Method for preparing high-quality CrSb film on Al2O3 substrate by using magnetron sputtering method

Abstract

The invention discloses a method for preparing a high-quality CrSb film on an Al2O3 substrate, the high-quality CrSb film is prepared on the Al2O3 substrate through a magnetron sputtering device, and the method mainly comprises the following steps: (1) installing a required target material, and vacuumizing a cavity to enable the vacuum degree of the cavity to reach more than 1 * 10 <-8 > Torr; (2) carrying out pretreatment operation on an Al2O3 substrate required by film growth, cleaning the surface of the Al2O3 (0001) substrate, fixing the Al2O3 (0001) substrate on a tray, and transferring a sample after the vacuum degree meets the requirement; (3) pre-sputtering the placed target material for 5-10 minutes so as to remove impurities and obtain a clean target material surface; and (4) carrying out magnetron sputtering deposition on the required film material, wherein the target-substrate distance is fixed at 100 + / -10 mm during sputtering, the rotating speed of a sample table is 2-10 rpm, a film is deposited on the sample when a shuttle is opened, and proper sputtering parameters are selected according to the required film layer and thickness.

Description

Technical Field

[0001] This invention belongs to the field of interlaced ferromagnetic thin film growth and preparation technology, and uses magnetron sputtering equipment to prepare high-quality CrSb thin films on Al2O3(0001) substrates. Background Technology

[0002] The CrSb crystal structure belongs to the hexagonal P63 / mmc space group and exhibits high symmetry. In CrSb, Cr... 3+ Ions and six equivalent Sb 3- The ions form CrSb6 octahedrons, which are interconnected through shared faces, edges, and corners. The Cr-Sb bond length is... This three-dimensional structure exhibits complex interatomic interactions and geometric arrangements. CrSb has attracted widespread attention in the field of spintronics, particularly due to its spin band splitting phenomenon. Studies have shown that CrSb possesses spin band splitting up to 1 eV near the Fermi energy and, due to its high Nell temperature and excellent thin-film growth characteristics, demonstrates its potential for applications in spintronics. Researchers are exploring how to utilize its unique spin properties to develop novel spintronic devices.

[0003] Previously, researchers had used molecular beam epitaxy to grow high-quality CrSb films (CN120082977A). However, compared with magnetron sputtering, molecular beam epitaxy equipment and operating costs are extremely high, and the growth rate is extremely slow and inefficient, making it unsuitable for large-area uniform growth and hindering industrial applications. Summary of the Invention

[0004] This invention addresses the prominent problem of extremely slow growth rate and low efficiency in the current CrSb thin film growth process by proposing a method for preparing high-quality CrSb thin films on Al2O3(0001) substrates using magnetron sputtering.

[0005] The technical solution of the present invention is as follows: A method for preparing high-quality CrSb thin films on Al2O3(0001) substrates using magnetron sputtering, comprising the following steps:

[0006] 1) Install the required target material and evacuate the cavity;

[0007] 2) The required Al2O3 substrate is cleaned and transferred into the cavity through a vacuum interconnect system;

[0008] 3) Connect the required DC or RF power supply, close the molecular pump valve to 60%–80%, and set the gas pressure and flow rate.

[0009] 4) After the air pressure stabilizes, turn on the power switch to pre-treat the target material to remove surface impurity atoms and avoid affecting the film quality due to impurity contamination.

[0010] 5) Turn on the shutter to perform thin film deposition;

[0011] 6) Turn off the shutter; film growth is complete. If a multilayer film structure needs to be grown, repeat steps 5 and 6. After all growth is complete, transfer the film out of the cavity again through the vacuum interconnect system.

[0012] In step 1), the required target material (Cr, Sb, etc.) must be installed, and the vacuum level must be greater than 1×10⁻⁶. -8 Torr;

[0013] In step 2), the required Al2O3(0001) substrate is cleaned to remove impurities from its surface, and then dried using an air gun before being transferred into the chamber via a vacuum interconnect system. The sample transfer and growth process are both performed in a vacuum environment, effectively avoiding oxidation and contamination problems caused by prolonged exposure of the sample to air, thus significantly improving the quality of the thin film growth.

[0014] In step 3), during film growth, the molecular pump valve is closed to 60%–80%, and the gas pressure stabilizes when the introduced argon gas reaches dynamic equilibrium with the pumping process. Insulating targets such as MgO and TiO2 require connection to an RF power supply.

[0015] In step 4), the pre-sputtering time is 15±5 min;

[0016] In step 5), a buffer layer (Ta, W, Ru, etc.) with a thickness of 2±0.5 nm is first grown on an Al2O3(0001) substrate. Then, co-sputtering is used, and the thickness of the CrSb layer is controlled by the sputtering time. The target-substrate distance is fixed at 100±10 mm, and the sample stage rotation speed is 2-10 rpm. The growth of the buffer layer alleviates the lattice mismatch between the Al2O3 substrate and the upper CrSb film, which can reduce defects such as dislocations and cracks caused by strain. At the same time, it can induce the upper CrSb film to grow along a specific crystal orientation, improve the crystallinity of the film, and give it good orientation.

[0017] The advantages of this invention are:

[0018] (1) The process is simple to operate and has high repeatability;

[0019] (2) The rate is controllable, the efficiency is high, the cost is low, and it is suitable for large-scale industrial applications.

[0020] (3) The reaction produces few gases and causes no pollution;

[0021] (4) Good crystal orientation;

[0022] (5) The film has good quality, few defects, and good crystallinity;

[0023] (6) The substrate has wide adaptability, is compatible with micro and nano processes, and is suitable for device integration in the industry;

[0024] (7) The composition and thickness of CrSb are highly controllable during co-sputtering growth. Attached Figure Description

[0025] Figure 1 The diagram shows the CrSb thin film structure for a specific implementation method.

[0026] Figure 2 The image shows the XRD pattern of the CrSb film in the specific implementation method.

[0027] Figure 3 This is the EDS image of the CrSb thin film in the specific implementation method.

[0028] Figure 4 The image shows the RHEED diffraction pattern of the CrSb thin film in the specific implementation method.

[0029] Figure 5 This is a scanning electron microscope image of the CrSb thin film in the specific implementation method.

[0030] Figure 6 The image shows the MT test pattern and DSC heat flow-temperature curve of the CrSb thin film in the specific implementation method. Detailed Implementation

[0031] This invention utilizes magnetron sputtering to grow thin film materials, preparing high-quality CrSb films on Al2O3(0001) substrates. Various characterization tests were performed on the grown film materials to demonstrate the superior growth performance. The magnetron sputtering method for growing CrSb films is simple to operate, highly reproducible, has a controllable growth rate, and is highly efficient. It is suitable for large-area industrial applications and produces minimal reaction gases and no pollution.

[0032] The advantages of this invention will be better illustrated below with specific examples and accompanying drawings:

[0033] Obtain Cr, Sb, W, Pt, and Al targets and install them at target positions 1, 2, 3, and 4 respectively. After installation, evacuate the cavity to a vacuum level of 1×10⁻⁶. -8 Torr or above;

[0034] The 10mm*10mm Al2O3(0001) substrate was pretreated by first immersing it in acetone solution and sonicating it for 20 minutes, then removing it and immersing it in anhydrous ethanol solution and sonicating it for 20 minutes, and finally immersing it in deionized water and sonicating it for 20 minutes. After that, it was removed and dried with high-purity nitrogen gas. The dried and clean Al2O3(0001) substrate was fixed on a tray and transferred to the cavity through a vacuum interconnection system.

[0035] First, the Al2O3(0001) substrate was preheated to 800℃ for 30 min. After preheating, the temperature was lowered to 680℃, and argon gas was introduced to start growing a 2 nm W layer. Then, the temperature was raised to 800℃ for annealing for 30 min. After the temperature dropped to 300℃, Cr and Sb targets were co-sputtered, with the Cr target power being 30 W and the Sb target power being 12.5 W. After 2 minutes and 36 seconds, the shutter was turned off. Then, the temperature was raised to 500℃ for annealing for 30 min to obtain a 30 nm CrSb layer. After cooling to room temperature, a 4 nm Al layer was grown as a capping layer.

[0036] Figure 1 The overall structure of the thin film is shown, from bottom to top: Al2O3(0001) substrate, buffer layer W, interleaved ferromagnetic layer CrSb, and capping layer Pt.

[0037] Figure 2 The XRD pattern of the thin film material is shown, and obvious CrSb (101) and (110) characteristic peaks can be found, indicating that the grown CrSb film has high orientation.

[0038] Figure 3 The EDS test results of the thin film material are shown, which revealed that the sample was locally composed of 49% Sb and 51% Cr, indicating that the overall elemental composition of the thin film meets the target.

[0039] Figure 4 The RHEED diffraction pattern of the thin film material is shown. The diffraction pattern presents concentric rings or diffuse spots, indicating that the prepared CrSb thin film sample is a high-quality, highly oriented thin film.

[0040] Figure 5 Scanning electron microscope (SEM) images of the thin film material are shown. Under 3000x SEM magnification, the CrSb film surface is smooth and without protrusions, indicating that a high-quality CrSb film was obtained.

[0041] Figure 6The MT test curves and DSC heat flow-temperature curves of the thin film material are shown. These curves exhibit a highly linear relationship, indicating that CrSb possesses a pure antiferromagnetic order and lacks tilted magnetic moment components. The inset shows the enthalpy change that may accompany the antiferromagnetic phase transition, detected using differential scanning calorimetry (DSC). Significant exothermic and endothermic peaks were observed near 680 K during heating and cooling. These transitions did not exhibit hysteresis, indicating that they are of second-order origin, meaning the thermodynamic properties change continuously without significant abrupt temperature differences.

[0042] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing high-quality CrSb thin films on Al2O3 substrates using magnetron sputtering, characterized in that, The method includes the following steps: Step 1: Install the required target material and evacuate the cavity; Step 2: Clean the required Al2O3 substrate and transfer it into the cavity through a vacuum interconnect system; Step 3: Connect the required DC or RF power supply, close the molecular pump valve to 60%–80%, and set the gas pressure and flow rate. Step 4: After the air pressure stabilizes, turn on the power switch to pre-treat the target material to remove surface impurity atoms, thereby obtaining a clean surface. Step 5: Turn on the shutter to perform thin film deposition; Step 6: Turn off the shutter. Thin film growth is complete. If a multilayer film structure needs to be grown, repeat steps 5 and 6. After all growth is complete, the film is transmitted out of the cavity again through the vacuum interconnection system.

2. The method for preparing high-quality CrSb thin films on an Al2O3 substrate using magnetron sputtering according to claim 1, characterized in that, In step 1, a mechanical pump is first used to evacuate to a rough vacuum environment, and then a molecular pump is used to pressurize to 1×10⁻⁶. -8 High vacuum environments above Torr.

3. The method for preparing high-quality CrSb thin films on an Al2O3 substrate using magnetron sputtering according to claim 1, characterized in that, In step 2, the required Al2O3 substrate is cleaned. First, the substrate is placed in an acetone solution and ultrasonically cleaned for 20±5 minutes using an ultrasonic oscillator to remove organic matter from the surface. Then, the Al2O3 substrate is placed in anhydrous ethanol and ultrasonically cleaned for 20±5 minutes to remove acetone from the surface of the Al2O3 substrate. Finally, high-purity nitrogen is used to blow away the liquid residue to obtain a dry and clean Al2O3 substrate.

4. The method for preparing high-quality CrSb thin films on an Al2O3 substrate using magnetron sputtering according to claim 1, characterized in that, While applying voltage, high-purity argon gas (99.999%) is introduced, and pre-sputtering is performed for 15±5 minutes to remove impurities from the target surface.

5. The method for preparing high-quality CrSb thin films on an Al2O3 substrate using magnetron sputtering according to claim 1, characterized in that, The target-substrate distance is fixed at 100±10mm, the sample stage rotation speed is 2~10rpm, and the film is deposited on the sample when the shutter is turned on. Select appropriate sputtering parameters according to the required film layer and thickness.

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