Thin-film thermoelectric refrigerating unit and preparation method of thin-film thermoelectric refrigerating unit

Abstract

The invention provides a thin-film thermoelectric refrigerating unit. Comprising a substrate, a P-type thermoelectric unit, an N-type thermoelectric unit, a first electrode and a second electrode, and the substrate is provided with a hollow area; the P-type thermoelectric units and the N-type thermoelectric units are stacked on one side of the substrate in the direction perpendicular to the substrate to form a thermocouple pair; the cold ends of the thermocouple pair are connected through a first electrode; the hot end of the thermocouple pair is connected with the second electrode; the cold ends of the thermocouple pairs are distributed in an area of the thin-film thermoelectric refrigerating unit in a concentrated mode to form a cold load thin-film area, and the cold ends of the thermocouple pairs and part of thermocouple arms connected with the cold ends are located in the hollow-out area of the substrate. The efficiency of thermoelectric conversion is improved by combining the layout of the stacked thermocouple pair and the substrate hollowing technology and distributing the cold ends in a relatively concentrated area. The refrigerating capacity of the horizontal thin film thermoelectric device is improved, and efficient heat dissipation is achieved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a thin film thermoelectric cooler and a method for preparing the thin film thermoelectric cooler. Background Art

[0002] As microelectronic and optoelectronic devices develop towards smaller size, higher integration and lower power consumption, new challenges are posed to the thermal management of micro low-power devices such as photoelectric emitters. In order to effectively solve the heat dissipation problem of such devices, thin-film thermoelectric devices have attracted widespread attention due to their lightness, high efficiency and integrability. Thin-film thermoelectric devices are mainly divided into two types: horizontal and vertical according to their structural characteristics.

[0003] Among them, the thermocouple arm of the horizontal thin-film thermoelectric device extends in the horizontal direction. This structure makes the cold end and hot end of the thermocouple arm located on both sides of the film respectively. The thermocouple arm of the horizontal thin-film thermoelectric device is closely attached to the substrate, and the cold end and hot end are located on both sides of the thermocouple arm, making the lower substrate one of the main paths of heat conduction, introducing the problem of thermal bypass. This thermal bypass phenomenon significantly weakens the actual cooling effect of the thermoelectric cooling device and reduces the output power.

[0004] Therefore, how to improve the cooling capacity of horizontal thin-film thermoelectric devices and achieve efficient heat dissipation is a key issue that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present application provides a thin film thermoelectric cooler and a method for preparing the thin film thermoelectric cooler, aiming to improve the cooling capacity of horizontal thin film thermoelectric devices and achieve efficient heat dissipation.

[0006] In a first aspect, the present application provides a thin film thermoelectric cooler, comprising a substrate, a P-type thermoelectric unit, an N-type thermoelectric unit, a first electrode and a second electrode, wherein the substrate is provided with a hollow area;

[0007] On one side of the substrate, along a direction perpendicular to the substrate, the P-type thermoelectric unit and the N-type thermoelectric unit are stacked to form a thermocouple pair; the cold end of the thermocouple pair is connected through the first electrode; and the hot end of the thermocouple pair is connected to the second electrode;

[0008] The cold ends of the multiple thermocouple pairs are concentrated in an area of ​​the thin film thermoelectric cooler to form a cold load thin film area, and the cold ends of the multiple thermocouple pairs and part of the thermocouple arms connected to the cold ends are located in the hollow area of ​​the substrate.

[0009] Optionally, the base is provided with a hollow area including an annular hollow section; the annular hollow section is provided with a plurality of concentrically arranged annular gaps, a plurality of radially distributed strip gaps, or a combination of a plurality of concentrically arranged annular gaps and a plurality of radially distributed strip gaps.

[0010] Optionally, the cold load film area is located at a central position of the thin film thermoelectric cooler.

[0011] Optionally, the cold load film area includes one of a rectangle, a circle and a complex polygon.

[0012] Optionally, the material of the P-type thermoelectric unit and the thermoelectric material of the N-type thermoelectric unit are any one or more of bismuth telluride-based binary or ternary material, antimony telluride-based binary or ternary material, lead telluride-based binary or ternary material, tin selenide-based binary or ternary material, magnesium-based binary or ternary material, tellurium-based binary or ternary material, tin-based binary or ternary material, germanium-silicon alloy material, semi-Heusler alloy, graphene, skutterudite or filled skutterudite material.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a thin film thermoelectric cooler, the method comprising:

[0014] providing a substrate;

[0015] Depositing a first insulating layer, a P-type thermoelectric unit layer, a second insulating layer and an N-type thermoelectric unit layer in sequence on one side of the substrate in a direction perpendicular to the substrate to obtain a multi-layered thermoelectric film;

[0016] Thermocouple arms are prepared on the multi-layered thermoelectric film by etching to obtain thermocouple pairs and cold load film areas of the multi-layered structure; one end of a plurality of thermocouple pairs is concentratedly distributed in an area of ​​the thin film thermoelectric cooler;

[0017] Using a vacuum coating method, one end of a thermocouple pair concentrated in an area of ​​the thin film thermoelectric cooler is connected through a first electrode to form a cold end; and the other end of the thermocouple pair is connected to a second electrode to form a hot end;

[0018] A portion of the substrate is removed by using an etchant to form a hollow area on the substrate.

[0019] Optionally, the step of preparing thermocouple arms on the multi-layered thermoelectric film by etching to obtain a multi-layered thermocouple pair includes:

[0020] Coating a photoresist on the multi-layered thermoelectric film, and forming a pattern on the photoresist by a photolithography process, in which one end of a plurality of thermocouple pairs is concentratedly distributed in an area of ​​the thin film thermoelectric cooler;

[0021] Based on the pattern, a plurality of thermocouple arms are etched on the multi-layered thermoelectric film by using a photolithography and etching process to obtain a multi-layered thermocouple pair.

[0022] Optionally, the cold load film zone is prepared by:

[0023] depositing a third insulating layer on the thermocouple pair of the multilayer structure;

[0024] The third insulating layer is patterned by photolithography and etching process to obtain a cold load film area.

[0025] Optionally, the deposition method is any one or more of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, sol-gel method, pulsed laser deposition and atomic layer deposition.

[0026] Optionally, the corrosive agent includes any one or more of tetramethylammonium hydroxide, ethylenediamine pyrrolidone, a mixed solution of nitric acid and hydrogen peroxide, a mixed solution of sulfuric acid and hydrogen peroxide, potassium hydroxide, sodium hydroxide and xenon fluoride.

[0027] The present application provides a thin film thermoelectric cooler. It includes a substrate, a P-type thermoelectric unit, an N-type thermoelectric unit, a first electrode and a second electrode, and the substrate is provided with a hollow area; on one side of the substrate perpendicular to the substrate direction, the P-type thermoelectric unit and the N-type thermoelectric unit are stacked to form a thermocouple pair; the cold end of the thermocouple pair is connected through the first electrode; the hot end of the thermocouple pair is connected to the second electrode; the cold ends of multiple thermocouple pairs are concentrated in an area of ​​the thin film thermoelectric cooler to form a cold load thin film area, and the cold ends of multiple thermocouple pairs and part of the thermocouple arms connected to the cold ends are located in the hollow area of ​​the substrate. In this way, by stacking the P-type and N-type thermoelectric units instead of arranging them side by side, the number of thermocouple pairs per unit area is significantly increased, and then by setting a hollow area on the substrate, part of the thermocouple arms and the cold end are not in contact with the substrate to eliminate thermal bypass, and the cold end is distributed in a relatively concentrated area, and the synergistic effect of multiple thermocouples on the cold end effectively absorbs heat from the surrounding environment, thereby improving the efficiency of thermoelectric conversion. In this way, the cooling capacity of the horizontal thin-film thermoelectric device can be improved and efficient heat dissipation can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of a thin film thermoelectric cooler in the related art;

[0030] Figure 2 A schematic diagram of the structure of another thin-film thermoelectric cooler provided in an embodiment of the present application;

[0031] Figure 3 yes Figure 2 A schematic cross-sectional view along the A-A' direction;

[0032] Figure 4a-4d A schematic diagram of a hollowed-out substrate provided in an embodiment of the present application;

[0033] Figure 5a-5c A schematic diagram of cold end concentration provided in an embodiment of the present application;

[0034] Figure 6a-6c A schematic diagram of a cold load film area provided in an embodiment of the present application;

[0035] Figure 7 A flow chart of a method for preparing a thin film thermoelectric cooler provided in an embodiment of the present application;

[0036] Figure 8 A schematic diagram of the structure of a thin film thermoelectric cooler preparation process provided in an embodiment of the present application;

[0037] Fig. 9 A schematic diagram of the structure of a "U"-shaped horizontal thin-film thermoelectric cooling device and its thermocouple arm provided in an embodiment of the present application;

[0038] Fig.10 A schematic diagram of the temperature distribution of a "U"-shaped horizontal thin-film thermoelectric cooling device provided in an embodiment of the present application;

[0039] Among them, 1, substrate; 11, annular hollow section; 12, cavity; 101, annular gap; 102, strip gap; 2, thermocouple arm; 21, P-type thermoelectric unit; 22, N-type thermoelectric unit; 23, silicon oxide insulating layer; 24, silicon nitride insulating layer; 3, metal electrode; 4, cold load film area. DETAILED DESCRIPTION

[0040] Figure 1 FIG. 1 is a schematic diagram of the structure of a thin film thermoelectric cooler in the related art. Figure 1 As shown in the figure, the thermocouple arms of the horizontal thin-film thermoelectric device are parallel to the substrate, so its preparation process is relatively simple and compatible with the current mature integrated circuit preparation process. However, the thermal conductivity of the substrate material may cause thermal bypass, that is, heat is transferred from the hot end to the cold end through the substrate, offsetting the cooling capacity of the cold end, which will reduce the thermoelectric conversion efficiency. In addition, if the substrate is completely removed to eliminate the thermal bypass, then supporting the cold end only with the thermocouple arms may cause mechanical stability problems, especially in large devices.

[0041] In view of this, the present application provides a thin film thermoelectric cooler. It includes a substrate, a P-type thermoelectric unit, an N-type thermoelectric unit, a first electrode and a second electrode, and the substrate is provided with a hollow area; on one side of the substrate perpendicular to the substrate direction, the P-type thermoelectric unit and the N-type thermoelectric unit are stacked to form a thermocouple pair; the cold end of the thermocouple pair is connected through the first electrode; the hot end of the thermocouple pair is connected to the second electrode; the cold ends of multiple thermocouple pairs are concentrated in an area of ​​the thin film thermoelectric cooler to form a cold load thin film area, and the cold ends of multiple thermocouple pairs and part of the thermocouple arms connected to the cold ends are located in the hollow area of ​​the substrate. In this way, by stacking the P-type and N-type thermoelectric units instead of arranging them side by side, the number of thermocouple pairs per unit area is significantly increased, and then by setting a hollow area on the substrate, part of the thermocouple arms and the cold end are not in contact with the substrate to eliminate thermal bypass, and the cold end is distributed in a relatively concentrated area, and the synergistic effect of multiple thermocouples on the cold end effectively absorbs heat from the surrounding environment, thereby improving the efficiency of thermoelectric conversion. In this way, the cooling capacity of the horizontal thin-film thermoelectric device can be improved and efficient heat dissipation can be achieved.

[0042] In order to facilitate understanding of the following embodiments of the present application, the principle of the thin film thermoelectric cooler is now described.

[0043] Thermoelectric cooler is a cooling device that uses the Peltier effect to achieve local thermal management of instruments. The Peltier effect, also known as the Peltier effect, is one of the thermoelectric phenomena, which refers to the phenomenon that when current passes through a thermocouple composed of two different conductors or semiconductor materials, heat absorption or heat release will occur at the junction.

[0044] The Peltier effect includes two main aspects: Peltier effect: When current passes through a thermocouple, heat is released at the end where the current enters (usually called the hot end), and heat is absorbed at the end where the current leaves (usually called the cold end). This means that when current passes through a thermocouple, a temperature difference can be generated between the two junctions, thereby achieving a cooling effect, which is thermoelectric cooling. Seebeck effect: This is the reverse process of the Peltier effect. When a temperature difference exists at both ends of a thermocouple, an electric current is generated. This process is actually thermoelectric power generation, which converts thermal energy into electrical energy.

[0045] The Peltier effect is widely used in thermoelectric coolers and thermoelectric generators. Thermoelectric coolers (TECs) use the positive Peltier effect to achieve cooling without mechanical moving parts, and are suitable for small systems that require precise temperature control, such as laser diode cooling, microprocessor cooling, portable refrigerators, etc. Thermoelectric generators (TEGs) use the reverse Peltier effect to convert thermal energy directly into electrical energy, and are commonly found in space probes, thermopiles, and some wearable devices.

[0046] In order to be able to understand the characteristics and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, in order to simplify the drawings, well-known structures and devices can be simplified for display. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0047] Figure 2 A schematic diagram of the structure of a thin film thermoelectric cooler provided in an embodiment of the present application is shown in FIG. Figure 3 yes Figure 2 A schematic cross-sectional view along the A-A' direction, see Figure 2 and Figure 3 A thin film thermoelectric cooler provided in an embodiment of the present application includes a substrate 1, a P-type thermoelectric unit 21, an N-type thermoelectric unit 22, an insulating layer 23, a first electrode 31 and a second electrode 32, and the substrate is provided with a hollow area 12.

[0048] On one side of the substrate 1, along a direction perpendicular to the substrate 1, the P-type thermoelectric unit 21 and the N-type thermoelectric unit 22 are stacked to form a thermocouple pair 2; the cold end of the thermocouple pair is connected through the first electrode; the hot end of the thermocouple pair is connected to the second electrode; the cold end of the thermocouple pair 2 is connected through the first electrode 31; the hot end of the thermocouple pair is connected to the second electrode 32;

[0049] The cold ends of multiple thermocouple pairs 1 are concentrated in an area of ​​the thin film thermoelectric cooler to form a cold load thin film area 4, and the cold ends of multiple thermocouple pairs 2 and part of the thermocouple arms connected to the cold ends are located in the hollow area 12 of the substrate 1.

[0050] Specifically, Figure 2 In the embodiment shown, the thin film thermoelectric cooler includes a substrate 1 and 16 pairs of thermocouple pairs 2. The substrate 1 is usually made of a material with good thermal conductivity and mechanical stability, such as ceramic, metal or polymer composite material. The substrate serves as a supporting structure for the thermocouple pairs and effectively conducts heat. At least one pair of thermocouple pairs means that multiple pairs of thermocouple pairs may be included to increase the cooling effect. Each pair of thermocouple pairs consists of two main parts: a thermoelectric unit made of N-type and P-type semiconductor materials ( Figure 2The P-type thermoelectric unit and the N-type thermoelectric unit are connected by a conductive material 3 (such as a first electrode 31 and a second electrode 32) to form a structure that is electrically connected in series but thermally connected in parallel, so as to generate a temperature difference effect when current passes through, wherein the conductive material can be a metal wire or a conductive film, which is not limited in the present application.

[0051] When a direct current passes through a series circuit, electrons flow from the N-type thermoelectric unit to the P-type thermoelectric unit, while holes flow from the P-type thermoelectric unit to the N-type thermoelectric unit. Since the N-type and P-type thermoelectric units have different Seebeck coefficients (i.e., the ability of different materials to generate electromotive force when the temperature changes), a temperature difference is generated at the connection point of the N-type and P-type thermoelectric units when current passes through. Specifically, the end where the current flows in (usually called the hot end) releases heat, causing the temperature to rise; while the end where the current flows out (usually called the cold end) absorbs heat, causing the temperature to drop.

[0052] Specifically, the substrate 1 is also hollowed out to form one or more cavities 12 ( Figure 1 This hollow design means that the base material in the cavity 12 area is removed, and the resulting cavity can provide space for part of the thermocouple arm and the cold end of the thermocouple arm, so that it is suspended in the air to eliminate the influence of thermal bypass.

[0053] like Figure 3 As shown, the thermocouple pair 2 includes a P-type thermoelectric unit 21 and an N-type thermoelectric unit 22. In the direction perpendicular to the substrate 1, the P-type thermoelectric unit 21 and the N-type thermoelectric unit 22 of the thermocouple pair 2 are stacked. Exemplarily, the N-type thermoelectric unit is an electron-type semiconductor, with electrons as its main carriers; while the P-type thermoelectric unit is a hole-type semiconductor, with holes as its main carriers. The N-type and P-type thermoelectric units are respectively connected at both ends by conductive materials (such as metal wires or metal films) to form an electrically series structure, but the thermocouple pairs are thermally connected in parallel. The hot ends of the P-type thermoelectric unit 21 and the N-type thermoelectric unit 22 are connected to the unremoved portion of the hollowed-out substrate, and the cold ends are suspended in the cavity of the hollowed-out area. That is, the cold end is not in direct contact with the substrate, but is supported above the cavity by the thermocouple arm itself.

[0054] In this embodiment, the design of the hollow substrate reduces the influence of the thermal conductivity of the substrate material itself on the thermoelectric performance. Traditionally, the substrate material may cause heat to flow directly from the hot end to the cold end instead of through the thermocouple arm for thermoelectric conversion. The hollow substrate can significantly reduce this thermal bypass, thereby improving the thermoelectric conversion efficiency.

[0055] Since the cold end is suspended, the thermal isolation from the substrate is better, and the cold end can absorb heat more effectively without being negatively affected by the thermal conductivity of the substrate. This improves the cooling effect, especially for microchips that require local efficient cooling. In addition, the suspended design of the cold end allows for a greater temperature difference between the hot and cold ends of the thermocouple arm, because the cold end is not subject to additional heat from the substrate. A larger temperature difference can improve the thermoelectric performance of the thermocouple arm, thereby improving the cooling capacity and efficiency of the entire thin-film thermoelectric cooler.

[0056] The hollow cavity of the substrate provides a more direct path for heat flow, and the heat transfer from the hot end to the cold end is not interfered by the substrate material, which helps to optimize the heat flow path and reduce energy loss. In addition, the hollow design reduces the use of substrate materials, making the entire thin-film thermoelectric cooler lighter and thinner, which is especially important for mobile devices or portable applications that require light weight and small size.

[0057] On the basis of the above embodiments, considering that the horizontally arranged thin-film thermoelectric cooler in the related art generally adopts an arrangement with a hot end on one side and a cold end on the other side, but this arrangement makes the cold end more dispersed, thereby reducing the cooling effect. Therefore, in this embodiment, the cold ends of multiple thermocouple pairs 2 are further concentrated in a specific area of ​​the thin-film cooler to form a cold load thin film area 4.

[0058] In an optional embodiment, the material of the P-type thermoelectric unit and the thermoelectric material of the N-type thermoelectric unit are any one or more of bismuth telluride (Bi2Te3)-based binary or ternary material, antimony telluride (Sb2Te3)-based binary or ternary material, lead telluride (Pb2Te3)-based binary or ternary material, tin selenide SnSe-based binary or ternary material, magnesium Mg-based binary or ternary material, tellurium Te-based binary or ternary material, tin Sn-based binary or ternary material, germanium silicon SiGe alloy material, semi-Heusler alloy, graphene, skutterudite or filled skutterudite material.

[0059] Among them, bismuth telluride (Bi2Te3) is a compound composed of bismuth and tellurium elements with excellent thermoelectric properties and is often used in the fields of thermoelectric materials and infrared detection. When combined with other elements to form binary or ternary materials, its performance may be further optimized. Antimony telluride (Sb2Te3) is also a compound composed of antimony and tellurium elements with topological insulator properties and good thermoelectric properties. Lead telluride (PbTe) is a medium-temperature thermoelectric material with excellent thermoelectric properties. Binary or ternary materials formed in combination with other elements may have higher thermoelectric conversion efficiency.

[0060] Tin selenide (SnSe) is a semiconductor material with high thermoelectric properties, especially at low temperatures. Combining with other elements may further improve its performance. Magnesium-based materials refer to alloys or compounds with magnesium as the main element. When magnesium is combined with other metal elements to form binary or ternary alloys, it may have excellent mechanical properties, corrosion resistance, or light weight and high strength. Tellurium-based materials refer to compounds or alloys with tellurium as the main element. Tin-based materials refer to alloys or compounds with tin as the main element. Germanium-silicon alloy (SiGe) is an alloy material composed of silicon and germanium elements with excellent semiconductor properties.

[0061] Half-Heusler alloy is a compound composed of three elements with special crystal structure and electronic properties, and has unique energy band structure and thermoelectric properties. Graphene is a two-dimensional material composed of carbon atoms, which has extremely high electrical conductivity, thermal conductivity and mechanical strength. Skutterudites are a class of compounds with special crystal structures, which are often used in the field of thermoelectric materials. Filled skutterudites refer to materials that are filled with other elements or compounds in the crystal structure of skutterudites to improve their thermoelectric properties.

[0062] In the above embodiment, the number of thermocouple pairs per unit area is significantly increased by stacking the P-type and N-type thermoelectric units instead of arranging them side by side, and then by setting a hollow area on the substrate, some thermocouple arms and cold ends are not in contact with the substrate to eliminate thermal bypass, and the cold ends are distributed in a relatively concentrated area. Through the synergistic effect of multiple thermocouples on the cold ends, heat is effectively absorbed from the surrounding environment, thereby improving the efficiency of thermoelectric conversion. In this way, the cooling capacity of the horizontal thin-film thermoelectric device can be improved, and efficient heat dissipation can be achieved.

[0063] Optionally, there are multiple possible implementations for setting the hollow area of ​​the substrate. Figure 4a-4d Schematic diagram of a hollowed-out substrate provided in an embodiment of the present application (the side away from the thermocouple arm, the thermocouple arm is not shown). Figure 4a-4d As shown, the base hollowing arrangement may include an annular hollowing segment 11 ( Figure 4a ); the annular hollow section 11 is provided with a plurality of concentrically arranged annular slits 101 ( Figure 4b ), multiple radially distributed strip slits 102 ( Figure 4c ) or a combination of multiple concentrically arranged annular slits 101 and multiple radially distributed strip slits 102 ( Figure 4d ).

[0064] In this embodiment, the annular hollow section refers to one or more annular hollow areas formed on the substrate. These areas can be complete annular or partially annular. The annular hollow section provides a larger heat dissipation area for the hot end of the thermoelectric unit, which helps to quickly transfer heat from the hot end to the external environment. At the same time, it may also serve as a supporting part of the internal structure of the device to enhance the overall stability of the device. It should be noted that the annular shape described in the embodiment of the present application may include a circle, a rectangle, etc., and can be specifically designed according to the needs of the thin film thermoelectric cooler.

[0065] Specifically, various gaps can be opened on the annular hollow section to further increase the heat dissipation area and optimize the heat dissipation effect:

[0066] See also Figure 4b As shown in the figure, these gaps are centered at the center of the annular hollow section and expand outward layer by layer according to different radii. They can be continuous or discontinuous, depending on the process capabilities and design requirements. The annular gap can increase the heat dissipation area and guide the heat flow along the gap direction, thereby improving the heat dissipation efficiency.

[0067] See also Figure 4c As shown, the gaps 102 start from the center of the annular hollow section and extend outward in the radial direction. They can be straight or curved, depending on the design goal. Strip gaps can also increase the heat dissipation area, and because they are distributed radially, they can more effectively transfer heat from the central area to the edge area and then dissipate it to the external environment.

[0068] See also Figure 4d As shown, a combination of multiple concentrically arranged annular gaps and multiple radially distributed strip gaps can also be used at the same time. This combination design can combine the advantages of both and achieve more efficient heat dissipation performance. By reasonably arranging the position and size of the gaps, the path and distribution of the heat flow can be further optimized, the heat dissipation efficiency can be improved, and the thermal stress can be reduced.

[0069] In this embodiment, by increasing the heat dissipation area and changing the path of heat flow, this gap design can significantly improve the heat dissipation performance of the thermoelectric cooling device. Reasonable gap design can reduce the thermal stress generated by the device during operation and improve the reliability and life of the device. Although the cold end is suspended, the designed thermocouple arm and base structure can ensure sufficient mechanical stability to avoid deformation or damage during operation.

[0070] In an optional embodiment, the cold ends of the plurality of thermocouple pairs are concentrated in one area of ​​the thin film thermoelectric cooler, and there are multiple possible implementations for forming a cold load thin film area. In this embodiment, the cold ends of the P-type thermoelectric unit and the N-type thermoelectric unit are concentrated in the center of the thin film thermoelectric cooler.

[0071] Specifically, concentrating the cold end at the center can make the cooling effect more concentrated and efficient. In the thermoelectric cooling process, the cold end is the part that absorbs heat and produces the cooling effect. Since the cold end is concentrated at the center, it can absorb heat through a relatively uniform heat conduction path, making the heat absorption effect of the cold end of the same thin-film thermoelectric cooler more uniform, reducing the problem of local overheating or insufficient cooling caused by uneven distribution of the cold end, making the temperature distribution of the entire cooling surface more uniform, which is conducive to faster transfer of heat from the surrounding environment to the refrigerator and discharge, thereby improving the overall cooling efficiency.

[0072] In addition, the centralized cold end design helps to achieve the compactness of the cooler structure. This layout can reduce the required space, making the thin-film thermoelectric cooler easier to integrate in small devices or limited spaces. By designing a suitable heat conduction path and heat dissipation structure, the heat absorbed by the cold end can be more effectively transferred and dissipated to the environment, thereby maintaining the stable operation of the cooler.

[0073] Centralizing the cold end reduces heat loss due to conduction or radiation. Any unnecessary heat loss during the cooling process reduces cooling efficiency. By centralizing the cold end, it is easier to control the flow of heat and reduce these losses. This design may also support modular manufacturing and assembly. The refrigerator can be designed to consist of multiple thermoelectric unit modules, each containing a cold end and a hot end, which can be assembled in a central location to form an efficient cooling system.

[0074] In an optional embodiment, there are many possible implementations of centrally arranging the cold ends of the P-type thermoelectric unit 21 and the N-type thermoelectric unit 22 at the center of the thin-film thermoelectric cooler.

[0075] Central island design: On the base of the thin-film thermoelectric cooler, a central island structure is designed, which is slightly higher than the surrounding area. The cold ends of the P-type thermoelectric unit and the N-type thermoelectric unit are directly fixed on this central island to form a concentrated cold end area. This design has a simple structure and is easy to manufacture and assemble. The concentrated cold end is conducive to thermal management and reduces heat loss.

[0076] Embedded cold end design: One or more central grooves or through holes are pre-processed in the substrate of the thin film thermoelectric cooler as the accommodation space for the cold end. The cold ends of the P-type thermoelectric unit and the N-type thermoelectric unit are embedded in these grooves or through holes and connected to the substrate by appropriate fixing methods (such as welding, bonding, etc.). The large thermal contact area between the cold end and the substrate is conducive to the rapid transfer of heat. The embedded design can reduce the heat loss of the cold end and improve the cooling efficiency.

[0077] Multi-layer stacking design: A multi-layer thin film structure is used to alternately stack thermoelectric units and insulating layers. During the stacking process, the cold ends of the first thermoelectric unit and the second thermoelectric unit are aligned and concentrated at the center, and they are connected by wires or conductive layers. This method has a compact structure and can achieve a high thermoelectric conversion efficiency. The multi-layer stacking design helps reduce heat loss and improve the cooling effect.

[0078] Thermal bridge design: A thermal bridge structure is constructed on the substrate of the thin-film thermoelectric cooler, and the cold ends of the first thermoelectric unit and the second thermoelectric unit are connected through a thermal bridge and centrally arranged at a central location. The thermal bridge material should have good thermal conductivity to ensure heat transfer between the cold ends. The thermal bridge design can achieve rapid thermal balance of the cold end and improve cooling efficiency. At the same time, it can also optimize thermal management strategies and reduce heat loss.

[0079] Flexible connection design: Use flexible materials (such as conductive glue, metal foil, etc.) to connect the cold ends of the first thermoelectric unit and the second thermoelectric unit, and concentrate them at the center of the thin-film thermoelectric cooler through appropriate fixing methods. The flexible connection design can adapt to substrates of different shapes and sizes. The flexible connection design has good adaptability and flexibility, and can adapt to various complex manufacturing processes and working environments. At the same time, it can also reduce heat loss caused by mechanical stress.

[0080] Figure 5a-5c The cold end concentration schematic diagram provided in the embodiment of the present application is combined with Figure 5a-5c As shown, the cold ends of the P-type thermoelectric unit and the N-type thermoelectric unit are concentrated at the center of the thin film thermoelectric cooler, including: a thermocouple pair 2 composed of a stacked P-type thermoelectric unit 21 and an N-type thermoelectric unit 22 is arranged around a central cold load film area 4; the cold load film area 4 is set at the center of the thin film thermoelectric cooler.

[0081] Specifically, Figure 5a The thermocouple arms are arranged in a ring shape around the cold load film area 4. Through this ring arrangement, more thermocouple arms can be connected to the cold load film area 4, thereby improving the refrigeration efficiency.

[0082] Figure 5b The thermocouple arms in are distributed above, below, left and right of the cold load film area 4. For example, Figure 5b The number and length of the thermocouple arms in each direction are equal. In this embodiment, a U-shaped thin film thermoelectric cooler is formed. The number and length of the thermocouple arms are equal, which can make the structure more stable, and this regular pattern is more convenient for preparation and mass production.

[0083] Figure 5c The thermocouple arms in are distributed above, below, left and right of the cold load film area 4. For example, Figure 5cThe number and length of the thermocouple arms in each direction are not equal. In some application scenarios, irregular devices such as rectangles are required, but rectangular devices will cause the thermocouple arms on the long sides to bear greater pressure. In view of this, the thermocouple arms provided in this embodiment are distributed in the long side direction using wider thermocouple arms to ensure sufficient support for the cold end, and the number of thermocouple arms is increased in the short side arrangement to improve the cooling effect.

[0084] In an optional embodiment, the cold load film area includes one of a rectangle, a circle and a complex polygon. Figure 6a-6c A schematic diagram of a cold load film area provided in an embodiment of the present application. Figure 6a to Figure 6c As shown in the figure, the rectangular cold load film area is easier to prepare. The circular cold load film area can make the heat distribution at the cold end more uniform. The polygonal design provides the possibility of assembling multiple thin film thermoelectric coolers in the future.

[0085] The thin film thermoelectric cooler provided in the embodiments of the present application is introduced above. The preparation method of the thin film thermoelectric cooler is exemplarily described below in combination with specific application scenarios.

[0086] Figure 7 A flow chart of a method for preparing a thin film thermoelectric cooler provided in an embodiment of the present application. Figure 7 As shown, the method for preparing a thin film thermoelectric cooler provided in the embodiment of the present application may include:

[0087] S701, providing a substrate.

[0088] In this embodiment, a suitable substrate material is selected, such as silicon, sapphire or ceramic. These materials generally have good thermal stability and mechanical strength and are suitable for supporting the thermoelectric film.

[0089] For example, Figure 8 A schematic diagram of the structure of a thin film thermoelectric cooler preparation process provided in an embodiment of the present application. Figure 8 As shown in (a), a double-sided polished silicon substrate is prepared. <100> , thickness 350μm.

[0090] S702, depositing a first insulating layer, a P-type thermoelectric unit layer, a second insulating layer and an N-type thermoelectric unit layer in sequence on one side of the substrate along a direction perpendicular to the substrate to obtain a multi-layered thermoelectric thin film.

[0091] The first insulating layer, the P-type thermoelectric unit layer, the second insulating layer and the N-type thermoelectric unit layer are deposited on the substrate in sequence by physical vapor deposition (PVD) or chemical vapor deposition (CVD) and other techniques. This step builds the foundation of the thermoelectric film, in which the insulating layer is used to isolate different types of thermoelectric materials to avoid short circuits. Among them, the insulating layer is made of silicon nitride material. In actual application, the insulating layer material can also be selected from other types of insulating materials, which is not limited in this application.

[0092] See also Figure 8 (b) The P-type thermoelectric unit and the N-type thermoelectric unit are made of bismuth telluride material, and the insulating layer is made of silicon nitride material. Silicon oxide film (0.5μm), bismuth telluride (P-type 1.2um), silicon oxide film (0.5μm), and bismuth telluride (N-type 1.2um) are deposited on the silicon substrate in sequence by chemical vapor deposition (LPCVD).

[0093] In an optional embodiment, there are many possible forms of deposition methods for preparing multilayer structures, including chemical vapor deposition (LPCVD), physical vapor deposition (PVD), molecular beam epitaxy (MBE), sol-gel method, pulsed laser deposition (PLD) and atomic layer deposition (ALD), etc.

[0094] Among them, chemical vapor deposition introduces a gaseous precursor containing the elements required for the thin film into a high-temperature reaction chamber, causing the precursor molecules to undergo a chemical reaction on the surface of the substrate to generate the desired solid thin film.

[0095] Physical vapor deposition is a technology that converts materials from solid to gaseous state through physical processes (such as evaporation, sputtering, etc.) and deposits them into films on substrates. For silicon oxide thin films, sputtering methods (such as radio frequency sputtering, magnetron sputtering, etc.) can be used for deposition.

[0096] Molecular beam epitaxy is a technology that directly sprays thermally evaporated atomic or molecular beams onto a substrate under ultra-high vacuum conditions, and precisely controls the growth rate, thickness, and composition of the thin film by controlling parameters such as beam intensity and substrate temperature. MBE technology is suitable for preparing the multilayer structure and complex component materials of this embodiment.

[0097] The sol-gel method is a method for preparing thin films through the gelation process of sol. First, the desired metal alkoxide or inorganic salt is dissolved in a solvent to form a uniform sol; then, the sol is gradually gelled by heating, stirring, etc.; finally, the gelled film is coated on a substrate and heat treated to form a dense film.

[0098] Pulsed laser deposition is a technology that uses a high-energy pulsed laser beam to bombard the surface of a target material, causing the atoms or molecules on the surface of the target material to evaporate and deposit on the substrate to form a thin film. PLD technology can produce high-quality, high-purity thin films and can achieve co-deposition of multiple elements.

[0099] Atomic layer deposition is a thin film deposition technology based on surface chemical reactions. By alternately introducing reaction precursors and inert gases, a self-limiting reaction occurs on the substrate surface, and thin films are deposited layer by layer. ALD technology can precisely control the thickness and composition of the film, and has a high degree of uniformity and conformality.

[0100] S703, preparing thermocouple arms on the multi-layered thermoelectric film by an etching process to obtain a multi-layered thermocouple pair and a cold load film area.

[0101] In this embodiment, photolithography and dry etching or wet etching are used to accurately form thermocouple arm patterns on the multilayer structure. One end of a plurality of thermocouple pairs is concentratedly distributed in one area of ​​the thin film thermoelectric cooler.

[0102] In an optional embodiment, the method of using an etching process to prepare thermocouple arms on the multi-layer thermoelectric film to obtain a multi-layer thermocouple pair includes: coating a photoresist on the multi-layer thermoelectric film, and forming a pattern on the photoresist by a photolithography process in which one end of a plurality of thermocouple pairs are concentrated in an area of ​​the thin film thermoelectric cooler; and etching a plurality of thermocouple arms on the multi-layer thermoelectric film by a photolithography etching process based on the pattern to obtain a multi-layer thermocouple pair.

[0103] Specifically, a layer of photoresist is coated on the multilayer thermoelectric film, and a pattern corresponding to the desired thermocouple pair shape is formed on the photoresist by a photolithography process. The selection of photoresist and the conditions of the photolithography process need to be determined according to specific materials and design requirements, and the embodiments of the present application do not limit this.

[0104] Then, an etchant (such as a chemical solution in wet etching or a gas plasma in dry etching) is used to etch the multilayer thermoelectric film that is not protected by the photoresist to remove the unnecessary part of the material. After the etching is completed, a stripper is used to completely remove the photoresist from the multilayer thermoelectric film to expose the final thermocouple pair structure.

[0105] Through the above etching process, multiple thermocouple pairs can be formed, and due to the design of the photolithography mask, one end of these thermocouple pairs (usually the cold end) can be concentrated in a specific area of ​​the thin film thermoelectric cooler. This layout helps to improve the cooling efficiency because the cold end can more effectively extract heat from the cooling area.

[0106] After the thermocouple pair is prepared, the cold load thin film area is prepared by the following method: a third insulating layer is deposited on the thermocouple pair with a multi-layer structure; and the third insulating layer is patterned by a photolithography and etching process to obtain the cold load thin film area.

[0107] See also Figure 8 As shown in (e), a 0.5 μm silicon nitride film is deposited as an insulating layer on the patterned thermocouple arm by chemical vapor deposition (LPCVD) to subsequently etch out the cold load film area and prepare the electrode. After the silicon nitride film is deposited as an insulating layer on the thermocouple arm (formed by alternating stacks of P-type bismuth telluride and N-type bismuth telluride), in order to determine the actual heat exchange in the thermoelectric cooling device (i.e., the area where cold or heat is generated), the silicon nitride film needs to be patterned by a photolithography etching process. This process will remove the unnecessary parts of the silicon nitride film, and the remaining parts will cover specific areas of the thermocouple arm, which are the so-called "cold load film areas."

[0108] "Cold load film area" usually refers to the area in the thermoelectric cooling device that is directly involved in the heat exchange process, that is, the area that can significantly feel the temperature change (such as cooling or heating). Since the silicon nitride film is insulating, it not only protects the thermocouple arm from the external environment, but also acts as a thermal isolation layer, so that the heat on the thermocouple arm can be more effectively gathered or dissipated in a specific area.

[0109] See also Figure 8 (f) When patterning the silicon nitride film, a specific pattern is formed on the silicon nitride film through a photolithography process, and then an etching technique (such as dry etching or wet etching) is used to remove the silicon nitride portion not protected by the photoresist, thereby obtaining the required "cold load film area". The design of this area will take into account the overall structure and performance requirements of the thermoelectric cooling device to ensure that heat can be efficiently transferred and exchanged.

[0110] In an optional embodiment, a plurality of thermocouple pairs concentrated in a region of the thin film thermoelectric cooler may be arranged along the same straight line. Specifically, two thermocouple arms (i.e., at least two thermocouple pairs, each thermocouple pair consisting of a P-type thermocouple arm and an N-type thermocouple arm) are arranged along the same straight line, and a preset distance is set between them (so as to form a cold load thin film area).

[0111] Since the thermocouple arms are arranged along the same straight line and form at least two pairs of thermocouples, the cold ends of these thermocouple pairs (i.e., the ends that produce the cooling effect) can be conveniently concentrated together. This centralized arrangement helps to more effectively utilize the cooling capacity of the cold ends, because all the cold ends are located in the same area and can work together on the object or space that needs to be cooled, thereby improving the cooling efficiency.

[0112] In this embodiment, since the thermocouple arms are arranged along the same straight line and separated by a preset distance, thermal management is convenient. The hot ends can be designed on both sides of the thermocouple arms, and heat dissipation can be effectively performed through heat dissipation devices such as heat sinks and heat pipes.

[0113] S704, using a vacuum coating method to connect one end of a thermocouple pair concentrated in an area of ​​the thin film thermoelectric cooler through a first electrode to form a cold end; and connect the other end of the thermocouple pair to a second electrode to form a hot end.

[0114] In this embodiment, see Figure 8 (g) 30nm of metal gold is deposited separately by magnetron sputtering. Specifically, the multilayer thermocouple arm is placed in the vacuum chamber of the magnetron sputtering equipment, and the vacuum pump is started to evacuate the chamber to the required vacuum degree, which is usually required to reach a vacuum degree of several Pa or lower to eliminate the interference of gas molecules on the sputtering process. In the vacuum chamber, the metal gold target is bombarded by high-energy particles (such as argon ions), so that the atoms or molecules on the surface of the target are sputtered out and fly to the surface of the multilayer thermocouple arm. In magnetron sputtering technology, the magnetic field is used to control the motion trajectory of the sputtered particles so that they are more concentratedly deposited on a specific area of ​​the thermocouple arm. By adjusting parameters such as the sputtering time, power, and the distance between the target and the thermocouple arm, the thickness of the deposited metal gold layer is precisely controlled to achieve the desired thickness, such as 30nm.

[0115] See also Figure 8 As shown in (h), a layer of photoresist is coated on the surface of the thermocouple arm on which metal gold is deposited. A photolithography machine is used to expose the thermocouple arm coated with photoresist. During exposure, part of the light is blocked by a mask (on which the patterns of the first electrode, the second electrode and the lead are printed) so that the photoresist undergoes a chemical reaction only in the area where the electrodes and leads need to be formed. Then, a developer is used to remove the unexposed or exposed (depending on the type of photoresist) portion, leaving a photoresist layer corresponding to the electrode and lead pattern. The metal gold layer without photoresist protection is etched away using wet etching or dry etching technology. In this way, an electrode and lead structure corresponding to the photoresist pattern is formed on the metal gold layer. Finally, a stripping solution is used to remove the remaining photoresist layer, revealing clear metal electrodes and leads. These electrodes and leads connect the P-type thermoelectric unit and the N-type thermoelectric unit to form a complete thermoelectric cooling device circuit.

[0116] S705, using an etchant to remove part of the substrate to form a hollow area on the substrate.

[0117] In this embodiment, see Figure 8As shown in (i), the silicon substrate is etched with tetramethylammonium hydroxide at a concentration of 10% to release the suspended portion. In this embodiment, the etchant removes part of the substrate away from the thermocouple arm to release the suspended portion, thereby reducing the influence of substrate heat transfer.

[0118] In an optional embodiment, the corrosive agent includes any one or more of tetramethylammonium hydroxide, ethylenediamine pyrrolidone, a mixed solution of nitric acid and hydrogen peroxide, a mixed solution of sulfuric acid and hydrogen peroxide, potassium hydroxide, sodium hydroxide and xenon fluoride.

[0119] In this embodiment, a multi-layered thermocouple arm beam body is constructed, which is composed of alternately stacked P-type thermoelectric units and N-type thermoelectric units separated by an insulating layer to form an efficient thermoelectric conversion unit sequence. At the cold end, the P-type and N-type thermoelectric units are electrically connected through metal electrode buckles, ensuring that the charge carriers can smoothly migrate between the interfaces of materials at different energy levels, thereby absorbing heat at the cold end to achieve an efficient refrigeration effect. The refrigeration zone is suspended above the substrate, and the dual functions of support and heat transfer are achieved through the layout of multiple thermocouple arms. The hot end of the thermocouple arm is firmly fixed on the substrate, while the cold end is suspended and evenly distributed around the refrigeration zone. This design not only optimizes the heat conduction path, but also enhances the refrigeration efficiency of the refrigeration zone. The refrigeration zone film is directly and tightly attached to the heat source, ensuring that heat can be efficiently transferred from the heat source to the refrigeration zone, further improving the performance of the entire refrigeration device.

[0120] Fig. 9 This is a schematic diagram of the structure of a "U"-shaped horizontal thin-film thermoelectric cooling device and its thermocouple arm provided in an embodiment of the present application. Fig. 9 As shown, the 1 metal electrode, 2 multi-layer thermocouple arms, 3 cold load film area, 4 metal wires, 5 substrate, 6 suspended area, 7 P-type thermoelectric unit, 8 N-type thermoelectric unit, and 9 insulating layer.

[0121] In this embodiment, a "U"-shaped horizontal thin-film thermoelectric cooling device is constructed, and this structure is suitable for most nano-multilayer thin-film thermoelectric devices. The multi-layer thermocouple arms formed by stacking P-type thermoelectric units and N-type thermoelectric units are arranged in a surrounding manner, so that the cold end is concentrated in the cold load area, thereby obtaining efficient cooling power. At the same time, the base is hollowed out, and the thermocouple arms can also be used as cantilever beams to support the middle cooling area, reducing the influence of base heat transfer.

[0122] Fig.10 This is a schematic diagram of the temperature distribution of a "U"-shaped horizontal thin-film thermoelectric cooling device provided in an embodiment of the present application. Fig.10As shown in the figure, the temperature distribution of a single thermocouple arm of a "U"-shaped horizontal thin-film thermoelectric cooling device calculated based on COMSOL simulation software is shown, and the temperature distribution along the center line is shown under the conditions of 0.05V voltage and 1mW central thermal power. The lowest temperature is 242.63K, which occurs at the end of the thermocouple arm. The center temperature rises slightly and the temperature at the center is 266.23K. The temperature rise is mainly limited by the thermal conductivity of SiNx. This parameter condition is not the theoretical maximum cooling performance, and the power can be further improved by adjusting the current parameters.

[0123] In this embodiment, the performance of the thin film thermoelectric refrigeration device can be improved through simulation software simulation.

[0124] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.

[0125] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0126] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0127] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application.

Claims

1. A thin film thermoelectric cooler, characterized in that: It includes a substrate, a P-type thermoelectric unit, an N-type thermoelectric unit, a first electrode and a second electrode, wherein the substrate is provided with a hollow area; On one side of the substrate, along a direction perpendicular to the substrate, the P-type thermoelectric unit and the N-type thermoelectric unit are stacked to form a thermocouple pair; the cold end of the thermocouple pair is connected through the first electrode; and the hot end of the thermocouple pair is connected to the second electrode; The cold ends of the multiple thermocouple pairs are concentrated in an area of ​​the thin film thermoelectric cooler to form a cold load thin film area, and the cold ends of the multiple thermocouple pairs and part of the thermocouple arms connected to the cold ends are located in the hollow area of ​​the substrate.

2. The thin film thermoelectric cooler according to claim 1, characterized in that: The base is provided with a hollow area including an annular hollow section; the annular hollow section is provided with a plurality of concentrically arranged annular gaps, a plurality of radially distributed strip gaps, or a combination of a plurality of concentrically arranged annular gaps and a plurality of radially distributed strip gaps.

3. The thin film thermoelectric cooler according to claim 1, characterized in that: The cold load film area is located at the center of the thin film thermoelectric cooler.

4. The thin film thermoelectric cooler according to claim 3, characterized in that: The cold load film area includes one of a rectangle, a circle and a complex polygon.

5. The thin film thermoelectric cooler according to claim 1, characterized in that: The material of the P-type thermoelectric unit and the thermoelectric material of the N-type thermoelectric unit are any one or more of bismuth telluride-based binary or ternary materials, antimony telluride-based binary or ternary materials, lead telluride-based binary or ternary materials, tin selenide-based binary or ternary materials, magnesium-based binary or ternary materials, tellurium-based binary or ternary materials, tin-based binary or ternary materials, germanium-silicon alloy materials, semi-Heusler alloys, graphene, skutterudites or filled skutterudite materials.

6. A method for preparing a thin film thermoelectric cooler, characterized in that: The method comprises: providing a substrate; Depositing a first insulating layer, a P-type thermoelectric unit layer, a second insulating layer and an N-type thermoelectric unit layer in sequence on one side of the substrate in a direction perpendicular to the substrate to obtain a multi-layered thermoelectric film; Thermocouple arms are prepared on the multi-layer thermoelectric film by etching to obtain thermocouple pairs and cold load film areas of the multi-layer structure; one end of a plurality of thermocouple pairs is concentratedly distributed in an area of ​​the thin film thermoelectric cooler; Using a vacuum coating method, one end of a thermocouple pair concentrated in an area of ​​the thin film thermoelectric cooler is connected through a first electrode to form a cold end; and the other end of the thermocouple pair is connected to a second electrode to form a hot end; A portion of the substrate is removed by using an etchant to form a hollow area on the substrate.

7. The method for preparing a thin film thermoelectric cooler according to claim 6, characterized in that: The method of using an etching process to prepare thermocouple arms on the multi-layer thermoelectric film to obtain a multi-layer thermocouple pair comprises: Coating a photoresist on the multi-layered thermoelectric film, and forming a pattern on the photoresist by a photolithography process, in which one end of a plurality of thermocouple pairs is concentratedly distributed in an area of ​​the thin film thermoelectric cooler; Based on the pattern, a plurality of thermocouple arms are etched on the multi-layered thermoelectric film by using a photolithography and etching process to obtain a multi-layered thermocouple pair.

8. The method for preparing a thin film thermoelectric cooler according to claim 6, characterized in that: The cold load film zone is prepared by the following method: depositing a third insulating layer on the thermocouple pair of the multilayer structure; The third insulating layer is patterned by photolithography and etching process to obtain a cold load film area.

9. The method for preparing a thin film thermoelectric cooler according to claim 6, characterized in that: The deposition method is any one or more of chemical vapor deposition, physical vapor deposition, molecular beam epitaxy, sol-gel method, pulsed laser deposition and atomic layer deposition.

10. The method for preparing a thin film thermoelectric cooler according to claim 6, characterized in that: The corrosive agent includes any one or more of tetramethylammonium hydroxide, ethylenediamine pyrrolidone, a mixed solution of nitric acid and hydrogen peroxide, a mixed solution of sulfuric acid and hydrogen peroxide, potassium hydroxide, sodium hydroxide and xenon fluoride.

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