Titanium nitride single crystal film and preparation method and application thereof

Abstract

The invention discloses a titanium nitride single-crystal thin film and a preparation method and application thereof, and the preparation method comprises the following steps: S1, cleaning a single-crystal substrate, and feeding the single-crystal substrate into a sputtering chamber of magnetron sputtering equipment; s2, vacuumizing the sputtering chamber, and heating the single crystal substrate; s3, nitrogen and argon are introduced into the sputtering chamber, a high-purity titanium target is used as a sputtering target material, a radio-frequency power supply or a direct-current power supply is turned on, and pre-sputtering is conducted; s4, the power of a power source is set, the flow ratio of nitrogen to argon is adjusted to be 0.1-0.5, and a titanium nitride film grows on the single crystal substrate through magnetron sputtering; and S5, turning off the power supply, keeping the air pressure in the original cavity unchanged, and cooling to obtain the titanium nitride single crystal film. According to the method, the titanium nitride single crystal film is prepared by adopting a magnetron sputtering technology, and the stress between crystal lattices of the TiN film can be changed by adjusting the growth atmosphere and introducing nitrogen and argon mixed gas according to a certain proportion, so that the superconducting transition temperature is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of thin film preparation, and in particular to a titanium nitride single crystal thin film and a preparation method and application thereof. Background Art

[0002] In the field of superconducting quantum chips, titanium nitride (TiN) has become an important superconducting material due to its excellent mechanical properties and chemical stability, showing great application potential in superconducting quantum devices. The superconducting transition temperature (Tc) of superconducting materials is an important property, which is crucial to ensure the stability of quantum bits and the accuracy of operations.

[0003] In order to increase the superconducting transition temperature of single-crystal TiN, new preparation methods need to be developed. At present, the preparation of titanium nitride films mainly adopts physical vapor deposition (PVD) technology. For example, patents CN201710198901.X and CN202310187145.6 respectively disclose a method for preparing titanium nitride films by magnetron sputtering. Although these methods can produce films of a certain quality, there are challenges in controlling the superconducting properties of the films, and the superconducting transition temperature of the obtained titanium nitride films is low. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is how to increase the superconducting transition temperature of the titanium nitride film to meet the high performance requirements of the material for the superconducting quantum chip.

[0005] To achieve the above object, the present invention provides a method for preparing a titanium nitride single crystal thin film in a first aspect, comprising the following steps:

[0006] S1, cleaning the single crystal substrate and sending it into the sputtering chamber of the magnetron sputtering equipment;

[0007] S2, evacuating the sputtering chamber and heating the single crystal substrate;

[0008] S3, nitrogen and argon are introduced into the sputtering chamber, a high-purity titanium target is used as the sputtering target, and the RF power supply or DC power supply is turned on to perform pre-sputtering;

[0009] S4, setting the power of the power supply, adjusting the flow ratio of nitrogen and argon to 0.1-0.5, and magnetron sputtering growing a titanium nitride film on the single crystal substrate;

[0010] S5. Turn off the power supply, keep the air pressure in the original cavity unchanged, cool down, and obtain a titanium nitride single crystal film.

[0011] The present invention adopts magnetron sputtering technology to prepare titanium nitride single crystal thin film, and by adjusting the growth atmosphere and introducing nitrogen and argon mixed gas in a certain proportion, the stress between the TiN thin film lattices can be changed, thereby increasing the superconducting transition temperature.

[0012] Furthermore, in step S2, the vacuum pressure of the sputtering chamber is evacuated to a value less than or equal to 10 -7 Pa. Better back vacuum can produce titanium nitride films with better superconducting properties.

[0013] Furthermore, in step S2, the single crystal substrate is heated to 600-1200° C. Heating the single crystal substrate to a relatively high temperature can grow a single crystal with superconducting properties.

[0014] Furthermore, in step S4, the total flow rate of nitrogen and argon is 5 to 15 sccm.

[0015] Furthermore, in step S4, the gas pressure in the chamber is controlled to be 1-10 Pa. In this gas pressure range, the kinetic energy of the sputtered atomic clusters is moderate, which is beneficial to improving the crystal quality of the TiN film.

[0016] Furthermore, in step S4, the power of the power source is controlled to be 50-200 W. In this power range, the sputtering rate of the target material is moderate, which is conducive to the epitaxial growth of the TiN film.

[0017] Furthermore, the single crystal substrate is selected from one of Al2O3, MgO, (La, Sr)(Al, Ta)O3, and LaAlO3. Selecting a suitable single crystal substrate is conducive to the formation of single crystal titanium nitride.

[0018] A second aspect of the present invention provides a titanium nitride single crystal film, which is prepared by the above-mentioned preparation method, and the superconducting transition temperature of the titanium nitride single crystal film is greater than 5.5K.

[0019] By adopting the preparation method of the present invention, under appropriate process conditions, a titanium nitride film with a single crystal structure can be prepared, which greatly increases the superconducting critical temperature, thereby meeting the demand for high-performance materials of superconducting quantum chips.

[0020] A second aspect of the present invention provides an application of a titanium nitride single crystal film, which is used in superconducting quantum devices.

[0021] Applying the high-performance titanium nitride film of the present invention to quantum devices can significantly improve the working efficiency and stability of the devices and promote the development of superconducting technology in fields such as quantum computing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 High-resolution X-ray 2θ-ω scanning images of the titanium nitride films prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0023] Figure 2The resistivity of the titanium nitride films prepared in Examples 1 and 2 of the present invention and Comparative Example 1 varies with temperature near the superconducting critical temperature.

[0024] Figure 3 Schematic diagram of the relationship between the strain and superconducting critical temperature of the titanium nitride films prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0025] Figure 4 This is a test diagram of the superconducting critical temperature of the titanium nitride film prepared in Comparative Example 2 of the present invention.

[0026] Figure 5 This is a high-resolution X-ray 2θ-ω scanning image of the titanium nitride film prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the present invention. Other embodiments obtained from the present invention description will be apparent to those skilled in the art.

[0030] A specific embodiment of the present invention provides a method for preparing a titanium nitride single crystal film, using a high-purity titanium target as a sputtering target material, a mixed gas of nitrogen and argon as a sputtering gas, and using a radio frequency power supply or a direct current power supply to implement magnetron sputtering on a single crystal substrate. During the magnetron sputtering epitaxial growth process, the ratio of nitrogen to argon is adjusted to obtain a titanium nitride single crystal film with a specific lattice structure.

[0031] The specific preparation steps of titanium nitride single crystal thin film are as follows:

[0032] S1. Clean the single crystal substrate and send it into the sputtering chamber of the magnetron sputtering equipment.

[0033] In a specific embodiment, selecting a suitable single crystal substrate is conducive to forming single crystal titanium nitride. The optional single crystal substrates include Al2O3, MgO, (La, Sr)(Al, Ta)O3, LaAlO3, etc., preferably Al2O3.

[0034] In some embodiments, the single crystal substrate is placed in an acetone and ethanol solution for ultrasonic cleaning for 1 to 15 minutes, blown dry with high-purity nitrogen, mounted on a heating table of a magnetron sputtering setup, and sent into a sputtering chamber. Cleaning can improve the performance and reliability of electronic devices made from thin films.

[0035] S2. The sputtering chamber is evacuated and the single crystal substrate is heated.

[0036] In a specific embodiment, the vacuum pressure of the sputtering chamber is evacuated to a value less than or equal to 10 -7 Pa, a better back vacuum can obtain a titanium nitride film with better superconducting properties. The single crystal substrate is heated to 600-1200°C, preferably 700-1000°C. In this temperature range, the organic reagents remaining on the single crystal substrate can be effectively removed, and the impurity gases adsorbed on the single crystal substrate can be desorbed, providing a high-cleanliness substrate for the growth of TiN film; and this temperature range provides sufficient kinetic energy for the sputtering clusters adsorbed on the substrate surface, so that it forms a high-quality continuous film.

[0037] S3. Nitrogen and argon are introduced into the sputtering chamber, a high-purity titanium target is used as the sputtering target, and the RF power supply or DC power supply is turned on for pre-sputtering.

[0038] In a specific embodiment, the pre-sputtering power supply is 50-200W, and the pre-sputtering time is 10-30min. The pre-sputtering can fully remove the contaminated part of the target surface and desorb the impurity gas on the target.

[0039] S4. Set the power of the power supply, adjust the flow ratio of nitrogen and argon to 0.1-0.5, and grow a titanium nitride film on a single crystal substrate by magnetron sputtering.

[0040] In a specific embodiment, the power of the power supply is 50-200W, preferably 80W-150W.

[0041] In a specific embodiment, the flow ratio of nitrogen and argon is adjusted to 0.1-0.5, the total flow of nitrogen and argon is 5-15 sccm, and the pressure in the chamber is controlled to be 1-10 Pa. Under this condition, high-quality crystals can be obtained, and the stress between the TiN film lattices can be changed, thereby increasing the superconducting transition temperature.

[0042] S5. Turn off the power supply, keep the air pressure in the original cavity unchanged, cool down, and obtain a titanium nitride single crystal film.

[0043] The above method can produce a single-crystal titanium nitride film, which greatly increases the superconducting critical temperature and the superconducting transition temperature is greater than 5.5K, thus meeting the demand for high-performance materials for superconducting quantum chips. Applying this high-performance titanium nitride film to quantum devices can significantly improve the working efficiency and stability of the devices.

[0044] The technical solutions and effects of the present invention are illustrated below in conjunction with specific embodiments.

[0045] Example 1

[0046] (1) The Al2O3 substrate was placed in an ethanol solution for ultrasonic cleaning for 5 min, and then dried using a nitrogen air gun. The dried Al2O3 substrate was mounted on the heating table of the magnetron sputtering equipment and placed in the sputtering chamber.

[0047] (2) Start the mechanical pump and molecular pump to pump the back vacuum of the sputtering chamber to 10 -7 Pa. Turn on the heating system and set the temperature to 1100°C. When the temperature of the single crystal substrate stabilizes at 1100°C, continue baking for 20 minutes. At the same time, set the nitrogen flow rate to 0.6 sccm, set the argon flow rate to 2.6 sccm, and adjust the gas valve to maintain the nitrogen pressure in the sputtering chamber at 2.67 Pa.

[0048] (3) After the temperature and pressure are stable, turn on the RF power supply, use a high-purity Ti target as the sputtering target, and set the pre-sputtering power supply to 60 W. With the heating platform baffle closed, perform pre-sputtering for 10 minutes. After that, set the RF power supply to 100 W, open the heating platform baffle, and officially start sputtering.

[0049] (4) After sputtering for 5 h, the RF power supply was turned off, the original nitrogen pressure was kept unchanged, and the temperature was lowered at a rate of 30 °C / min until it dropped to 200 °C and then naturally cooled to finally prepare a TiN film.

[0050] The TiN film prepared in this embodiment was subjected to an X-ray diffraction experiment (XRD), and the results are as follows: Figure 1 As shown in the figure, only the TiN (111) characteristic peak appears, indicating that the TiN film grows along a single (111) orientation without the presence of other impurities.

[0051] The TiN film prepared in this embodiment was subjected to a comprehensive physical properties test (PPMS), and the results are as follows: Figure 2 As shown, the superconducting critical temperature of TiN film is 5.55K.

[0052] Example 2

[0053] (1) The Al2O3 substrate was placed in an ethanol solution for ultrasonic cleaning for 5 min, and then dried using a nitrogen air gun. The dried Al2O3 substrate was mounted on the heating table of the magnetron sputtering equipment and placed in the sputtering chamber.

[0054] (2) Start the mechanical pump and molecular pump to pump the back vacuum of the sputtering chamber to 10 -7 Pa. Turn on the heating system and set the temperature to 1100°C. When the temperature of the single crystal substrate stabilizes at 1100°C, continue baking for 20 minutes. At the same time, set the nitrogen flow rate to 0.875 sccm, set the argon flow rate to 5.8 sccm, and maintain the nitrogen pressure in the sputtering chamber at 2.67 Pa by adjusting the gas valve.

[0055] (3) After the temperature and pressure are stable, turn on the RF power supply, use a high-purity Ti target as the sputtering target, and set the pre-sputtering power supply to 60 W. With the heating platform baffle closed, perform pre-sputtering for 10 minutes. After that, set the RF power supply to 100 W, open the heating platform baffle, and officially start sputtering.

[0056] (4) After sputtering for 5 h, the RF power supply was turned off, the original nitrogen pressure was kept unchanged, and the temperature was lowered at a rate of 30 °C / min until it dropped to 200 °C and then naturally cooled to finally prepare a TiN film.

[0057] The TiN film prepared in this embodiment was subjected to an X-ray diffraction experiment (XRD), and the results are as follows: Figure 1 As shown in the figure, only the TiN (111) characteristic peak appears, indicating that the TiN film grows along a single (111) orientation without the presence of other impurities.

[0058] The TiN film prepared in this embodiment was subjected to a comprehensive physical properties test (PPMS), and the results are as follows: Figure 2 As shown, the superconducting critical temperature of TiN film is 5.7K.

[0059] Comparative Example 1

[0060] (1) The Al2O3 substrate was placed in an ethanol solution for ultrasonic cleaning for 5 min, and then dried using a nitrogen air gun. The dried Al2O3 substrate was mounted on the heating table of the magnetron sputtering equipment and placed in the sputtering chamber.

[0061] (2) Start the mechanical pump and molecular pump to pump the back vacuum of the sputtering chamber to 10 -7 Pa. Turn on the heating system and set the temperature to 1100°C. When the temperature of the single crystal substrate stabilizes at 1100°C, continue baking for 20 minutes. At the same time, set the nitrogen flow rate to 3.2 sccm, and maintain the nitrogen pressure in the sputtering chamber at 2.67 Pa by adjusting the gas valve.

[0062] (3) After the temperature and pressure are stable, turn on the RF power supply, use a high-purity Ti target as the sputtering target, and set the pre-sputtering power supply to 60 W. With the heating platform baffle closed, perform pre-sputtering for 10 minutes. After that, set the RF power supply to 100 W, open the heating platform baffle, and officially start sputtering.

[0063] (4) After sputtering for 5 h, the RF power supply was turned off, the original nitrogen pressure was kept unchanged, and the temperature was lowered at a rate of 30 °C / min until it dropped to 200 °C and then naturally cooled to finally prepare a TiN film.

[0064] The TiN film prepared in this comparative example was subjected to an X-ray diffraction experiment (XRD), and the results are as follows: Figure 1 As shown in the figure, only the TiN (111) characteristic peak appears, indicating that the TiN film grows along a single (111) orientation without the presence of other impurities.

[0065] The TiN film prepared in this comparative example was subjected to a comprehensive physical properties test (PPMS), and the results are as follows: Figure 2 As shown, the superconducting critical temperature of TiN film is 5.31K.

[0066] The test results show that ( Figure 2 As shown in Figure 2, when other conditions are the same, the superconducting transition temperature of the prepared TiN single crystal film can be greatly improved by adjusting the ratio of argon and nitrogen in the mixed gas. Figure 1 The results of medium and high resolution X-ray diffraction show that as the proportion of argon increases, the peak position of the TiN film moves to the right, which indicates that the superconducting transition temperature is increased through lattice distortion. Figure 3 The relationship between lattice changes and changes in superconducting critical temperature is demonstrated.

[0067] Comparative Example 2

[0068] (1) The Al2O3 substrate was placed in an ethanol solution for ultrasonic cleaning for 5 min, and then dried using a nitrogen air gun. The dried Al2O3 substrate was mounted on the heating table of the magnetron sputtering equipment and placed in the sputtering chamber.

[0069] (2) Start the mechanical pump and molecular pump to pump the back vacuum of the sputtering chamber to 10 -4 Pa. Turn on the heating system and set the temperature to 1100°C. When the temperature of the single crystal substrate stabilizes at 1100°C, continue baking for 20 minutes. At the same time, set the nitrogen flow rate to 6.4 sccm, and maintain the nitrogen pressure in the sputtering chamber at 2.67 Pa by adjusting the gas valve.

[0070] (3) After the temperature and pressure are stable, turn on the RF power supply, use a high-purity Ti target as the sputtering target, and set the pre-sputtering power supply to 60 W. With the heating platform baffle closed, perform pre-sputtering for 10 minutes. After that, set the RF power supply to 100 W, open the heating platform baffle, and officially start sputtering.

[0071] (4) After sputtering for 5 h, the RF power supply was turned off, the original nitrogen pressure was kept unchanged, and the temperature was lowered at a rate of 30 °C / min until it dropped to 200 °C and then naturally cooled to finally prepare a TiN film.

[0072] The TiN film prepared in this comparative example was subjected to a comprehensive physical properties test (PPMS), and the results are as follows: Figure 4 As shown, the superconducting critical temperature of TiN film is 3.89K.

[0073] Comparative Example 3

[0074] (1) The single crystal Si substrate was placed in an ethanol solution for ultrasonic cleaning for 5 minutes, and then dried using a nitrogen air gun. The dried Si substrate was mounted on a heating table of a magnetron sputtering device and placed in a sputtering chamber.

[0075] (2) Start the mechanical pump and molecular pump to pump the back vacuum of the sputtering chamber to 10 -7 Pa. Turn on the heating system and set the temperature to 1100°C. When the temperature of the single crystal substrate stabilizes at 1100°C, continue baking for 20 minutes. At the same time, set the nitrogen flow rate to 6.4 sccm, and maintain the nitrogen pressure in the sputtering chamber at 2.67 Pa by adjusting the gas valve.

[0076] (3) After the temperature and pressure are stable, turn on the RF power supply, use a high-purity Ti target as the sputtering target, and set the pre-sputtering power supply to 60 W. With the heating platform baffle closed, perform pre-sputtering for 10 minutes. After that, set the RF power supply to 100 W, open the heating platform baffle, and officially start sputtering.

[0077] (4) After sputtering for 5 h, the RF power supply was turned off, the original nitrogen pressure was kept unchanged, and the temperature was lowered at a rate of 30 °C / min until it dropped to 200 °C and then naturally cooled to finally prepare a TiN film.

[0078] The TiN film prepared in this comparative example was subjected to an X-ray diffraction experiment (XRD), and the results are as follows: Figure 5 As shown, there are multiple impurity peaks in the figure, the surface film is a polycrystalline structure, and the crystallization quality is poor.

[0079] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a titanium nitride single crystal thin film, characterized in that: The following steps are involved: S1, cleaning the single crystal substrate and sending it into the sputtering chamber of the magnetron sputtering equipment; S2, evacuating the sputtering chamber and heating the single crystal substrate; S3, nitrogen and argon are introduced into the sputtering chamber, a high-purity titanium target is used as the sputtering target, and the RF power supply or DC power supply is turned on to perform pre-sputtering; S4, setting the power of the power supply, adjusting the flow ratio of nitrogen and argon to 0.1-0.5, and magnetron sputtering growing a titanium nitride film on the single crystal substrate; S5. Turn off the power supply, keep the air pressure in the original cavity unchanged, cool down, and obtain a titanium nitride single crystal film.

2. The method for preparing a titanium nitride single crystal thin film according to claim 1, characterized in that: In step S2, the vacuum pressure in the sputtering chamber is evacuated to a value less than or equal to 10 -7 Pa.

3. The method for preparing a titanium nitride single crystal thin film according to claim 1, characterized in that: In step S2, the single crystal substrate is heated to 600-1200°C.

4. The method for preparing a titanium nitride single crystal thin film according to claim 1, characterized in that: In the step S4, the total flow rate of nitrogen and argon is 5-10 sccm.

5. The method for preparing a titanium nitride single crystal thin film according to claim 4, characterized in that: In step S4, the air pressure in the cavity is controlled to be 1-10Pa.

6. The method for preparing a titanium nitride single crystal thin film according to claim 1, characterized in that: In step S4, the power of the power supply is controlled to be 50-200W.

7. The method for preparing a titanium nitride single crystal thin film according to any one of claims 1 to 6, characterized in that: The single crystal substrate is selected from one of Al2O3, MgO, (La, Sr)(Al, Ta)O3, and LaAlO3.

8. A titanium nitride single crystal thin film, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

9. The titanium nitride single crystal thin film according to claim 8, characterized in that: The superconducting transition temperature of the titanium nitride single crystal film is greater than 5.5K.

10. Use of the titanium nitride single crystal thin film as claimed in claim 8 or 9, characterized in that: The titanium nitride single crystal thin film is used in superconducting quantum devices.

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