In-situ magnetic field heat treatment clamp in magnetron sputtering furnace and magnetic field heat treatment method

Abstract

The invention discloses an in-situ magnetic field heat treatment clamp in a magnetron sputtering furnace and a magnetic field heat treatment method.The in-situ magnetic field heat treatment clamp comprises a control mechanism, a magnet generating device and a cubic sample table, the control mechanism is connected with the magnet generating device, the magnet generating device comprises a baffle, two limiting frames are arranged at the top of the baffle, and magnets are arranged in the limiting frames; a first hinge is arranged on one side of each limiting frame, the other end of each first hinge is connected with a baffle through a screw, second hinges are arranged on the other sides of the two sets of limiting frames at the same end, two sets of long-strip-shaped through holes are formed in each second hinge, four sets of studs are arranged on the baffle, and the studs are matched with the long-strip-shaped through holes; according to the invention, the substrate is fixed on the specially-made sample stage, so that the magnetic field induction effect can be realized in the heating process; after the surfaces of the magnet and the clamp are coated, the heat conduction efficiency of the system is obviously reduced, and when the sample table is continuously subjected to heat preservation for 55 minutes in a high-temperature environment of 550 DEG C, the magnetic field generating device can still maintain relatively high magnetic field intensity.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic thin film materials, in particular to an in-situ magnetic field heat treatment fixture in a magnetron sputtering furnace and a magnetic field heat treatment method. Background Art

[0002] In recent years, in the era of the Internet of Everything, the market demand for electronic components has surged. Micro-Electro-Mechanical Systems (MEMS) have become the mainstream of the market due to their high integration, strong reliability, and small size.

[0003] SmCo-based permanent magnetic films are considered ideal permanent magnetic materials for MEMS applications in harsh environments such as high temperature and high vacuum due to their ultra-high magnetocrystalline anisotropy, high thermal stability, and high Curie temperature. To provide a sufficiently strong local magnetic field within a limited size, the key to research is the preparation of micron-scale SmCo films with both high coercivity (Hc) and high remanence (Mr).

[0004] In recent years, magnetic field heat treatment has been widely used in the preparation of magnetic materials. Unlike traditional heat treatment, adding an external magnetic field can promote the formation of magnetic nuclei based on the change in magnetic Gibbs free energy, allowing phase transformation to occur at lower temperatures. Furthermore, the crystallization temperature of SmCo5 is lower than its Curie temperature. During magnetic field heat treatment, the magnetic field can directly act on the crystallization process of the hard magnetic phase, causing the grains within the film to grow in a preferential orientation along the magnetic field direction. This can adjust the arrangement of the magnetic domain structure to control the magnetic anisotropy of the film, potentially having a beneficial effect on the magnetic properties of the material.

[0005] Existing magnetic field heat treatment devices have a single function, which means that the target film layer needs to be deposited in the coating equipment first and then transferred to the heat treatment device for treatment. The operation of the magnetic field heat treatment device is complicated, which increases the processing time and cost, and also increases the risk of sample contamination, especially rare earth materials such as SmCo are extremely easy to oxidize. Summary of the Invention

[0006] The purpose of the present invention is to provide an in-situ magnetic field heat treatment fixture in a magnetron sputtering furnace to solve the problems proposed in the above background technology, such as the complex operation of the magnetic field heat treatment device, the high processing time and cost, the high risk of sample contamination, and the easy oxidation of rare earth materials such as SmCo.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: an in-situ magnetic field heat treatment fixture in a magnetron sputtering furnace, comprising a control mechanism, a magnet generating device and a cubic sample stage, wherein the control mechanism is connected to the magnet generating device, and the magnet generating device comprises a baffle, two groups of limit frames are provided on the top of the baffle, magnets are provided inside the limit frames, one side of each limit frame is provided with a first hinge, the other end of the first hinge is connected to the baffle by a screw, the other side of the two groups of limit frames at the same end are provided with a second hinge, and the second hinges are each provided with two groups of long strip through holes, the baffle is provided with four groups of studs, and the studs are adapted to the long strip through holes, the outer sides of the studs are all threaded with hexagonal nuts, and four groups of support columns are connected between the two groups of limit frames;

[0008] The cubic sample stage is placed above the magnet generating device, and a substrate is pasted on the cubic sample stage.

[0009] Preferably, the control mechanism includes a connecting block, a guide rail, a screw, a slider, a large seal, a knob, a small seal and a handle. The connecting blocks are provided with two groups, two groups of guide rails are provided between the two groups of connecting blocks, a screw is provided in the middle between the two groups of connecting blocks, a slider adapted to the screw is provided on the screw, the slider is slidably connected to the guide rail, a large seal is installed on the top of the upper connecting block, a knob is installed on the top of the large seal, a small seal is provided on the top of the knob, the screw passes through the upper group of connecting blocks, the large seal, the knob and the small seal in sequence, and a handle is provided on the top of the screw, and the bottom of the screw is provided with a ball bearing connected to the lower connecting block.

[0010] Preferably, the magnets are 2:17 samarium cobalt magnets with a Curie temperature of ≥800° C., and the distance between the two groups of magnets is 15 mm.

[0011] Preferably, the surfaces of the control mechanism and the magnet generating device are coated with a low-emissivity protective film, and the low-emissivity protective film is a Zn film or Au film with a thickness of ≥2 μm and a surface emissivity of ≤0.1.

[0012] Preferably, a cylindrical grip block is provided on the top of the handle, three groups of holes are opened on the baffle, and the slider is threadedly connected to the baffle via screws.

[0013] Preferably, the material of the magnet generating device is austenitic heat-resistant stainless steel.

[0014] Preferably, the baffle is in the shape of a water droplet with a cut-off tip.

[0015] A magnetic field heat treatment method, the heat treatment method steps are as follows:

[0016] Step 1: Use COMSOL software to simulate the magnetic field distribution of the magnet and optimize the magnet spacing and the position of the cubic sample stage;

[0017] Step 2: Fix the substrate on the surface of the cubic sample stage (stick it to the side or bottom surface according to the required magnetic field direction) and complete the thin film deposition in the magnetron sputtering furnace;

[0018] Step 3: Turn the knob to make the magnet generator symmetrically distributed on both sides of the cubic sample stage, and turn the handle to control the magnet generator to move up and down, so that the sample is finally located at the center of the magnetic field;

[0019] Step 4: Heat the cubic sample stage to the target temperature (400-600°C) under vacuum and keep it warm for 20-60 minutes.

[0020] Preferably, during the heat treatment process, the surface protection film is used to maintain the magnet temperature ≤ 300° C. and the magnetic field intensity attenuation rate ≤ 10%.

[0021] Compared with the existing technology, the beneficial effects of the present invention are: the in-situ magnetic field heat treatment fixture in the magnetron sputtering furnace fixes the substrate on a special sample stage, which can achieve the effect of magnetic field induction during the heating process; after the magnet and the fixture surface are coated, the system's heat conduction efficiency is significantly reduced. When the sample stage is continuously kept warm in a high-temperature environment of 550°C for 55 minutes, the magnetic field generating device can still maintain a relatively high magnetic field strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a perspective view of the control mechanism and magnet generating device of the present invention;

[0023] Figure 2 It is the front view of the present invention;

[0024] Figure 3 A magnetic flux density distribution diagram of a simulated magnet according to the present invention;

[0025] Figure 4 It is a front view of the control mechanism of the present invention;

[0026] Figure 5 A top view of the magnet generating device of the present invention;

[0027] Figure 6 A perspective view of a magnet generating device according to the present invention;

[0028] Figure 7 A top view of the cubic sample stage of the present invention;

[0029] Figure 8 Schematic diagram of the temperature distribution in the magnetron sputtering furnace during the heat treatment of the SmCo film of the present invention and the high-temperature performance of the fixture without surface treatment;

[0030] Figure 9 This is a schematic diagram of the high-temperature performance of the fixture surface after Zn film coating of the present invention;

[0031] Figure 10 Schematic diagram of the high-temperature performance of the Zn film on the surface of the fixture of the present invention after oxidation;

[0032] Figure 11 Schematic diagram of the high-temperature performance of the fixture of the present invention after the surface is coated with Au film.

[0033] In the figure: 1, control mechanism; 11, connecting block; 12, guide rail; 13, screw; 14, slider; 15, large seal; 16, knob; 17, small seal; 18, handle;

[0034] 2. Magnet generating device; 21. Baffle; 22. Limiting frame; 23. First hinge; 24. Second hinge; 25. Long strip through hole; 26. Stud; 27. Hexagonal nut; 28. Support column; 29. ​​Magnet;

[0035] 3. Cubic sample stage; 31. Substrate. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] See also Figure 1-11 The present invention provides an embodiment of an in-situ magnetic field heat treatment fixture in a magnetron sputtering furnace, comprising a control mechanism 1, a magnet generating device 2, and a cubic sample stage 3. The control mechanism 1 is connected to the magnet generating device 2, and the magnet generating device 2 includes a baffle 21. Two sets of limit frames 22 are provided on the top of the baffle 21. The baffle 21 is shaped like a teardrop with a cutoff tip. A magnet 29 is provided inside the limit frame 22. The internal dimensions of the limit frame are substantially consistent with the specifications of the samarium cobalt magnet described above, which can prevent the magnet from slipping and ensure a uniform and stable magnetic field. After being fixed, the two magnets are parallel and spaced 15 mm apart.

[0038] A first hinge 23 is provided on one side of the limit frame 22, and the other end of the first hinge 23 is connected to the baffle 21 by a screw. A second hinge 24 is provided on the other side of the two sets of limit frames 22 at the same end, and two sets of long strip through holes 25 are opened on the second hinge 24. Four sets of studs 26 are provided on the baffle 21. The four studs welded on the surface are used to support the magnet and isolate the sputtering flow during coating. The studs 26 are adapted to the long strip through holes 25. The outer sides of the studs 26 are all threaded with hexagonal nuts 27. Four sets of support columns 28 are connected between the two sets of limit frames 22. The four support columns with large strength and hardness prevent the limit frames from deformation.

[0039] The cubic sample stage 3 is placed above the magnet generator 2, and a substrate 31 is attached to the cubic sample stage 3. A cube with a size of 10mm×10mm×10mm is added to the edge of the original sample stage. The substrate 31 for depositing the thin film will be fixed on the surface of the cube. The details of the cubic sample stage 3 are as follows: Figure 7 shown.

[0040] In this embodiment, the control mechanism 1 includes a connecting block 11, a guide rail 12, a screw 13, a slider 14, a large seal 15, a knob 16, a small seal 17 and a handle 18. There are two groups of connecting blocks 11, two groups of guide rails 12 are provided between the two groups of connecting blocks 11, a screw 13 is provided in the middle between the two groups of connecting blocks 11, a slider 14 adapted to the screw 13 is provided, and the slider 14 is slidably connected to the guide rail 12. A large seal 15 is installed on the top of the upper connecting block 11, a knob 16 is installed on the top of the large seal 15, and a small seal 17 is provided on the top of the knob 16. The small seal 17 and the large seal 15 ensure airtightness after complete assembly. The screw 13 passes through the upper group of connecting blocks 11, the large seal 15, the knob 16 and the small seal 17 in sequence, and the top of the screw 13 is provided with a handle 18, and the bottom of the screw 13 is provided with a ball bearing connected to the lower connecting block 11.

[0041] In this embodiment, the magnets 29 are 2:17 samarium cobalt magnets with a Curie temperature of ≥800° C. The distance between the two groups of magnets 29 is 15 mm.

[0042] In this embodiment, the surfaces of the control mechanism 1 and the magnet generating device 2 are coated with a low-emissivity protective film, and the low-emissivity protective film is a Zn film or Au film with a thickness of ≥2 μm and a surface emissivity of ≤0.1.

[0043] In this embodiment, a cylindrical grip block is provided on the top of the handle 18, three groups of holes are opened on the baffle 21, and the slider 14 is threadedly connected to the baffle 21 by screws, and the magnet is detachable and replaceable.

[0044] In this embodiment, the material of the magnet generating device 2 is austenitic heat-resistant stainless steel.

[0045] A magnetic field heat treatment method, the heat treatment method steps are as follows:

[0046] Step 1: Simulate the magnetic field distribution of the magnet using COMSOL software to optimize the spacing between the magnet 29 and the position of the cubic sample stage 3;

[0047] Step 2: Fix the substrate 31 on the surface of the cubic sample stage 3 and stick it on the side or bottom surface according to the required magnetic field direction, and complete the thin film deposition in the magnetron sputtering furnace;

[0048] Step three: Turn the knob 16 so that the magnet generating device 2 is symmetrically distributed on both sides of the cubic sample stage 3, and turn the handle 18 to control the magnet generating device 2 to move up and down, so that the sample is finally located at the center of the magnetic field;

[0049] Step 4: Heat the cubic sample stage 3 to the target temperature of 400-600°C under a vacuum environment and keep it warm for 20-60 minutes.

[0050] In this embodiment, the surface protection film is used to maintain the magnet temperature ≤ 300° C. and the magnetic field intensity attenuation rate ≤ 10% during the heat treatment process.

[0051] The theoretical basis of this invention is that the crystallization temperature of SmCo5 is lower than its Curie temperature. The application of a magnetic field during heat treatment can directly affect the crystallization process of the hard magnetic phase, causing atomic rearrangement and preferentially oriented growth of grains within the material along the direction of the magnetic field, forming a texture aligned with the field. Under the influence of the magnetic field, magnetic domains tend to align along the field, forming a more regular domain structure, improving the orientation consistency of the magnetic moment, eliminating stray magnetic fields or reverse magnetic domains within the film, reducing the negative effects of the demagnetization field, and increasing the remanence. Furthermore, the applied magnetic field can provide additional energy, causing a change in the system's magnetic Gibbs free energy, thereby promoting grain refinement and obtaining SmCo-based films with smaller grain sizes.

[0052] Example 1,

[0053] A 2:17 type samarium cobalt magnet (brand BMSG-22) with a size of 40mmx20mmx20mm was selected, with a spacing of 15mm between the two magnets. The finite element analysis of the magnetic field was performed using COMSOL software. Both magnets were polarized along the width direction, and the magnetic field line distribution of the magnets was simulated to calculate the magnetic flux density and the range of the magnetic field action area. The simulated magnetic flux density distribution of the magnet is shown in the figure below. Figure 3 As shown, the maximum magnetic flux density calculated by simulation is 0.75T;

[0054] The knob 16 is mounted on the neck of the frame. When turned, it controls the entire screw's rotation around its axis, thereby controlling the horizontal position of the magnetic field generator. The screw shaft is connected to the frame via a ball bearing and can rotate freely. When the handle 18 rotates the screw shaft, the threaded fit between the screw and the slider 14 converts the feed motion into vertical linear motion, thus controlling the vertical position of the magnetic field generator. During assembly, the fixture passes through the magnetron sputtering furnace, and sealing rings and gaskets are used at the connection to ensure airtightness.

[0055] In the present invention, the horizontal magnetic field condition of the substrate 31 when it is attached to the lower surface of the cubic sample stage 3 is mainly observed. The relative positions of the sample stage and the fixture are as follows: Figure 2 As shown; the temperature distribution in the magnetron sputtering furnace, the temperature rise of the magnet, and the magnetic flux density generated on the sample surface are simulated under the heat treatment conditions of the SmCo film, wherein the observation point of the magnetic flux density change curve is the center point of the lower surface of the cubic sample stage 3;

[0056] The magnet and fixture were surface treated and coated with Zn and Au films with a thickness of more than 2μm, respectively. The temperature distribution in the magnetron sputtering furnace, the temperature rise of the magnet, and the magnetic flux density generated on the sample surface were simulated.

[0057] Example 2. In the present invention, the integrated operation of thin film deposition and magnetic field heat treatment can be achieved through the screw device; the preparation of SmCo thin film samples requires two steps, thin film deposition and heat treatment, in sequence; first, the thin film is deposited, the handle is turned to lower the vertical position of the magnetic field generating device, and the knob is turned at a position that does not affect the horizontal rotation to adjust the magnetic field generating device to a position that does not affect the sputtering flow, and the cubic sample stage 3 is controlled to turn the switch to deposit the Cr layer, SmCo layer, and Cr layer at the relative position of the target head respectively; then, magnetic field heat treatment is performed, the cubic sample stage 3 is stopped at a position directly above the B target, and the screw is controlled so that the two magnets on the fixture are symmetrically distributed on both sides of the sample stage, heated to 550°C, and kept warm for 50 minutes.

[0058] like Figure 3 As shown: two 40mmx20mmx20mm BMSG-22 magnets 29 will form a uniform parallel magnetic field at their centers;

[0059] like Figures 8-11As shown in the figure, during the heat treatment of the SmCo film, the fixture without surface treatment was exposed to thermal radiation, and the temperature increased rapidly. The magnets on both sides reached 300°C after 35 minutes and then increased slowly. The magnetic flux density at the center of the lower surface of the cubic sample stage 3 decreased significantly with the temperature increase, then tended to a steady state, eventually dropping from 0.37T to 0.33T. After the surface was plated with Zn, the heating rate decreased significantly. At the end of the heat treatment, the temperature of the magnets on both sides reached 190°C, and the magnetic flux density on the sample surface was 0.35T. If the surface Zn film oxidizes, the emissivity will increase. After heat treatment, the magnet temperature is significantly higher, reaching 280°C, and the magnetic flux density also decreases. According to the metal surface emissivity data released by FLUKE, when the surface coating is replaced with Au with lower emissivity, the magnet temperature only increases from 20°C to 75°C, and the change in magnetic flux density is relatively small. It is obvious that it can play a role in heat treatment processes with higher temperatures and longer holding times.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention may be implemented in other specific forms without departing from the spirit or scope of the present invention. Therefore, the embodiments of the present invention are illustrative and non-restrictive. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and scope of equivalents of the claims be encompassed within the present invention. Any reference numerals in the claims should not be construed as limiting the claim to which they relate.

[0061] In the description of the present invention, unless otherwise specified, "plurality" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head structure" and operation are not to be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0062] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

Claims

1. A fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace, comprising a control mechanism (1), a magnet generating device (2) and a cubic sample stage (3), characterized in that: The control mechanism (1) is connected to a magnet generating device (2), and the magnet generating device (2) includes a baffle (21), two groups of limit frames (22) are provided on the top of the baffle (21), a magnet (29) is provided inside the limit frame (22), a first hinge (23) is provided on one side of each limit frame (22), the other end of the first hinge (23) is connected to the baffle (21) by a screw, and the other side of the two groups of limit frames (22) at the same end are provided with a second hinge (24), and two groups of long strip through holes (25) are opened on the second hinge (24), and four groups of studs (26) are provided on the baffle (21), and the studs (26) are adapted to the long strip through holes (25), and the outer sides of the studs (26) are threadedly sleeved with hexagonal nuts (27), and four groups of support columns (28) are connected between the two groups of limit frames (22); The cubic sample stage (3) is placed above the magnet generating device (2), and a substrate (31) is attached to the cubic sample stage (3).

2. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 1, characterized in that: The control mechanism (1) comprises a connecting block (11), a guide rail (12), a screw (13), a slider (14), a large seal (15), a knob (16), a small seal (17) and a handle (18). The connecting block (11) is provided with two groups, two groups of guide rails (12) are provided between the two groups of connecting blocks (11), a screw (13) is provided in the middle between the two groups of connecting blocks (11), a slider (14) adapted thereto is provided on the screw (13), and the slider (14) is slidably connected to the guide rail (12). A large seal (15) is installed on the top of the upper connecting block (11), a knob (16) is installed on the top of the large seal (15), and a small seal (17) is provided on the top of the knob (16). The screw (13) passes through the upper group of connecting blocks (11), the large seal (15), the knob (16) and the small seal (17) in sequence, and a handle (18) is provided on the top of the screw (13). The bottom of the screw (13) is provided with a ball bearing connected to the lower connecting block (11).

3. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 1, characterized in that: The magnets (29) are 2:17 type samarium cobalt magnets with a Curie temperature of ≥800°C. The distance between the two groups of magnets (29) is 15 mm.

4. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 1, characterized in that: The surfaces of the control mechanism (1) and the magnet generating device (2) are plated with a low-emissivity protective film, and the low-emissivity protective film is a Zn film or an Au film with a thickness of ≥2 μm and a surface emissivity of ≤0.

1.

5. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 2, characterized in that: A cylindrical grip block is provided on the top of the handle (18), three groups of holes are opened on the baffle (21), and the slider (14) is threadedly connected to the baffle (21) via screws.

6. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 1, characterized in that: The material of the magnet generating device (2) is austenitic heat-resistant stainless steel.

7. The fixture for in-situ magnetic field heat treatment in a magnetron sputtering furnace according to claim 1, characterized in that: The baffle (21) is in the shape of a water droplet with a cut-off tip.

8. A magnetic field heat treatment method, comprising the in-situ magnetic field heat treatment fixture in a magnetron sputtering furnace according to any one of claims 1 to 7, wherein the heat treatment method comprises the following steps: Step 1: Simulate the magnetic field distribution of the magnet using COMSOL software to optimize the spacing between the magnets (29) and the position of the cubic sample stage (3); Step 2: Fix the substrate (31) on the surface of the cubic sample stage (3) (stick it on the side or the bottom surface according to the required magnetic field direction), and complete the thin film deposition in a magnetron sputtering furnace; Step three: Turn the knob (16) to make the magnet generating device (2) symmetrically distributed on both sides of the cubic sample stage, and turn the handle (18) to control the magnet generating device (2) to move up and down, so that the sample is finally located at the center of the magnetic field; Step 4: Heat the cubic sample stage (3) to the target temperature (400-600°C) under a vacuum environment and keep it warm for 20-60 minutes.

9. The magnetic field heat treatment method according to claim 8, characterized in that: During the heat treatment, the surface protection film is used to maintain the temperature of the magnet at ≤300° C. and the attenuation rate of the magnetic field intensity at ≤10%.

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