A thermoelectric thin film device with a film-coated thermoelectric arm and a preparation method thereof

Abstract

The present invention belongs to the technical field of thin film thermoelectric devices, and specifically discloses a thermoelectric thin film device with a film-coated thermoelectric arm and a preparation method thereof, which comprises the following steps: S1 depositing a first bonding layer, an n-type thermoelectric film, a second bonding layer, and a solder layer on the surface of a metal substrate in sequence to obtain an n-type film-coated metal substrate, and then dividing the n-type film-coated metal substrate into a plurality of n-type film-coated thermoelectric arms; S2 depositing a third bonding layer, a p-type thermoelectric film, a second bonding layer, and a solder layer on the surface of a metal substrate in sequence to obtain a p-type film-coated metal substrate, and then dividing the p-type film-coated metal substrate into a plurality of p-type film-coated thermoelectric arms; S3 fixing the n-type film-coated thermoelectric arm and the p-type film-coated thermoelectric arm in a mold, and hot pressing and welding them with a substrate with electrodes to obtain a thermoelectric thin film device. The present invention can realize the introduction of high-performance thermoelectric thin films by introducing a special structure of the film-coated type, while avoiding the complex patterning process in the processing of thin film devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin film thermoelectric devices, and more specifically, relates to a thermoelectric thin film device with a film-coated thermoelectric arm and a preparation method thereof. Background Art

[0002] In recent years, thin film thermoelectric materials have received extensive attention and research due to their excellent performance. Correspondingly, thermoelectric thin film cooling devices have also become a research hotspot due to their high integration and high cooling flux, and have great application prospects in thermal management of microelectronic devices.

[0003] Thin-film thermoelectric devices are divided into Cross-plane and In-plane types according to the direction of heat transfer. In-plane type devices have the same heat transfer direction as the current, while Cross-plane type devices have a wide range of applications in the fields of refrigeration and power generation. The basic building block of a Cross-plane thin-film thermoelectric device is a thermoelectric arm consisting of upper and lower electrodes and a p / n-type thermoelectric film. However, the output of a single pair of thermoelectric arms is limited. In order to achieve high power density of the device, it is necessary to integrate as many thermoelectric arms as possible per unit area, that is, to achieve high-density array integration of thermoelectric arms. This process requires high-precision thin film patterning and needs to be based on traditional silicon-based MEMS technology. The specific steps are:

[0004] 1. Use photolithography technology to prepare a patterned mask on the substrate, then use physical vapor deposition to deposit the bottom electrode on the surface of the substrate, then put it into the glue solution to remove the photoresist and the material attached to its surface, and complete the production of the bottom patterned electrode; 2. Continue to use photolithography technology to prepare a patterned mask on the bottom electrode pattern, deposit n-type thermoelectric material, and then use photolithography technology to prepare a layer of mask on the top and then deposit p-type thermoelectric material; 3. On the basis of the above, use photolithography technology again to prepare a layer of mask and deposit the top electrode layer; 4. Finally, put the substrate into the glue solution, remove the photoresist and the material attached to its surface, and complete the production of the top patterned electrode.

[0005] It can be found from the above steps that high-quality patterned films can be obtained by photolithography technology, but the overall process equipment and material requirements are extremely high, the process is complex and the cost is very high. In addition, the characteristic that photoresist cannot withstand high temperatures also limits the manufacturing process of the device, so that the film performance cannot be improved by high-temperature deposition or heat treatment, resulting in poor performance. For Cross-plane type thin film thermoelectric devices, the deposition process of high-performance thermoelectric films, film patterning and the incompatibility of the two are the bottlenecks in the current development of thin film thermoelectric devices. Conventional scale TEC has a simple preparation process, and only needs to cut the thermoelectric material into thermoelectric arm particles and then weld it with a substrate with electrodes, but due to the limitations of structure and material properties, the performance of conventional TEC is far inferior to that of Cross-plane type thermoelectric film devices. Therefore, it is urgent to develop a new structure thermoelectric film device and its preparation method that does not require complex processes, can be compatible with high-temperature material deposition in the process, and has low equipment requirements, is easy to operate, and is low in cost. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a thermoelectric thin film device with a coated thermoelectric arm and a preparation method thereof, the purpose of which is to simplify the preparation process of the thermoelectric thin film device while being compatible with high-temperature material deposition to achieve the introduction of high-performance thermoelectric films.

[0007] To achieve the above object, according to one aspect of the present invention, a method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm is provided, comprising the following steps:

[0008] S1. Depositing a coating including a first bonding layer, an n-type thermoelectric thin film, a second bonding layer, and a solder layer on the surface of a metal substrate in sequence to obtain an n-type coated metal substrate, and then dividing the n-type coated metal substrate into a plurality of n-type coated thermoelectric arms;

[0009] S2, depositing a coating including a third bonding layer, a p-type thermoelectric thin film, a second bonding layer, and a solder layer on the surface of the metal substrate in sequence to obtain a p-type coated metal substrate, and then dividing the p-type coated metal substrate into a plurality of p-type coated thermoelectric arms;

[0010] S3, fixing the n-type film-coated thermoelectric arm and the p-type film-coated thermoelectric arm in a mold, and hot-pressing welding them with a substrate with electrodes to obtain a thermoelectric thin film device.

[0011] As a further preference, in steps S1 and S2, a single surface of the metal substrate is coated, or both the upper and lower surfaces of the metal substrate are coated, and then segmentation is performed.

[0012] As a further preferred embodiment, in steps S1 and S2, any multiple layers of metal substrates coated on a single surface and / or metal substrates coated on both upper and lower surfaces are stacked, hot pressed, and then divided.

[0013] As further preferred, the first bonding layer is a composite thin film of one or more of Ag, Ti, Ta, W, Au and their nitrides, and the thickness of the first bonding layer is 150nm to 500nm.

[0014] As a further preference, the third bonding layer is a composite thin film of one or more of Cr, Ti, Ta, W, Au and their nitrides, and the thickness of the third bonding layer is 150nm to 500nm.

[0015] As further preferred, the second bonding layer is made of a composite film of one or more of Ni, Ti, Au, W and their nitrides, and the thickness of the second bonding layer is 2um to 5um.

[0016] As further preferred, the material of the solder layer is Sn, and the thickness of the solder layer is 15um-20um.

[0017] As further preferred, the metal matrix material is one of Cu, Al, Ag and alloys thereof, and the metal matrix is ​​in sheet form with a thickness of 100um to 1000um.

[0018] As further preferred, in steps S1 and S2, the deposition temperature of the n-type thermoelectric film and the p-type thermoelectric film is not less than 200°C.

[0019] According to another aspect of the present invention, a thermoelectric thin film device having a film-coated thermoelectric arm is provided, which is prepared by the above method.

[0020] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0021] 1. The present invention designs a special film-coated thermoelectric arm structure, directly deposits a high-performance thermoelectric film on a metal substrate at high temperature and then divides it to obtain film-coated thermoelectric arm particles, and then adopts the conventional TEC preparation process to complete the preparation of thermoelectric thin film devices. Since the resistance of the metal substrate can be basically ignored, the resistance of the film-coated thermoelectric arm is basically equal to the resistance of the thermoelectric film thereon, and the presence of the metal substrate will not affect other properties of the thermoelectric film. Therefore, the device prepared by using the film-coated thermoelectric arm is not only simple in structure, but also has performance close to that of a device directly composed of high-performance thermoelectric films. At the same time, the thermoelectric film and the metal substrate are directly composed of independent thermoelectric arm particles, so that the preparation of the thermoelectric thin film device does not require film patterning, and the subsequent preparation of the device can be completed by a simple welding process, which greatly simplifies the preparation process of the thermoelectric thin film device, reduces the requirements for equipment and materials, improves the yield rate, and reduces the cost of the device.

[0022] 2. The present invention eliminates the temperature limitation in the thermoelectric film deposition process by designing a special coating-type thermoelectric arm structure. Compared with room temperature deposition, the thermoelectric film prepared by high temperature deposition can achieve the optimal orientation and porous structure, which greatly simplifies the process and improves the performance of the thermoelectric film.

[0023] 3. The independent coated thermoelectric arms not only enable the device to have the high heat flow handling capability of thermoelectric thin film devices, but also can be freely combined and assembled according to needs to obtain thermoelectric thin film devices that meet various application scenarios, which greatly simplifies the preparation process and difficulty of thermoelectric thin film devices and significantly reduces costs. It has extremely high commercial value and application prospects.

[0024] 4. The present invention studies the thickness of the bonding layer. A thickness greater than 150 nm can effectively prevent the diffusion of the metal matrix and achieve a good connection effect, while avoiding excessive costs caused by excessive thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a single-layer film-coated thermoelectric arm structure and preparation flow chart of an embodiment of the present invention;

[0026] Figure 2 This is a double-layer coating type thermoelectric arm structure and preparation flow chart of the embodiment of the present invention;

[0027] Figure 3 The sandwich structure film-coated thermoelectric arm structure and its preparation flow chart of the embodiment of the present invention.

[0028] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 - metal substrate, 2 - first bonding layer, 3 - third bonding layer, 4 - thermoelectric film, 5 - second bonding layer, 6 - solder layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The embodiment of the present invention provides a thermoelectric thin film device with a film-coated thermoelectric arm, such as Figure 1 As shown, the following steps are included:

[0031] (1) Metal substrate treatment

[0032] Select a sheet metal substrate of a certain thickness according to the needs, polish its surface until it presents a mirror effect, and then clean and dry it;

[0033] (2) Preparation of n-type film-coated thermoelectric arms

[0034] A first bonding layer 2, a thermoelectric film 4 (specifically an n-type thermoelectric film), a second bonding layer 5, and a solder layer 6 are sequentially deposited on the surface of the pretreated metal substrate 1 to form a coating, and then the coating is cut, cleaned, and dried to obtain n-type coated thermoelectric arm particles;

[0035] (3) Preparation of p-type film-coated thermoelectric arms

[0036] The third bonding layer 3, the thermoelectric film 4 (specifically, a p-type thermoelectric film), the second bonding layer 5, and the solder layer 6 are sequentially deposited on the surface of the pretreated metal substrate 1, and then cut, cleaned, and dried to obtain p-type coated thermoelectric arm particles;

[0037] (4) Welding to form devices

[0038] The plurality of n-type film-coated thermoelectric arm particles and p-type film-coated thermoelectric arm particles prepared separately are fixed in a mold, and then aligned with an insulating substrate with electrodes, and then hot-pressed and brazed to complete the preparation of the thermoelectric thin film device.

[0039] Furthermore, the metal substrate selected in step (1) may be Cu, Al, Ag and their alloys, with a thickness ranging from 100um to 1000um and a surface roughness Ra≤0.025um.

[0040] Furthermore, in step (2), the n-type thermoelectric thin film material adopts Bi-Te based material, the deposition temperature is not less than 200°C, and the corresponding first bonding layer adopts one of Ag, Ti, Ta, Au, W and their nitride films or a composite multilayer film with a thickness of 150nm to 500nm.

[0041] Furthermore, in step (3), the p-type thermoelectric thin film material adopts Bi-Te based material, the deposition temperature is not less than 200°C, and the corresponding second bonding layer adopts one of Cr, Ti, Ta, Au, W and their nitride films or a composite multilayer film with a thickness of 150nm to 500nm.

[0042] Furthermore, in the steps (2) and (3), the second bonding layer used is one of Ni, Ti, W, Au thin films or a composite multilayer film with a thickness of 2um to 5um.

[0043] Furthermore, in steps (2) and (3), the cutting method adopted is wire cutting or laser cutting.

[0044] Furthermore, the steps (2) and (3) are as follows: Figure 2As shown, the prepared coated thermoelectric arm can not only deposit a thin film on one side of the metal substrate, and obtain a single-layer coated thermoelectric arm after cutting; it can also deposit the same thin film on both sides of the metal substrate through the same process, and obtain a double-layer coated thermoelectric arm after cutting; further, as Figure 3 As shown, multiple metal substrates with thin films deposited on one side or two sides can be stacked in any multiple layers, that is, single-sided coated metal substrates can be stacked, or double-sided coated metal substrates can be stacked, or single-sided coated metal substrates and double-sided coated metal substrates can be stacked in any multiple layers, and then hot pressed and split to obtain a sandwich structure coated thermoelectric arm.

[0045] The following are specific embodiments:

[0046] Thermoelectric thin film devices with a novel thermoelectric arm structure are prepared using magnetron sputtering technology. The specific process and parameters are as follows:

[0047] (1) Pretreatment

[0048] A copper with a diameter of 50.4 cm and a thickness of 500 um was selected as the metal substrate, and both sides thereof were polished to a mirror surface (Ra ≤ 0.025 um), and then ultrasonically cleaned with ethanol and acetone in turn and dried;

[0049] (2) preparing a single-layer n-type film-coated thermoelectric arm;

[0050] The pre-treated metal substrate is placed in the chamber, and the deposition temperature is fixed at 200°C by DC sputtering. 300nm thick Ti, 200nm thick Ag, 7.5um thick Bi2Te3, 200nm thick Ag, 300nm thick Ti, 2um thick Ni, and 15um thick Sn are deposited on the lower substrate in sequence. Then, laser cutting is used to divide the substrate into 0.25x0.25x0.5mm n-type film-coated thermoelectric arms. The above process is as follows: Figure 1 As shown;

[0051] (3) Preparation of single-layer p-type film-coated thermoelectric arm

[0052] The pre-treated metal substrate is placed in the chamber, and the deposition temperature is fixed at 200°C by DC sputtering. 300nm thick Ti, 200nm thick Cr, 7.5um thick Bi0.5Sb1.5Te3, 200nm thick Cr, 300nm thick Ti, 2um thick Ni, and 15um thick Sn are deposited on the lower substrate in sequence. Then, laser cutting is used to divide the substrate into 0.25x0.25x0.5mm p-type film-coated thermoelectric arms. The above process is as follows: Figure 1 As shown;

[0053] (4) Assembly welding

[0054] An AlN insulating substrate with electrodes is selected. First, solder is attached to the electrodes. Then, the p-type and n-type thermoelectric arms are aligned with the substrate through a mold, and then hot pressing is performed to complete the device manufacturing.

[0055] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm, characterized in that: The steps include: S1. Depositing a coating including a first bonding layer, an n-type thermoelectric thin film, a second bonding layer, and a solder layer on the surface of a metal substrate in sequence to obtain an n-type coated metal substrate, and then dividing the n-type coated metal substrate into a plurality of n-type coated thermoelectric arms; S2, depositing a coating including a third bonding layer, a p-type thermoelectric thin film, a second bonding layer, and a solder layer on the surface of the metal substrate in sequence to obtain a p-type coated metal substrate, and then dividing the p-type coated metal substrate into a plurality of p-type coated thermoelectric arms; The first bonding layer adopts a composite film of one or more of Ag, Ti, Ta, W, Au and their nitrides, and the thickness of the first bonding layer is 150nm to 500nm; the second bonding layer adopts a composite film of one or more of Ni, Ti, Au, W and their nitrides, and the thickness of the second bonding layer is 2um to 5um; the third bonding layer adopts a composite film of one or more of Cr, Ti, Ta, W, Au and their nitrides, and the thickness of the third bonding layer is 150nm to 500nm; S3, fixing the n-type film-coated thermoelectric arm and the p-type film-coated thermoelectric arm in a mold, and hot-pressing welding them with a substrate with electrodes to obtain a thermoelectric thin film device.

2. The method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm according to claim 1, characterized in that: In steps S1 and S2, a single surface of the metal substrate is coated, or both the upper and lower surfaces of the metal substrate are coated, and then the metal substrate is segmented.

3. The method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm according to claim 2, characterized in that: In steps S1 and S2, a metal substrate with a single surface coated and / or a metal substrate with a film coated on both the upper and lower surfaces are stacked in any number of layers, hot pressed, and then divided.

4. The method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm according to claim 1, characterized in that: The material of the solder layer is Sn, and the thickness of the solder layer is 15um-20um.

5. The method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm according to claim 1, characterized in that: The metal matrix material is one of Cu, Al, Ag and alloys thereof, and the metal matrix is ​​in sheet form with a thickness of 100um to 1000um.

6. The method for preparing a thermoelectric thin film device having a film-coated thermoelectric arm according to any one of claims 1 to 5, characterized in that: In steps S1 and S2, the deposition temperature of the n-type thermoelectric film and the p-type thermoelectric film is not less than 200°C.

7. A thermoelectric thin film device having a film-coated thermoelectric arm, characterized in that: The method is prepared by the method according to any one of claims 1 to 6.

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