence of the corresponding components by such terms.

[0039] When a component is described as being "connected", "coupled", or "joined" to another component, that component can be directly connected, coupled, or joined to the other component, or can also be "connected", "coupled", or "joined" by one or more additional components disposed between the component and the other component.

[0040] Also, when something is described as being formed or disposed "above or below" each component, above or below includes not only the case where two components are in direct contact with each other, but also the case where one or more additional components are formed or disposed between the two components. Also, when expressed as "above or below", it can include the meaning not only in the upward direction but also in the downward direction with respect to one component.

[0041] FIG. 1 is a cross-sectional view of a thermoelectric element, and FIG. 2 is a perspective view of the thermoelectric element. FIG. 3 is a perspective view of a thermoelectric element including a sealing member, and FIG. 4 is an exploded perspective view of a thermoelectric element including a sealing member.

[0042] Referring to FIGS. 1 to 2, the thermoelectric element 100 includes a lower substrate 110, a lower electrode 120, P-type thermoelectric legs 130, N-type thermoelectric legs 140, an upper electrode 150, and an upper substrate 160.

[0043] The lower electrode 120 is disposed between the lower substrate 110 and the lower bottom surfaces of the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140, and the upper electrode 150 is disposed between the upper substrate 160 and the upper bottom surfaces of the P-type thermoelectric legs 130 and the N-type thermoelectric legs 140. Accordingly, the plurality of P-type thermoelectric legs 130 and the plurality of N-type thermoelectric legs 140 are electrically connected by the lower electrode 120 and the upper electrode 150. A pair of P-type thermoelectric legs 130 and N-type thermoelectric legs 140 disposed between and electrically connected to the lower electrode 120 and the upper electrode 150 can form a unit cell.

[0044] For example, when a voltage is applied to the lower electrode 120 and the upper electrode 150 through the output lines (181, 182), a substrate in which current flows from the P-type thermoelectric leg 130 to the N-type thermoelectric leg 140 due to the Peltier effect absorbs heat and acts as a cooling part, and a substrate in which current flows from the N-type thermoelectric leg 140 to the P-type thermoelectric leg 130 can be heated and act as a heat generating part. Or when a temperature difference is applied between the lower electrode 120 and the upper electrode 150, charges in the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 may move due to the Seebeck effect, generating electricity.

[0045] Here, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be bismuth telluride (Bi-Te)-based thermoelectric legs containing bismuth (Bi) and tellurium (Te) as main raw materials. The P-type thermoelectric leg 130 can be a bismuth telluride (Bi-Te)-based thermoelectric leg containing at least one of antimony (Sb), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), tellurium (Te), bismuth (Bi), and indium (In). For example, the P-type thermoelectric leg 130 contains 99 to 99.999 wt% of Bi-Sb-Te, which is the main raw material substance, with respect to the total weight of 100 wt%, and can contain at least one of nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), and indium (In) at 0.001 to 1 wt%. The N-type thermoelectric leg 140 can be a bismuth telluride (Bi-Te)-based thermoelectric leg containing at least one of selenium (Se), nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), tellurium (Te), bismuth (Bi), and indium (In). For example, the N-type thermoelectric leg 140 contains 99 to 99.999 wt% of Bi-Se-Te, which is the main raw material substance, with respect to the total weight of 100 wt%, and can contain at least one of nickel (Ni), aluminum (Al), copper (Cu), silver (Ag), lead (Pb), boron (B), gallium (Ga), and indium (In) at 0.001 to 1 wt%.

[0046] Accordingly, in this specification, the thermoelectric leg may be referred to as a semiconductor structure, a semiconductor element, a semiconductor material layer, a semiconductor substance layer, a semiconductor material layer, a thermoelectric structure, a thermoelectric material layer, a thermoelectric substance layer, a thermoelectric material layer, a thermoelectric semiconductor structure, a thermoelectric semiconductor element, a thermoelectric semiconductor material layer, a thermoelectric semiconductor substance layer, a thermoelectric semiconductor material layer, etc.

[0047] The P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be formed in a bulk type or a laminated type. Generally, the bulk type P-type thermoelectric leg 130 or the bulk type N-type thermoelectric leg 140 can be obtained through a process of heat-treating a thermoelectric material to produce an ingot, crushing the ingot, sieving it to obtain powder for the thermoelectric leg, sintering this powder, and then cutting the sintered body. At this time, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be polycrystalline thermoelectric legs. For polycrystalline thermoelectric legs, when sintering the powder for the thermoelectric leg, it can be compressed at 100 MPa to 200 MPa. For example, when sintering the P-type thermoelectric leg 130, the powder for the thermoelectric leg can be sintered at 100 to 150 MPa, preferably 110 to 140 MPa, more preferably 120 to 130 MPa. And when sintering the N-type thermoelectric leg 130, the powder for the thermoelectric leg can be sintered at 150 to 200 MPa, preferably 160 to 195 MPa, more preferably 170 to 190 MPa. Thus, when the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 are polycrystalline thermoelectric legs, the strength of the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can be increased. The laminated type P-type thermoelectric leg 130 or the laminated type N-type thermoelectric leg 140 can be obtained through a process of applying a paste containing a thermoelectric material on a sheet-like substrate to form a unit member, and then laminating and cutting the unit members.

[0048] At this time, the pair of P-type thermoelectric legs 130 and N-type thermoelectric legs 140 can have the same shape and volume, or can have different shapes and volumes from each other. For example, since the electrical conduction characteristics of the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 are different, the height or cross-sectional area of the N-type thermoelectric leg 140 may be formed to be different from the height or cross-sectional area of the P-type thermoelectric leg 130.

[0049] At this time, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 can have a cylindrical shape, a polygonal prism shape, an elliptical column shape, or the like.

[0050] Alternatively, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 may have a laminated structure. For example, the P-type thermoelectric leg or the N-type thermoelectric leg can be formed by a method of laminating a plurality of structures in which a semiconductor material is applied to a sheet-like base material and then cutting this. Accordingly, material loss can be prevented and electrical conduction characteristics can be improved. Each structure can further include a conductive layer having an opening pattern, and accordingly, the adhesive force between the structures can be increased, the thermal conductivity can be lowered, and the electrical conductivity can be increased.

[0051] Alternatively, the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140 may be formed such that the cross-sectional area is different within one thermoelectric leg. For example, the cross-sectional areas of both end portions arranged so as to face the electrodes within one thermoelectric leg may be formed larger than the cross-sectional area between both end portions. According to this, since a large temperature difference can be formed between both end portions, the thermoelectric efficiency can be increased.

[0052] The performance of the thermoelectric element according to one embodiment of the present invention can be indicated by a thermoelectric performance index (figure of merit, ZT). The thermoelectric performance index ZT can be expressed as in Mathematical Formula 1.

[0053]

Equation

[0054] Here, α is the Seebeck coefficient [V / K], σ is the electrical conductivity [S / m], and α 2 σ is the power factor (Power Factor, [W / mK 2 ). And T is the temperature, and k is the thermal conductivity [W / mK]. k can be expressed as a·cp·ρ, where a is the thermal diffusivity [cm 2 / S], cp is the specific heat [J / gK], and ρ is the density [g / cm 3 .

[0055] In order to obtain the thermoelectric performance index of the thermoelectric element, a Z-meter can be used to measure the Z value (V / K), and the measured Z value can be used to calculate the thermoelectric performance index ZT.

[0056] Here, the lower electrode 120 disposed between the lower substrate 110 and the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140, and the upper electrode 150 disposed between the upper substrate 160 and the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 include at least one of copper (Cu), silver (Ag), aluminum (Al), and nickel (Ni), and can have a thickness of 0.01 mm to 0.3 mm. When the thickness of the lower electrode 120 or the upper electrode 150 is less than 0.01 mm, the function as an electrode may deteriorate and the electrical conduction performance may become low. When it exceeds 0.3 mm, the conduction efficiency may become low due to an increase in resistance.

[0057] And, the lower substrate 110 and the upper substrate 160 facing each other can be metal substrates, and their thickness can be 0.1 mm to 1.5 mm. When the thickness of the metal substrate is less than 0.1 mm or exceeds 1.5 mm, the heat dissipation characteristics or the thermal conductivity may become excessively high, so the reliability of the thermoelectric element may decrease. Also, when the lower substrate 110 and the upper substrate 160 are metal substrates, insulating layers 170 can be further formed between the lower substrate 110 and the lower electrode 120 and between the upper substrate 160 and the upper electrode 150, respectively. The insulating layer 170 can include a material having a thermal conductivity of 1 to 20 W / mK.

[0058] At this time, the lower substrate 110 and the upper substrate 160 may be formed to have different sizes. For example, one of the volume, thickness, or area of the lower substrate 110 and the upper substrate 160 may be formed larger than the other volume, thickness, or area. Accordingly, the heat absorption performance or heat dissipation performance of the thermoelectric element can be enhanced. Preferably, the volume, thickness, or area of the lower substrate 110 may be formed larger than at least one of the volume, thickness, or area of the upper substrate 160. At this time, when the lower substrate 110 is disposed in the high-temperature region due to the Seebeck effect, applied to the heat generation region due to the Peltier effect, or when a sealing member for protecting from the external environment of the thermoelectric module described later is disposed on the lower substrate 110, at least one of the volume, thickness, or area can be made larger than the upper substrate 160. At this time, the area of the lower substrate 110 can be formed in the range of 1.2 to 5 times the area of the upper substrate 160. When the area of the lower substrate 110 is formed to be less than 1.2 times that of the upper substrate 160, the influence on the improvement of the heat transfer efficiency is not high. When it exceeds 5 times, on the contrary, the heat transfer efficiency significantly drops, and it may be difficult to maintain the basic shape of the thermoelectric module.

[0059] Also, a heat dissipation pattern, for example, a concavo-convex pattern, may be formed on at least one surface of the lower substrate 110 and the upper substrate 160. Accordingly, the heat dissipation performance of the thermoelectric element can be enhanced. When the concavo-convex pattern is formed on the surface in contact with the P-type thermoelectric leg 130 or the N-type thermoelectric leg 140, the bonding characteristics between the thermoelectric leg and the substrate can also be improved. The thermoelectric element 100 includes a lower substrate 110, a lower electrode 120, a P-type thermoelectric leg 130, an N-type thermoelectric leg 140, an upper electrode 150, and an upper substrate 160.

[0060] As shown in FIGS. 3 to 4, a sealing member 190 may be further disposed between the lower substrate 110 and the upper substrate 160. The sealing member may be disposed on the side surfaces of the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150 between the lower substrate 110 and the upper substrate 160. Accordingly, the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150 can be sealed from external moisture, heat, contamination, etc. Here, the sealing member 190 includes a sealing case 192 disposed at a predetermined distance from the side surfaces of the outermost periphery of the plurality of lower electrodes 120, the outermost periphery of the plurality of P-type thermoelectric legs 130 and the plurality of N-type thermoelectric legs 140, and the outermost periphery of the plurality of upper electrodes 150, a sealing material 194 disposed between the sealing case 192 and the lower substrate 110, and a sealing material 196 disposed between the sealing case 192 and the upper substrate 160. In this way, the sealing case 192 can contact the lower substrate 110 and the upper substrate 160 through the sealing materials 194 and 196. Accordingly, when the sealing case 192 is in direct contact with the lower substrate 110 and the upper substrate 160, heat conduction occurs through the sealing case 192, and as a result, it is possible to prevent the problem that the temperature difference between the lower substrate 110 and the upper substrate 160 becomes low. Here, the sealing materials 194 and 196 may include at least one of an epoxy resin and a silicone resin, or may include a tape with at least one of an epoxy resin and a silicone resin coated on both sides. The sealing materials 194 and 194 serve to airtight the space between the sealing case 192 and the lower substrate 110 and between the sealing case 192 and the upper substrate 160, and can enhance the sealing effect of the lower electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the upper electrode 150, and can be mixed with a wall material, a finishing layer, a waterproof material, a waterproof layer, etc. Here, the sealing material 194 for sealing between the sealing case 192 and the lower substrate 110 may be disposed on the upper surface of the lower substrate 110, and the sealing material 196 for sealing between the sealing case 192 and the upper substrate 160 may be disposed on the side surface of the upper substrate 160. For this purpose, the area of the lower substrate 110 may be larger than the area of the upper substrate 160.On one hand, the sealing case 192 may be formed with guide grooves G for drawing out the outlet lines 180 and 182 connected to the electrodes. For this purpose, the sealing case 192 may be an injection molded product made of plastic or the like and may be used in combination with the sealing cover. However, the above description regarding the sealing member is merely illustrative, and the sealing member may be deformed into various forms. Although not shown, a heat insulating material may be further included so as to surround the sealing member. Or the sealing member may include a heat insulating component.

[0061] On one hand, the P-type thermoelectric leg 130 and the N-type thermoelectric leg 140 can have the structures illustrated in FIG. 1(a) or FIG. 1(b). Referring to FIG. 1(a), the thermoelectric legs 130 and 140 can include thermoelectric material layers 132 and 142, first plating layers 134-1 and 144-1 laminated on one surface of the thermoelectric material layers 132 and 142, and second plating layers 134-2 and 144-2 laminated on the other surface disposed opposite to one surface of the thermoelectric material layers 132 and 142. Or referring to FIG. 1(b), the thermoelectric legs 130 and 140 can include thermoelectric material layers 132 and 142, first plating layers 134-1 and 144-1 laminated on one surface of the thermoelectric material layers 132 and 142, second plating layers 134-2 and 144-2 laminated on the other surface disposed opposite to one surface of the thermoelectric material layers 132 and 142, first buffer layers 136-1 and 146-1 and second buffer layers 136-2 and 146-2 respectively disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1 and between the thermoelectric material layers 132 and 142 and the second plating layers 134-2 and 144-2. Or the thermoelectric legs 130 and 140 may further include metal layers laminated between the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 and the lower substrate 110 and the upper substrate 160 respectively.

[0062] Here, the thermoelectric material layers 132 and 142 can include bismuth (Bi) and tellurium (Te) which are semiconductor materials. The thermoelectric material layers 132 and 142 can have the same material or shape as the aforementioned P-type thermoelectric leg 130 or N-type thermoelectric leg 140. When the thermoelectric material layers 132 and 142 are polycrystalline, the bonding force between the thermoelectric material layers 132 and 142, the first buffer layers 136-1 and 146-1, and the first plating layers 134-1 and 144-1 and the bonding force between the thermoelectric material layers 132 and 142, the second buffer layers 136-2 and 146-2, and the second plating layers 134-2 and 144-2 can be increased. Along with this, even when the thermoelectric element 100 is applied to an application where vibration occurs, such as a vehicle, etc., the problem that the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 are detached from the P-type thermoelectric leg 130 or N-type thermoelectric leg 140 and carbonize can be prevented, and the durability and reliability of the thermoelectric element 100 can be enhanced.

[0063] And the metal layer can be selected from copper (Cu), copper alloy, aluminum (Al), and aluminum alloy, and can have a thickness of 0.1 to 0.5 mm, preferably 0.2 to 0.3 mm.

[0064] Next, the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 can each include at least one of Ni, Sn, Ti, Fe, Sb, Cr, and Mo, and can have a thickness of 1 to 20 μm, preferably 1 to 10 μm. The first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 can not only prevent the performance degradation of the thermoelectric element to prevent the reaction between the Bi or Te which is a semiconductor material in the thermoelectric material layers 132 and 142 and the metal layer, but also prevent the oxidation of the metal layer.

[0065] At this time, first buffer layers 136-1 and 146-1 and second buffer layers 136-2 and 146-2 may be disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1, and between the thermoelectric material layers 132 and 142 and the second plating layers 134-2 and 144-2. At this time, the first buffer layers 136-1 and 146-1 and the second buffer layers 136-2 and 146-2 can contain Te. For example, the first buffer layers 136-1 and 146-1 and the second buffer layers 136-2 and 146-2 can contain at least one of Ni-Te, Sn-Te, Ti-Te, Fe-Te, Sb-Te, Cr-Te, and Mo-Te. According to an embodiment of the present invention, when the first buffer layers 136-1 and 146-1 and the second buffer layers 136-2 and 146-2 containing Te are disposed between the thermoelectric material layers 132 and 142 and the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2, diffusion of Te in the thermoelectric material layers 132 and 142 into the first plating layers 134-1 and 144-1 and the second plating layers 134-2 and 144-2 can be prevented. Along with this, it is possible to prevent the problem that the electrical resistance in the thermoelectric material layer increases due to the Bi-rich region.

[0066] Although the terms lower substrate 110, lower electrode 120, upper electrode 150, and upper substrate 160 have been used above, this is merely an arbitrary reference to upper and lower for ease of understanding and convenience of explanation, and the positions may be reversed such that the lower substrate 110 and the lower electrode 120 are disposed above, and the upper electrode 150 and the upper substrate 160 are disposed below.

[0067] FIG. 5 is a cross-sectional view of a thermoelectric element according to an embodiment of the present invention, FIG. 6 is a cross-sectional view of a thermoelectric element according to another embodiment of the present invention, and FIG. 7 is a cross-sectional view of a thermoelectric element according to still another embodiment of the present invention. Redundant descriptions for the same content described in FIGS. 1 to 4 are omitted.

[0068] Referring to FIGS. 5 to 7, a thermoelectric element 300 according to an embodiment of the present invention includes a first substrate 310, a first insulating layer 320 disposed on the first substrate 310, a second insulating layer 330 disposed on the first insulating layer 320, a plurality of first electrodes 340 disposed on the second insulating layer 330, a plurality of P-type thermoelectric legs 350 and a plurality of N-type thermoelectric legs 355 disposed on the plurality of first electrodes 340, a plurality of second electrodes 360 disposed on the plurality of P-type thermoelectric legs 350 and the plurality of N-type thermoelectric legs 355, a third insulating layer 370 disposed on the plurality of second electrodes 360, and a second substrate 380 disposed on the third insulating layer 370. Although not shown, a heat sink may be further disposed on the first substrate 310 or the second substrate 380. Although not shown, a sealing member may be further disposed between the first substrate 310 and the second substrate 380. Although not shown, a power source may be connected to the first electrode 340 or the second electrode 360, and a wire may be drawn out through the insulating layer and the substrate, or may be drawn out from the side on the substrate and the insulating layer.

[0069] Here, the first electrode 340, the P-type thermoelectric leg 350, the N-type thermoelectric leg 360, and the second electrode 370 may respectively correspond to the upper electrode 120, the P-type thermoelectric leg 130, the N-type thermoelectric leg 140, and the lower electrode 150 described in FIGS. 1 to 2, and the contents described in FIGS. 1 to 2 may be applied so as to be the same or similar.

[0070] Here, at least one of the first substrate 310 and the second substrate 380 may be made of at least one of aluminum, an aluminum alloy, copper, and a copper alloy. The first substrate 310 and the second substrate 380 may be made of different materials. For example, among the first substrate 310 and the second substrate 320, the substrate that requires more withstand voltage performance may be made of an aluminum substrate, and the substrate that requires more heat conduction performance may be made of a copper substrate.

[0071] The withstand voltage performance according to an embodiment of the present invention may mean the characteristic of being maintained without breakdown for 10 seconds under a voltage of AC2.5 kV and a current of 1 mA. In this specification, the withstand voltage performance is measured by a method in which, after arranging an insulating layer on a substrate, one terminal is connected to the substrate, and the other terminals are respectively connected to nine points of the insulating layer, and it is tested whether it can be maintained without breakdown for 10 seconds under a voltage of AC2.5 kV and a current of 1 mA.

[0072] On the other hand, according to an embodiment of the present invention, two layers of insulating layers may be arranged between the first substrate 310 and the first electrode 340. That is, the first insulating layer 320 may be arranged on the first substrate 310, the second insulating layer 330 may be arranged on the first insulating layer 320, and the first electrode 340 may be arranged on the second insulating layer 330. At this time, one surface of the first insulating layer 320 may be in direct contact with the first substrate 310, and the other surface of the first insulating layer 320 may be in direct contact with the second insulating layer 330. And the second insulating layer 330 may be in direct contact with the first electrode 340.

[0073] Here, the first insulating layer 320 and the second insulating layer 330 may have different compositions and elasticities from each other. That is, the first insulating layer 320 may be composed of a composition having insulating performance and heat conduction performance, and the second insulating layer 330 may be composed of a composition having insulating performance, heat conduction performance, adhesion performance, and thermal shock relaxation performance. Also, although both the first insulating layer 320 and the second insulating layer 330 have insulating performance and heat conduction performance, the withstand voltage performance of the first insulating layer 320 may be higher than that of the second insulating layer 330, and the heat conduction performance of the second insulating layer 330 may be higher than that of the first insulating layer 320. Here, the fact that the withstand voltage performance is relatively high may mean that it is maintained without breakdown for a relatively long time under a voltage of AC2.5 kV and a current of 1 mA.

[0074] For this purpose, the first insulating layer 320 can include a composite containing silicon and aluminum. Here, the composite can be at least one of oxides, carbides, and nitrides containing silicon and aluminum. For example, the composite can include at least one of Al - Si bonds, Al - O - Si bonds, Si - O bonds, Al - Si - O bonds, and Al - O bonds. Thus, a composite containing at least one of Al - Si bonds, Al - O - Si bonds, Si - O bonds, Al - Si - O bonds, and Al - O bonds has excellent insulating performance, and accordingly, high breakdown voltage performance can be obtained. Or the composite can be an oxide, carbide, or nitride that further contains titanium, zirconium, boron, zinc, etc. together with silicon and aluminum. For this purpose, the composite can be obtained through a process of mixing at least one of an inorganic binder and an organic / inorganic hybrid binder with aluminum and then performing heat treatment. The inorganic binder can include, for example, at least one of silica (SiO2), metal alkoxides, boron oxide (B2O3), and zinc oxide (ZnO2). Although the inorganic binder is an inorganic particle, it can be sol - or gel - formed when in contact with water and play a binding role. At this time, at least one of silica (SiO2), metal alkoxides, and boron oxide (B2O3) can play a role in enhancing the adhesion between aluminums or the adhesion with the first substrate 310, and zinc oxide (ZnO2) can play a role in enhancing the strength and thermal conductivity of the first insulating layer 320.

[0075] Here, the composite can be contained at 80 wt% or more, preferably 85 wt% or more, and more preferably 90 wt% or more of the entire first insulating layer 320.

[0076] At this time, the first insulating layer 320 may include uneven portions. For example, a surface roughness (Ra) of 0.1 μm or more may be formed on the first insulating layer 320. The surface roughness may be formed by particles forming a composite protruding from the surface of the first insulating layer 320 and may be measured using a surface roughness measuring machine. The surface roughness measuring machine can measure a cross-sectional curve using a probe and calculate the surface roughness using the peak line, valley line, average line, and reference length of the cross-sectional curve. In this specification, the surface roughness may mean the arithmetic mean roughness (Ra) by the center line average calculation method. The arithmetic mean roughness (Ra) can be obtained through the following mathematical formula 2.

[0077]

Number

[0078] That is, when a cross-sectional curve obtained by the probe of the surface roughness measuring machine is extracted by a reference length L, with the average line direction as the x-axis and the height direction as the y-axis and expressed by a function (f(x)), the value obtained by Mathematical formula 2 can be expressed in μm meters.

[0079] At this time, the uneven portions of the first insulating layer 320 may be formed on the surface of the first insulating layer 320 that contacts the second insulating layer 330 among both surfaces of the first insulating layer 320. Thus, when the surface roughness (Ra) of the first insulating layer 320 is 0.1 μm or more, the contact area with the second insulating layer 330 becomes wider, and accordingly, the bonding strength with the second insulating layer 330 may increase. In particular, as will be described later, when the second insulating layer 330 is made of a resin layer, since the resin layer of the second insulating layer 330 easily infiltrates into the grooves formed by the surface roughness of the first insulating layer 320, the bonding strength between the first insulating layer 320 and the second insulating layer 330 may be further increased.

[0080] At this time, the first insulating layer 320 may be formed on the first substrate 310 through a wet process. Here, the wet process may be a spray coating process, a dip coating process, a screen printing process, or the like. According to this, it is easy to control the thickness of the first insulating layer 320, and it is possible to apply composites of various compositions.

[0081] According to an embodiment of the present invention, the first insulating layer 320 is made of a composite containing silicon and aluminum, and since it is formed by a wet process, the surface roughness can be formed to be 0.1 μm or more. FIGS. 8(a) to 8(c) are graphs showing the measurement of the surface roughness of three samples in which the first insulating layer 320 is formed according to an embodiment of the present invention on an aluminum substrate, and FIGS. 9(a) to 9(c) are graphs showing the measurement of the surface roughness of three samples in which the aluminum substrate is anodized. Referring to FIGS. 8(a) to 8(c) and FIGS. 9(a) to 9(c), it can be seen that the surface roughness of the first insulating layer according to the embodiment of the present invention can be formed to be 0.1 μm or more.

[0082] On the other hand, the second insulating layer 330 may be composed of a resin layer containing at least one of an epoxy resin composition containing an epoxy resin and an inorganic filler and a silicone resin composition containing PDMS (polydimethylsiloxane). Accordingly, the second insulating layer 330 can improve the insulation, bonding force, and heat conduction performance between the first insulating layer 320 and the first electrode 340.

[0083] Here, the inorganic filler may be contained in the resin layer at 60 to 80 wt%. If the inorganic filler is contained less than 60 wt%, the heat conduction effect may be low, and if the inorganic filler is contained in excess of 80 wt%, it is difficult for the inorganic filler to be uniformly dispersed in the resin, and the resin layer may be easily broken.

[0084] And the epoxy resin can contain an epoxy compound and a curing agent. At this time, the curing agent can be contained in a volume ratio of 1 to 10 with respect to 10 volumes of the epoxy compound. Here, the epoxy compound can contain at least one of a crystalline epoxy compound, an amorphous epoxy compound, and a silicone epoxy compound. The inorganic filler can contain at least one of aluminum oxide and nitride. When the inorganic filler contains nitride, the nitride can be contained in 55 to 95 wt% of the inorganic filler, and more preferably 60 to 80 wt%. When the nitride is contained within such a numerical range, the thermal conductivity and the bonding strength can be increased. Here, the nitride can contain at least one of boron nitride and aluminum nitride.

[0085] At this time, the particle size D50 of the boron nitride aggregate particles is 250 to 350 μm, and the particle size D50 of the aluminum oxide particles can be 10 to 30 μm. When the particle size D50 of the boron nitride aggregate particles and the particle size D50 of the aluminum oxide particles satisfy such a numerical range, the boron nitride aggregate and the aluminum oxide can be uniformly dispersed in the resin layer, and accordingly, the resin layer can have an overall uniform thermal conduction effect and adhesion performance.

[0086] When the second insulating layer 330 is a resin composition containing PDMS (polydimethylsiloxane) resin and aluminum oxide, the content (for example, weight ratio) of silicon in the first insulating layer 320 is higher than the content of silicon in the second insulating layer 330, and the content of aluminum in the second insulating layer 330 can be higher than the content of aluminum in the first insulating layer 320. According to this, the silicon in the first insulating layer 320 can mainly contribute to the improvement of the breakdown voltage performance, and the aluminum oxide in the second insulating layer 330 can mainly contribute to the improvement of the thermal conduction performance. Accordingly, although both the first insulating layer 320 and the second insulating layer 330 have insulating performance and thermal conduction performance, the breakdown voltage performance of the first insulating layer 320 may be higher than the breakdown voltage performance of the second insulating layer 330, and the thermal conduction performance of the second insulating layer 330 may be higher than the thermal conduction performance of the first insulating layer 320.

[0087] On the other hand, the second insulating layer 330 can be formed by applying a resin composition in an uncured state or a semi-cured state onto the first insulating layer 320 and then arranging and pressing a plurality of pre-aligned first electrodes 340. According to this, since the resin composition forming the second insulating layer 330 soaks into the grooves due to the surface roughness (Ra) of the first insulating layer 320, the bonding strength between the first insulating layer 320 and the second insulating layer 330 can be increased. Also, a part of the side surfaces of the plurality of first electrodes 340 can be embedded in the second insulating layer 330. At this time, the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second resin layer 330 can be 0.1 to 1.0 times, preferably 0.2 to 0.9 times, and more preferably 0.3 to 0.8 times the thickness H of the plurality of first electrodes 340. Thus, when a part of the side surfaces of the plurality of first electrodes 340 are embedded in the second insulating layer 330, the contact area between the plurality of first electrodes 340 and the second insulating layer 330 becomes wider, and accordingly, the heat transfer performance and the bonding strength between the plurality of first electrodes 340 and the second insulating layer 330 can be further increased. When the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second insulating layer 330 is less than 0.1 times the thickness H of the plurality of first electrodes 340, it may be difficult to sufficiently obtain the heat transfer performance and the bonding strength between the plurality of first electrodes 340 and the second insulating layer 330. When the height H1 of the side surfaces of the plurality of first electrodes 340 embedded in the second insulating layer 330 exceeds 1.0 times the thickness H of the plurality of first electrodes 340, the second insulating layer 330 may rise above the plurality of first electrodes 340, and accordingly, there is a possibility of electrical short circuit.

[0088] More specifically, the second insulating layer 330 may include a recess recessed from the side surface of the first electrode 340 toward the first electrode 320. At this time, the recess is disposed between two adjacent first electrodes 340, and the thickness of the second insulating layer 330 may decrease from the side surfaces of the two adjacent first electrodes 340 toward the central region between the two adjacent first electrodes 340. That is, the thickness of the second insulating layer 330 between the plurality of first electrodes 340 may decrease from the side surfaces of the respective electrodes toward the central region and have a smooth "V" shape at the apex. Therefore, the second insulating layer 330 between the plurality of first electrodes 340 has a thickness deviation, and the height T2 in the region in direct contact with the side surfaces of the plurality of first electrodes 340 is the highest, and the height T3 in the central region may be lower than the height T2 in the region in direct contact with the side surfaces of the plurality of first electrodes 340. That is, the height T3 of the central region of the second insulating layer 330 between the plurality of first electrodes 340 may be the lowest within the second insulating layer 330 between the plurality of first electrodes 340. Also, the height T1 of the second insulating layer 330 under the plurality of first electrodes 340 may be lower than the height T3 of the central region of the second insulating layer 330 between the plurality of first electrodes 340. According to this, since the second insulating layer 330 can be disposed not only on the lower surface but also on the side surfaces of the first electrodes 340, the contact area between the first electrodes 340 and the second insulating layer 330 can be increased, and the bonding force and heat transfer performance between the first electrodes 340 and the second insulating layer 330 can be improved. At this time, the recess of the second insulating layer 330 may overlap perpendicularly with the uneven portions of the first insulating layer 320, and the recess of the second insulating layer 330 may be formed on the opposite surface of the two surfaces of the second insulating layer 330 that is joined to the uneven portions of the first insulating layer 320. According to this, since uneven portions corresponding to the uneven portions of the first insulating layer 320 can also be formed on the surface of the two surfaces of the second insulating layer 330 that is joined to the uneven portions of the first insulating layer 320, the bonding force and heat transfer performance between the first insulating layer 320 and the second insulating layer 330 can be improved.

[0089] On the one hand, due to the compositions of the first insulating layer 320 and the second insulating layer 330, at least one of the hardness, elastic modulus, elongation, and Young's modulus of the first insulating layer 320 and the second insulating layer 330 can be changed. Accordingly, it is possible to control the withstand voltage performance, heat conduction performance, bonding performance, heat shock mitigation performance, and the like.

[0090] For example, the weight ratio of the composite with respect to the entire first insulating layer 320 may be higher than the weight ratio of the inorganic filler with respect to the entire second insulating layer 330. As described above, the composite may be a composite containing silicon and aluminum, and more specifically, a composite containing at least one of oxides, carbides, and nitrides containing silicon and aluminum. For example, the weight ratio of the composite with respect to the entire first insulating layer 320 may exceed 80 wt%, and the weight ratio of the inorganic filler with respect to the entire second insulating layer 320 may be 60 to 80 wt%. Thus, when the content of the composite contained in the first insulating layer 320 is higher than the content of the ceramic particles contained in the second insulating layer 330, the hardness of the first insulating layer 320 may be higher than the hardness of the second insulating layer 330. Accordingly, the first insulating layer 320 can simultaneously have high withstand voltage performance and high heat conduction performance.

[0091] Accordingly, the second insulating layer 330 can have higher elasticity than the first insulating layer 320. Accordingly, the second insulating layer 330 can enhance the adhesion performance between the first insulating layer 320 and the first electrode 340, and can mitigate the heat shock during the driving of the thermoelectric element 300. At this time, the elasticity can be indicated by the tensile strength. For example, the tensile strength of the second insulating layer 330 may be 2 to 5 MPa, preferably 2.5 to 4.5 MPa, more preferably 3 to 4 MPa, and the tensile strength of the first insulating layer 320 may be 10 MPa to 100 Mpa, preferably 15 MPa to 90 MPa, more preferably 20 MPa to 80 MPa.

[0092] At this time, the thickness of the first insulating layer 320 is 20 to 35 μm, and the thickness of the second insulating layer 330 can be 20 to 70 μm, preferably 30 to 60 μm, and more preferably 35 to 50 μm. At this time, the thickness of the second insulating layer 330 can be 1 to 3.5 times, preferably 1 to 3 times, and more preferably 1 to 2 times the thickness of the first insulating layer 320.

[0093] When the thicknesses of the first insulating layer 320 and the second insulating layer 330 satisfy such numerical ranges respectively, it is possible to obtain breakdown voltage performance, heat conduction performance, bonding performance, and thermal shock mitigation performance simultaneously. In particular, if the thickness of the first insulating layer 320 is less than 20 μm, it is difficult to obtain high breakdown voltage performance, and it is easily broken due to the thermal expansion of the second insulating layer 330. If it exceeds 35 μm, the heat conduction performance may decrease.

[0094] On the other hand, the insulating layer 370 disposed on the second substrate 380 side can also have the same structure as the insulating layers 320 and 330 disposed on the first substrate 310 side. That is, the insulating layer 370 disposed on the second substrate 380 side can include a third insulating layer 372 made of a resin layer containing at least one of an epoxy resin composition and a silicone resin composition and a fourth insulating layer 374 made of a composite containing silicon and aluminum.

[0095] At this time, the fourth insulating layer 374 is in direct contact with the second substrate 380, and the third insulating layer 372 can be disposed between the fourth insulating layer 374 and the second electrode 360. The specific description regarding the third insulating layer 372 can be applied in the same way as the description regarding the second insulating layer 330, and the specific description regarding the fourth insulating layer 374 can be applied in the same way as the description regarding the first insulating layer 320.

[0096] Alternatively, the third insulating layer 372 may be composed of a resin layer containing at least one of an epoxy resin composition and a silicone resin composition, and the fourth insulating layer 374 may also be composed of a resin layer containing at least one of an epoxy resin composition and a silicone resin composition. At this time, the resin layer forming the third insulating layer 372 and the resin layer forming the fourth insulating layer 374 may have the same composition or different compositions. Here, different compositions may mean that at least one of the resin type, resin content, inorganic filler type, and inorganic filler content is different.

[0097] On the other hand, since a power source is generally connected to the electrode disposed on the low-temperature part side of the thermoelectric element 300, higher withstand voltage performance may be required on the low-temperature part side than on the high-temperature part side. On the contrary, when the thermoelectric element 300 is driven, the high-temperature part side of the thermoelectric element 300 may be exposed to a high temperature, for example, about 180 °C or higher, and peeling between the electrode, the insulating layer, and the substrate may become a problem due to the different thermal expansion coefficients of the electrode, the insulating layer, and the substrate. Accordingly, higher thermal shock mitigation performance may be required on the high-temperature part side of the thermoelectric element 300 than on the low-temperature part side. Accordingly, the structure of the high-temperature part side insulating layer and the structure of the low-temperature part side insulating layer may be made different.

[0098] Hereinafter, it will be described on the assumption that the first substrate 310 is disposed on the low-temperature part side of the thermoelectric element 300 and the second substrate 380 is disposed on the high-temperature part side of the thermoelectric element 300.

[0099] Referring to FIG. 6, the thickness of the fourth insulating layer 374 on the second substrate 380 side may be smaller than the thickness of the first insulating layer 320 on the first substrate 310 side, and the thickness of the third insulating layer 372 on the second substrate 380 side may be larger than the thickness of the second insulating layer 330 on the first substrate 310 side. Or referring to FIG. 7, although the insulating layer on the first substrate 310 side is composed of the first insulating layer 320 and the second insulating layer 330, the insulating layer 370 on the second substrate 380 side may be composed only of a resin layer containing at least one of an epoxy resin composition and a silicone resin composition.

[0100] Accordingly, the thermal shock mitigation performance on the high-temperature part side can be enhanced, and the possibility of peeling that may occur due to the difference in the coefficient of thermal expansion between the substrate and the electrode on the high-temperature part side can be minimized.

[0101] The thermoelectric element according to an embodiment of the present invention can be applied to power generation devices, cooling devices, heating devices, etc. Specifically, the thermoelectric element according to an embodiment of the present invention can be mainly applied to optical communication modules, sensors, medical devices, measuring devices, the aerospace industry, refrigerators, chillers, automotive ventilation seats, cup holders, washing machines, dryers, wine cellars, water purifiers, power supply devices for sensors, thermopiles, etc.

[0102] Here, as an example of applying the thermoelectric element according to an embodiment of the present invention to a medical device, there is a PCR (Polymerase Chain Reaction) device. The PCR device is equipment for amplifying DNA to determine the base sequence of DNA, and requires precise temperature control and a thermal cycle. For this purpose, a thermoelectric element of a Peltier substrate can be applied.

[0103] As another example of applying the thermoelectric element according to an embodiment of the present invention to a medical device, there is a photodetector. Here, the photodetector includes an infrared / ultraviolet detector, a CCD (Charge Coupled Device) sensor, an X-ray detector, a TTRS (Thermoelectric Thermal Reference Source), etc. A thermoelectric element of a Peltier substrate can be applied for cooling the photodetector. Accordingly, it is possible to prevent wavelength changes, output reduction, and resolution reduction due to temperature rise inside the photodetector.

[0104] As yet another example of the application of the thermoelectric element according to an embodiment of the present invention to a medical device, there are the fields of immunoassay, in vitro diagnostics, general temperature control and cooling systems, physical therapy, liquid chiller systems, blood / plasma temperature control, and the like. Along with this, precise temperature control is possible.

[0105] As yet another example of the application of the thermoelectric element according to an embodiment of the present invention to a medical device, there is an artificial heart. Along with this, it is possible to supply power to the artificial heart.

[0106] Examples of the application of the thermoelectric element according to an embodiment of the present invention to the aerospace industry include a star tracking system, a thermal imaging camera, an infrared / ultraviolet detector, a CCD sensor, the Hubble Space Telescope, the TTRS, and the like. Along with this, it is possible to maintain the temperature of the image sensor.

[0107] As other examples of the application of the thermoelectric element according to an embodiment of the present invention to the aerospace industry, there are a cooling device, a heater, a power generation device, and the like.

[0108] In addition to this, the thermoelectric element according to an embodiment of the present invention can be applied for power generation, cooling, and heating in other industrial fields.

[0109] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the relevant art that the present invention can be variously modified and changed without departing from the spirit and scope of the present invention described in the following claims.

Claims

1. A substrate, a first insulating layer disposed on the substrate, a second insulating layer disposed on the first insulating layer, an electrode disposed on the second insulating layer, and a semiconductor structure disposed on the electrode, wherein an upper surface of the second insulating layer includes a first recess where the electrode is disposed and a second recess disposed around the first recess and recessed in a direction toward the substrate, a height between a lower surface of the second recess and the substrate is greater than a height between a lower surface of the first recess and the substrate, a thickness of the second insulating layer is greater than a thickness of the first insulating layer, the first insulating layer is made of a composite including silicon and aluminum, the second insulating layer includes an epoxy resin composition including an epoxy resin and an inorganic filler, the second recess includes a region where a height with respect to an upper surface of the substrate decreases as the distance from a side surface of the electrode increases, a concavo-convex pattern is disposed on an upper surface of the first insulating layer, and the second recess overlaps the concavo-convex pattern perpendicularly, a thermoelectric element.

2. The thermoelectric element according to claim 1, wherein a part of the electrode is buried in the first recess.

3. A side surface of the electrode includes a first surface that contacts the first recess of the second insulating layer, the thermoelectric element according to claim 2, wherein a height of the first surface is 0.1 to 0.9 times a thickness of the electrode.

4. The thermoelectric element according to claim 2, wherein a maximum height of the electrode is higher than a maximum height of the second insulating layer with respect to the substrate.

5. The thermoelectric element according to claim 1, wherein a lower surface of the second insulating layer includes a concavo-convex pattern corresponding to the concavo-convex pattern on the upper surface of the first insulating layer.

6. an upper electrode disposed on the semiconductor structure, a third insulating layer disposed on the upper electrode, and an upper substrate disposed on the third insulating layer, the thermoelectric element according to claim 1.

7. The thermoelectric element according to claim 6, wherein a thickness of the third insulating layer is greater than a thickness of the second insulating layer.

8. The thermoelectric element according to claim 6, wherein the second recess overlaps the upper electrode perpendicularly.

9. A first substrate, a first insulating layer disposed on the first substrate, a second insulating layer disposed on the first insulating layer, a first electrode disposed on the second insulating layer, a semiconductor structure disposed on the first electrode, a second electrode disposed on the semiconductor structure, a third insulating layer disposed on the second electrode, and a second substrate disposed on the third insulating layer, The upper surface of the second insulating layer includes a first recess in which the first electrode is disposed, and a second recess that is disposed around the first recess and recessed in a direction toward the first substrate. The third insulating layer includes a third recess in which the second electrode is disposed. The third recess of the third insulating layer perpendicularly overlaps with the first recess of the second insulating layer and a part of the second recess of the second insulating layer. The thickness of the third insulating layer is greater than the thickness of the first insulating layer. The first insulating layer is made of a composite including silicon and aluminum. The second insulating layer includes an epoxy resin composition including an epoxy resin and an inorganic filler. The second recess includes a region where the height with respect to the upper surface of the first substrate decreases as the distance from the side surface of the first electrode increases. A concavo-convex pattern is disposed on the upper surface of the first insulating layer, and the second recess perpendicularly overlaps with the concavo-convex pattern. A thermoelectric element.

10. The side surface of the first electrode includes a first surface that contacts the first recess of the second insulating layer. The thermoelectric element according to claim 9, wherein the height of the first surface is 0.1 to 0.9 times the thickness of the first electrode.

11. The thermoelectric element according to claim 9, wherein the maximum height of the first electrode is higher than the maximum height of the second insulating layer with respect to the first substrate.

12. The thermoelectric element according to claim 11, wherein the height between the lower surface of the second recess and the first substrate is greater than the height between the lower surface of the first recess and the first substrate.

13. The first recess of the second insulating layer includes a side surface that contacts the side surface of the first electrode. The thermoelectric element according to claim 12, wherein the lower surface of the first recess of the second insulating layer corresponds to the lower surface of the first electrode.

14. The second recess is disposed between two first recesses so as to be spaced apart from each other and includes a curved surface having a curvature, and The thermoelectric element according to claim 13, wherein a region including the center between the side surfaces of the two first recesses includes a region of the curved surface that is closest to the first substrate.

15. The thermoelectric element according to claim 9, wherein the thickness of the third insulating layer is greater than the thickness of the second insulating layer.

16. Further includes a fourth insulating layer disposed between the third insulating layer and the second substrate. The thermoelectric element according to claim 9, wherein the thickness of the third insulating layer is greater than the thicknesses of the first insulating layer, the second insulating layer, and the fourth insulating layer, respectively.

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