Superconducting thin film preparation method based on nanotechnology

Abstract

The invention discloses a superconducting thin film preparation method based on a nanotechnology, and the method comprises the steps: carrying out the cutting and cleaning of a substrate, carrying out the annealing process of the substrate, carrying out the nanodot modification of the substrate through the plasma-liquid interaction, obtaining a modified substrate, carrying out the sintering of a sputtering target material, carrying out the magnetron co-sputtering, and taking out a substrate tray, thereby obtaining a superconducting thin film. The superconducting thin film based on the nanotechnology is obtained, and the problems that in a traditional post-annealing method, the heating rate is low, and conversion is often not thorough enough are solved; the annealing function is that energy is given to bound atoms in a solid by utilizing high temperature, so that the bound atoms obtain the capability of position transition and migrate to a more stable position, and the annealing can enable crystals to be converted from an unstable non-equilibrium state to a stable equilibrium state, so that the purpose of solving the surface morphology of the superconducting thin film is achieved; and the annealing process is improved, so that the crystal conversion is more thorough, and a more pure-phase superconducting thin film is obtained.

Description

Technical Field

[0001] The invention relates to the field of thin film technology, and in particular to a method for preparing a superconducting thin film based on nanotechnology. Background Art

[0002] The application of superconducting materials is mainly concentrated in electronic devices, while electronic devices based on thin films have the advantages of integration and miniaturization. Compared with bulk materials, thin films are easier to obtain single phases to facilitate the research and analysis of material structure and characteristics. At present, the preparation methods of high-temperature superconducting thin films can be divided into two categories, physical deposition and chemical vapor deposition. Physical deposition is mainly divided into magnetron sputtering, electron beam evaporation, molecular beam epitaxy and pulsed laser deposition, etc. Chemical vapor deposition is divided into metal organic chemical vapor deposition and laser assisted chemical vapor deposition. Due to the different preparation methods, the prepared thin film materials have great differences in specific microstructure and macroscopic electrical properties. Among them, magnetron sputtering and laser deposition are two relatively effective methods for preparing high-temperature superconducting thin films. Laser deposition technology has high quality and simple process for preparing thin films, while magnetron sputtering can flexibly control the composition of the film to obtain a large area of ​​smooth surface composition and uniform thickness film.

[0003] However, in the traditional post-annealing method, the heating rate is low, and the crystallization process is mainly in the form of transformation. This transformation is often not thorough enough. In addition, when the precursor film undergoes high-temperature annealing, it takes a long time to cross other superconducting phase temperature zones. The entire preparation process takes a long time, so the generated superconducting film often presents an intergrowth phase, that is, in addition to the target superconducting phase, it also contains a lot of other superconducting phase components. In addition, the surface morphology of the superconducting film is not very good. The superconductivity of the intergrowth phase superconducting film is usually poor, and it is difficult to be used as a superconducting film for practical application.

[0004] The sputtering method requires the introduction of inert gas and reactive gas into the vacuum chamber. The high voltage applied between the cathode (target material) and the anode (substrate) will break down the gas. The ions generated after ionization are accelerated toward the target material under the action of the electric field, bombarding the target material so that the material on the target material is sputtered onto the substrate to form a thin film deposition. The crystallization state and superconductivity of the thin film often depend on the step of sintering the precursor film. During the high-temperature sintering process, Tl2O3 volatilizes severely, resulting in the disadvantages of difficult control of the thickness of the superconducting film, uneven distribution of component thickness, and difficult control of the film composition. Summary of the invention

[0005] In order to overcome the above technical problems, the object of the present invention is to provide a method for preparing a superconducting thin film based on nanotechnology:

[0006] (1) Cutting and cleaning the substrate, performing an annealing process on the substrate substrate, utilizing plasma-liquid interaction to perform nano-dot modification on the substrate substrate to obtain a modified substrate, sintering the sputtering target, placing the modified substrate substrate on a tray, transferring it into a vacuum chamber, not removing the target baffle, performing empty target plating, after the empty target plating is completed, removing the baffle, performing magnetron co-sputtering, and then taking out the substrate tray to obtain a superconducting film based on nanotechnology, solving the problem that the heating rate in the traditional post-annealing method is low, the crystallization process is mainly in the form of transformation, this transformation is often not thorough enough, the superconductivity of the intergrowth phase superconducting film is usually poor, and it is difficult to be used as a superconducting film for practical application;

[0007] (2) placing the cleaned substrate wafer into a vacuum tube high temperature furnace, flowing O2 into the furnace, raising the temperature from room temperature to 100°C, then to 500°C, and then to 1100°C and maintaining the temperature there, then lowering the temperature to 800°C, then to 500°C, and finally naturally cooling to room temperature and taking it out, thus completing the annealing of the substrate wafer, thus solving the problem that the traditional precursor film undergoes a long time in other superconducting phase formation temperature zones during high temperature annealing, and the surface morphology of the superconducting film is also poor;

[0008] (3) mixing chloroauric acid solution with sodium dodecyl sulfate, depositing the mixture on the annealed substrate by solution deposition, using the chloroauric acid sodium dodecyl sulfate solution as the cathode, discharging, centrifuging, and drying to complete the nano-dot modification of the substrate to obtain a modified substrate, thereby solving the problem of too few modified points on the substrate during the process of controlling the formation of the thin film by the magnetron sputtering method;

[0009] (4) BaO2, CaO and CuO are mixed and ground, and then calcined in a flowing oxygen environment. After cooling, they are crushed and ground to obtain an intermediate A. Intermediate A is calcined in a flowing oxygen environment, cooled and crushed to obtain an intermediate B. Tl2O3 powder is added to intermediate B, and the mixture is ground and pressed into tablets. The tablets are subjected to constant temperature treatment in a flowing oxygen environment to obtain a sintered target. The sintered target and the modified substrate are placed in a crucible together. The crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid temperature rise sintering. After sintering, a sputtering target is obtained, which solves the problem that the thickness of the superconducting film is difficult to control, the thickness distribution of the component is uneven, and the composition of the film is difficult to control due to the serious volatilization of Tl2O3 during the high-temperature sintering process.

[0010] The purpose of the present invention can be achieved through the following technical solutions:

[0011] A superconducting film based on nanotechnology is prepared by the following steps:

[0012] S1: Cut and clean the substrate to remove impurities such as oil stains on its surface during the production and cutting process. First, soak the substrate in dilute hydrochloric acid and apply ultrasonic vibration. The process does not exceed 5-10 minutes. Then rinse the substrate with clean water 3-4 times to wash away the hydrochloric acid. Then soak the substrate in acetone and apply ultrasonic vibration. The ultrasonic time is 30-50 minutes. Then soak the substrate in ethanol and apply ultrasonic vibration. The process is not less than 30-50 minutes to complete the cleaning of the substrate.

[0013] S2: performing an annealing process on the substrate substrate;

[0014] S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate;

[0015] S4: sintering the sputtering target;

[0016] S5: Place the modified substrate wafer on a tray and transfer it into a vacuum chamber. Do not remove the target baffle temporarily. Empty the target for 600-650s at a power of 250-280W. After the empty target plating is completed, remove the baffle and adjust the gas pressure in the magnetron co-sputtering chamber to 5-10Pa. The working gas is argon, the sputtering power is 50-55W, the deposition rate is 40-50nm / min, the distance from the sputtering target to the modified substrate wafer is 40-50mm, the sputtering time is 6-8h, and the target is naturally cooled in the chamber for 30-60min. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

[0017] As a further solution of the present invention: the substrate in step S1 is sapphire.

[0018] As a further solution of the present invention: the annealing process in step S2 includes the following steps:

[0019] Place the cleaned substrate wafer into a vacuum tube high-temperature furnace, and flow 02 into the furnace. First, increase the temperature from room temperature to 100℃ at a temperature change rate of 3-3.5℃ / min, then increase it to 500℃ at 4-4.5℃ / min, and then increase it to 1100℃ at 5-5.5℃ / min and keep it constant at this temperature for 24-36h. After the constant temperature ends, first reduce it to 800℃ at 3.5-4℃ / min, and then reduce it to 500℃ at 5-5.5℃ / min. Finally, cool it naturally to room temperature and take it out to complete the annealing of the substrate wafer.

[0020] As a further solution of the present invention: the preparation of the modified substrate in step S3 comprises the following steps:

[0021] S41: mixing the chloroauric acid solution with sodium dodecyl sulfate and stirring for 20-30 min to obtain a chloroauric acid sodium dodecyl sulfate solution;

[0022] S42: Deposit on the annealed substrate by solution deposition method, use chloroauric acid sodium dodecyl sulfate solution as cathode, set the discharge time to 20-30min, the discharge current to 20-25mA, the circulation flow rate of the reaction solution to 50-60mL / min, the flow rate of the working gas argon to 20-30sccm, set the solution constant temperature to 25-30℃ with a constant temperature magnetic stirrer and start stirring, centrifuge at 2500-2800r / min for 20-30min, and dry at 200-230℃ for 24-30h to complete the nanodot modification of the substrate to obtain a modified substrate.

[0023] As a further solution of the present invention: the mass ratio of the chloroauric acid solution to sodium dodecyl sulfate in step S41 is 7g:63g.

[0024] As a further solution of the present invention: the preparation of the sputtering target in step S4 comprises the following steps:

[0025] S61: BaO2, CaO and CuO are mixed and ground, and then calcined for 6-8 hours at 900-1000°C in a flowing oxygen environment, and then crushed and ground after cooling to obtain an intermediate A;

[0026] S62: calcining the intermediate A in a flowing oxygen environment at 900-1000° C. for 6-8 hours, cooling and crushing to obtain the intermediate B;

[0027] S63: Add Tl2O3 powder to the intermediate B, mix, grind and press the mixture into tablets. In a flowing oxygen environment, keep the temperature at 880-940°C for 1.5-3h to obtain a sintered target. Place the sintered target and the modified substrate together in a crucible. The crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid heating and sintering. The temperature is raised to 850-950°C at a temperature rise rate of 10°C / min and sintered for 5-8h to obtain a sputtering target.

[0028] As a further solution of the present invention: the mass ratio of BaO2, CaO and CuO in step S61 is 2g:5g:3g.

[0029] As a further solution of the present invention: the mass ratio of the intermediate B to Tl2O3 in step S63 is 13g:3g.

[0030] The method for preparing a superconducting thin film based on nanotechnology comprises the following steps:

[0031] S1: Cut and clean the substrate to remove impurities such as oil stains on its surface during the production and cutting process. First, soak the substrate in dilute hydrochloric acid and apply ultrasonic vibration. The process does not exceed 5-10 minutes. Then rinse the substrate with clean water 3-4 times to wash away the hydrochloric acid. Then soak the substrate in acetone and apply ultrasonic vibration. The ultrasonic time is 30-50 minutes. Then soak the substrate in ethanol and apply ultrasonic vibration. The process is not less than 30-50 minutes to complete the cleaning of the substrate.

[0032] S2: performing an annealing process on the substrate substrate;

[0033] S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate;

[0034] S4: sintering the sputtering target;

[0035] S5: Place the modified substrate wafer on a tray and transfer it into a vacuum chamber. Do not remove the target baffle temporarily. Empty the target for 600-650s at a power of 250-280W. After the empty target plating is completed, remove the baffle and adjust the gas pressure in the magnetron co-sputtering chamber to 5-10Pa. The working gas is argon, the sputtering power is 50-55W, the deposition rate is 40-50nm / min, the distance from the sputtering target to the modified substrate wafer is 40-50mm, the sputtering time is 6-8h, and the target is naturally cooled in the chamber for 30-60min. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

[0036] Beneficial effects of the present invention:

[0037] (1) The present invention cuts and cleans the substrate, performs an annealing process on the substrate, utilizes plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate, performs sputtering target sintering, places the modified substrate on a tray, transfers it into a vacuum chamber, does not remove the target baffle, performs empty target plating, removes the baffle after the empty target plating is completed, performs magnetron co-sputtering, and then takes out the substrate tray to obtain a superconducting film based on nanotechnology, thereby improving the annealing process, making the crystal transformation more thorough, and obtaining a more pure phase superconducting film;

[0038] (2) placing the cleaned substrate wafer into a vacuum tube high temperature furnace, flowing O2 into the furnace, raising the temperature from room temperature to 100°C, then to 500°C, and then to 1100°C and maintaining the temperature there. After the temperature is maintained at this temperature, the temperature is lowered to 800°C, and then to 500°C. Finally, the temperature is naturally cooled to room temperature and taken out, thereby completing the annealing of the substrate wafer. The purpose of annealing is to use high temperature to give energy to the bound atoms in the solid so that they can obtain the ability to transition to a more stable position. Annealing can transform the crystal from an unstable non-equilibrium state to a stable equilibrium state, thereby achieving the purpose of solving the surface morphology of the superconducting film.

[0039] (3) mixing chloroauric acid solution with sodium dodecyl sulfate, depositing the mixture on the annealed substrate by solution deposition, using chloroauric acid sodium dodecyl sulfate solution as cathode, discharging, centrifuging, drying, and completing the nano-dot modification of the substrate to obtain a modified substrate. The modified substrate can maintain stable performance even when exposed to humid air for a long time, and has low requirements for refrigeration. The effective pinning center can greatly improve the superconducting critical current of the high-temperature superconducting material, and has good pinning strength both under high magnetic field conditions and in the microwave field, thereby improving its practical application value. Artificially introducing nano-dots on the substrate surface can form extended pinning centers, which directly improve the superconducting critical current of the high-temperature superconducting film.

[0040] (4) BaO2, CaO and CuO are mixed and ground, and then calcined in a flowing oxygen environment, and then pulverized and ground after cooling to obtain an intermediate A. Intermediate A is calcined in a flowing oxygen environment, and then cooled and pulverized to obtain an intermediate B. Tl2O3 powder is added to intermediate B, and the mixture is mixed, ground and pressed into tablets, and then subjected to constant temperature treatment in a flowing oxygen environment to obtain a sintered target. The sintered target and the modified substrate substrate are placed in a crucible together, and the crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid temperature rise sintering. After sintering, a sputtering target is obtained, and each metal oxide can fully react in proportion to generate a relatively pure superconducting phase with less residual amount and too low TI ion content, so as to reduce the occurrence of enrichment phenomenon, thereby achieving the purpose of reducing the volatilization of surface components of the superconducting film; DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Embodiment 1:

[0043] This embodiment is a method for preparing a superconducting film based on nanotechnology. The superconducting film based on nanotechnology is prepared by the following steps:

[0044] S1: Cut and clean the substrate to remove impurities such as oil stains on its surface during the production and cutting process. First, soak the substrate in dilute hydrochloric acid and apply ultrasonic oscillation. The process should not exceed 5 minutes. Then, rinse the substrate with clean water for 3 times to wash away the hydrochloric acid. Then, soak the substrate in acetone and apply ultrasonic oscillation. The ultrasonic time is 30 minutes. Then, soak the substrate in ethanol and apply ultrasonic oscillation. The process should not be less than 30 minutes. The cleaning of the substrate is completed.

[0045] S2: Put the cleaned substrate into a vacuum tube high temperature furnace, flow 02 into the furnace, first increase the temperature from room temperature to 100°C at a temperature change rate of 3°C / min, then increase it to 500°C at 4°C / min, and then increase it to 1100°C at 5°C / min and keep it constant for 24 hours. After the constant temperature is completed, first reduce it to 800°C at 3.5°C / min, then reduce it to 500°C at 5°C / min, and finally cool it naturally to room temperature and take it out to complete the annealing of the substrate;

[0046] S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate;

[0047] S4: sintering the sputtering target;

[0048] S5: Place the modified substrate on a tray and transfer it into a vacuum chamber. Do not remove the target baffle temporarily. Empty the target for 600 seconds at a power of 250W. After the empty target is plated, remove the baffle. Adjust the gas pressure in the magnetron co-sputtering chamber to 5Pa. The working gas is argon. The sputtering power is 50W. The deposition rate is 40nm / min. The distance from the sputtering target to the modified substrate is 40mm. The sputtering time is 6h. Cool naturally in the chamber for 30min. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

[0049] The preparation of the modified substrate in step S3 comprises the following steps:

[0050] S41: mixing the chloroauric acid solution with sodium dodecyl sulfate and stirring for 20 min to obtain a chloroauric acid sodium dodecyl sulfate solution;

[0051] S42: using a solution deposition method to deposit on the annealed substrate, using chloroauric acid sodium dodecyl sulfate solution as the cathode, setting the discharge time to 20 min, the discharge current to 20 mA, the circulation flow rate of the reaction solution to 50 mL / min, the flow rate of the working gas argon to 20 sccm, setting the solution constant temperature to 25° C. with a constant temperature magnetic stirrer and starting stirring, centrifuging at 2500 r / min for 20 min, and drying at 200° C. for 24 h to complete the nanodot modification of the substrate to obtain a modified substrate;

[0052] The preparation of the sputtering target in step S4 comprises the following steps:

[0053] S61: BaO2, CaO and CuO are mixed and ground, and then calcined at 900°C for 6 hours in a flowing oxygen environment, and then crushed and ground after cooling to obtain an intermediate A;

[0054] S62: calcining the intermediate A in a flowing oxygen environment at 900° C. for 6 h, cooling and crushing the intermediate B;

[0055] S63: Add Tl2O3 powder to intermediate B, mix, grind and press the mixture into tablets. In a flowing oxygen environment, keep the temperature at 880°C for 1.5 hours to obtain a sintered target. Place the sintered target and the modified substrate wafer in a crucible. The crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid sintering. The temperature is increased to 850°C at a temperature rise rate of 10°C / min and sintered for 5 hours to obtain a sputtering target.

[0056] Embodiment 2:

[0057] This embodiment is a method for preparing a superconducting film based on nanotechnology. The superconducting film based on nanotechnology is prepared by the following steps:

[0058] S1: Cut and clean the substrate to remove impurities such as oil stains on its surface during the production and cutting process. First, soak the substrate in dilute hydrochloric acid and apply ultrasonic oscillation. The process should not exceed 10 minutes. Then, rinse the substrate with clean water for 3 times to wash away the hydrochloric acid. Then, soak the substrate in acetone and apply ultrasonic oscillation. The ultrasonic time is 30 minutes. Then, soak the substrate in ethanol and apply ultrasonic oscillation. The process should not be less than 30 minutes. The cleaning of the substrate is completed.

[0059] S2: Place the cleaned substrate into a vacuum tube high temperature furnace, flow 02 into the furnace, first increase the temperature from room temperature to 100°C at a temperature change rate of 3.5°C / min, then increase it to 500°C at 4°C / min, and then increase it to 1100°C at 5.5°C / min and keep it constant for 36 hours. After the constant temperature is completed, first reduce it to 800°C at 4°C / min, then reduce it to 500°C at 5°C / min, and finally cool it naturally to room temperature and take it out to complete the annealing of the substrate;

[0060] S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate;

[0061] S4: sintering the sputtering target;

[0062] S5: Place the modified substrate on a tray and transfer it into a vacuum chamber. Do not remove the target baffle temporarily. Empty the target for 600 seconds at a power of 280W. After the empty target is plated, remove the baffle. Adjust the gas pressure of the magnetron co-sputtering chamber to 10Pa. The working gas is argon. The sputtering power is 50W. The deposition rate is 50nm / min. The distance from the sputtering target to the modified substrate is 40mm. The sputtering time is 8h. Cool naturally in the chamber for 60min. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

[0063] The preparation of the modified substrate in step S3 comprises the following steps:

[0064] S41: mixing the chloroauric acid solution with sodium dodecyl sulfate and stirring for 30 min to obtain a chloroauric acid sodium dodecyl sulfate solution;

[0065] S42: using a solution deposition method to deposit on the annealed substrate, using chloroauric acid sodium dodecyl sulfate solution as the cathode, setting the discharge time to 20 min, the discharge current to 20 mA, the circulation flow rate of the reaction solution to 60 mL / min, the flow rate of the working gas argon to 20 sccm, setting the solution constant temperature to 30° C. with a constant temperature magnetic stirrer and starting stirring, centrifuging at 2500 r / min for 20 min, and drying at 230° C. for 30 h to complete the nanodot modification of the substrate to obtain a modified substrate;

[0066] The preparation of the sputtering target in step S4 comprises the following steps:

[0067] S61: BaO2, CaO and CuO are mixed and ground, and then calcined at 900°C for 6 hours in a flowing oxygen environment, and then crushed and ground after cooling to obtain an intermediate A;

[0068] S62: calcining the intermediate A in a flowing oxygen environment at 900° C. for 8 h, cooling and crushing the intermediate B;

[0069] S63: Add Tl2O3 powder to the intermediate B, mix, grind and press the mixture into tablets. In a flowing oxygen environment, keep the temperature at 880°C for 1.5 hours to obtain a sintered target. Place the sintered target and the modified substrate wafer in a crucible. The crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid heating and sintering. The temperature is raised to 850°C at a temperature rise rate of 10°C / min and sintered for 8 hours to obtain a sputtering target.

[0070] Embodiment 3:

[0071] This embodiment is a method for preparing a superconducting film based on nanotechnology. The superconducting film based on nanotechnology is prepared by the following steps:

[0072] S1: Cut and clean the substrate to remove impurities such as oil stains on its surface during the production and cutting process. First, soak the substrate in dilute hydrochloric acid and apply ultrasonic oscillation. The process should not exceed 10 minutes. Then, rinse the substrate with clean water for 4 times to wash away the hydrochloric acid. Then, soak the substrate in acetone and apply ultrasonic oscillation. The ultrasonic time is 50 minutes. Then, soak the substrate in ethanol and apply ultrasonic oscillation. The process should not be less than 50 minutes. The cleaning of the substrate is completed.

[0073] S2: Place the cleaned substrate into a vacuum tube high temperature furnace, flow 02 into the furnace, first increase the temperature from room temperature to 100°C at a temperature change rate of 3.5°C / min, then increase it to 500°C at 4.5°C / min, and then increase it to 1100°C at 5.5°C / min and keep it constant for 36 hours. After the constant temperature is completed, first reduce it to 800°C at 4°C / min, then reduce it to 500°C at 5.5°C / min, and finally cool it naturally to room temperature and take it out to complete the annealing of the substrate;

[0074] S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate;

[0075] S4: sintering the sputtering target;

[0076] S5: Place the modified substrate on a tray and transfer it into a vacuum chamber. Do not remove the target baffle temporarily. Empty the target for 650 seconds at a power of 280W. After the empty target is plated, remove the baffle. Adjust the gas pressure in the magnetron co-sputtering chamber to 10Pa. The working gas is argon. The sputtering power is 55W. The deposition rate is 50nm / min. The distance from the sputtering target to the modified substrate is 50mm. The sputtering time is 8h. Cool naturally in the chamber for 60min. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

[0077] The preparation of the modified substrate in step S3 comprises the following steps:

[0078] S41: mixing the chloroauric acid solution with sodium dodecyl sulfate and stirring for 30 min to obtain a chloroauric acid sodium dodecyl sulfate solution;

[0079] S42: using a solution deposition method to deposit on the annealed substrate substrate, using chloroauric acid sodium dodecyl sulfate solution as the cathode, setting the discharge time to 30 min, the discharge current to 25 mA, the circulation flow rate of the reaction solution to 60 mL / min, the flow rate of the working gas argon to 30 sccm, setting the solution constant temperature to 30° C. with a constant temperature magnetic stirrer and starting stirring, centrifuging at 2800 r / min for 30 min, and drying at 230° C. for 30 h to complete the nanodot modification of the substrate substrate, and obtain a modified substrate substrate;

[0080] The preparation of the sputtering target in step S4 comprises the following steps:

[0081] S61: BaO2, CaO and CuO are mixed and ground, and then calcined at 1000°C for 8 hours in a flowing oxygen environment, and then crushed and ground after cooling to obtain an intermediate A;

[0082] S62: calcining the intermediate A in a flowing oxygen environment at 1000° C. for 8 h, cooling and crushing the intermediate B;

[0083] S63: Add Tl2O3 powder to intermediate B, mix, grind and press the mixture into tablets. In a flowing oxygen environment, keep the temperature at 940°C for 3 hours to obtain a sintered target. Place the sintered target and the modified substrate wafer in a crucible. The crucible is sealed in silver foil and placed in a rapid thermal treatment equipment for rapid heating and sintering. The temperature is raised to 950°C at a temperature rise rate of 10°C / min and sintered for 8 hours to obtain a sputtering target.

[0084] Comparative Example 1:

[0085] The difference between Comparative Example 1 and Example 1 is that no annealing process is performed.

[0086] Comparative Example 2:

[0087] The difference between Comparative Example 2 and Example 1 is that no modified substrate preparation is performed.

[0088] Comparative Example 3:

[0089] The difference between Comparative Example 3 and Example 1 is that Tl2O3 powder is not added in step S63.

[0090] The superconducting films of Examples 1-3 and Comparative Examples 1-3 were tested. The samples were placed between two coils. A certain high-frequency alternating current was passed through the primary coil, which generated an induced electromotive force at both ends of the secondary coil. When the magnetic permeability of the sample between the two coils changed, it would affect the induced electromotive force at both ends of the secondary coil. The samples were placed in a coolant. As the temperature decreased, when the sample showed the Meissner effect, the transmission of the magnetic field would be blocked. At this time, no induced electromotive force was generated at both ends of the secondary coil. By measuring the change from the induced electromotive force at both ends of the secondary coil to the non-existence and the temperature when the change occurred, the critical transition temperature of the sample could be obtained.

[0091] First, a microbridge structure is etched on the surface of the sample and the electrodes are fixed. Then, the sample is immersed in a coolant until it enters a superconducting state. The current flowing through the microbridge is increased. When the current reaches the critical current, the superconducting state disappears and a voltage appears at both ends of the microbridge. The current when a 1uV voltage appears at both ends of the microbridge is taken as the critical current of the sample. The critical current density of the sample is then calculated based on the width of the microbridge and the thickness of the sample.

[0092] The test results are shown in the following table:

[0093] sample Critical transition temperature / K Critical current density / (MA / cm2) Example 1 128 3.8 Example 2 130 3.7 Example 3 129 3.8 Comparative Example 1 77 1.3 Comparative Example 2 55 1.0 Comparative Example 3 73 1.3

[0094] It can be seen from the above table that the critical transition temperature of the embodiment reaches 128-130K, while the critical transition temperature of comparative example 1 without annealing process is 77K, the critical transition temperature of comparative example 2 without modified substrate preparation is 55K, and the critical transition temperature of comparative example 3 without adding Tl2O3 powder in step S63 is 73K. The critical current density of the embodiment reaches 3.7-3.8MA / cm2, while the critical current density of comparative example 1 without annealing process is 1.3MA / cm2, the critical current density of comparative example 2 without modified substrate preparation is 1.0MA / cm2, and the critical current density of comparative example 3 without adding Tl2O3 powder in step S63 is 1.3MA / cm2. All data of the embodiment are better than those of the comparative examples, indicating that the superconducting film prepared by the present invention has better performance.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0096] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A superconducting film based on nanotechnology, characterized in that: The superconducting film based on nanotechnology is prepared by the following steps: S1: cutting the substrate, soaking the substrate in dilute hydrochloric acid and applying ultrasonic oscillation, then rinsing the substrate with clean water, then soaking the substrate in acetone and applying ultrasonic oscillation, then soaking the substrate in ethanol and applying ultrasonic oscillation, to complete the cleaning of the substrate; S2: performing an annealing process on the substrate substrate; S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate; S4: sintering the sputtering target; S5: Place the modified substrate on a tray and transfer it into a vacuum chamber. Do not remove the target baffle and perform empty target plating. After the empty target plating is completed, remove the baffle and perform magnetron co-sputtering. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.

2. The superconducting film based on nanotechnology according to claim 1, characterized in that: The substrate in step S1 is made of sapphire.

3. The superconducting film based on nanotechnology according to claim 1, characterized in that: The annealing process in step S2 includes the following steps: Place the cleaned substrate wafer into a vacuum tube high-temperature furnace, and flow 02 into the furnace. First, increase the temperature from room temperature to 100℃ at a temperature change rate of 3-3.5℃ / min, then increase it to 500℃ at 4-4.5℃ / min, and then increase it to 1100℃ at 5-5.5℃ / min and keep it constant at this temperature for 24-36h. After the constant temperature ends, first reduce it to 800℃ at 3.5-4℃ / min, and then reduce it to 500℃ at 5-5.5℃ / min. Finally, cool it naturally to room temperature and take it out to complete the annealing of the substrate wafer.

4. The superconducting film based on nanotechnology according to claim 1, characterized in that: The preparation of the modified substrate in step S3 comprises the following steps: S41: mixing the chloroauric acid solution with sodium dodecyl sulfate to obtain a chloroauric acid sodium dodecyl sulfate solution; S42: using a solution deposition method to deposit on the annealed substrate, using a chloroauric acid sodium dodecyl sulfate solution as a cathode, discharging, centrifuging, and drying to complete the nano-dot modification of the substrate to obtain a modified substrate.

5. The superconducting film based on nanotechnology according to claim 4, characterized in that: The mass ratio of the chloroauric acid solution to sodium dodecyl sulfate in step S41 is 7g:63g.

6. The superconducting film based on nanotechnology according to claim 1, characterized in that: The preparation of the sputtering target in step S4 comprises the following steps: S61: BaO2, CaO and CuO are mixed and ground, and then burned in a flowing oxygen environment, and then crushed and ground after cooling to obtain an intermediate A; S62: burning the intermediate A in a flowing oxygen environment, cooling and crushing, to obtain the intermediate B; S63: Add Tl2O3 powder to the intermediate B, mix, grind and press the mixture into tablets, and perform constant temperature treatment in a flowing oxygen environment to obtain a sintered target. Place the sintered target and the modified substrate substrate in a crucible together. The crucible is sealed in silver foil and placed in a rapid thermal treatment device for rapid temperature rise sintering. After sintering, a sputtering target is obtained.

7. The superconducting film based on nanotechnology according to claim 6, characterized in that: The mass ratio of BaO2, CaO and CuO in step S61 is 2g:5g:3g.

8. The nanotechnology-based superconducting film according to claim 6, characterized in that: The mass ratio of the intermediate B to Tl2O3 in step S63 is 13g:3g.

9. The method for preparing a superconducting thin film based on nanotechnology according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: cutting the substrate, soaking the substrate in dilute hydrochloric acid and applying ultrasonic oscillation, then rinsing the substrate with clean water, then soaking the substrate in acetone and applying ultrasonic oscillation, then soaking the substrate in ethanol and applying ultrasonic oscillation, to complete the cleaning of the substrate; S2: performing an annealing process on the substrate substrate; S3: using plasma-liquid interaction to perform nano-dot modification on the substrate to obtain a modified substrate; S4: sintering the sputtering target; S5: Place the modified substrate on a tray and transfer it into a vacuum chamber. Do not remove the target baffle and perform empty target plating. After the empty target plating is completed, remove the baffle and perform magnetron co-sputtering. Then take out the substrate tray to obtain a superconducting film based on nanotechnology.