A samarium-cobalt-based thin film, a preparation method and application thereof

Abstract

This invention discloses a samarium-cobalt-based thin film, its preparation method, and its applications. The samarium-cobalt-based thin film comprises Sm x Co y Combined target layer, the Sm x Co y The combined target layer is composed of Sm x Co y Combined target, where x:y = 1:3~7; this invention achieves synergistic regulation of target material composition (Sm x Co y SmCo-based thin films were prepared by adjusting the atomic ratio and / or Cu doping and the deposition / heat treatment temperature. The phase composition was precisely controlled to achieve a synergistic improvement in coercivity and remanence ratio, resulting in SmCo5-based thin films with superior overall magnetic properties.

Description

Technical Field

[0001] This invention relates to the field of thin film materials technology, and in particular to a samarium cobalt-based thin film, its preparation method, and its applications. Background Technology

[0002] As a stable source of passive permanent magnetic fields in microelectromechanical systems (MEMS), SmCo-based permanent magnet thin films are considered ideal permanent magnet materials for MEMS applications in harsh environments such as high temperature and high vacuum due to their ultra-high magnetocrystalline anisotropy, small critical superparamagnetic size, and high Curie temperature. Improving the magnetic properties of SmCo permanent magnet thin films to provide sufficiently strong local magnetic fields within finite dimensions has become a key research objective.

[0003] The binary SmCo compound has a complex phase composition, and the intrinsic magnetic properties of different phases vary greatly. During thin film deposition, sputtered atoms on the target are affected by backscattering, causing a deviation between the film composition and the nominal composition of the target. This makes the phase composition of the film even more complex and difficult to control. In addition, since the amorphous SmCo phase dominates in the deposited film, the formation of hard magnetic crystalline phases such as SmCo5 requires a certain activation energy. SmCo-based films require additional heat treatment processes to obtain hard magnetic properties. However, the harsh crystallization conditions of the SmCo5 hard magnetic phase often result in the growth of non-hard magnetic phases during crystallization. For example, at low crystallization temperatures or insufficient heating time, the presence of large-sized amorphous phases can cause complete decoupling between hard magnetic phase grains, reducing the remanence of the SmCo-based film. After prolonged or high-temperature heating, SmCo5 is prone to oxidative decomposition, resulting in severe degradation of the hard magnetic properties of the film. As two key magnetic parameters determining the overall magnetic properties of SmCo permanent magnet thin films, synergistically improving coercivity and remanence is often contradictory. For example, while the commonly used Fe doping can improve the saturation magnetization and remanence of the film, it also leads to a decrease in coercivity. Similarly, while doping with transition elements such as Cu and Ti can improve the magnetic anisotropy and coercivity of SmCo5, the excessive introduction of non-magnetic atoms can also easily lead to a decrease in magnetic moment and remanence. Therefore, synergistically improving the remanence and coercivity of SmCo-based thin films requires consideration of both film composition and fabrication process control.

[0004] Currently, composition control is primarily achieved by altering thin film deposition parameters and elemental doping. However, simply controlling composition alone cannot simultaneously improve the coercivity and remanence of the thin film. Crystallization of the hard magnetic phase in thin films is generally achieved through high-temperature deposition or high-temperature annealing, but simply changing the heat treatment process parameters cannot completely prevent the formation of non-hard magnetic phases, thus failing to achieve precise control of the thin film phase composition. In conclusion, relying solely on composition or temperature control methods cannot achieve synergistic improvement in both the phase composition control and overall magnetic properties of SmCo5-based thin films. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a samarium-cobalt-based thin film, which achieves this through synergistic regulation of the target material composition (Sm). x Co y SmCo-based thin films were prepared by adjusting the atomic ratio and / or Cu doping and the deposition / heat treatment temperature. The phase composition was precisely controlled to achieve a synergistic improvement in coercivity and remanence ratio, resulting in SmCo5-based thin films with superior overall magnetic properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a samarium-cobalt-based thin film, the samarium-cobalt-based thin film comprising Sm x Co y Combined target layer, the Sm x Co y The combined target layer is composed of Sm x Co y Combined target, where x:y = 1:3 to 7.

[0008] In some embodiments of the present invention, the Sm x Co y The composite target layer contains a crystalline structure.

[0009] In some embodiments of the present invention, the crystal structure includes SmCo5, elemental Co, and Sm2Co. 17 At least one of them.

[0010] In some embodiments of the present invention, the Sm x Co y The thickness of the combined target layer is 400–500 nm.

[0011] In some embodiments of the present invention, the Sm x Co y The combined target is a circular spliced ​​target.

[0012] In some embodiments of the present invention, the Sm x Co y The combined target can be Cu-doped Sm x Co y Combined target.

[0013] In some embodiments of the present invention, the doping amount of Cu atoms is 3 to 5 at.%.

[0014] In some embodiments of the present invention, the samarium cobalt-based thin film further includes a Cr buffer underlayer and a Cr protective top layer, which are stacked sequentially from bottom to top. x Co y The target layer consists of a composite target layer and a Cr protective top layer. The Cr buffer bottom layer prevents Co atoms from interdiffusion with the Si substrate; the Cr protective top layer prevents oxidation of the SmCo composite target atoms.

[0015] In some embodiments of the present invention, the thickness of the Cr buffer layer is 70-90 nm.

[0016] In some embodiments of the present invention, the thickness of the Cr protective top layer is 70-90 nm.

[0017] In a second aspect, the present invention provides a method for preparing the samarium-cobalt-based thin film, comprising the following steps:

[0018] After bonding the Sm target and the Co target together, a samarium-cobalt-based thin film is deposited on the substrate and annealed to obtain the film.

[0019] In some embodiments of the present invention, the deposition temperature is 25–400°C, the deposition time is 10–30 min, the deposition power is 80–100 W, and the deposition pressure is 0.3–1.0 Pa.

[0020] In some preferred embodiments of the present invention, the deposition temperature is 250°C.

[0021] In some embodiments of the present invention, the vacuum degree of the annealing is 5 × 10⁻⁶. -4 ~8×10 -4 Pa, wherein the annealing temperature is 500–580°C and the annealing time is 25–35 min.

[0022] In some preferred embodiments of the present invention, the annealing temperature is 580°C and the annealing time is 35 min.

[0023] In some embodiments of the present invention, the Co target is a fan-shaped target and the Sm target is a circular target.

[0024] In some embodiments of the present invention, the central angle of the sector target is 15° to 30°.

[0025] In some embodiments of the present invention, the ratio of Sm atoms in the Sm target to Co atoms in the Co target is 1:1 to 5.

[0026] In some embodiments of the present invention, the ratio of Sm atoms in the Sm target to Co atoms in the Co target is 1:4.

[0027] In some embodiments of the present invention, the thickness of the Sm target is 1 to 2 mm.

[0028] In some embodiments of the present invention, the thickness of the Sm target is 1 mm.

[0029] In some embodiments of the present invention, the thickness of the Co target is 1 to 2 mm.

[0030] In some embodiments of the present invention, the Co target has a thickness of 1 mm.

[0031] In some embodiments of the present invention, the method for preparing the samarium-cobalt-based thin film may further include the following steps:

[0032] Sm targets and Co targets are bonded together, and then Cu sheets are bonded together. The resulting film is deposited on a substrate and annealed to obtain a samarium-cobalt-based thin film.

[0033] In some embodiments of the present invention, the ratio of Cu atoms to Co atoms in the Cu sheet is 1:18 to 20.

[0034] In some embodiments of the present invention, the Cu sheet is a fan-shaped sheet.

[0035] In some embodiments of the present invention, the central angle of the sector is 15°.

[0036] In some embodiments of the present invention, the substrate layer includes a Cr buffer layer deposited on a Si substrate. The function of the Cr buffer layer is to prevent Co atoms from interdiffusion with the Si substrate.

[0037] In some embodiments of the present invention, after deposition on the substrate layer, a Cr protective top layer is formed. The function of the Cr protective top layer is to prevent oxidation of the atoms of the SmCo composite target.

[0038] In some embodiments of the present invention, the step of Sm x Co y The deposition temperature for forming the Cr protective top layer on the composite target is 25–400 °C. x Co y The deposition time for the Cr protective top layer on the combined target is 2-4 minutes. x Co y The deposition power for forming the Cr protective top layer on the composite target is 80–100 W. x Co y The deposition pressure for the Cr protective top layer deposited on the composite target is 1.0–1.2 Pa.

[0039] A third aspect of the present invention provides a microelectromechanical system thin film comprising the aforementioned samarium cobalt-based thin film.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) This invention adjusts Sm x Co y By combining the ratio of Sm atoms to Co atoms in the target, the phase composition of the samarium cobalt-based thin film can be controlled, thereby obtaining the SmCo5 hard magnetic phase while suppressing the formation of non-magnetic phases (such as the Co elemental phase); at the same time, in-situ heating is used to promote the crystallization and grain growth of the SmCo5 hard magnetic phase during deposition and annealing, thereby comprehensively improving the coercivity and remanence of the samarium cobalt-based thin film.

[0042] (2) This method changes Sm x Co y By adjusting the ratio of Sm to Co targets in the combined target material and coordinating the deposition and annealing temperatures during the preparation process, the coercivity of the thin film can reach a maximum of 51 kOe, and a significant improvement in remanence ratio can be achieved under Cu doping.

[0043] (3) In the process of preparing samarium cobalt-based thin films, the present invention synergistically controls the ratio of Sm atoms to Co atoms, heat treatment temperature and annealing temperature in samarium cobalt-based thin films, and promotes the crystallization and grain growth of the SmCo5 hard magnetic phase of samarium cobalt-based thin films by Cu doping, effectively improving the coercivity of the film and increasing the remanence ratio, thus preparing samarium cobalt-based thin films with both high coercivity and high remanence ratio.

[0044] (4) The preparation method of the present invention is simple and efficient, and the samarium cobalt-based thin film prepared has excellent performance. It can simultaneously improve the coercivity and remanence ratio of the samarium cobalt-based thin film and has good application prospects. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the SmCo spliced ​​target material used in Examples 1, 2, and 3.

[0046] Figure 2 This is a schematic diagram of the samarium-cobalt-based thin film of the present invention.

[0047] Figure 3 The diagram shows the elemental distribution and atomic percentage of Cu-doped samarium cobalt-based thin films in Example 5.

[0048] Figure 4 The images show a comparison of the transmission electron microscopy (TEM) microstructure and polycrystalline diffraction (PCD) microstructures of Cu-doped and undoped samarium cobalt-based thin films in Example 5.

[0049] Figure 5The image shows the phase structure diagrams obtained by X-ray diffraction of samarium cobalt-based thin films prepared at different annealing times in Example 1.

[0050] Figure 6 The graph shows the demagnetization curves of samarium cobalt-based thin films prepared at different annealing times in Example 1.

[0051] Figure 7 The diagram shows the phase structure of the samarium cobalt-based thin film after being kept at 580°C for 25–40 min in Example 2.

[0052] Figure 8 Demagnetization curve of samarium cobalt-based thin film held at 580℃ for 25-40 min in Example 2.

[0053] Figure 9 The diagram shows the phase structure of samarium cobalt-based thin films with different SmCo atomic ratios in Example 3.

[0054] Figure 10 This is a demagnetization curve of samarium cobalt-based thin films with different SmCo atomic ratios in Example 3.

[0055] Figure 11 This is a demagnetization curve of samarium cobalt-based thin films at different deposition temperatures in Example 4.

[0056] Figure 12 This is a comparison chart of the demagnetization curves of the samarium cobalt-based thin film doped with Cu atoms and the samarium cobalt-based thin film without Cu atoms in Example 5. Detailed Implementation

[0057] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0058] The demagnetization curves of samarium cobalt-based thin films were tested using a Physical Integrated Testing System (PPMS). During the test, an external magnetic field of at least 6T was applied to ensure that the samarium cobalt-based thin films were magnetized to saturation. Then, demagnetization was performed in steps of 180 Oe to obtain the demagnetization curves.

[0059] X-ray diffraction (XRD) was used to test the phase structure pattern of samarium cobalt-based thin films. The sample scanning angle range was 20° to 70°, and the step size was 0.05°.

[0060] The elemental distribution and atomic percentage of samarium cobalt-based thin films were determined using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS).

[0061] Microstructure and polycrystalline diffraction patterns of samarium cobalt-based thin films were obtained by transmission electron microscopy (TEM). Before testing, the sample was thinned to expose the fresh surface of the film, and the microstructure was captured under TEM.

[0062] Example 1

[0063] This embodiment provides a samarium-cobalt-based thin film, including the following steps:

[0064] (1) Cut a 1mm thick Co target line to obtain a 30° or 15° sheet-shaped fan-shaped target material, and attach it to the surface of a circular Sm target to form a circular spliced ​​target. Adjust the number of Co sheets so that the ratio of Sm atoms to Co atoms in the circular spliced ​​target is set to 1:5.

[0065] (2) Pre-treat the single-crystal Si substrate. After cleaning and drying, the Si substrate is attached to the sample stage. The sample stage is then placed into the chamber, and the distance between the sample stage and the target (target-substrate distance) is adjusted and determined. The distance between the sample stage and the Cr target is 10.0 cm, and the distance between the sample stage and the SmCo target is 7.0 cm. The chamber is then evacuated to a high vacuum (background vacuum 3 × 10⁻⁶). -4 After Pa), argon gas is introduced, and ion beam cleaning is performed for 5 minutes to remove residual stains and oxide layers from the substrate surface.

[0066] (3) A three-layer thin film was deposited using a multi-target sputtering system. The gas pressure in the chamber was kept stable by controlling the argon flow rate. A Cr buffer layer, an SmCo layer, and a Cr protective layer were deposited sequentially on the Si substrate using DC magnetron sputtering mode. The deposition parameters for the SmCo layer were 80W, 0.8Pa, and 20min. The deposition parameters for the Cr buffer layer and the Cr protective layer were 80W, 1.0Pa, and 3min. The deposition temperature was controlled by a heating device connected to the sample stage. The deposition temperature was room temperature (25℃).

[0067] (4) Perform in-situ annealing on the deposited three-layer film. Use the heating device described in step (3) to perform in-situ high-vacuum annealing on the deposited three-layer film. Close the argon input valve and wait for the chamber to be re-evacuated to 8×10. -4 After Pa, the sample stage was heated to annealing temperatures of 500℃, 530℃, 550℃, 580℃ and 600℃ respectively using a heating device and held at these temperatures for 30 minutes before being cooled with the furnace.

[0068] (5) After the three-layer film formed by deposition has cooled to room temperature, turn off the molecular pump and mechanical pump, open the vent valve and wait for the air pressure inside and outside the chamber to be balanced, then open the chamber and take out the three-layer film formed by deposition to obtain the samarium cobalt-based film.

[0069] The phase structure and demagnetization curves of samarium-cobalt-based thin films annealed at different temperatures were tested using X-ray diffraction (XRD) and a physical property measurement system (PPMS), as shown below. Figure 5 and Figure 6 As shown, the samarium cobalt-based thin films annealed at 500℃ and 530℃ lack hard magnetism, and their demagnetization curves do not show any hard magnetism. Figure 6 The sample exhibited the highest coercivity (Hc = 28 kOe) after annealing at 580℃; the thin film phase structure consisted of a SmCo5 main phase and an accompanying Co elemental phase.

[0070] Example 2

[0071] This embodiment provides a samarium-cobalt-based thin film, including the following steps:

[0072] (1) Cut a 1mm thick Co target line to obtain a 30° or 15° sheet fan-shaped target material, and attach it to the surface of a circular Sm target to form a circular spliced ​​target. Adjust the number of Co sheets so that the ratio of Sm atoms to Co atoms in the spliced ​​target is set to 1:5.

[0073] (2) Pre-treat the single-crystal Si substrate. After cleaning and drying, the Si substrate is attached to the sample stage. The sample stage is then placed into the chamber, and the distance between the sample stage and the target (target-substrate distance) is adjusted. The distance between the sample stage and the Cr target is 10.0 cm, and the distance between the sample stage and the SmCo target is 7.0 cm. The chamber is then evacuated to a high vacuum (background vacuum 3 × 10⁻⁶). -4 After Pa), argon gas is introduced, and ion beam cleaning is performed for 5 minutes to remove residual stains and oxide layers from the substrate surface.

[0074] (3) A three-layer thin film was deposited using a multi-target sputtering system. The gas pressure in the chamber was kept stable by controlling the argon flow rate. A Cr buffer layer, an SmCo layer, and a Cr protective layer were deposited sequentially on the Si substrate using DC magnetron sputtering mode. The deposition parameters for forming the SmCo layer were 80W, 0.8Pa, and 20min. The deposition parameters for forming the Cr buffer layer and the Cr protective layer were 80W, 1.0Pa, and 3min. The deposition temperature was controlled by a heating device connected to the sample stage. The deposition temperature was room temperature (25℃).

[0075] (4) Perform in-situ annealing on the deposited three-layer film. Use the heating device described in step (3) to perform in-situ high-vacuum annealing on the deposited three-layer film. Close the argon input valve and wait for the chamber to be re-evacuated to 8×10. -4 After Pa, the sample stage was heated to an annealing temperature of 580℃ using a heating device and held at that temperature for 25 min, 30 min, 35 min and 40 min respectively before being cooled with the furnace.

[0076] (5) After the three-layer film formed by deposition has cooled to room temperature, turn off the molecular pump and mechanical pump, open the vent valve and wait for the air pressure inside and outside the chamber to be balanced, then open the chamber and take out the three-layer film formed by deposition to obtain the samarium cobalt-based film.

[0077] The phase structure and demagnetization curves of samarium-cobalt-based thin films annealed at different temperatures were tested using X-ray diffraction (XRD) and a physical property measurement system (PPMS), as shown below. Figure 7 and Figure 8 As shown, the crystallization degree of the SmCo5 hard magnetic phase in the samarium cobalt-based thin film annealed at 580℃ for 30 min was further improved, and the highest coercivity of the film was Hc = 30kOe.

[0078] Example 3

[0079] This embodiment provides a samarium-cobalt-based thin film, including the following steps:

[0080] (1) Cut a 1mm thick Co target line to obtain a 30° or 15° sheet fan-shaped target material, and attach it to the surface of a circular Sm target to form a circular spliced ​​target. Adjust the number of Co sheets so that the ratio of Sm atoms to Co atoms in the spliced ​​target is set to 1:5, 1:4 and 1:3 respectively.

[0081] (2) Pre-treat the single-crystal Si substrate. After cleaning and drying, the Si substrate is attached to the sample stage. The sample stage is then placed into the chamber, and the distance between the sample stage and the target (target-substrate distance) is adjusted. The distance between the sample stage and the Cr target is 10.0 cm, and the distance between the sample stage and the SmCo target is 7.0 cm. The chamber is then evacuated to a high vacuum (background vacuum 3 × 10⁻⁶). -4 After Pa), argon gas is introduced, and ion beam cleaning is performed for 5 minutes to remove residual stains and oxide layers from the substrate surface.

[0082] (3) The three-layer thin film deposited by the multi-target sputtering system is used to maintain the gas pressure in the chamber by controlling the argon flow rate. The Cr buffer layer, SmCo layer and Cr protective layer are deposited sequentially on the Si substrate by DC magnetron sputtering mode. The deposition parameters for forming the SmCo layer are 80W, 0.8Pa and 20min. The deposition parameters for forming the Cr buffer layer and Cr protective layer are 80W, 1.0Pa and 3min. The deposition temperature is controlled by the heating device connected to the sample stage. The deposition temperature is room temperature 25℃.

[0083] (4) Perform in-situ annealing on the deposited three-layer film. Use the heating device described in step (3) to perform in-situ high-vacuum annealing on the deposited three-layer film. Close the argon input valve and wait for the chamber to be re-evacuated to 8×10. -4 After Pa, the sample stage is heated to an annealing temperature of 580℃ using a heating device and held at that temperature for 35 minutes before being cooled with the furnace.

[0084] (5) After the three-layer film formed by deposition has cooled to room temperature, turn off the molecular pump and mechanical pump, open the vent valve and wait for the air pressure inside and outside the chamber to be balanced, then open the chamber and take out the three-layer film formed by deposition to obtain the samarium cobalt-based film.

[0085] The phase structure, elemental distribution, and demagnetization curves of samarium-cobalt-based thin films annealed at different temperatures were tested using an X-ray diffractometer (XRD) and a physical property measurement system (PPMS), as shown in the figures below. Figure 9 and Figure 10 As shown, when the ratio of Sm atoms to Co atoms is 1:4, the phase structure of the samarium-cobalt-based thin film obtained by target sputtering is a single SmCo5 hard magnetic phase. The Sm content in the thin film was measured using EDS energy dispersive spectroscopy. x Co y The elemental contents are listed in Table 1. The composition ratio of the samarium cobalt-based thin film obtained by sputtering with a target material with an Sm / Co atom ratio of 1:4 is closer to that of SmCo5, and the coercivity is also improved to Hc = 34kOe.

[0086] Table 1. Sm and Co content and coercivity of samarium cobalt-based thin films with different Sm / Co atom ratios.

[0087]

[0088] Example 4

[0089] This embodiment provides a samarium-cobalt-based thin film, including the following steps:

[0090] (1) Cut a 1mm thick Co target line to obtain a 30° or 15° sheet fan-shaped target material, and attach it to the surface of a circular Sm target to form a circular spliced ​​target. Adjust the number of Co sheets so that the ratio of Sm atoms to Co atoms in the spliced ​​target is set to 1:4.

[0091] (2) Pre-treat the single-crystal Si substrate. After cleaning and drying, the Si substrate is attached to the sample stage. The sample stage is then placed into the chamber, and the distance between the sample stage and the target (target-substrate distance) is adjusted. The distance between the sample stage and the Cr target is 10.0 cm, and the distance between the sample stage and the SmCo target is 7.0 cm. The chamber is then evacuated to a high vacuum (background vacuum 3 × 10⁻⁶). -4 After Pa), argon gas is introduced, and ion beam cleaning is performed for 5 minutes to remove residual stains and oxide layers from the substrate surface.

[0092] (3) The three-layer thin film deposited by the multi-target sputtering system was used to maintain the gas pressure in the chamber by controlling the argon flow rate. The Cr buffer layer, SmCo layer and Cr protective layer were deposited on the Si substrate in sequence by DC magnetron sputtering mode. The deposition parameters for forming the SmCo layer were 80W, 0.8Pa and 20min. The deposition parameters for forming the Cr buffer layer and Cr protective layer were 80W, 1.0Pa and 3min. The deposition temperature was controlled by the heating device connected to the sample stage. The deposition temperatures were 25℃, 150℃, 200℃, 250℃, 300℃, 350℃ and 400℃.

[0093] (4) Perform in-situ annealing on the deposited three-layer film. Use the heating device described in step (3) to perform in-situ high-vacuum annealing on the deposited three-layer film. Close the argon input valve and wait for the chamber to be re-evacuated to 8×10. -4 After Pa, the sample stage is heated to an annealing temperature of 580℃ using a heating device and held at that temperature for 35 minutes before being cooled with the furnace.

[0094] (5) After the three-layer film formed by deposition has cooled to room temperature, turn off the molecular pump and mechanical pump, open the vent valve and wait for the air pressure inside and outside the chamber to be balanced, then open the chamber and take out the three-layer film formed by deposition to obtain the samarium cobalt-based film.

[0095] The demagnetization curves of thin films deposited at different temperatures were tested using a Power Property Measurement System (PPMS), such as... Figure 11 As shown, a samarium-cobalt-based thin film prepared by sputtering a target with a Sm to Co atom ratio of 1:4 at 250 °C achieved a coercivity of Hc = 51 kOe after annealing at 580 °C for 35 min.

[0096] Example 5

[0097] This embodiment provides a samarium-cobalt-based thin film, including the following steps:

[0098] (1) Cut a 1mm thick Co target line to obtain a 30° or 15° sheet fan-shaped target material, and attach it to the surface of a circular Sm target to form a circular spliced ​​target. Adjust the number of Co sheets so that the ratio of Sm atoms to Co atoms in the spliced ​​target is set to 1:4. Attach a 15° fan-shaped Cu sheet to the SmCo4 combined target with a ratio of Sm atoms to Co atoms of 1:4.

[0099] (2) Pre-treat the single-crystal Si substrate. After cleaning and drying, the Si substrate is attached to the sample stage. The sample stage is then placed into the chamber, and the distance between the sample stage and the target (target-substrate distance) is adjusted. The distance between the sample stage and the Cr target is 10.0 cm, and the distance between the sample stage and the SmCo target is 7.0 cm. The chamber is then evacuated to a high vacuum (background vacuum 3 × 10⁻⁶). -4After Pa), argon gas is introduced, and ion beam cleaning is performed for 5 minutes to remove residual stains and oxide layers from the substrate surface.

[0100] (3) The three-layer thin film deposited by the multi-target sputtering system was maintained by controlling the argon flow rate to keep the gas pressure in the chamber stable. The Cr buffer layer, SmCo(Cu) layer and Cr protective layer were deposited on the Si substrate by DC magnetron sputtering mode. The deposition parameters of the SmCo(Cu) layer were 80W, 0.3Pa and 20min; the deposition parameters of the Cr layer were 80W, 1.0Pa and 3min. The deposition temperature was controlled by the heating device connected to the sample stage. The deposition temperature was room temperature 25℃.

[0101] (4) Perform in-situ annealing on the deposited three-layer film. Use the heating device described in step (3) to perform in-situ high-vacuum annealing on the deposited three-layer film. Close the argon input valve and wait for the chamber to be re-evacuated to 8×10. -4 After Pa, the sample stage is heated to an annealing temperature of 580℃ using a heating device and held at that temperature for 35 minutes before being cooled with the furnace.

[0102] (5) After the three-layer film formed by deposition has cooled to room temperature, turn off the molecular pump and mechanical pump, open the vent valve and wait for the air pressure inside and outside the chamber to be balanced, then open the chamber and take out the three-layer film formed by deposition to obtain the samarium cobalt-based film.

[0103] The demagnetization curves of samarium cobalt-based thin films annealed at different temperatures were tested using a Power Physical Measurement System (PPMS), such as... Figure 12 Cu doping significantly improves the crystallinity of the deposited thin film, enhances the squareness of the demagnetization curve, and increases the remanence ratio from 0.5 to 0.8 while maintaining the same coercivity.

[0104] The results show that the coercivity and remanence of the samarium-cobalt-based thin film can be simultaneously improved by synergistically controlling the ratio of Sm to Co atoms in the film and temperature. Combined with Examples 1-4, it is known that when the ratio of Sm to Co atoms in the samarium-cobalt-based thin film is 1:4, the film consists of a single-phase SmCo5. Controlling the deposition and annealing temperatures can promote SmCo5 crystallization, significantly improving the film's coercivity. The optimal deposition temperature was determined to be 250℃, and the optimal annealing temperature to be 580℃. Under the optimal composition ratio and annealing process, Cu doping significantly improves the squareness and remanence of the film.

[0105] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a samarium-cobalt-based thin film, characterized in that, Includes the following steps: After bonding the Sm target and the Co target, and then bonding the Cu sheet, a samarium cobalt-based thin film is deposited on the substrate and annealed to obtain the samarium cobalt-based thin film. The ratio of Sm atoms in the Sm target to Co atoms in the Co target is 1:4; The ratio of Cu atoms to Co atoms in the Cu sheet is 1:18 to 20; The deposition temperature is 250°C; The vacuum degree of the annealing is 5×10. -4 ~8×10 -4 Pa, the annealing temperature is 580℃, and the annealing time is 25~35 min.

2. The method for preparing samarium-cobalt based thin films according to claim 1, characterized in that, The samarium-cobalt-based thin film contains a crystalline structure.

3. The method for preparing samarium-cobalt based thin films according to claim 2, characterized in that, The crystal structure includes SmCo5, elemental Co, and Sm2Co. 17 At least one of them.

4. The method for preparing samarium-cobalt based thin films according to claim 1, characterized in that, The thickness of the samarium-cobalt-based thin film is 400~500 nm.

5. The method for preparing samarium-cobalt based thin films according to claim 1, characterized in that, The doping amount of Cu atoms is 3~5 at.%.

6. The method for preparing the samarium-cobalt-based thin film according to claim 1, characterized in that, The deposition time is 10-30 min, the deposition power is 80-100 W, and the deposition pressure is 0.3-1.0 Pa.

7. A microelectromechanical system (MEMS) thin film, characterized in that, The microelectromechanical system thin film includes the samarium cobalt-based thin film prepared by the method of any one of claims 1 to 6.

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