Large-area WC superconducting thin film prepared by magnetron sputtering

Abstract

The application discloses a large-area WC superconducting film prepared by a magnetron sputtering method and belongs to the technical field of superconducting materials. The steps are as follows: a WC film with a thickness of 7 nm is prepared on a cleaned sapphire substrate by using a magnetron sputtering method, and the sputtering temperature is room temperature or 500 DEG C. The WC superconducting film with a large area can be produced by using the magnetron sputtering method, the thickness of the film is uniform, the process operation difficulty is low, the process flow is simple, the efficiency is high, and the repetition rate is high. The WC superconducting film can be used as a superconducting material and is very suitable for manufacturing wafer-level superconducting thin film electronic devices.

Description

Technical Field

[0001] This invention belongs to the field of superconducting thin film materials technology, specifically relating to large-area WC thin films exhibiting superconductivity prepared by magnetron sputtering technology. Background Technology

[0002] Superconducting materials are novel materials possessing three fundamental properties: zero resistance, perfect diamagnetism, and macroscopic quantum effects. Based on their zero resistance and perfect diamagnetism, applying large currents to superconducting materials enables technologies such as high-current transport, strong magnetic fields, and magnetic levitation. Based on the quantum tunneling effect, superconductivity can be applied to quantum computing and the detection of weak magnetic fields. Therefore, superconducting materials are widely used in power transmission, medical devices, electronic communications, and national defense. Superconducting electronic devices are a class of electronic devices developed based on the principles of superconductivity. Compared to ordinary electronic devices, they have faster response rates, lower energy consumption, and higher computational accuracy. Superconducting electronic devices have broad application prospects in superconducting quantum computing, superconducting electric vehicles, and power transmission.

[0003] Currently, WC materials are mainly prepared in the form of WC powder and WC thin films. The three main methods for preparing WC powder materials are solid-phase, gas-phase, and liquid-phase methods. Solid-phase methods are simple to operate and produce powder products with good particle size uniformity, but their production efficiency is low and they are prone to introducing impurities. Gas-phase methods can be used to prepare fine-particle-size powder products, but the reaction temperature required for this process is relatively high. Liquid-phase methods can also be used to prepare fine-particle-size WC powder materials and have relatively lower requirements for reaction temperature, but their preparation process is complex, making mass production and application less feasible. WC thin films are mainly obtained through chemical vapor deposition (CVD) and physical vapor deposition (PVD). However, the complex process of chemical vapor deposition limits the transition of WC thin films from laboratory to industrial production. Summary of the Invention

[0004] The purpose of this invention is to provide a large-area WC superconducting thin film, which can be grown on the entire substrate by magnetron sputtering equipment, and is particularly suitable for industrial mass production.

[0005] The technical solution to achieve the purpose of this invention is:

[0006] In a first aspect, the present invention provides a large-area WC superconducting thin film, which is prepared on a substrate by magnetron sputtering.

[0007] Preferably, to prevent oxidation of the WC superconducting thin film, an Al protective layer is prepared on the WC superconducting thin film using magnetron sputtering technology.

[0008] Preferably, the substrate is a rigid substrate commonly used in the art, such as (0001) crystal plane single crystal sapphire.

[0009] Preferably, the WC superconducting thin film has a thickness of 7 nm;

[0010] In a second aspect, the present invention provides a method for preparing a large-area WC superconducting thin film as described in the first aspect, comprising the following steps: using a WC target as the target material, performing vacuum magnetron sputtering on a cleaned substrate, wherein the sputtering temperature is room temperature or 500°C.

[0011] Preferably, a clean substrate refers to a substrate that has been ultrasonically cleaned for 10 minutes in sequence with acetone and anhydrous ethanol, and then dried with a nitrogen gun.

[0012] Ideally, the purity of the WC sputtering target is 99.9%.

[0013] Preferably, the protective gas is argon with a purity of 99.995%, and the sputtering pressure is 0.6 Pa.

[0014] Thirdly, the present invention provides an application of the large-area WC superconducting thin film described in the first aspect as a superconducting material.

[0015] Preferably, the WC superconducting thin film prepared at a sputtering temperature of room temperature has a resistance of 0 at a temperature of 4.4 K and exhibits superconductivity.

[0016] Preferably, the WC superconducting thin film prepared at a sputtering temperature of 500℃ has a resistivity of 0 at a temperature of 3.93K and exhibits superconductivity.

[0017] Fourthly, the present invention provides a superconducting sensor / detector comprising the large-area WC superconducting thin film described in the first aspect.

[0018] Fifthly, the present invention provides a microwave resonant cavity comprising the large-area WC superconducting thin film described in the first aspect.

[0019] In a sixth aspect, the present invention provides a superconducting digital circuit comprising the large-area WC superconducting thin film described in the first aspect.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention utilizes magnetron sputtering technology to control the growth temperature of WC thin films by altering the temperature of the sputtering chamber, thereby producing large-area continuous thin films with uniform thickness. The process is simple, efficient, and highly reproducible, making it a suitable industrial-scale production method. The WC thin films prepared using this method exhibit superconductivity at certain temperatures. Subsequent micro / nano fabrication techniques can be used to fabricate WC superconducting devices, which have broad application prospects in superconducting electronics research: First, the steep superconducting transition of superconducting materials can be used to achieve high sensitivity in superconducting sensors / detectors, making them widely applicable in superconducting quantum interference devices, superconducting nanowire single-photon detectors, and high-temperature superconducting terahertz technology; Second, the surface resistance of superconducting materials is extremely low when microwaves pass through them, resulting in minimal microwave loss in microwave resonant cavities and very low insertion loss in superconducting filters, significantly improving performance compared to conventional filters; Third, superconducting digital circuits have lower power consumption, smaller size, and lower signal loss compared to semiconductor digital circuits.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The image shows the Raman spectrum of the WC thin film prepared in Example 1 of this invention.

[0025] Figure 2 The image shows the Raman spectrum of the WC thin film prepared in Example 2 of this invention.

[0026] Figure 3 This is a low-resolution transmission electron microscope image of the WC thin film prepared in Example 3 of the present invention.

[0027] Figure 4 This is a low-resolution transmission electron microscope image of the WC thin film prepared in Example 4 of the present invention.

[0028] Figure 5 The WC resistance temperature (RT) curve prepared in Example 5 of this invention.

[0029] Figure 6 The WC resistance temperature (RT) curve prepared in Example 6 of the present invention. Detailed Implementation

[0030] The present application will be further described below with reference to specific embodiments.

[0031] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0033] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0034] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0035] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0036] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0037] The magnetron sputtering technique provided in this invention for preparing large-area WC thin films is an important physical vapor deposition method. It features lower deposition temperatures and higher deposition rates, simplifying the fabrication process, reducing production costs, and making it more suitable for industrial mass production. Using ultraviolet lithography and ion etching techniques, room-temperature WC thin films and 500°C WC thin films prepared by magnetron sputtering were used to fabricate six-electrode Hall devices. During the testing of the longitudinal resistance of the WC Hall devices at different temperatures using a magnetoelectric transport system, superconductivity was incidentally discovered in both the room-temperature and 500°C WC thin films. These superconducting films can be used for the subsequent fabrication of WC superconducting devices, exhibiting higher industrial value compared to WC powder.

[0038] Example 1:

[0039] In this embodiment, the thickness of the WC thin film is 7 nm.

[0040] The specific steps are as follows:

[0041] Step (1): Cut the 2-inch sapphire wafer into 1×1cm pieces.

[0042] Step (2): Clean the cut sapphire substrate with an ultrasonic cleaner for 10 minutes in acetone with an industrial purity of 99.95% or higher and anhydrous ethanol with a purity of 99.97% or higher. After cleaning, dry it with a nitrogen gun.

[0043] Step (3): Install a WC target with a purity of 99.9% and a diameter of 50.8 mm on the DC target position of the magnetron sputtering; fix the cleaned sapphire substrate on the sample holder.

[0044] Step (4): Evacuate the vacuum sputtering chamber to a level better than 5 × 10⁻⁶ using a mechanical pump and a molecular pump. -5 Pa.

[0045] Step (5): Keep the temperature of the sputtering chamber at room temperature, introduce 99.995% argon gas as working gas, adjust the sputtering pressure to 0.6 Pa, adjust the DC power supply to 20 W, adjust the spin rate of the sample holder to 20 rpm, and the sputtering rate to 0.067 nm / s.

[0046] Step (6): Open the baffle to start sputtering for 104.5 seconds, then close the baffle to obtain a WC film with a thickness of 7nm.

[0047] The Raman spectrum of the WC superconducting thin film prepared in Example 1 is as follows: Figure 1 As shown, Figure 1 The x-axis can be seen to be 750cm. -1 800cm -1 1350cm -1 1580cm-1 The Raman characteristic peaks of WC observed nearby are consistent with those reported in the literature. Furthermore, tests were conducted at multiple locations on the sample, and the characteristic peaks remained consistent, demonstrating the uniformity of the thin film.

[0048] Example 2

[0049] The other processes are the same as in Example 1, except that the temperature of the sputtering chamber in step (5) is adjusted to 500°C.

[0050] The Raman spectrum of the WC superconducting thin film prepared in this embodiment is as follows: Figure 2 As shown, Figure 2 The x-axis can be seen to be 750cm. -1 800cm -1 1350cm -1 1580cm -1 The Raman characteristic peaks of WC observed nearby are consistent with those reported in the literature. Furthermore, tests were conducted at multiple locations on the sample, and the characteristic peaks remained consistent, demonstrating the uniformity of the thin film.

[0051] Example 3

[0052] In this embodiment, all processes for the WC thin film are the same as in Example 1, except that the WC thin film is characterized by transmission electron microscopy.

[0053] The low-resolution transmission electron microscope image of the WC thin film prepared in this embodiment is as follows: Figure 3 As shown, a WC thin film with excellent continuity and flatness was prepared.

[0054] Example 4

[0055] In this embodiment, all processes for the WC thin film are the same as in Example 2, except that the WC thin film is characterized by transmission electron microscopy.

[0056] The low-resolution transmission electron microscope image of the WC thin film prepared in this embodiment is as follows: Figure 4 As shown, a WC thin film with excellent continuity and flatness was prepared.

[0057] Example 5

[0058] The WC thin film prepared in Example 1 was fabricated into a six-electrode Hall device using ultraviolet lithography and ion etching techniques. A DC current of 0.1 mA was applied, and the longitudinal resistance of the WC Hall device at different temperatures was tested.

[0059] The temperature-resistance (RT) curve of the WC Hall device prepared in this embodiment is as follows: Figure 5 As shown. By Figure 5 It can be seen that the resistance of WC drops to 0 at a temperature of 4.4K, indicating that superconductivity has occurred.

[0060] Example 6

[0061] The WC thin film prepared in Example 2 was fabricated into a six-electrode Hall device using ultraviolet lithography and ion etching techniques. A DC current of 0.1 mA was applied, and the longitudinal resistance of the WC Hall device at different temperatures was measured.

[0062] The temperature-resistance (RT) curve of the WC Hall device prepared in this embodiment is as follows: Figure 6 As shown. By Figure 6 It can be seen that the resistance of WC drops to 0 at a temperature of 3.93K, indicating that superconductivity has occurred.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Therefore, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a large-area WC superconducting thin film, characterized in that, The process includes the following steps: using a WC target as the target material, vacuum magnetron sputtering is performed on a cleaned substrate at a sputtering temperature of room temperature or 500 °C; specifically, the following steps are included: Step (1): Install a WC target with a purity of 99.9% on the DC target position of the magnetron sputtering; fix the cleaned sapphire substrate on the sample holder; Step (2): Evacuate the vacuum sputtering chamber to a level better than 5 × 10⁻⁶. -5 Pa; Step (3): Keep the temperature of the sputtering chamber at room temperature or 500 °C, introduce 99.995% argon gas as working gas, adjust the sputtering pressure to 0.6 Pa, adjust the DC power supply to 20 W, adjust the spin rate of the sample holder to 20 rpm, and the sputtering rate to 0.067 nm / s. Step (4): Open the baffle to start sputtering for a period of time, then close the baffle to obtain a WC film with a thickness of 7 nm; A six-electrode Hall device was fabricated from the prepared WC thin film using ultraviolet lithography and ion etching techniques. A 0.1 mA DC current was applied, and the longitudinal resistance of the WC Hall device at different temperatures was measured. The results are as follows: The WC superconducting thin film prepared at room temperature exhibits zero resistance at 4.4 K, demonstrating superconductivity. The WC superconducting thin film prepared at a sputtering temperature of 500 °C exhibits zero resistance at 3.93 K, demonstrating superconductivity.

2. The preparation method according to claim 1, characterized in that, An Al protective layer was prepared on the WC superconducting thin film by magnetron sputtering.

3. Large-area WC superconducting thin films prepared by the preparation method according to any one of claims 1-2.

4. A superconducting sensor / detector, characterized in that, It comprises a large-area WC superconducting thin film prepared by the preparation method as described in any one of claims 1-2.

5. A microwave resonant cavity, characterized in that, It comprises a large-area WC superconducting thin film prepared by the preparation method as described in any one of claims 1-2.

6. A superconducting digital circuit, characterized in that, It comprises a large-area WC superconducting thin film prepared by the preparation method as described in any one of claims 1-2.

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