JP4444797B2 - Magnetic circuit for generating radial magnetic field used for film formation by sputtering process - Google Patents

Description

  The present invention relates to a magnetic circuit for generating a radial magnetic field, and more particularly to a magnetic circuit for generating a radial magnetic field required in a film forming process or a heat treatment process of a substrate in the manufacture of a magnetic disk device.

  There are two methods of information recording in a magnetic disk device: a horizontal magnetic recording method and a vertical recording method. In general, a horizontal magnetic recording system that magnetizes in a horizontal direction with respect to a track of a recording medium is widely used. In this method, the micromagnets magnetized in the horizontal direction with respect to the recording film have a relationship of exerting a demagnetizing field between the adjacent micromagnets. For this reason, as the recording density increases and the micromagnet becomes smaller, there is a possibility that the magnetization is demagnetized or demagnetized, and the recording signal cannot be read out.

  A vertical recording method has been proposed as a method for solving the limitation of the high density recording of the horizontal recording method. The recording medium of the perpendicular recording system can have, for example, a two-layer structure in which a recording hard magnetic film magnetized in the perpendicular direction is laminated on a high magnetic permeability soft magnetic film. This high permeability soft magnetic film functions as a magnetic circuit that recirculates the recording magnetic field from the magnetic head to the magnetic head side during signal recording, and increases the strength of the recording magnetic field for recording and reproduction. It plays a role in improving efficiency. For this reason, it is desired that the high magnetic permeability soft magnetic film has a higher magnetic permeability. In addition, if a stray magnetic field exists around the recording medium or the magnetic head, the stray magnetic field is concentrated on the magnetic pole of the magnetic head, and the magnetic wall of the soft magnetic film is moved by the concentrated magnetic field, thereby changing the reproduction output and recording magnetization. There was something to do.

  As one method for solving this problem, it has been proposed to impart a circumferential or radial magnetic anisotropy to the soft magnetic film with respect to the substrate. A soft magnetic film having magnetic anisotropy has improved magnetic permeability and improved magnetic efficiency during recording and writing. Further, a magnetic disk 110 having a three-layer film structure has been proposed as a magnetic field generation source for giving this magnetic anisotropy (see Patent Document 1). FIG. 12 shows an example of the film configuration in such a magnetic disk. That is, as shown in FIG. 12, a three-layer film structure in which a hard magnetic film (undercoat film) 112 is formed between a ring-shaped substrate 111 and a soft magnetic film (undercoat film) 113 is recorded on the soft magnetic film 113. A hard magnetic film 114 as a film is laminated. The hard magnetic film 112 as the base film is magnetized in the radial direction, and a magnetic field in the radial direction is always applied to the soft magnetic film 113. For this reason, the movement of the domain wall due to the stray magnetic field is suppressed, and problems such as a change in reproduction output and demagnetization of recording magnetization can be solved.

  In addition to this, in order to solve various problems, a method having a medium structure of a further multilayer structure is adopted, and a multilayer structure for solving the above-mentioned problem in high density is also proposed in the horizontal recording method. Has been. However, in these multilayer films, there are increasing cases in which a step of uniformly magnetizing the substrate in the circumferential direction and the radial direction is required.

  As described above, in the manufacturing process of a magnetic disk medium substrate, the effectiveness of applying a circumferential or radial magnetic field to a soft magnetic film or a hard magnetic film, and the heat treatment process after the film formation In addition, the effectiveness of applying a magnetic field in the above direction to the substrate has been proposed. Film formation on the substrate is mainly performed by various film formation methods such as sputtering, but a magnetic circuit for generating a magnetic field suitable for each is required.

JP-A-5-258274

  In the manufacturing process of the medium substrate of the magnetic disk, when a magnetic field is applied to the substrate in the radial direction or the circumferential direction, it is preferable that these magnetic field directions are more parallel to the substrate surface. If the direction of the applied magnetic field is tilted with respect to the substrate surface, the magnetization direction of the hard magnetic film is similarly tilted, and the direction of magnetic anisotropy of the soft magnetic film is not uniform. This is because it is disadvantageous in realizing the above.

  Accordingly, the present invention provides a magnetic circuit for generating a magnetic field in the radial direction of a ring-shaped substrate, wherein the direction of the magnetic field formed on the arrangement surface on which the ring-shaped substrate is disposed is relative to the radial direction of the ring-shaped substrate. The goal is to be more completely parallel. In particular, in the manufacturing process of the magnetic disk medium substrate, the magnetic field applied to the soft magnetic film and the hard magnetic film formed on the ring-shaped substrate is more completely parallel to the radial direction of the substrate. It is an object of the present invention to provide a magnetic circuit as a generation source.

According to the present invention, a ring that includes a ring-shaped first permanent magnet unit and a second permanent magnet unit, and is an object to be processed in a space sandwiched between the first and second permanent magnet units. A radial magnetic field for generating a magnetic field in the radial direction of the ring-shaped substrate on the arrangement surface when a plane including the ring-shaped substrate is the arrangement surface when the ring-shaped substrate is arranged. A magnetic circuit for generation,
A space is provided so that a film can be formed between the first permanent magnet unit and the second permanent magnet unit ,
The magnetic field formed by each of the first and second permanent magnet units has a magnetic field component in the radial direction of the ring-shaped substrate and substantially does not have a magnetic field component in the circumferential direction on the arrangement surface. It is located in,
The first and second permanent magnet units have a magnetization direction and a shape symmetric with respect to the arrangement surface, and are provided at positions symmetrical with respect to the arrangement surface ;
An inner diameter of the first and second permanent magnet units is set to be larger than an outer diameter of a ring-shaped substrate that is an object to be processed, and the first and second permanent magnet units are in a direction perpendicular to the arrangement surface. the magnetization component possess to,
There is provided a magnetic circuit for generating a radial magnetic field used in a film forming process by sputtering, wherein the first and second permanent magnet units further have a magnetization component in a direction parallel to the radial direction of the ring-shaped substrate.

As described in detail below, according to the present invention, in the magnetic circuit for generating a magnetic field in the radial direction of the ring-shaped substrate, the direction of the magnetic field formed on the arrangement surface on which the ring-shaped substrate is disposed is Can be made more completely parallel to the radial direction of the substrate. In particular, according to the present invention, a magnetic circuit capable of generating a radial magnetic field required in a substrate film formation process (a heat treatment process or the like as a reference example ) for the manufacture of a magnetic disk device is provided. A radial magnetic field oriented radially can be generated.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the embodiments described below do not limit the present invention.

  As described above, according to the present invention, the ring-shaped first permanent magnet unit and the second permanent magnet unit are included, and the space between the first and second permanent magnet units is covered. A ring-shaped substrate that is a processed object can be disposed, and when the ring-shaped substrate is disposed, a plane including the ring-shaped substrate is defined as a placement surface, and a magnetic field is generated in the radial direction of the ring-shaped substrate on the placement surface. A magnetic circuit for generating a radial magnetic field is provided.

  Although not particularly limited, the magnetic circuit according to the present invention can be suitably used for manufacturing a perpendicular magnetic recording medium. In this case, although not particularly limited, it is preferable to use a non-magnetic substrate such as glass, Al, Si, or the like as the ring-shaped substrate that is the object to be processed. By subjecting such a ring-shaped substrate to a predetermined treatment while applying a magnetic field in the radial direction, a perpendicular magnetic recording medium can be suitably manufactured. Although not particularly limited, examples of such treatment include CVD, plating, PVD (including sputtering), and the like. By these treatments, a perpendicular magnetic recording medium having a high magnetic permeability soft magnetic film and a recording hard magnetic film on a substrate, and preferably a hard magnetic film formed between the substrate and the soft magnetic film, is obtained. It can manufacture suitably (refer patent document 1). Further, a radial magnetic field can be applied not in the film formation but in the heat treatment step. The use of the magnetic circuit according to the present invention is not limited to the manufacture of a perpendicular magnetic recording medium. In this case, the ring-shaped substrate and the treatment can be appropriately selected by those skilled in the art. Although not particularly limited, the ring shape preferably has an inner diameter and an outer diameter concentrically.

  The first permanent magnet unit has a ring shape, and the magnetic field formed by the first permanent magnet unit has a magnetic field component in the radial direction of the ring-shaped substrate on the arrangement surface, and the magnetic field in the circumferential direction. Arranged so as to be substantially free of components. For this reason, generally, the first permanent magnet unit is arranged so that the axis is the same as the ring-shaped substrate to be processed. As described above, by generating a magnetic field in the radial direction without substantially generating a magnetic field in the circumferential direction as described above, for example, for a ring-shaped substrate that is an object to be processed, A thin film forming process or a processing process of the magnetic material can be suitably performed. However, with only the first permanent magnet unit, the magnetic field formed by the first permanent magnet unit has a magnetic field component in the direction perpendicular to the arrangement surface on the arrangement surface according to the distance from the center. Note that “substantially no magnetic field component in the circumferential direction” means that there is no magnetic field component in the circumferential direction as long as there is no inconvenience in the intended processing of the radial magnetic field generating magnetic circuit according to the present invention. Say.

  FIG. 13 shows a schematic diagram of a conventional magnetic circuit for generating a radial magnetic field including Patent Document 1 (see Patent Document 1 and FIG. 2). Specifically, for example, as shown in FIG. 13, a ring-shaped permanent magnet 121 is disposed only on one side with respect to the ring-shaped substrate 111. The ring-shaped permanent magnet has the same central axis as the ring-shaped substrate, and is arranged so as to have a magnetization direction perpendicular to the arrangement surface on which the ring-shaped substrate is arranged. Further, a cylindrical permanent magnet 122 is arranged on the same plane as the ring-shaped permanent magnet 121 and on the central axis of the ring-shaped permanent magnet 121. The columnar permanent magnet 122 is disposed so as to have a magnetization direction in a direction different from that of the ring-shaped permanent magnet 121. Preferably, ring-shaped permanent magnet 121 and columnar permanent magnet 122 are magnetically coupled by yoke 126 on a side different from ring-shaped substrate 111. Further, a target is provided between the ring-shaped permanent magnet 121 and the columnar permanent magnet 122 and the ring-shaped substrate 111. When the permanent magnets and the like are arranged in this way, these permanent magnets form a magnetic field schematically shown by magnetic lines of force 125 in FIG. Will have a tilt. At this time, as described above, the uniformity of the film quality may be adversely affected. FIG. 14 shows an example of the relationship between the magnetic field distribution at this time, that is, the radial position on the arrangement surface, the radial magnetic field strength, and the vertical magnetic field strength. The horizontal axis represents the radial position on the arrangement surface, and the vertical axis represents the magnetic field strength. As can be seen from FIG. 14, the vertical magnetic field Bz is generated on the arrangement surface. If the magnet is arranged only on one side with respect to the substrate in this way, a vertical magnetic field is generated, which may adversely affect the film quality.

  Therefore, the radial magnetic field generating magnetic circuit according to the present invention is a second permanent magnet unit arranged on a side different from the first permanent magnet unit with respect to the arrangement surface, and the second permanent magnet A second permanent magnet unit arranged such that the magnetic field formed by the unit has a magnetic field component in the radial direction of the ring-shaped substrate on the arrangement surface and substantially has no magnetic field component in the circumferential direction. In addition. Thus, the second permanent magnet unit is arranged on the side different from the first permanent magnet unit with respect to the arrangement surface, so that the vertical magnetic field formed on the arrangement surface by the first permanent magnet unit, The second permanent magnet unit can cancel the vertical magnetic field formed on the placement surface by the second permanent magnet unit, thereby reducing the vertical magnetic field formed on the placement surface as a whole. Depending on the position or the like, the vertical magnetic field formed on the arrangement surface as a whole can be completely eliminated. In particular, the magnetic field formed by each of the first and second permanent magnet units has a magnetic field component in the radial direction of the ring-shaped substrate on the arrangement surface and substantially has a magnetic field component in the circumferential direction. The second permanent magnet unit is provided without disturbing the radial magnetic field formed on the arrangement surface by the first permanent magnet unit, that is, without generating a magnetic field in the circumferential direction. It is possible to reduce the vertical magnetic field formed on the substrate. Furthermore, it is preferable that the radial direction magnetic field component of the magnetic field which each of the first and second permanent magnet units forms on the arrangement surface is in the same direction. As described above, the first and second permanent magnet units form a radial magnetic field in the same direction on the arrangement surface, whereby a stronger radial magnetic field can be formed on the arrangement surface.

  Here, the shape, position, magnetization direction and the like of the second permanent magnet unit are not particularly limited and can be arbitrarily determined. In particular, it is preferable that the first and second permanent magnet units have magnetization directions and shapes that are symmetric with respect to the arrangement surface, and are provided at positions that are symmetric with respect to the arrangement surface. The first and second permanent magnet units preferably have the same residual magnetization. The first and second permanent magnet units preferably have the same coercive force. Thus, by providing the first and second permanent magnet units symmetrically with respect to the arrangement surface, the vertical direction magnetic field by the first permanent magnet unit and the second permanent magnet at any point on the arrangement surface. The vertical magnetic field generated by the unit can be canceled out, and the vertical magnetic field on the arrangement surface can be more effectively reduced, and a radial magnetic field that is completely in the radial direction can be obtained in the entire substrate.

Although not particularly limited, more specifically, the inner diameters of the first and second permanent magnet units are set larger than the outer diameter of the ring-shaped substrate that is the object to be processed. The second permanent magnet unit may have a magnetization component in a direction perpendicular to the arrangement surface. FIG. 1 shows a cross-sectional schematic view (upper view) and a plan view (lower view) of the radial direction magnetic field generating magnetic circuit according to the first embodiment of the reference example . As shown in FIG. 1, in the first embodiment of the reference example , a plane including the ring-shaped substrate 11 is a placement surface 22, and the ring has a symmetrical shape at a symmetrical position with respect to the placement surface. A permanent magnet 21 is disposed. Each ring-shaped permanent magnet 21 is arranged so that the ring-shaped substrate and the central axis 23 are the same.

Here, as described above, it is preferable that the first and second permanent magnet units have a magnetization component in a direction perpendicular to the arrangement surface. Thereby, a radial direction magnetic field can be suitably formed in an arrangement surface. In the first embodiment of the reference example shown in FIG. 1, the first and second permanent magnet units have a magnetization direction perpendicular to the arrangement surface. That is, the magnetization direction 24 of each permanent magnet unit is perpendicular to the placement surface and is symmetric with respect to the placement surface 22. When the permanent magnet unit is arranged as described above, the permanent magnet unit forms a magnetic field schematically shown by magnetic field lines 25 in FIG. 1 as a whole, and the magnetic field lines 25 are radial, that is, radially directed on the arrangement surface. Furthermore, since the magnet is in a symmetrical position with respect to the substrate, the direction of the lines of magnetic force on the substrate is completely parallel to the substrate. FIG. 2 shows an example of the relationship between the magnetic field distribution at this time, that is, the radial position on the arrangement surface and the radial magnetic field strength. The horizontal axis represents the radial position on the arrangement surface, and the vertical axis represents the magnetic field strength. As shown in FIG. 2, according to the radial magnetic field generating magnetic circuit according to the reference example , the radial magnetic field Br is generated on the arrangement surface, but the vertical magnetic field Bz is always zero.

  The first and second permanent magnet units may further have a magnetization component in a direction parallel to the radial direction of the ring-shaped substrate. FIG. 3 shows a schematic cross-sectional view in the central axis direction of such a magnetic circuit for generating a radial magnetic field according to the second embodiment of the present invention. That is, the magnetization direction of each permanent magnet unit may have a certain inclination from the perpendicular to the substrate as shown in FIG. This is because only the radial magnetic field can be generated on the arrangement surface as long as the magnetization direction is inclined as long as it is symmetrical with respect to the arrangement surface. In some cases, it is possible to increase the strength of the radial magnetic field by giving an inclination to the magnetization direction. This is based on the fact that the inclination of the magnetic field lines formed on the arrangement surface becomes more parallel to the arrangement surface.

  Although not particularly limited, the inclination is preferably 0 ≦ t <90 ° or 180 ≦ t <270 °, and 0 ≦ t ≦ 60 ° or 180 ≦ t <240 °. Further preferred. Here, the difference between the direction perpendicular to the placement surface and away from the placement surface and the direction of magnetization of the permanent magnet unit was defined as the inclination t. FIG. 4 shows an example of the relationship between the radial position on the arrangement surface and the radial magnetic field strength when the magnetization direction inclination of the permanent magnet unit is changed. FIG. 4 shows an example of the radial magnetic field distribution on the arrangement surface. In this case, the highest magnetic field is obtained when the tilt angle = 30 °. The relationship between the amount of tilt in the magnetization direction and the amount of increase in magnetic field strength varies depending on the geometric conditions of the substrate and the magnet, and the tilt of 30 ° is not necessarily the best. In general, the larger the magnet height dimension, the greater the magnetization. A smaller slope is better. This is because the lines of magnetic force approach parallel to the substrate as described above. Moreover, since giving the magnetization direction inclination leads to an increase in the cost of the magnet, the magnitude of the inclination in the magnetization direction must be selected in consideration of cost performance. In addition, in FIG. 1 etc., although the aspect which the radial direction magnetic field was outward was described in the arrangement | positioning surface, it can also be made inward conversely.

Here, it is preferable that the inner diameters of the first and second permanent magnet units are set larger than the outer diameter of the ring-shaped substrate that is the object to be processed. In other words, it is preferable that the entire first and second permanent magnet units are provided above and below the outside of the outer diameter of the ring-shaped substrate. That is, as shown in FIG. 1, the permanent magnet unit 21 is preferably provided entirely outside the substrate 11. FIG. 5 schematically shows the state of film formation by sputtering using the magnetic circuit for generating a radial magnetic field according to the reference example . When the radial magnetic field generating magnetic circuit according to the present invention is used together with a sputtering apparatus, in an actual sputtering apparatus, as shown in FIG. 5, particles flying from the target 31 enter from a direction substantially perpendicular to the substrate surface. Deposited on the substrate (in FIG. 5, a track 32 of sputtered particles is schematically shown). For this reason, it is preferable to arrange the entire permanent magnet outside the substrate so as not to interfere with the sputtering process. Further, even when the front and back surfaces of the substrate are simultaneously formed, if such a magnet arrangement is used, processing can be performed without any problem. Further, in such a magnet arrangement, there is a space between magnets placed symmetrically with respect to the substrate, so that the substrate can be exchanged through this space. For example, the substrate on which film formation has been completed can be set by moving the substrate to be filmed to the right in FIG. Thus, since a complicated path is not required for substrate transport, it is very beneficial in terms of cost and quality control.

As long as a complicated path is allowed, the radial magnetic field generating magnetic circuit according to the present invention may further include a permanent magnet. FIG. 6 shows a schematic cross-sectional view in the central axis direction of a radial magnetic field generating magnetic circuit according to a third embodiment of the reference example . As shown by a permanent magnet unit 41 in FIG. 6, a radial magnetic field generating magnetic circuit according to a reference example is a ring-shaped permanent magnet unit provided on the same plane as the arrangement surface, and the permanent magnet The inner diameter of the unit is set larger than the outer diameter of the ring-shaped substrate that is the object to be processed, and has a magnetization direction parallel to the radial direction of the ring-shaped substrate, and the magnetic field formed by the permanent magnet unit is The first and second permanent magnet units 21 may further include a permanent magnet unit arranged on the arrangement surface so as to have a magnetic field component in the same direction as the radial magnetic field component formed on the arrangement surface. Such an aspect has a structure in which a ring-shaped permanent magnet unit 41 having a radial magnetization direction is added to the space between the permanent magnet units in the magnet arrangement according to the first embodiment of the reference example . . In this way, the permanent magnet unit 41 is arranged outside the outer diameter of the ring-shaped substrate along the circumference of the substrate, and the first and second permanent magnet units form the magnetization direction on the arrangement surface. By making it the same as the radial magnetic field, the radial magnetic field formed on the arrangement surface as a whole can be strengthened.

In addition, as shown by a permanent magnet unit 42 in FIG. 6, the radial magnetic field generating magnetic circuit according to the reference example is a ring-shaped permanent magnet unit provided on the same plane as the arrangement surface, The outer diameter of the permanent magnet unit is set to be smaller than the inner diameter of the ring-shaped substrate that is the object to be processed, has a magnetization direction parallel to the radial direction of the ring-shaped substrate, and the magnetic field formed by the permanent magnet unit is The arrangement may further include a permanent magnet unit arranged so that the first permanent magnet unit has a magnetic field component in the same direction as the radial magnetic field component formed on the arrangement surface on the arrangement surface. In addition, as shown by a permanent magnet 43 in FIG. 6, the radial magnetic field generating magnetic circuit according to the reference example is provided on the central axis of the permanent magnet unit and at a symmetrical position with respect to the arrangement surface. A pair of permanent magnets having a symmetrical shape with respect to the placement surface, having a magnetization direction perpendicular to the placement surface, and a magnetic field formed by each of the pair of permanent magnets, The first and second permanent magnet units may further include a pair of permanent magnets arranged to have a magnetic field component in the same direction as the radial magnetic field component formed on the arrangement surface. That is, as shown in FIG. 4, in the magnet arrangement according to the first embodiment, the magnetic field near the center of the substrate may be low. For this reason, in order to correct this, as shown in FIG. 6, permanent magnets 42 and 43 can be added at the center provided at the center of the substrate, that is, inside the inner diameter of the ring-shaped substrate. Also in this case, as described above, the magnetization direction of the magnet arranged at the center can be given in the same way as the magnet arranged at the outer peripheral portion of the substrate. That is, a magnet 43 having a perpendicular magnetization direction can be arranged above and below the central portion of the substrate, and a permanent magnet unit 42 having a radial magnetization can be arranged in the space between the upper and lower permanent magnets 43. In this way, the magnet arrangement shown in FIG. 6 can be adopted when the increase in the magnetic field strength is required even when the disadvantage of complicated substrate transfer is accepted. In addition, when a pair of permanent magnets is provided on the central axis of the permanent magnet unit at a symmetrical position with respect to the arrangement surface, the distance between the pair of permanent magnets and the arrangement surface is particularly limited. Instead, the pair of permanent magnets can be provided at any distance.

Here, when a plating method is used instead of a sputtering method as a film formation method for the substrate, or when a radial magnetic field is applied in a heat treatment process rather than during film formation, a space needs to be provided above the substrate as shown in FIG. There is no. In such a case, as a reference example, in the radial magnetic field generating magnetic circuit, the inner diameters of the first and second permanent magnet units are set smaller than the outer diameter of the ring-shaped substrate that is the object to be processed, The outer diameters of the first and second permanent magnet units are set larger than the inner diameter of the ring-shaped substrate that is the object to be processed, and the first and second permanent magnet units are arranged in the radial direction of the ring-shaped substrate. It can have a magnetization component in a parallel direction. In particular, the inner diameters of the first and second permanent magnet units are preferably the same as or substantially the same as the inner diameter of the ring-shaped substrate, and particularly preferably 50 to 100% of the inner diameter of the ring-shaped substrate. The outer diameters of the first and second permanent magnet units are preferably the same as or substantially the same as the outer diameter of the ring-shaped substrate, and in particular, 100 to 150% of the outer diameter of the ring-shaped substrate. preferable. Here, the substantially the same, the magnetic field intensity required for processing for the purpose of magnetic circuits, refers to those formed on the substrate surface. In this embodiment as well, the magnetization direction of the ring-shaped substrate can be inclined from a parallel state.

FIG. 7 shows a schematic cross-sectional view in the central axis direction of a magnetic circuit for generating a radial magnetic field according to the fourth embodiment of such a reference example . That is, permanent magnet units 51 that are ring-shaped and magnetized in the radial direction are arranged at positions just above and below the substrate so as to provide a significant radial magnetic field in the vicinity of the substrate inner diameter with the same inner diameter as the substrate. Also in this case, a radial magnetic field can be generated on the substrate surface. That is, also in this case, by arranging the magnets vertically symmetrical with respect to the substrate, the magnetic lines of force 52 are completely horizontal on the substrate surface and are in the radial direction. Further, in this way, by providing at least a part of the first and second permanent magnet units above and below the inside of the ring-shaped substrate and the outside of the inside of the inside of the ring, the magnetic field compared to the magnet arrangement in the above aspect is provided. A stronger radial magnetic field can be obtained. This is because the magnet arrangement in this aspect can bring the magnet closer to the entire surface of the substrate than the magnet arrangement in the above aspect. In addition, a stronger magnetic field can be generated by combining this embodiment with the arrangement of magnets illustrated in FIGS. 1 and 6.

  The ring-shaped permanent magnet unit constituting the magnetic circuit according to the present invention does not necessarily have to be an integral magnet having a ring shape, and is divided into permanent magnet pieces, preferably equally divided permanent magnet pieces. You may comprise a ring-shaped permanent magnet unit by arranging in a ring shape. FIG. 8 shows an example of an aspect in which such a ring-shaped permanent magnet unit is constituted by a plurality of permanent magnet pieces. Note that the distance between the first and second permanent magnet units and the arrangement surface is not particularly limited, and should be set as appropriate in accordance with a target process or the like.

  Although not particularly limited, ferrite, rare earth, alnico bond, and sintered magnet can be used as the magnet to be used. Among them, rare earth permanent magnets are preferable. Further, with respect to the magnet characteristics, although it depends on the size of the substrate to be used, it is desirable that residual magnetization = 0.8 T or more and coercive force = 800 kA / m or more.

Hereinafter, Reference Examples of the present invention will be described with reference to the accompanying drawings.

Reference Example 1 of the present invention is shown below. In Reference Example 1, the magnetic circuit for generating a radial magnetic field having the mode shown in FIG. 1 was employed. The used permanent magnet is an Nd—Fe—B sintered magnet (N32Z manufactured by Shin-Etsu Chemical Co., Ltd., residual magnetization = 1.13 T, coercive force iHc = 2480 kA / m) in a ring shape. The magnet dimensions are an inner diameter of 100 mm, an outer diameter of 150 mm, and a height of 30 mm. The distance between the magnets was 30 mm. As shown in FIG. 1, the magnetization direction of the magnet was set to the vertical direction perpendicular to the arrangement surface.

This magnet was placed in a symmetrical relationship with respect to the placement surface as shown in FIG. 1, and the magnetic field on the placement surface was measured. Figure 9 shows the relationship between the position and the radial direction magnetic field and the vertical magnetic field on the reference example magnetic circuit definitive for the radial direction magnetic field generator according to one arrangement surface. In FIG. 9, the horizontal axis represents the distance r from the substrate center, and the vertical axis represents the radial magnetic field strength B. FIG. 9 shows that a radial magnetic field (Br) of 0.02T to 0.12T is generated on the substrate. Also, it can be seen that the vertical magnetic field (Bz) is zero throughout the substrate. As described above, in the magnetic circuit according to Reference Example 1, it was possible to generate a magnetic field that was completely directed in the radial direction over the entire substrate.

Further, in Reference Example 2, a radial magnetic field generating magnetic circuit in which the ring-shaped permanent magnet unit of Reference Example 1 was divided into 24 as shown in FIG. 8 was adopted. In the present reference example, the ring-shaped permanent magnet unit was divided so that the gap between the permanent magnet pieces was 2 mm, and other conditions were the same as those in the reference example 1. FIG. 10 shows the relationship between the position on the arrangement surface, the radial magnetic field, and the vertical magnetic field in the radial magnetic field generating magnetic circuit according to Reference Example 2. Even in this case, the vertical magnetic field was always zero. The horizontal magnetic field is slightly lower in the vicinity of the outer periphery than in Reference Example 1 due to the gap between the magnets. However, since the magnetic field in the vicinity of the outer periphery is considerably stronger than that in the vicinity of the inner periphery, there is no problem with a slight decrease. . If lowering of the magnetic field becomes a problem, a magnet with higher residual magnetization may be used or the size of the magnet may be increased.

Further, in Reference Example 3, the radial magnetic field generating magnetic circuit having the mode shown in FIG. 7 was employed. The used permanent magnet is an Nd—Fe—B sintered magnet (N32Z manufactured by Shin-Etsu Chemical Co., Ltd., residual magnetization = 1.13 T, coercive force iHc = 2480 kA / m) in a ring shape. The magnet dimensions are an inner diameter of 20 mm, an outer diameter of 100 mm, and a height of 20 mm. The distance between the magnets was 30 mm. FIG. 11 shows the relationship between the position on the arrangement surface, the radial magnetic field, and the vertical magnetic field in the radial magnetic field generating magnetic circuit according to the third embodiment. Even in this case, the vertical magnetic field was always zero. The horizontal magnetic field was 0.19 T to 0.35 T, and a higher magnetic field was generated compared to Examples 1 and 2. Thus, when the structure of the aspect shown in FIG. 7 is employed, a high magnetic field can be applied to the entire substrate.

The central-axis direction cross-sectional schematic diagram (upper figure) and the top view (lower figure) of the radial direction magnetic field generation magnetic circuit concerning 1st embodiment of a reference example are shown. An example of the relationship between the radial position on the arrangement surface and the radial magnetic field strength in the first embodiment of the reference example is shown. The central axis direction cross-sectional schematic diagram of the magnetic circuit for radial direction magnetic field generation concerning 2nd embodiment of this invention is shown. An example of the relationship between the radial position on the arrangement surface and the radial magnetic field strength when the inclination of the magnetization direction of the permanent magnet unit is changed will be shown. A state of film formation by sputtering using a magnetic circuit for generating a radial magnetic field according to a reference example is schematically shown. The central axis direction cross-sectional schematic diagram of the magnetic circuit for radial direction magnetic field generation concerning 3rd embodiment of a reference example is shown. The central-axis direction cross-sectional schematic diagram of the magnetic circuit for radial direction magnetic field generation concerning 4th Embodiment of a reference example is shown. An example of the aspect which comprised the ring-shaped permanent magnet unit by the several permanent magnet piece is shown. The relationship between the position on the arrangement surface, the radial magnetic field, and the vertical magnetic field in the radial magnetic field generating magnetic circuit according to Reference Example 1 is shown. The relationship between the position on the arrangement surface, the radial magnetic field, and the vertical magnetic field in the magnetic circuit for generating a radial magnetic field according to Reference Example 2 is shown. The relationship between the position on the arrangement surface, the radial magnetic field, and the vertical magnetic field in the magnetic circuit for generating a radial magnetic field according to Reference Example 3 is shown. 2 shows an example of a film configuration in a magnetic disk. The schematic diagram of the conventional magnetic circuit for radial direction magnetic field generation is shown. An example of the relationship between the radial position on the arrangement surface, the radial magnetic field strength, and the vertical magnetic field strength in a conventional magnetic circuit for generating a radial magnetic field is shown.

Explanation of symbols

11, 111 Ring-shaped substrates 21, 41, 42, 51, 121 Ring-shaped permanent magnet units 43, 122 Permanent magnet 22 Arrangement surface 23 Center axis 24 Magnetization directions 25, 52, 125 Magnetic field lines 126 Yoke 31, 131 Target 32 Sputtered particles Track 110 Magnetic disk 112 Hard magnetic film (underlayer)
113 Soft magnetic film (underlayer)
114 Hard magnetic film (recording film)

Claims (6)

A ring-shaped first permanent magnet unit and a second permanent magnet unit are included, and a ring-shaped substrate that is an object to be processed can be disposed in a space sandwiched between the first and second permanent magnet units. A magnetic circuit for generating a radial magnetic field for generating a magnetic field in the radial direction of the ring-shaped substrate on the arrangement surface when the plane including the ring-shaped substrate is an arrangement surface when the ring-shaped substrate is arranged. There,
A space is provided so that a film can be formed between the first permanent magnet unit and the second permanent magnet unit ,
The magnetic field formed by each of the first and second permanent magnet units has a magnetic field component in the radial direction of the ring-shaped substrate and substantially does not have a magnetic field component in the circumferential direction on the arrangement surface. It is located in,
The first and second permanent magnet units have a magnetization direction and a shape symmetric with respect to the arrangement surface, and are provided at positions symmetrical with respect to the arrangement surface ;
An inner diameter of the first and second permanent magnet units is set to be larger than an outer diameter of a ring-shaped substrate that is an object to be processed, and the first and second permanent magnet units are in a direction perpendicular to the arrangement surface. the magnetization component possess to,
A magnetic circuit for generating a radial magnetic field used in a film forming process by sputtering, wherein the first and second permanent magnet units further have a magnetization component in a direction parallel to a radial direction of the ring-shaped substrate. The magnetization component in the direction parallel to the radial direction of the ring-shaped substrate included in the first and second permanent magnet units is a direction perpendicular to the arrangement surface and away from the arrangement surface; 2. The sputtering process according to claim 1, which is based on an inclination t which is a difference from a magnetization direction of the second permanent magnet unit, and the inclination t is 0 <t <90 ^o or 180 <t <270 ^o. A magnetic circuit for generating a radial magnetic field used in a film forming process by the method . The magnetic circuit for generating a radial magnetic field used in a film forming process by sputtering according to claim 2 , wherein the inclination t is 0 <t ≦ 60 ^o or 180 <t ≦ 240 ^o . A pair of permanent magnets provided on a central axis of the permanent magnet unit and symmetrically with respect to the arrangement surface, and having a symmetrical shape with respect to the arrangement surface and being perpendicular to the arrangement surface And the magnetic field formed by each of the pair of permanent magnets has the same orientation as the radial magnetic field component formed on the placement surface by the first and second permanent magnet units. The magnetic circuit for radial direction magnetic field generation used for the film-forming process by the sputter | spatter process in any one of Claims 1-3 further including a pair of permanent magnet arrange | positioned so that it may have a magnetic field component. A ring-shaped permanent magnet unit provided on the same plane as the arrangement surface, wherein an inner diameter of the permanent magnet unit is set larger than an outer diameter of a ring-shaped substrate that is an object to be processed, and the ring-shaped substrate The magnetic field formed by the permanent magnet unit has a magnetization direction parallel to the radial direction, and the radial magnetic field component formed on the placement surface by the first and second permanent magnet units The magnetic circuit for radial magnetic field generation used for the film-forming process by the sputter | spatter process in any one of Claims 1-4 further including the permanent magnet unit arrange | positioned so that it may have a magnetic field component of the same direction. A ring-shaped permanent magnet unit provided on the same plane as the arrangement surface, wherein an outer diameter of the permanent magnet unit is set smaller than an inner diameter of a ring-shaped substrate that is an object to be processed, and the ring-shaped substrate The magnetic field formed by the permanent magnet unit has the same orientation as the radial magnetic field component formed on the placement surface by the first permanent magnet unit. The magnetic circuit for radial magnetic field generation used for the film-forming process by the sputter | spatter process in any one of Claims 1-5 further including the permanent magnet unit arrange | positioned so that it may have a magnetic field component.

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