JP2018174214A - Permanent magnet thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet thin film having high residual magnetization in the in-plane direction.SOLUTION: In a permanent magnet thin film consisting of a magnetic layer 2 formed on the surface of a substrate 1, arithmetic average roughness Ra in the surface 1a of the substrate is 0.50-1000 μm. Root-mean-square gradient RΔq on surface of the substrate is 0.50-20. The permanent magnet thin film is an R-T-B system permanent magnet thin film, where R is one kind or more of rare earth element, T is Fe or one kind or more of transition metal element essential for Fe and Co, B is boron, a part of boron may be replaced by carbon, and R/T is atomic ratio of 0.18-0.40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a permanent magnet thin film.

R—T—B system permanent magnet having a tetragonal R ₂ T ₁₄ B compound as a main phase (R is one or more rare earth elements, T is one or more transition metal elements in which Fe or Fe and Co are essential, and B is Boron) is known to have excellent magnetic properties and has been a typical high performance permanent magnet since the invention in 1982 (Patent Document 1). In particular, an R—T—B system permanent magnet material in which the rare earth element R is one or more selected from Nd, Pr, Dy, Ho, and Tb has been widely used as a permanent magnet material having a large anisotropic magnetic field Ha. Among these, Nd—Fe—B permanent magnets with rare earth element R as Nd have a good balance of saturation magnetization Ms, residual magnetization Mr, Curie temperature Tc, and anisotropic magnetic field Ha, and other rare earth elements R in terms of resource and corrosion resistance. It is widely used in consumer, industrial, transportation equipment, etc.

  In recent years, along with the downsizing and high performance of electronic devices, there is a demand for downsizing and thinning of permanent magnets used in consumer, industrial, transportation equipment and the like. However, there is a limit to reducing the size and thickness of an R-T-B system permanent magnet manufactured mainly by powder metallurgy. Therefore, research on an RTB-based permanent magnet thin film using a film forming process has been activated.

  Recently, a physical film-forming method such as sputtering has been proposed as a method for producing an RTB-based permanent magnet thin film having a thickness of less than 0.50 mm. This is a method in which an R-T-B system permanent magnet is deposited on a substrate in a vacuum or a reduced pressure space and subjected to heat treatment, and the R-T-B system is a relatively simple process compared to the sintering method. A permanent magnet thin film can be obtained.

JP 59-46008 A

Applied Physics Letters, 90, 092509, 2007

  In order to extract high remanent magnetization from a single R-T-B system main phase particle, three directions of the easy axis of magnetization, the direction of magnetizing the particle, and the direction of extracting the remanent magnetization are the same direction. It is necessary to. In order to extract high residual magnetization from a permanent magnet that is an aggregate of R-T-B main phase particles, in addition to the above conditions, it is necessary to orient the easy axis direction of the main phase particles. For example, when an RTB-based permanent magnet is produced by sintering, an isotropic magnet can be obtained by molding in a non-magnetic field, and an oriented magnet can be obtained by molding in a magnetic field.

  On the other hand, in an RTB-based permanent magnet thin film, the easy axis of magnetization of main phase particles tends to be oriented in the direction perpendicular to the surface of the thin film. Therefore, it is easy to produce a permanent magnet thin film that can easily extract residual magnetization in the direction perpendicular to the surface of the thin film. On the other hand, when it is desired to produce a permanent magnet thin film intended to extract residual magnetization in the in-plane direction of the thin film, the easy axis of magnetization of the R-T-B system main phase particles is oriented in the in-plane direction of the thin film. Have difficulty.

  In Non-Patent Document 1, the surface of the thin film is obtained by performing a heat treatment so that the R-T-B main phase particles are not oriented in the direction perpendicular to the surface, and producing an isotropic R-T-B permanent magnet thin film. The residual magnetization is easily extracted in the inward direction. However, the remanent magnetization in the in-plane direction of the isotropic RTB-based permanent magnet thin film remains at about 0.5 T, and cannot be said to be sufficiently high.

  The present invention has been made in view of the above circumstances, and an object thereof is to obtain high residual magnetization in the in-plane direction of a permanent magnet thin film.

In order to solve the above-mentioned problems and achieve the object, the permanent magnet thin film of the present invention is a permanent magnet thin film comprising a magnetic layer formed on the surface of a substrate,
Arithmetic mean roughness Ra on the surface of the substrate is 0.50 μm or more and 1000 μm or less,
The root mean square slope RΔq on the surface of the substrate is 0.50 or more and 20 or less.

    In the permanent magnet thin film of the present invention, the root mean square slope RΔq may be 0.50 or more and 3.0 or less.

The permanent magnet thin film of the present invention has a plurality of convex portions formed on the surface of the substrate,
The convex portion may have a shape that continues along the surface of the substrate.

    The permanent magnet thin film of the present invention may have a linear shape in which the convex portions are continuous along the surface of the substrate, and the directions of the convex portions may be aligned in one direction.

In the permanent magnet thin film of the present invention, the magnetic layer has main phase particles,
When the angle formed between the easy axis of the main phase particles and the perpendicular direction perpendicular to the surface of the substrate is θ, the average value of θ may be 30 ° or more and 90 ° or less.

The permanent magnet thin film is an RTB-based permanent magnet thin film,
R is one or more rare earth elements, T is one or more transition metal elements essential to Fe or Fe and Co, B is boron, and a part of the boron may be substituted with carbon,
R / T may be 0.18 or more and 0.40 or less in atomic ratio.

  In the present invention, it is possible to increase the residual magnetization in the in-plane direction of the permanent magnet thin film by reducing the angle formed between the easy axis direction of the main phase particles and the in-plane direction of the thin film.

It is a schematic diagram of the cross section of the permanent magnet thin film which concerns on one Embodiment of this invention. It is a schematic diagram of the cross section of the board | substrate which concerns on one Embodiment of this invention. It is a schematic diagram showing the relationship between a magnetic particle and a magnetization easy axis. It is a schematic diagram showing angle (theta) which a magnetization easy axis | shaft and a perpendicular direction make. It is a schematic diagram of the cross section of a permanent magnet thin film with a small root mean square inclination R (DELTA) q. It is a schematic diagram of the cross section of a permanent magnet thin film with a large root mean square inclination R (DELTA) q. It is a schematic diagram of the board | substrate which concerns on one Embodiment of this invention. It is a schematic diagram of the permanent magnet thin film which concerns on one Embodiment of this invention.

  A mode (embodiment) for carrying out the present invention will be described in detail. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

There is no limitation in particular in the kind of permanent magnet thin film which concerns on this embodiment. For example, it may be an RTB-based permanent magnet thin film including a magnetic layer whose main phase particles are particles having an R ₂ T ₁₄ B structure. R is one or more rare earth elements, T is one or more transition metal elements essential for Fe or Fe and Co, and B is boron. A part of boron may be substituted with carbon.

  In consideration of obtaining a permanent magnet thin film having a high anisotropic magnetic field, R is preferably at least one selected from Nd, Pr, Dy, Ho, and Tb. Furthermore, Nd is particularly preferable from the viewpoint of improving raw material cost and corrosion resistance in addition to residual magnetization.

Regarding the T, in the present embodiment, the entire T may be 100 at%, and the Co content may be 10.0 at% or less. Co forms an R ₂ T ₁₄ B phase similar to Fe. By containing Co, the Curie temperature is easily improved, and the corrosion resistance of the grain boundary phase is easily improved.

  With respect to B, the carbon content is preferably 10.0 at% or less, where the total carbon content is 100 at%.

  Said magnetic layer can contain 1 type or 2 types selected from Al and Cu in the range of 0.01 at% or more and 1.2 at% by making the whole magnetic layer into 100 at%. By containing one or two selected from Al and Cu within this range, it is possible to increase the coercive force, increase the corrosion resistance, and improve the temperature characteristics of the obtained permanent magnet thin film.

  In addition, the magnetic layer allows the inclusion of elements other than those described above. For example, elements such as Zr, Ti, Bi, Sn, Ga, Nb, Ta, Si, V, Ag, and Ge can be appropriately contained.

  The magnetic layer described above may include other components as impurities derived from raw materials or impurities mixed during manufacturing.

It is preferable that R / T in the magnetic layer of the RTB-based permanent magnet thin film is 0.18 or more and 0.40 or less in atomic ratio. When R / T is 0.18 or more in atomic ratio, it becomes easy to prevent precipitation of α-Fe or the like that has soft magnetism and lowers remanent magnetization. On the other hand, when R / T is an atomic ratio of 0.40 or less, the volume ratio of the main phase particles having the R ₂ T ₁₄ B structure is likely to increase, and the residual magnetization is easily improved.

_{Incidentally,} the axis of easy magnetization of the main phase grains having a R _{2 T 14} B structure _is a c-axis of the R _{2 T 14} B structure.

  As shown in FIG. 1, the permanent magnet thin film according to this embodiment includes a substrate 1, a convex portion 1 b, and a magnetic layer 2. Further, the convex portion 1 b is formed on the surface 1 a of the substrate 1.

The magnetic layer 2 is composed of main phase particles and a grain boundary phase. There is no particular limitation on the structure of the grain boundary phase, for example including R-rich phase and / or RFe ₄ B ₄ phase. Moreover, there is no restriction | limiting in particular in the thickness of the magnetic layer 2, For example, it is 10 nm or more and 200000 nm or less.

The R-rich phase is composed of, for example, an R phase, an RO phase, an R ₂ O ₃ phase, or an RT phase. The R-T phase is a phase composed of R and T and mainly composed of amorphous. Since the RT phase is an amorphous phase, the composition ratio is not constant, unlike the crystal phase.

  As the substrate 1, a polyimide substrate, a PEEK substrate, an Al substrate, a Si substrate, a glass substrate, a quartz substrate, or the like can be used. Preferably, a polyimide substrate or an Al substrate is used.

  Here, the convex portion 1b may be made of the same material as the substrate 1 as shown in FIGS. 2 to 4, 7 and 8, and different materials as shown in FIGS. It may consist of

  In the case where the convex portion 1b is made of the same material as the substrate 1, for example, the substrate 1 is subjected to surface processing by a processing method such as paper finishing, sand blasting, grinding, liquid honing, electric discharge engraving, electrolytic polishing, etc. As shown in FIG. 3, the convex portion 1b can be formed on the surface 1a of the substrate 1.

  In the case where the convex portion 1b is made of a material different from that of the substrate 1, the convex portion 1b can be formed by forming a so-called underlayer on the substrate 1, for example. The material for the underlayer is not particularly limited, and for example, polyimide, PEEK, Al, Si, or the like can be used. There is no particular limitation on the method for forming the underlayer.

  In general, there are various types of surface roughness, each having different characteristics. In this specification, the term “surface roughness” simply refers to two types of surface roughness: arithmetic average roughness Ra and root mean square slope RΔq. There are no particular limitations on the method of measuring these surface roughnesses. It can be measured by a commonly used roughness measuring device, and can also be measured by cross-sectional observation.

“Arithmetic average roughness Ra” means that only the reference length is extracted from the roughness curve in the direction of the average line, the x-axis is taken in the direction of the average line of the extracted portion, and the y-axis is taken in the direction of the vertical magnification. When the roughness curve is expressed by Equation 1, it is defined as shown in Equation 2. That is, the distance from the center line of the roughness curve to the roughness curve is averaged.

“Root mean square slope RΔq” is defined as Equation 3 when the roughness curve is expressed by Equation 1 like “Arithmetic mean roughness Ra”. That is, it is the square root of the root mean square of the slope.

  In the present specification, the surface roughness when the substrate 1 and the convex portion 1b are viewed integrally is referred to as “surface roughness on the surface of the substrate”. Further, it may be expressed as “arithmetic mean roughness Ra on the surface of the substrate” and “root mean square slope RΔq on the surface of the substrate”.

  As for the surface roughness on the surface of the substrate according to this embodiment, the arithmetic average roughness Ra is 0.50 μm or more and 1000 μm or less, and the root mean square slope RΔq is 0.50 or more and 20 or less. Preferably, the root mean square slope RΔq is 0.50 or more and 3.0 or less. By forming the magnetic layer 2 on the substrate 1 and the convex portion 1b having the above characteristics, the residual magnetization in the in-plane direction of the obtained permanent magnet thin film can be improved.

  In the permanent magnet thin film of this embodiment, it is considered that the reason why the residual magnetization in the in-plane direction can be improved is as follows.

As shown in FIG. 3, the magnetic layer 2 according to the present embodiment has main phase particles 2a. The shape of the main phase particle 2a is not particularly limited. For example, when the main phase particle 2a has an R ₂ T ₁₄ B structure, the c-axis usually exists in the direction of the maximum diameter and the easy magnetization axis direction 4 exists.

  The easy axis direction 4 of the main phase particles 2a included in the magnetic layer 2 is perpendicular to the portion of the convex portion 1b in contact with the main phase particles 2a, as shown in FIG. There is a tendency to face easily in any direction. Here, as shown in FIG. 4, an angle between the easy magnetization axis direction 4 and the perpendicular direction 5 perpendicular to the surface 1 a of the substrate 1 is defined as θ. In the permanent magnet thin film according to this embodiment, by increasing the angle θ, the in-plane direction component can be increased when the easy magnetization axis is decomposed into an in-plane direction component and a perpendicular direction component. it can. Therefore, the residual magnetization in the in-plane direction is improved. In FIG. 4, the main phase particles 2a are not shown.

  Although there is no restriction | limiting in particular in the average value of angle (theta) in the permanent magnet thin film which concerns on this embodiment, It is preferable that they are 30 degrees or more and 90 degrees or less, and it is more preferable that they are 36 degrees or more and 90 degrees or less.

  Although there is no restriction | limiting in particular in the formation method of the magnetic layer 2, For example, it can form by methods, such as sputtering and the pulsed laser deposition method (PLD: Pulsed Laser Deposition).

  When the magnetic layer 2 is formed by sputtering, the film formation temperature (substrate temperature during film formation) is not particularly limited, but is preferably 400 ° C. or higher and 700 ° C. or lower.

  By setting the film forming temperature to 400 ° C. or higher, the main phase particles 2a are sufficiently formed, and the residual magnetization in the in-plane direction can be improved. On the other hand, by setting the film forming temperature to 700 ° C. or less, the main phase particles can be prevented from growing abnormally, and the easy magnetization axis direction can be appropriately controlled.

  For the magnetic layer according to this embodiment, it is preferable not to make the easy axis of magnetization isotropic after film formation. For example, when heating is performed after film formation, main phase particles grow inside the magnetic layer 2 and are less susceptible to surface roughness on the surface of the substrate, resulting in an isotropic easy axis direction and in-plane The residual magnetization in the direction is difficult to improve. When the easy magnetization axis direction is isotropic, the variation in the angle θ becomes very large.

  When the arithmetic average roughness Ra on the surface of the substrate is smaller than 0.50 μm, the magnetic layer 2 is formed on the surface of the very smooth substrate. Therefore, when magnetization is applied in the in-plane direction, The easy axis direction 4 of the main phase particles 2 a is easily oriented in the perpendicular direction 5 perpendicular to the surface 1 a of the substrate 1. Therefore, the residual magnetization in the in-plane direction of the permanent magnet thin film is lowered.

  As shown in FIG. 5, when the root mean square slope RΔq on the surface of the substrate is small and less than 0.50, the main phase particles 2 are affected by the surface roughness of the substrate, but the surface of the substrate is smooth. Therefore, the easy magnetization axis direction 4 of each main phase particle 2 is not easily oriented in the direction perpendicular to the portion in contact with each main phase particle 2 and remains oriented in the perpendicular direction perpendicular to the surface 1 a of the substrate 1. It becomes easy. That is, the average value of θ tends to be small. As a result, the residual magnetization in the in-plane direction of the RTB-based permanent magnet thin film is reduced.

  As shown in FIG. 6, when the root mean square slope RΔq is large, it is difficult for the sputtered atoms to enter between the large convex portions 1b, and it is difficult to form the magnetic layer 2 uniformly. As a result, the residual magnetization of the permanent magnet thin film is likely to decrease.

  The permanent magnet thin film according to the present embodiment may have protective layers for preventing reaction with the substrate and preventing oxidation on the upper and lower sides of the magnetic layer. As the material of the protective layer, for example, Mo, Ta, resin and the like can be used.

  Moreover, it is preferable that the permanent magnet thin film which concerns on this embodiment is the shape where the convex part 1b of the board | substrate 1 continued along the surface 1a of the board | substrate 1. FIG. Furthermore, as shown in FIG. 7, the convex part 1b of the board | substrate 1 becomes the continuous linear shape along the surface 1a of the board | substrate 1, and the direction of the convex part 1b is aligned in one direction. Particularly preferred.

  When the magnetic layer 2 is formed on the substrate 1 and the convex portion 1b shown in FIG. 7, the in-plane component direction in the easy axis direction of the main phase particles becomes a direction perpendicular to the straight line direction. For this reason, the in-plane components in the easy axis direction of the main phase particles are also substantially parallel to each other. Therefore, the present R-T-B system permanent magnet thin film is effective in obtaining a particularly high residual magnetization in a specific in-plane direction of the thin film.

  For example, in FIG. 8, 7a to 7d are shown as examples of the direction 7 in which the magnetic field is applied when measuring the residual magnetization. Among these, when the remanent magnetization is measured by applying a magnetic field in a direction perpendicular to the direction of the straight line, that is, in the direction 7b, the remanent magnetization is particularly high. On the other hand, when the residual magnetization is measured by applying a magnetic field in the direction close to the horizontal direction of the straight line, that is, in the direction of 7d, the residual magnetization becomes particularly low.

  Hereinafter, the manufacturing method of the permanent magnet thin film which concerns on this embodiment, and the suitable example of the permanent magnet thin film manufactured by the said method are demonstrated.

  Among methods for producing a permanent magnet thin film, methods for forming a magnetic layer on a substrate include a vapor deposition method and a PLD method. In the following description, an example of a production method by sputtering in the vapor deposition method will be described.

  In the present embodiment, it is necessary to perform processing or the like so that the surface roughness on the surface of the substrate is appropriate before forming the magnetic layer. There are mainly two methods for obtaining the desired surface roughness. One is a method of directly processing a substrate, and the other is a method of forming a base layer on the substrate and processing the base layer.

  The case where the substrate is directly processed will be described in detail. The prepared substrate is subjected to mechanical or chemical processing for obtaining a desired surface roughness. Specific examples of the processing method include paper finishing, sand blasting, grinding, liquid honing, electric discharge engraving, and electrolytic polishing. It is preferred to use a paper finish or sand blast.

Next, when sputtering the magnetic layer, first, a target material is prepared. The following describes a case of forming a magnetic layer of the particles having a R 2 _T 14 _B structure as a main phase grains. In this case, an R single element target material, a T single element target material, and a B single element target material may be prepared as target materials. Moreover, you may prepare the alloy target material which consists of an alloy of the various elements contained in the target magnetic layer. Similarly, when using other elements such as Zr, Ti, Bi, Sn, Ga, Nb, Ta, Si, V, Ag, Ge, etc. in the magnetic layer as appropriate, a method using an alloy target material or a single element It can be contained by a method using a target material. On the other hand, since it is desirable to reduce impurity elements such as O and N as much as possible, it is preferable to reduce the impurity content in the target material as much as possible.

  The target material is oxidized from the surface during storage. In particular, the R single element target material has a high oxidation rate. Therefore, before using the target material, it is preferable to perform sputtering sufficiently to expose the clean surface of the target material.

There is no particular limitation on the film forming apparatus for performing sputtering. However, since it is desirable to reduce impurity elements such as O and N as much as possible, the inside of the vacuum chamber is 10 ⁻⁶ Pa or less, more preferably 10 ⁻⁸ Pa or less. Is preferably exhausted. In order to maintain a high vacuum state, it is desirable to have a base material introduction chamber connected to the film formation chamber. In addition, as described above, before the target material is used, it is necessary to perform sputtering sufficiently to bring out a clean surface of the target material. Therefore, the film forming apparatus is operated in a vacuum state between the substrate and the target material. It is desirable to have a possible shielding mechanism.

  The sputtering method is not particularly limited, but for the purpose of reducing impurity elements such as O and N as much as possible, it is preferable to use a magnetron sputtering method that enables sputtering in a lower Ar atmosphere. Here, it is particularly preferable to appropriately select the thickness of the target material containing Fe and / or Co. If the thickness of the target material containing Fe and / or Co is not properly selected, Fe and / or Co contained in the target material may greatly reduce the leakage magnetic flux of magnetron sputtering and make sputtering difficult. Because. As the power source for sputtering, either DC or RF can be used, and can be appropriately selected depending on the target material.

  A magnetic layer is produced by sputtering R, T and B. The easy magnetization axis direction of the main phase particles can be controlled by the film forming conditions.

  During sputtering, the substrate is preferably heated to 400 ° C. or more and 700 ° C. or less to be crystallized. However, this is the case where R is Nd and T is Fe. The optimum temperature of the substrate during sputtering varies with the type of R and / or T.

  In the above, the suitable manufacturing method of the permanent magnet thin film which concerns on this embodiment was demonstrated. Next, for the permanent magnet thin film of this embodiment, a method for measuring the surface roughness on the surface of the substrate, a method for evaluating the residual magnetization in the in-plane direction of the permanent magnet thin film, a method for analyzing the composition of the magnetic layer, and observing a cross section of the permanent magnet thin film A method (measuring method of the average value of the angle θ) will be described.

  The surface roughness on the surface of the substrate is measured immediately before the magnetic layer is formed. A commonly used surface roughness measuring machine is used to measure two types of surface roughness, the arithmetic average roughness Ra and the root mean square slope RΔq on the surface of the substrate.

  The residual magnetization in the in-plane direction of each permanent magnet thin film is measured by applying a magnetic field of ± 4 T in a direction parallel to the substrate direction using a vibrating sample magnetometer (VSM).

  The composition analysis of the magnetic layer is performed by using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) after evaluation of the remanent magnetization. Moreover, it can confirm that the main phase particle | grains of a magnetic layer have desired crystal structure by analyzing using a X-ray diffraction method (XRD: X-ray Diffraction).

Cross-sectional observation of the permanent magnet thin film in the vertical direction (perpendicular to the surface of the substrate) is performed by processing a sample with a focused ion beam (FIB) and then scanning transmission electron microscope (STEM). Microscope). The direction of the easy axis of magnetization can be determined from the atomic image of the main phase particles. For example, when the main phase particles have an R ₂ T ₁₄ B structure, the c-axis direction that is the maximum diameter direction is the easy magnetization axis direction. Then, the angle θ can be measured. Further, the easy axis direction of magnetization can be determined and the angle θ can be measured by observing the domain wall using Lorentz-STEM (Lorentz-Scanning Transmission Electron Microscope) of STEM. The average value of θ is calculated by measuring θ and averaging at least 5 or more, preferably 20 or more, for different main phase particles. When the number of main phase particles in the range of ± 20 ° from the average value of θ is less than 30%, the permanent magnet thin film is highly isotropic regardless of the average value of the angle θ. to decide.

  In addition, from the cross-sectional observation of the permanent magnet thin film in the vertical direction, the boundary line between the layer immediately below the RTB-based magnetic layer and the RTB-based magnetic layer is extracted by image processing, whereby the surface of the substrate It is also possible to obtain the arithmetic average roughness Ra and the root mean square slope RΔq.

  Hereinafter, although the content of the present invention is explained in detail using an example and a comparative example, the present invention is not limited to the following examples.

[Example 1]
First, a polyimide substrate was prepared as a substrate. Next, in order to perform surface processing on the substrate, paper finishing was performed on the substrate to form a large number of convex portions. The paper finishing was performed for a total of 280 seconds with a paper belt device using sandpaper of particle size # 30. In addition, in order to make the direction of a convex part become a random shape, the direction of paper finishing was changed every 20 seconds, and the direction of the surface processing method was made random.

Next, the surface roughness (arithmetic mean roughness Ra and root mean square slope RΔq) on the surface of the paper-finished substrate was measured. The surface roughness was measured by a surface roughness measuring device (Olympus Corporation: OLS4000). In addition, the surface roughness of the surface of the substrate was calculated by measuring and averaging the surface roughness at any 10 points on the substrate.

Next, the substrate after paper finishing was introduced into a vacuum chamber. Then, a permanent magnet thin film was manufactured by forming a magnetic layer having a composition of Nd _17.6 Fe _71.6 B _10.7 on the substrate by sputtering. Sputtering was performed by preparing a plurality of single element target materials and performing sputtering simultaneously. The temperature during sputtering (substrate temperature) was 400 ° C. The thickness of the magnetic layer was 500 nm. After the magnetic layer was formed on the substrate, it was cooled to 200 ° C. Then, Mo was formed into a 20 nm-thickness as a protective film by sputtering. Then, after cooling to room temperature in a vacuum, it was taken out from the vacuum chamber.

It was then measured residual magnetization Mr // in the in-plane direction of the permanent magnet thin film _[T]. The residual magnetization in the in-plane direction was measured using a vibrating sample magnetometer (VSM) (Tamagawa Seisakusho Co., Ltd .: TM-VSM311483-HGC type). Specifically, the residual magnetization was measured by applying a magnetic field of ± 4T in a direction parallel to the surface of the substrate. The residual magnetization in the in-plane direction of the permanent magnet thin film was measured four times while rotating the direction in which the magnetic field was applied at 45 ° intervals about the perpendicular direction perpendicular to the surface of the substrate. The measurement results of remanent magnetization are shown in Table 2. In Table 2, the remanent magnetization is rearranged in descending order. When the maximum value of the residual magnetization is 0.55 T or more, the permanent magnet thin film has good residual magnetization in the in-plane direction of the permanent magnet thin film. In addition, when the maximum value of the residual magnetization is 0.60 T or more, the permanent magnet thin film has a better residual magnetization. A permanent magnet thin film having better remanent magnetization when the maximum value of remanent magnetization is 0.70 or more, and a permanent film having better remanent magnetization when the remanent magnetization maximum value is 0.80 T or more. It is assumed that the permanent magnet thin film has the best residual magnetization when the maximum value of the residual magnetization is 1.00 T or more.

After measuring the magnetic properties, the composition of the magnetic layer of the permanent magnet thin film was confirmed by ICP-AES (Shimadzu Corporation: ICPS-8100). It was confirmed that the difference between the composition of the magnetic layer and the charged composition was within ± 1 at%. Furthermore, it was confirmed by XRD that the main phase particles of the magnetic layer of the permanent magnet thin film had an R ₂ T ₁₄ B structure.

  Next, for the permanent magnet thin film, a sample was processed using FIB, and cross-sectional observation in a direction perpendicular to the surface of the substrate was performed using STEM (Hitachi High-Technologies Corporation: Scanning Transmission Electron Microscope HD-2700). . The c-axis direction, that is, the easy magnetization axis direction, was determined from the atomic image of the main phase particles contained in the magnetic film. Next, the angle θ formed by the easy axis direction of main phase particles and the perpendicular direction was calculated. For 20 arbitrarily selected main phase particles, an angle θ formed by the easy axis direction of the main phase particles and the perpendicular direction was measured, and an average value of θ was calculated. However, when the variation in the angle θ formed by the easy axis direction of each main phase particle and the perpendicular direction is large, the entire permanent magnet thin film, etc., regardless of the average value of the calculated θ, etc. It is thought that the directionality is high. Therefore, when the number of main phase particles having θ within the range of ± 20 ° with respect to the calculated average value of θ is less than 6 out of 20, it is determined that the isotropic property of the permanent magnet thin film is high. To do. However, there were no examples and comparative examples that were actually judged to be highly isotropic.

[Examples 2, 2a, 3, 3a, 3b]
A permanent magnet thin film was produced in the same manner as in Example 1 except that the charged composition was changed to the composition shown in Table 1. The results are shown in Table 2.

[Examples 4, 4a, 5 and Comparative Example 3]
A permanent magnet thin film was prepared in the same manner as in Example 1 except that the particle size of sandpaper used for paper finishing was changed to the particle size shown in Table 1. The results are shown in Table 2.

[Examples 6, 6a, 7, 7a, 7b, Comparative Example 4]
A permanent magnet thin film was prepared in the same manner as in Example 1 except that the total paper finishing time was as shown in Table 1. The results are shown in Table 2. When the total time was not a multiple of 20, the last paper finishing time was shortened to make the total time shown in Table 1.

[Examples 8, 9, and 10]
A permanent magnet thin film was prepared in the same manner as in Example 1 except that sandblasting was performed instead of paper finishing. Sand blasting was performed by (Shinto Kogyo Co., Ltd .: MY-30AP). Glass beads # 400 (Example 8), # 80 (Example 9), and # 16 (Example 10) were used as polishing materials in sandblasting. After processing by low pressure blasting at a pressure of about 0.6 MPa, pure water cleaning was performed. The results are shown in Table 2. When sandblasting is performed, the surface processing direction is necessarily random, and the direction of the convex portion is random.

[Examples 11 and 12]
The substrate was changed from a polyimide substrate to an Al substrate. The substrate temperature during sputtering was also changed as shown in Table 1. Other conditions were the same as in Example 1, and a permanent magnet thin film was produced. The results are shown in Table 2.

[Example 13]
A permanent magnet thin film was prepared in the same manner as in Example 1 except that the charge composition R was changed from Nd to Pr. The results are shown in Table 2.

[Example 14]
For paper finishing, instead of changing the direction of paper finishing every 20 seconds as in Example 1 and making the direction of surface processing random, paper finishing is performed in a single direction for 280 seconds. Surface treatment was performed only in the direction. Other conditions were the same as in Example 1, and a permanent magnet thin film was produced. The results are shown in Table 2. In measuring the surface roughness on the surface of the substrate, the surface roughness at any 10 points was measured and averaged in a direction perpendicular to the single direction. When Example 14 is observed, unlike Examples 1 to 13 and the comparative example described above, the linear shape is continuous along the surface of the substrate as shown in FIG. 8, and the direction of each convex portion is simple. It was aligned in one direction.

  Table 1 shows the substrate type, surface processing conditions, and magnetic layer sputtering conditions. The surface processing conditions are described for the processing method, particle size, processing time and processing direction. The sputtering conditions are described for the feed composition, R / T and substrate temperature.

Table 2 shows the surface roughness of the substrate, the average value [°] of the angle θ formed by the direction of the easy axis of main phase particles and the direction perpendicular to the surface of the permanent magnet thin film, and the residual magnetization Mr 7 _{// in the} in-plane direction. The measurement result of [T] was shown.

  In Example 1, the arithmetic average roughness Ra and the root mean square slope RΔq on the surface of the substrate were within a predetermined range. As a result, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film became a suitable value. This is considered to be because the arithmetic average roughness Ra and root mean square slope RΔq on the surface of the substrate are appropriate values, and the easy axis direction of the main phase particles is preferably inclined in the in-plane direction of the substrate. It is done.

  Further, in Example 2 where R / T = 0.19 in the charge composition and Example 2a where R / T = 0.18, the maximum value of the residual magnetization is a suitable value of 0.60 T or more. However, it was lower than the maximum value of the remanent magnetization of Example 1 in which R / T = 0.27 in the charged composition. In Example 3 where R / T = 0.39 in the charged composition and Example 3a where R / T = 0.40, the maximum value of the residual magnetization was 0.61 T or more, which was a suitable value. It was lower than the maximum value of remanent magnetization in Example 1. In Example 3b in which R / T = 0.41 in the charged composition, the maximum value of remanent magnetization was 0.58T, which was higher than 0.55T but less than 0.60T.

  It is considered that the smaller the R / T in the charged composition, the more easily α-Fe having soft magnetism is precipitated and the lower the residual magnetization. Further, it is considered that the larger the R / T in the charged composition, the lower the volume ratio of the main phase particles in the magnetic layer, and the lower the residual magnetization.

  Further, it is considered that the arithmetic average roughness Ra of the surface roughness on the surface of the substrate could be controlled by changing the particle size of the sandpaper used for paper finishing. In Example 4 in which the arithmetic average roughness Ra is 0.55 μm and Example 4a in which the arithmetic average roughness Ra is 0.50 μm, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film is 0.60 T. Although it became the above suitable value, arithmetic mean roughness Ra was lower than the maximum value of the residual magnetization of Example 1 which is 1.4 micrometers. In Comparative Example 3 in which the arithmetic average roughness Ra is 0.42 μm, the maximum value of the residual magnetization rapidly decreases. In Example 5 where the arithmetic average roughness Ra is 3.5 μm, the residual magnetization in the in-plane direction of the permanent magnet thin film was as high as that in Example 1.

  The smaller the arithmetic average roughness Ra, the more the magnetic layer is formed on the surface of the smooth substrate. In this case, it is considered that when a magnetic field is applied in a direction parallel to the surface of the substrate, the easy axis of magnetization of the main phase particles is easily oriented in the direction perpendicular to the surface of the permanent magnet thin film. Therefore, it is considered that the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film has decreased.

  It is also considered that the root mean square slope RΔq of the surface of the substrate could be controlled by changing the substrate processing time. In Example 6 where the root mean square slope RΔq of the surface of the substrate is 0.52, and Example 6a which is 0.50, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film is preferably 0.60 T or more. However, the root mean square slope RΔq was 0.78, which was lower than the maximum value of residual magnetization in Example 1. In Comparative Example 4 in which the root mean square slope RΔq is 0.36, the maximum value of the residual magnetization rapidly decreases.

  The smaller the root mean square slope RΔq on the surface of the substrate, the more the magnetic layer is deposited on the smooth surface of the substrate. In this case, it is considered that when a magnetic field is applied in a direction parallel to the surface of the substrate, the easy axis of magnetization of the main phase particles is easily oriented in the direction perpendicular to the surface of the permanent magnet thin film. Therefore, it is considered that the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film has decreased.

  In Example 7 in which the root mean square slope RΔq of the surface of the substrate is 2.7 and Example 7a in which RΔq is 3.0, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film is 0.60 T or more. Although it was a suitable value, it was lower than the maximum value of the residual magnetization in Example 1 where RΔq was 0.78. In Example 7b in which the root mean square slope RΔq of the surface of the substrate was 3.3, the maximum value of the residual magnetization was 0.58T, which was 0.55T or more, but less than 0.60T.

  It is considered that the larger the root mean square slope RΔq of the surface of the substrate, the more difficult it is to form the magnetic film uniformly on the surface of the convex portion, and the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film tends to decrease.

  In Example 8, which adopted sandblasting instead of paper finishing as the substrate processing method, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film was 0.73 T, which is equivalent to Example 1 using paper finishing. The value was excellent. Even if the processing method of the substrate surface is different, the arithmetic average roughness Ra and the root mean square slope RΔq of the substrate surface are appropriate values, and the easy axis direction of the main phase particles is the in-plane direction of the permanent magnet thin film. This is thought to be because of the inclination.

  The permanent magnet thin films of Examples 9 and 10 were produced under the same conditions except that the particle size of the glass beads used for low-pressure blasting was changed. By changing the particle size of the glass beads, the arithmetic average roughness Ra of the surface of the substrate was increased, but the maximum value of the remanent magnetization in the in-plane direction of the permanent magnet thin film did not change significantly at least until Ra = 33 μm. .

  In Example 11 in which the substrate was changed from a polyimide substrate to an Al substrate, the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film was 0.74 T, which was an excellent value equivalent to that of Example 1 using a polyimide substrate. It became. Even in different substrates, when the arithmetic average roughness Ra and the root mean square slope RΔq on the surface of the substrate are appropriate values, the easy axis direction of the main phase particles is inclined in the in-plane direction of the permanent magnet thin film. It is thought that.

  In Example 12, which was the same as Example 11 except that the film forming temperature was changed from 400 ° C. to 650 ° C., the maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film was 0.74 T. The value was as excellent as 11. In Example 12, as in Example 11, since the substrate temperature during film formation was in an appropriate range, it is considered that the easy axis direction of main phase particles is inclined in the in-plane direction of the permanent magnet thin film.

  A permanent magnet thin film of Example 13 was produced in the same manner as in Example 1 except that R of the charged composition was Pr. The maximum value of the residual magnetization in the in-plane direction of the permanent magnet thin film was 0.69T, which was a preferable value.

  In Example 14, by performing paper finishing only in a single direction, as shown in FIG. 8, the convex portion becomes a continuous linear shape along the surface of the substrate, and the direction of each convex portion. Became a shape that is aligned in one direction. The residual magnetization in the in-plane direction of the permanent magnet thin film changed greatly depending on the direction in which the magnetic field was applied, unlike the other examples and comparative examples. The maximum value of remanent magnetization was 1.03T, and particularly high remanent magnetization was obtained. Since the in-plane component direction of the main phase particles in the direction of the easy axis of the thin film is the in-plane direction of the thin film perpendicular to the direction of the straight line, the in-plane components of the thin film in the direction of the easy axis are also substantially parallel. Therefore, it is considered that particularly high remanent magnetization was obtained in a specific in-plane direction of the thin film.

[Examples 21 to 39, Comparative Examples 23 and 24]
Examples 21 to 39 and Comparative Examples 23 and 24 are Examples and Comparative Examples in which paper finishing is performed only in a single direction as in Example 14 and other conditions are appropriately controlled. The results are listed in Tables 3 and 4.

  From Tables 3 and 4, in each example in which paper finishing was performed only in a single direction as in Example 14, the residual magnetization in the in-plane direction of the permanent magnet thin film changed greatly depending on the direction in which the magnetic field was applied. And in each Example, the permanent magnet thin film with a high maximum value of a residual magnetization was obtained compared with the Example of the conditions equivalent to Table 1 and Table 2. FIG.

  The permanent magnet thin film according to the present invention can increase the residual magnetization in the in-plane direction. In particular, in the field of MEMS devices, a permanent magnet thin film having a thickness of less than 0.50 mm needs to be manufactured, and the residual magnetization in the in-plane direction of the permanent magnet thin film needs to be increased, so that the availability is high.

DESCRIPTION OF SYMBOLS 1 Substrate 1a Substrate surface 1b Convex part 2 Magnetic layer 2a (R-T-B system) main phase particle 4 Easy axis direction 5 Surface perpendicular direction 7 Direction of applying magnetic field

Claims (6)

A permanent magnet thin film comprising a magnetic layer formed on the surface of a substrate,
Arithmetic mean roughness Ra on the surface of the substrate is 0.50 μm or more and 1000 μm or less,
A permanent magnet thin film having a root mean square slope RΔq of 0.50 or more and 20 or less on the surface of the substrate.   The permanent magnet thin film according to claim 1, wherein the root mean square slope RΔq is 0.50 or more and 3.0 or less. A plurality of convex portions are formed on the surface of the substrate,
The permanent magnet thin film according to claim 1, wherein the convex portion has a shape that is continuous along the surface of the substrate.   The permanent magnet thin film according to claim 3, wherein the convex portions have a linear shape continuous along the surface of the substrate, and the directions of the convex portions are aligned in one direction. The magnetic layer has main phase particles;
5. The average value of θ is 30 ° or more and 90 ° or less, where θ is an angle formed between the easy magnetization axis of the main phase particles and a perpendicular direction perpendicular to the surface of the substrate. A permanent magnet thin film according to claim 1. The permanent magnet thin film is an RTB-based permanent magnet thin film,
R is one or more rare earth elements, T is one or more transition metal elements essential to Fe or Fe and Co, B is boron, and a part of the boron may be substituted with carbon,
R / T is 0.18 or more and 0.40 or less by atomic ratio, The permanent-magnet thin film in any one of Claims 1-5.

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