In-situ preparation method of support-free non-epitaxial polycrystalline thermoelectric thin film
By applying adhesive to the surface of the polycrystalline thermoelectric film and peeling it off with solution tension, the problem of difficulty in characterizing the thermoelectric properties of the film and complex preparation is solved, and efficient, stable preparation and property protection of the unsupported film is achieved.
Patent Information
- Application Number
- CN202310868501.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-14
- Publication Date
- 2025-01-14
AI Technical Summary
The prior art is difficult to accurately characterize the thermoelectric properties of thin film thermoelectric materials, and traditional methods require expensive equipment and complex operations or change the film-substrate interface when preparing unsupported films, affecting the properties of the film.
Unsupported polycrystalline thermoelectric film preparation is achieved by coating the surface of the polycrystalline thermoelectric film, and peeling the film in the degreasing solution using solution tension, transferring it to the porous substrate, thereby avoiding the replacement of the intermediate layer and substrate.
Unsupported film preparation without changing the properties of the film is achieved, reducing experimental costs and operational complexity, expanding the selection range of substrates, and suitable for characterization of a variety of thermal properties.
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Figure CN119317342A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of thin films, and in particular to an in-situ preparation method of an unsupported non-epitaxial polycrystalline thermoelectric thin film. Background Art
[0002] With the development of 5G technology, the increasingly widespread multifunctional sensors and sensor arrays have an increasingly urgent need for distributed energy. Thermoelectric materials and devices can realize the direct conversion between thermal energy and electrical energy. They can not only use the medium and low-grade thermal energy in the environment to provide distributed and mobile energy, but also further alleviate the current energy shortage, environmental pollution and other problems. As product demand continues to develop towards miniaturization and flexibility, research on thin-film thermoelectric materials has become more extensive. Improving the thermoelectric properties of thin films has become an important topic in thermoelectric research, and how to accurately characterize the thermoelectric performance of thin films has become a key issue in this field.
[0003] For thin film thermoelectric materials, due to their thin thickness, they usually need a substrate to support them. When studying the intrinsic physical and chemical properties of thin film materials, especially thermodynamically related properties such as thermal conductivity and thermal diffusion coefficient, the substrate will have a non-negligible influence in the measurement, resulting in the inability to obtain true and accurate data. Therefore, it is necessary to exclude the substrate factor and prepare a suspended film without substrate support. At the same time, different thermoelectric thin film materials will be prepared on different substrates during the experimental design stage according to different preparation methods, usage scenarios, and scope of application. Even the same material will exhibit different properties on different substrates. Therefore, when obtaining an unsupported film, an in-situ preparation method should be sought to avoid introducing other factors in the process and destroying the crystallinity, grain orientation and other properties of the polycrystalline film.
[0004] There are currently two main methods for obtaining unsupported thin films. One is to use photolithography and etching technology to "hollow out" the substrate on the back of the film. Although this method has no restrictions on the type of thin film material, the substrate material is usually limited to Si wafers, and this method requires the use of photolithography, ion etching and other technologies, the equipment is expensive, and the operation is complicated. Another method is to use a soluble substrate or an intermediate sacrificial layer to separate the film from the substrate, and then transfer the film. In this method, the material in contact with the film is changed from the original substrate to a soluble substrate material or a sacrificial layer material, which changes the film-substrate interface in the original experiment, will affect the properties of the film, and thus make the obtained unsupported thin film material lose its representative significance. Therefore, it is very important to develop a simple method for preparing polycrystalline thermoelectric films without substrate support in situ. Summary of the invention
[0005] In order to overcome the deficiencies of the prior art, the present invention provides an in-situ preparation method of an unsupported non-epitaxial polycrystalline thermoelectric thin film.
[0006] The technical key of the present invention is that the non-epitaxial polycrystalline thermoelectric film has a weak bonding force with the substrate. By coating an adhesive on the surface of the film, and then using the solution tension in the debonding agent, the polycrystalline film and the substrate are peeled off, and then transferred to a porous substrate to obtain an unsupported polycrystalline thermoelectric film. Since no intermediate layer is introduced or the substrate used for growing the film is replaced during the process, the original properties of the film are not changed. At the same time, the range of choices for the film and substrate is greatly increased.
[0007] To achieve the above object, the technical solution of the present invention is as follows:
[0008] An in-situ preparation method of an unsupported polycrystalline thermoelectric film, the method comprising the following steps:
[0009] (1) coating an adhesive on a non-epitaxial polycrystalline thermoelectric thin film sample and then performing a film hardening process;
[0010] (2) soaking the sample obtained in step (1) in a debonding solution, causing the polycrystalline thermoelectric film to warp, crack, and fall off to form film fragments suspended in the debonding agent;
[0011] (3) Using a porous substrate to pick up the film fragments suspended in the degumming solution, and placing them in a clean degumming solution for cleaning and picking up until the film fragments are located at the holes and completely cover the holes, thus obtaining a polycrystalline thermoelectric film without substrate support.
[0012] Preferably, in the step (1), the non-epitaxial polycrystalline thermoelectric film sample is a polycrystalline thermoelectric film deposited on a substrate, and the polycrystalline thermoelectric film and the substrate are in a non-epitaxial growth relationship, and the thickness of the polycrystalline thermoelectric film is 100-1000nm, preferably 100-500nm; the film is preferably a tellurium-containing compound, such as germanium telluride, silver antimony telluride material.
[0013] Preferably, in step (1), the adhesive is photoresist or PMMA.
[0014] Preferably, in step (2), the degumming liquid is selected according to the type of adhesive, preferably acetone or 1-methyl-2-pyrrolidone.
[0015] Preferably, in step (2), the soaking time is 0.5h-24h, preferably 1h-3h.
[0016] Preferably, in step (3), the pore diameter of the porous substrate is 50-200 μm, preferably 100-200 μm.
[0017] Preferably, in step (3), the porous substrate is a conductive substrate or an insulating substrate.
[0018] The beneficial effects of the present invention are:
[0019] (1) The present invention has high universality for polycrystalline thermoelectric thin film materials, and the process is stable and easy to repeat, and has high operability;
[0020] (2) The present invention does not require the growth of an intermediate sacrificial layer or the replacement of the original thin film growth substrate, and does not change the film-substrate interface, thus having no effect on the crystallinity, grain orientation and other properties of the film;
[0021] (3) The present invention does not require the use of etching methods such as reactive ion etching, inductively coupled plasma reactive ion etching, and ion beam etching, which is convenient to operate, saves time, and greatly reduces experimental costs;
[0022] (4) The present invention does not require the use of acidic or alkaline degumming liquid, thus avoiding the possible chemical reaction between the film material and the degumming liquid;
[0023] (5) The unsupported thermoelectric thin film material prepared by the present invention can be used for the characterization and method development of various thermal properties, such as thermal conductivity, thermal diffusion coefficient and other thermodynamic parameters. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The present invention is a flow chart of the method for preparing a non-epitaxial polycrystalline thermoelectric thin film without substrate support. DETAILED DESCRIPTION
[0025] The following is a specific implementation of the present invention, which is used for more detailed and specific description, but is by no means limited to this embodiment.
[0026] Example 1
[0027] The method in this embodiment comprises the following steps:
[0028] 1) A single-sided polished quartz substrate with a size of 10 mm × 10 mm and a thickness of 500 μm was used as a substrate. After ultrasonic cleaning in acetone, isopropanol, and clean water, a silver antimony telluride thin film was deposited on the polished surface of the cleaned quartz substrate by magnetron sputtering. Then, the sample was annealed at 300°C for 1 hour.
[0029] 2) Spin-coat the annealed film with photoresist LOR5A at a speed of 3000 rpm for 1 min. After coating, place the substrate on a hot plate at 170°C for pre-baking for 3 min. Spin-coat the photoresist AZ1500 at a speed of 4000 rpm for 30 s. After coating, place the substrate on a hot plate at 100°C for mid-baking for 3 min. No exposure or development is required.
[0030] 3) Soak the sample in the degumming solution 1-methyl-2-pyrrolidone at room temperature. After soaking, the film can be observed to be warped. Shake the solution and the film fragments will fall off.
[0031] 4) Use a porous stainless steel plate with a thickness of 500um and multiple pores with a size of 100um to pick up the film fragments, soak them in clean 1-methyl-2-pyrrolidone, pick them up again, and then soak them in clean acetone. Repeat one or more times after picking them up to complete the cleaning, and a silver antimony tellurium thermoelectric film without substrate support can be obtained at the through hole.
[0032] Example 2
[0033] The method in this embodiment comprises the following steps:
[0034] 1) A 10 mm × 10 mm, 500 μm thick single-sided polished alumina single crystal (0001) was used as a substrate. After ultrasonic cleaning in acetone, isopropanol, and clean water, a germanium telluride film was deposited on the polished surface of the cleaned quartz substrate by magnetron sputtering. The sample was then annealed at 300°C for 1 h.
[0035] 2) Spin-coat the PMMA solution on the annealed film at a speed of 3000 rpm for 1 min. After coating, place the substrate on a hot plate at 180°C and heat for 5 min.
[0036] 3) Soak the sample in acetone at room temperature. After soaking, the film can be observed to be warped. Shake the solution and the film fragments will fall off.
[0037] 4) Use a porous stainless steel plate with a thickness of 500um and multiple pores of 100um to pick up the film fragments, and soak them in clean acetone after picking them up. Repeat one or more times after picking them up to complete the cleaning, and a germanium telluride film without substrate support can be obtained at the through hole.
[0038] The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principles of the present invention should all be included within the scope of the present invention.
Claims
1. A method for in-situ preparation of an unsupported non-epitaxial polycrystalline thermoelectric thin film, characterized in that: The method comprises the following steps: (1) coating an adhesive on a non-epitaxial polycrystalline thermoelectric thin film sample and then heating it on a hot plate to complete a film hardening process; (2) soaking the sample obtained in step (1) in a debonding solution, causing the polycrystalline thermoelectric film to warp, crack, and fall off to form film fragments suspended in the debonding agent; (3) Using a porous substrate to pick up the film fragments suspended in the degumming solution, and placing them in a clean degumming solution for cleaning and picking up until the film fragments are located at the holes and completely cover the holes, thus obtaining a polycrystalline thermoelectric film without substrate support.
2. The in-situ preparation method according to claim 1, characterized in that: In the step (1), the non-epitaxial polycrystalline thermoelectric film sample is a polycrystalline thermoelectric film deposited on a substrate, and the polycrystalline thermoelectric film and the substrate are in a non-epitaxial growth relationship, and the thickness of the polycrystalline thermoelectric film is 100-1000nm.
3. The in-situ preparation method according to claim 1, characterized in that: In the step (1), the adhesive is photoresist or PMMA.
4. The in-situ preparation method according to claim 1, characterized in that: In the step (2), the soaking time is 0.5h-24h.
5. The in-situ preparation method according to claim 1, characterized in that: In the step (3), the diameter of the pores of the porous substrate is 50-200 μm.
6. The in-situ preparation method according to claim 1, characterized in that: In the step (3), the porous substrate is a conductive substrate or an insulating substrate.