CN112038472B - Bismuth telluride-based thin film thermoelectric module manufacturing method, thermoelectric module and thermoelectric generator - Google Patents
Bismuth telluride-based thin film thermoelectric module manufacturing method, thermoelectric module and thermoelectric generator Download PDFInfo
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Abstract
The invention discloses a manufacturing method of a bismuth telluride-based thin film thermoelectric module, the thermoelectric module and a thermoelectric generator, wherein the manufacturing method comprises the following steps: depositing a silicon dioxide film layer on a heat sink substrate; preparing a plurality of metal strips which are arranged at intervals on the silicon dioxide film layer; alternately depositing a P-type bismuth telluride-based film and an N-type bismuth telluride-based film on the upper surfaces of the silicon dioxide film layers between different metal strips to obtain a first semi-finished product; coating photoresist on the upper surface of the first semi-finished product, and removing part of the photoresist on the metal strips, so that the metal strips with the photoresist removed and the metal strips without the photoresist removed are alternately arranged; depositing a metal layer on the metal strip from which the photoresist is removed to obtain a second semi-finished product; coating photoresist on the upper surface of the second semi-finished product, and removing the photoresist on the metal layer; a thermally conductive insulating layer is deposited over the photoresist-removed metal layer. The invention realizes the expandability of the planar bismuth telluride-based thin film thermoelectric generator by utilizing MEMS micromachining technology and thin film deposition technology.
Description
Technical Field
The invention relates to the field of thermoelectric material power generation, in particular to a manufacturing method of a planar bismuth telluride-based thin film thermoelectric module, the thermoelectric module and a thermoelectric generator.
Background
The environment energy collection technology is expected to realize the application of the portable, wearable and distributed sensor network system in the Internet of things society. Available energy sources include sunlight, indoor lighting, radio waves, mechanical vibrations, and heat. Efficient use of thermal energy has long been a problem, and Thermoelectric (TE) generators that utilize the Seebeck effect to convert temperature differences into electrical energy have received widespread attention. The energy conversion efficiency produced by TE is primarily dependent on the advantages of TE materials, zt=s 2σT k-1, where S represents the Seebeck coefficient, σ and k represent the electrical and thermal conductivity, respectively, and T represents the average temperature of the cold and heat source. Increasing ZT can increase conversion efficiency, but the correlation between S, σ and k prevents this. Only a few materials, such as bismuth-tellurium, lead-tellurium, are known to achieve high conversion efficiencies.
Over the last two decades, the basic understanding of electrical and heat transfer has increased. With the help of micro-nano technology, this understanding has led to a substantial enhancement of the properties of TE materials. Bismuth telluride based low dimensional materials have become promising candidates for TE due to the low thermal and high electrical conductivity characteristics that remain. Bismuth telluride based TE generators, which are highly compatible with MEMS technology, low pollution (unlike Pb), are also increasingly being manufactured and reported.
Thermoelectric (TE) phenomena are also known as thermoelectric phenomena. In 1822, thomas Seebeck found the thermoelectromotive effect (TE material power generation principle); in 1834 Jean Peltier discovered a cooling effect at the junction interface of two dissimilar materials in the current loop (TE material cooling principle). Some good semiconductor TE materials were found in the 50 s of the 20 th century. Materials with ZT > 0.5 are commonly referred to as TE materials. The larger the ZT, the higher the TE device efficiency. In order to overcome the obstacle of lack of high ZT value TE material types, people turn to the structural design of natural TE material and the development of artificial synthetic TE material, namely a low-dimensional thermoelectric material. Mesophysical theory studies show that under the same working conditions, the TE material with the low-dimensional thin film structure has a higher ZT value than other bulk materials.
To date, there are three typical classes of TE materials of low-dimensional thin film structure: (1) A quantum dot structure (quantum-dot structure) to increase the state density of near fermi level by means of quantum confinement effect (quantum-confinement effects), thereby increasing the conductivity of the material; (2) Phonon low-pass/electron high-pass superlattices (photo-blocking/electron-TRANSMITTING SUPERLATTICES), which structures reduce the lattice thermal conductivity (kL) of the material by introducing so-called "acoustic-mismatch" between the superlattice components, unlike conventional TE alloy materials, which typically have a significantly reduced carrier scattering rate, i.e. a high electrical conductivity is obtained; (3) A thin film structure material that utilizes the electron thermal effect (thermionic EFFECTS IN heterostructures) of a semiconductor heterojunction to increase the ZT value of the material. Hicks and Dresslhaus suggest that quantum well superlattices can greatly increase the ZT value of the material, while quantum wire superlattices can even bring about a larger increase.
Heretofore, the main materials are such as bismuth intermetallic compounds bismuth telluride (Bi 2Te3), lead telluride (PtTe), zinc antimonide (ZnSb), germanium, iron silicide (FeSi 2) and the like, among which, particularly, bi 2Te3 -based compounds have a large ZT value at relatively low temperatures, rising from room temperature to about 450K, and are currently widely used thermoelectric conversion materials. The research of the novel low-dimensional TE structural material has great theoretical and application values. It was found that high ZT value materials (ZT > 4) will lead to a technological revolution in the refrigeration industry, the energy industry and the semiconductor microelectronics industry. Although quantum dots or superlattice materials can obtain thermoelectric materials with dimensionless figure-of-merit factors of more than 2, the application of the quantum dots or superlattice materials is limited by factors such as complex process, high cost, difficult mass production and the like for manufacturing devices by using similar structural materials, so that the development of thermoelectric devices with micro-nano structures is probably a more realistic approach for the industrialized application of thermoelectric materials. In the conventional structure of planar bismuth telluride-based TE generators, bismuth telluride-based thin films are typically employed suspended over the cavities to sever the bypasses. Although the cavity guarantees the temperature difference at two ends of the film, the structure weakens the mechanical strength of the device and greatly increases the manufacturing cost.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a manufacturing method of a planar bismuth telluride-based thin film thermoelectric module, the thermoelectric module and a thermoelectric generator, and the technical scheme is as follows:
In one aspect, the present invention provides a method of fabricating a planar bismuth telluride-based thin film thermoelectric module comprising the steps of:
S1, depositing a silicon dioxide film layer on a heat sink substrate;
s2, preparing a plurality of metal strips which are arranged at intervals on the silicon dioxide film layer;
S3, alternately depositing a P-type bismuth telluride-based film and an N-type bismuth telluride-based film on the upper surface of the silicon dioxide film layer between different metal strips, so that one side of each metal strip is deposited with the P-type bismuth telluride-based film, and the other side is deposited with the N-type bismuth telluride-based film, and obtaining a first semi-finished product;
S4, coating photoresist on the upper surface of the first semi-finished product, and removing part of the photoresist on the metal strips, so that the metal strips with the photoresist removed and the metal strips without the photoresist removed are alternately arranged;
s5, depositing a metal layer on the metal strip from which the photoresist is removed to obtain a second semi-finished product;
S6, coating photoresist on the upper surface of the second semi-finished product, and removing the photoresist on the metal layer deposited in the step S5;
And S7, depositing a heat conduction insulating layer on the metal layer from which the photoresist is removed.
Further, after the step S7 is performed, a removal operation is performed on the thermally conductive and insulating layer deposited outside the metal layer.
Further, before step S1, the method further includes: and (3) carrying out micro-arc oxidation treatment on the upper surface and the lower surface of the heat sink substrate to obtain a ceramic oxide layer, wherein the thickness range of the ceramic oxide layer is 5-15 mu m.
Further, the thickness of the metal belt is 10-30 mu m, the length is 15-30mm, and the width is 0.8-1.2 mu m; the thickness range of the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film is 30-80nm, the length range is 0.8-1.2 mu m, and the width range is 0.6-0.8 mu m.
Further, the thickness range of the silicon dioxide film layer deposited in the step S1 is 80-120 mu m, and the amorphous silicon film is rapidly deposited by adopting a PECVD method and then is obtained by wet oxygen high-temperature oxidation; the thickness range of the photoresist coated in the step S4 and the photoresist coated in the step S6 is 50-100 mu m; s5, the thickness of the metal layer deposited in the step S50-100 mu m; and S7, the thickness of the heat conduction insulating layer in the step of S7 ranges from 50 to 100 mu m, and the heat conduction insulating layer is made of aluminum nitride.
In another aspect, the invention provides a planar bismuth telluride-based thin film thermoelectric module, comprising a heat sink substrate, a silicon dioxide film layer, a plurality of first metal strips, a plurality of second metal strips, a bismuth telluride-based thin film, photoresist and a heat conducting insulating layer, wherein the silicon dioxide film layer is arranged on the upper surface of the heat sink substrate, and the first metal strips and the second metal strips are alternately arranged on the upper surface of the silicon dioxide film layer at intervals; the adjacent first metal belt and the second metal belt are connected and conducted through bismuth telluride-based films deposited on the silicon dioxide film layer, the bismuth telluride-based films comprise a P-type bismuth telluride-based film and an N-type bismuth telluride-based film, different types of bismuth telluride-based films are distributed on two sides of the first metal belt and the second metal belt, and one or more bismuth telluride-based films of the same type are distributed between the adjacent first metal belt and the second metal belt;
The surface of the second metal strip is covered by the heat conductive insulating layer, and the surface covered by the heat conductive insulating layer is covered by the photoresist except for the surface covered by the heat conductive insulating layer, wherein the height of the heat conductive insulating layer is larger than the height of the photoresist.
Further, the adjacent first metal strips and the second metal strips are arranged at equal intervals, the width of the first metal strips is the same as that of the second metal strips, and the lengths of the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film are equal to the distance between the adjacent first metal strips and the second metal strips.
Further, the thickness of the second metal belt is not smaller than that of the first metal belt, the thickness of the first metal belt ranges from 10 mu m to 30 mu m, the length ranges of the first metal belt and the second metal belt ranges from 15mm to 30mm, the width ranges of the first metal belt and the second metal belt ranges from 0.8 mu m to 1.2 mu m, the first metal belt and the second metal belt are made of the same or different materials, and the first metal belt and the second metal belt are made of aluminum, gold or silver.
Further, the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film are alternately arranged on the upper surface of the silicon dioxide film layer at intervals in rows;
The pitch in the longitudinal direction of a plurality of bismuth telluride-based thin films of the same type between adjacent first metal strips and second metal strips is equal to the width of the bismuth telluride-based thin films of the same type.
In yet another aspect, the present invention provides a thermoelectric generator comprising the planar bismuth telluride-based thin film thermoelectric module described above.
The technical scheme provided by the invention has the following beneficial effects:
a. the planar bismuth telluride-based thin film thermoelectric module and the thermoelectric generator have good expansibility by utilizing MEMS micromachining technology and thin film deposition technology;
b. The length of bismuth telluride-NW is shortened to submicron scale, so that the thermoelectric power density is effectively improved;
c. The method is suitable for the synthesis and preparation of planar film TE generators of various material systems, and has strong applicability;
d. the application range is wide, and the method can be widely applied to the fields of portable, wearable, distributed sensor network systems and the like.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a front cross-sectional view of a planar bismuth telluride-based thin film thermoelectric generator provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of a top layer structure of a planar bismuth telluride-based thin film thermoelectric generator provided by an embodiment of the present invention;
Fig. 3 is a block diagram of a planar bismuth telluride-based thin film thermoelectric generator unit provided by an embodiment of the present invention.
Wherein, the reference numerals include: the semiconductor device comprises a 1-heat sink substrate, a 2-silicon dioxide film layer, a 3-first metal belt, a 4-second metal belt, a 5-P type bismuth telluride-based film, a 6-N type bismuth telluride-based film, a 7-heat conduction insulating layer and 8-photoresist.
Detailed Description
For better understanding of the present invention, the objects, technical solutions and advantages thereof will be more clearly understood by those skilled in the art, and the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the implementation manner not shown or described in the drawings is a manner known to those of ordinary skill in the art. Additionally, although examples of parameters including particular values may be provided herein, it should be appreciated that the parameters need not be exactly equal to the corresponding values, but may be approximated to the corresponding values within acceptable error margins or design constraints. It will be apparent that the described embodiments are merely some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, in the description and claims, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements that are expressly listed or inherent to such process, method, article, or device.
In one embodiment of the present invention, there is provided a method of manufacturing a planar bismuth telluride-based thin film thermoelectric module, comprising the steps of:
S1, depositing a silicon dioxide film layer on a heat sink substrate;
s2, preparing a plurality of metal strips which are arranged at intervals on the silicon dioxide film layer;
S3, alternately depositing a P-type bismuth telluride-based film and an N-type bismuth telluride-based film on the upper surface of the silicon dioxide film layer between different metal strips, so that one side of each metal strip is deposited with the P-type bismuth telluride-based film, and the other side is deposited with the N-type bismuth telluride-based film, and obtaining a first semi-finished product;
S4, coating photoresist on the upper surface of the first semi-finished product, and removing part of the photoresist on the metal strips, so that the metal strips with the photoresist removed and the metal strips without the photoresist removed are alternately arranged;
s5, depositing a metal layer on the metal strip from which the photoresist is removed to obtain a second semi-finished product;
S6, coating photoresist on the upper surface of the second semi-finished product, and removing the photoresist on the metal layer deposited in the step S5;
And S7, depositing a heat conduction insulating layer on the metal layer from which the photoresist is removed.
Wherein, before step S1, the method further comprises: micro-arc oxidation treatment is carried out on the upper surface and the lower surface of the heat sink substrate to obtain a ceramic oxide layer, wherein the thickness range of the ceramic oxide layer is 5-15 mu m; after the step S7 is performed, removing the heat conducting insulating layer deposited outside the metal layer, specifically removing the redundant heat conducting insulating layer by electron beam evaporation;
Specifically, the thickness range of the silicon dioxide film layer deposited in the step S1 is 80-120 mu m, and an amorphous silicon film with loose structure is rapidly deposited by adopting a PECVD method and is obtained by wet oxygen high-temperature oxidation, wherein the density of the amorphous silicon film is less than 2.2g/cm 3; the metal strip produced in step S2 has a thickness in the range of 10-30 μm, preferably 20 μm, a length in the range of 15-30mm, preferably 20mm, and a width in the range of 0.8-1.2 μm, preferably 1 μm; the thickness ranges of the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film deposited in the step S3 are 30-80nm, preferably 50nm, the length ranges are 0.8-1.2 mu m, preferably 1 mu m, and the width ranges are 0.6-0.8 mu m, preferably 0.7 mu m; the photoresist coated in the step S4 and the photoresist coated in the step S6 are spin-coated by a photoresist homogenizer, and the thickness ranges of the photoresist are 50-100 mu m, and are all preferably SU8 photoresist; s5, the thickness of the metal layer deposited in the step S50-100 mu m; the thickness range of the heat conduction insulating layer in the S7 step is 50-100 mu m, and the heat conduction insulating layer is made of aluminum nitride; in the steps S3 to S7, metal strips, P-type bismuth telluride-based films, N-type bismuth telluride-based films and metal layers are deposited and photoresist and heat conducting insulating layers are removed through the processes of masking, electron beam evaporation, photoetching and the like. It should be noted that, the silicon dioxide film layer deposited on the heat sink substrate in this embodiment is mainly convenient for the above-mentioned metal belt and the photolithography process of bismuth telluride based film, and has certain electric insulation and thermal insulation properties, and based on the function of the silicon dioxide film layer, if the simple replacement of the silicon dioxide film layer material is also within the protection scope of this embodiment, for example, the silicon dioxide film layer can be doped to form a silicon oxynitride film layer, which has similar function as the silicon dioxide film layer, and has better electric insulation and thermal insulation properties.
In one embodiment of the invention, the heat sink substrate is an aluminum substrate subjected to surface micro-arc oxidation treatment, the micro-arc oxidation can be controlled by plasma electrolysis process parameters to adjust the thickness, compactness and heat conductivity of an oxide layer, and the aluminum substrate can be replaced by a copper substrate to perform surface micro-arc oxidation treatment according to requirements, the upper surface and the lower surface of the heat sink substrate are both ceramic oxide layers, and the thickness range of the ceramic oxide layers is 5-15 mu m, preferably 10 mu m; the material of the metal layer and the material of the metal belt corresponding to the metal layer can be the same or different, for example, when the metal belt is preferably an aluminum belt, the deposited metal layer can be an aluminum layer, or a gold layer or a silver layer can be deposited, and the silver belt or the gold belt can be used for replacing the aluminum belt on the premise of permitting cost.
In one embodiment of the present invention, there is provided a planar bismuth telluride-based thin film thermoelectric module, see fig. 1 and 2, comprising a heat sink substrate 1, a silicon dioxide film layer 2, a plurality of first metal strips 3, a plurality of second metal strips 4, a bismuth telluride-based thin film, a photoresist 8, and a thermally conductive insulating layer 7; the heat sink substrate 1 is an aluminum substrate or a copper substrate, preferably an aluminum substrate; the silicon dioxide film layer 2 is arranged on the upper surface of the heat sink substrate 1; the first metal strips 3 and the second metal strips 4 are alternately arranged on the upper surface of the silicon dioxide film layer 2 at intervals, the first metal strips 3 and the second metal strips 4 are made of the same or different materials, the first metal strips 3 and the second metal strips 4 are made of aluminum, gold or silver, and for economic reasons, the first metal strips 3 and the second metal strips 4 are all preferably aluminum strips; the adjacent first metal belt 3 and second metal belt 4 are connected and conducted through bismuth telluride base films deposited on the silicon dioxide film layer 2, the bismuth telluride base films comprise a P-type bismuth telluride base film 5 and an N-type bismuth telluride base film 6, the P-type bismuth telluride base film 5 and the N-type bismuth telluride base film 6 are thermoelectric materials with opposite Seebeck coefficient signs and deposited in the plane heat flow transmission direction, different types of bismuth telluride base films are distributed on two sides of the first metal belt 3 and the second metal belt 4, and one or more bismuth telluride base films of the same type are distributed between the adjacent first metal belt 3 and the adjacent second metal belt 4;
the surface of the second metal strip 4 is covered by the thermally conductive insulating layer 7, preferably made of aluminum nitride, for interfacing as a heat source for heat injection, except that the surface covered by the thermally conductive insulating layer 7 is covered by the photoresist 8, and the height of the thermally conductive insulating layer 7 is greater than the height of the photoresist 8.
In one embodiment of the present invention, the adjacent first metal strips 3 and second metal strips 4 are arranged at equal intervals, the width of the first metal strip 3 is the same as the width of the second metal strip 4, the thickness of the second metal strip 4 is not smaller than the thickness of the first metal strip 3, preferably, the thickness of the second metal strip 4 is 60 μm larger than the thickness of the first metal strip 3, the thickness of the first metal strip 3 is 10-30 μm, the length of each of the first metal strip 3 and the second metal strip 4 is 15-30mm, preferably 20mm, and the width is 0.8-1.2 μm, preferably 1 μm;
The P-type bismuth telluride-based thin films 5 and the N-type bismuth telluride-based thin films 6 are alternately arranged on the upper surface of the silicon dioxide film layer 2in rows at intervals, the lengths of the P-type bismuth telluride-based thin films 5 and the N-type bismuth telluride-based thin films 6 are equal to the distance between the adjacent first metal belt 3 and the second metal belt 4, and the longitudinal intervals of a plurality of bismuth telluride-based thin films of the same type between the adjacent first metal belt 3 and the second metal belt 4 are equal to the width of the bismuth telluride-based thin films of the same type.
In one embodiment of the invention, the lengths and widths of the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film can be reduced to below 100nm on a processing platform with higher resolution, so that higher thermoelectric material performance and energy conversion efficiency are obtained; the cooperative control between the film dimension parameters in the steps S1 to S5 can modulate the heat flow transport and the current transport characteristics to obtain the highest electrical transmission performance and the lowest heat transmission performance, and the process flow is also suitable for the preparation of the gradient thermoelectric material energy conversion TE planar thin film generator, and it should be noted that the manufacturing method of the embodiment is also suitable for the preparation of the short planar thin film thermoelectric material TE generator with different components and without a cavity structure, and the bismuth telluride-based thin film in the embodiment can be replaced by similar high quality thermoelectric materials such as lead telluride-based and zhe silicon-based, and the equivalent replaced materials are also within the protection scope of the embodiment.
In one embodiment of the present invention, a thermoelectric generator is provided that includes a planar bismuth telluride-based thin film thermoelectric module as described above.
In one embodiment of the present invention, referring to fig. 3, the second metal strip 4 is directly contacted with a heat source through the heat conductive insulating layer 7 on the surface thereof to perform heat transfer, thereby forming a high temperature end at the bottom thereof, the first metal strip 3 is formed a low temperature end at the bottom thereof through heat transfer of a cold source, the first metal strip 3 is connected with the second metal strip 4 on one side thereof through a P-type bismuth telluride-based thin film 5, a temperature difference occurs at both ends of the P-type bismuth telluride-based thin film 5, referring to fig. 2, a bismuth telluride-based thin film generator without a cavity structure, as shown by thick arrows, a heat flow is perpendicular to a silicon substrate, as shown by thin arrows, a heat flux forms a steep temperature gradient in the bismuth telluride-based thin film, a steep temperature gradient can be obtained with a short bismuth telluride-based thin film generator array, carriers on the P-type bismuth telluride-based thin film 5 move from the high temperature end to the low temperature end due to the seebeck effect, the potential of the first metal belt 3 is smaller than that of the second metal belt 4 connected with the same P-type bismuth telluride-based film 5, likewise, the first metal belt 3 and the second metal belt 4 on the other side are connected through an N-type bismuth telluride-based film 6, the two ends of the N-type bismuth telluride-based film 6 also form potential differences, but because the signs of Seebeck coefficients of the N-type bismuth telluride-based film 6 and the P-type bismuth telluride-based film 5 are opposite, the potential of the first metal belt 3 is higher than that of the second metal belt 4 connected with the same N-type bismuth telluride-based film 6, the currents formed by the two potential differences are in the same direction, so that the second metal belt 4 on the two ends of the first metal belt 3 is larger, a plurality of bismuth telluride-based films exist between the adjacent first metal belt 3 and the second metal belt 4, the presence of a plurality of groups of the above-mentioned first metal strip 3 and second metal strip 4 is added, eventually leading to a further expansion of the potential difference, so as to increase the generation of higher power. It should be noted that, the seebeck effect belongs to the prior art, and the cause of the seebeck effect can be simply explained as that carriers in a conductor move from a hot end to a cold end under a temperature gradient and are accumulated at the cold end, so that a potential difference is formed inside a material, and meanwhile, a reverse charge flow is generated under the action of the potential difference, when the charge flow of thermal motion and an internal electric field reach dynamic balance, stable thermoelectromotive force is formed at two ends of a semiconductor, and two carriers, namely electrons and holes, exist in the semiconductor.
The invention relates to a design method of a semiconductor device, in particular to a design method of a semiconductor thermoelectric generator, and specifically relates to a design and preparation method of a planar bismuth telluride-based thin film Thermoelectric (TE) generator designed and prepared by combining MEMS micro-processing technology and thin film deposition technology. In order to solve the problems of low efficiency, large temperature difference, difficult realization of high energy density heat sources and the like of the traditional semiconductor thermoelectric device, the invention provides a preparation method of a planar bismuth telluride-based thin film Thermoelectric (TE) generator, so as to overcome the defects of the prior art; the invention obtains an effective temperature gradient maintaining structure through novel heat source and heat sink material selection and structural design, and then deposits the P type/N type thermoelectric material in the plane heat flow transmission direction by utilizing the property that the Seebeck coefficient of the P type/N type thermoelectric material has opposite signs, thereby obtaining the Thermoelectric (TE) generator with the power density reaching 20mW/cm 2 ℃ at the temperature difference.
The invention provides a manufacturing method of a planar bismuth telluride-based thin film thermoelectric module, the thermoelectric module and a thermoelectric generator, which utilize MEMS micro-processing technology and thin film deposition technology to design and prepare a short planar bismuth telluride-based thermoelectric generator without a cavity structure. This novel design concept takes advantage of the steep temperature gradient that forms near the main heat flow, by shortening the bismuth telluride-based NW to sub-micron lengths, the power density of the generator of the present invention is more scalable than conventional planar bismuth telluride-based thermoelectric generators. The thermoelectric device for heat flow and current transmission parallel to the thin film plane has great promotion on improving the performance of the semiconductor thermoelectric device, and can be widely applied to the fields of portable, wearable, distributed sensor network systems and the like.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (8)
1. A method of manufacturing a planar bismuth telluride-based thin film thermoelectric module comprising the steps of:
S1, depositing a silicon dioxide film layer on a heat sink substrate;
s2, preparing a plurality of metal strips which are arranged at intervals on the silicon dioxide film layer;
S3, alternately depositing a P-type bismuth telluride-based film and an N-type bismuth telluride-based film on the upper surface of the silicon dioxide film layer between different metal strips, so that one side of each metal strip is deposited with the P-type bismuth telluride-based film, and the other side is deposited with the N-type bismuth telluride-based film, and obtaining a first semi-finished product;
S4, coating photoresist on the upper surface of the first semi-finished product, and removing part of the photoresist on the metal strips, so that the metal strips with the photoresist removed and the metal strips without the photoresist removed are alternately arranged;
s5, depositing a metal layer on the metal strip from which the photoresist is removed to obtain a second semi-finished product;
S6, coating photoresist on the upper surface of the second semi-finished product, and removing the photoresist on the metal layer deposited in the step S5;
s7, depositing a heat conduction insulating layer on the metal layer from which the photoresist is removed;
after performing step S7, removing the thermally conductive and insulating layer deposited outside the metal layer is further included.
2. The method of manufacturing a planar bismuth telluride-based thin film thermoelectric module according to claim 1, further comprising, prior to step S1: and (3) carrying out micro-arc oxidation treatment on the upper surface and the lower surface of the heat sink substrate to obtain a ceramic oxide layer, wherein the thickness range of the ceramic oxide layer is 5-15 mu m.
3. The method of manufacturing a planar bismuth telluride based thin film thermoelectric module according to claim 1, wherein the metal strip has a thickness ranging from 10 to 30 μm, a length ranging from 15 to 30mm, and a width ranging from 0.8 to 1.2 μm; the thickness range of the P-type bismuth telluride-based thin film and the N-type bismuth telluride-based thin film is 30-80nm, the length range is 0.8-1.2 mu m, and the width range is 0.6-0.8 mu m.
4. The method for manufacturing a planar bismuth telluride based thin film thermoelectric module according to claim 1, wherein the thickness of the silicon dioxide film layer deposited in the step S1 ranges from 80 μm to 120 μm, and the amorphous silicon film is rapidly deposited by PECVD method and is then oxidized by wet oxygen at high temperature; the thickness range of the photoresist coated in the step S4 and the photoresist coated in the step S6 is 50-100 mu m; s5, the thickness of the metal layer deposited in the step S50-100 mu m; and S7, the thickness of the heat conduction insulating layer in the step of S7 ranges from 50 to 100 mu m, and the heat conduction insulating layer is made of aluminum nitride.
5. The planar bismuth telluride-based thin film thermoelectric module is characterized by comprising a heat sink substrate (1), a silicon dioxide film layer (2), a plurality of first metal strips (3), a plurality of second metal strips (4), a bismuth telluride-based thin film, photoresist (8) and a heat conduction insulating layer (7), wherein the silicon dioxide film layer (2) is arranged on the upper surface of the heat sink substrate (1), and the first metal strips (3) and the second metal strips (4) are alternately arranged on the upper surface of the silicon dioxide film layer (2) at intervals; the adjacent first metal belt (3) and the second metal belt (4) are connected and conducted through bismuth telluride-based films deposited on the silicon dioxide film layer (2), the bismuth telluride-based films comprise a P-type bismuth telluride-based film (5) and an N-type bismuth telluride-based film (6), and the P-type bismuth telluride-based film (5) and the N-type bismuth telluride-based film (6) are arranged on the upper surface of the silicon dioxide film layer (2) in a staggered interval manner; a plurality of bismuth telluride-based films of the same type between adjacent first metal strips (3) and second metal strips (4) have a pitch in the longitudinal direction equal to the width of the bismuth telluride-based films of the same type;
Different types of bismuth telluride-based films are distributed on two sides of the first metal belt (3) and the second metal belt (4), and one or more bismuth telluride-based films of the same type are distributed between the adjacent first metal belt (3) and the second metal belt (4);
The surface of the second metal belt (4) is covered by the heat conducting insulating layer (7), and the surface covered by the heat conducting insulating layer (7) is covered by the photoresist (8), wherein the height of the heat conducting insulating layer (7) is larger than the height of the photoresist (8).
6. The planar bismuth telluride-based thin film thermoelectric module as set forth in claim 5, wherein adjacent first metal strips (3) and second metal strips (4) are arranged at equal intervals, the width of the first metal strips (3) is the same as the width of the second metal strips (4), and the lengths of the P-type bismuth telluride-based thin film (5) and the N-type bismuth telluride-based thin film (6) are both equal to the distance between the adjacent first metal strips (3) and the second metal strips (4).
7. The planar bismuth telluride-based thin film thermoelectric module according to claim 6, wherein the thickness of the second metal strip (4) is not smaller than the thickness of the first metal strip (3), the thickness of the first metal strip (3) ranges from 10 to 30 μm, the length of each of the first metal strip (3) and the second metal strip (4) ranges from 15 to 30mm, the width ranges from 0.8 to 1.2 μm, the material of which the first metal strip (3) and the second metal strip (4) are made is the same or different, and the first metal strip (3) and the second metal strip (4) are made of aluminum, gold or silver.
8. A thermoelectric generator comprising a planar bismuth telluride based thin film thermoelectric module as claimed in any one of claims 5 to 7.
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