JPS61120349A - Manufacture of double layer film vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a couble-layer film vertical magnetic recording medium excellent in record reproducing efficiency and small in fluctuation of reproducing outputs by arranging one or more pair of magnets having the same poles facing each other in the nearly longitudinal direction of a long substrate near the part where a soft magnetic backing layer is formed. CONSTITUTION:Mangets having the same poles facing each other parallel to the longitudinal direction (MD direction) of a substrate, i.e. the direction of running of the substrate are arranged at the time of vapor deposition or sputtering of the soft magnetic backing layer. In the case where a soft magnetic body which is liable to be influenced by a magnetic field in vapor deposition in a magnetic field as a soft magnetic layer, a magnetic field that gives influences in vapor deposition or sputtering in a magnetic field in the flow of magnetic flux in arrangement of magnet in which the same poles face to each to other is a component at the inside of the face of soft magnetic backing layer at the place where the soft magnetic backing layer is formed. Most of magnetic fluxes enter in the direction of normal of the soft magnetic backing layer, and the direction to which the magnetic field is applied does not become an axis of easy magnetization, but obtaing of an isotropic film becomes possible. A double-layer film medium 7 in which a Co-Cr vertical anisotropic film is formed on the soft magnetic layer made into isotropic is blanked to a discoid shape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a double-layer perpendicular magnetic recording medium having excellent high-density recording characteristics.

2. Description of the Related Art A perpendicular magnetic recording method is known as a magnetic recording method with excellent short wavelength recording characteristics. This method requires a perpendicular magnetic recording medium whose axis of easy magnetization is approximately perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented in a direction substantially perpendicular to the film surface of the medium, and therefore, the shorter the wavelength of the signal, the smaller the demagnetizing field within the medium, resulting in excellent reproduction output. Perpendicular magnetic recording media, called single-layer media, are produced by forming a perpendicular anisotropic film on a substrate made of non-magnetic material using sputtering or vacuum evaporation (ionization of some of the evaporated atoms, as in ion blating). (including vapor deposition methods). For a single-layer film medium with such a structure,
A structure called a so-called double-layer perpendicular magnetic recording medium (hereinafter referred to as a single-layer double-layer medium) in which a soft magnetic underlayer is provided between a substrate made of a non-magnetic material and a perpendicular anisotropic film. It is known that recording efficiency and reproduction output are improved by K. In particular, when recording and reproducing using a known auxiliary pole excitation type vertical head, the recording efficiency is improved by about 20 dB and the reproduction output is improved by about 2 odB.

It is known that the recording and reproducing efficiency of the above-mentioned two-layer film medium is greatly influenced by the magnetic properties of the soft magnetic underlayer, and the smaller the coercive force of the soft magnetic underlayer, the higher the recording and reproducing efficiency. However, as shown in FIG.
If a soft magnetic underlayer with a low coercive force and a high rate of a is continuously formed on top by a sputtering method or a vapor deposition method (including a method in which a part of the evaporated atoms is ionized and vapor deposited like the ion blating method), Due to the self-shading effect, as shown in Figure 7, the width direction (TD) of the substrate 1 is the axis of easy magnetization, and the longitudinal direction (MD
) is the axis of difficulty in magnetization, resulting in in-plane-axis anisotropy. That is, the initial magnetic permeability μ of the formed soft magnetic underlayer is M
The D force direction is very small in the TD direction. Furthermore, when a disk-shaped medium is punched out from a two-layer film medium on which a vertically anisotropic film is formed, output fluctuations occur during one revolution due to the anisotropy of the soft magnetic underlayer. This situation will be explained using FIGS. 8 and 9. In FIG. 8, 7 is an elongated two-layer film medium in which two layers, a soft magnetic underlayer and a perpendicular anisotropic film, are formed on an elongated non-magnetic substrate 1.

8 is a disk-shaped medium punched out from the two-layer film medium. FIG. 9 shows how the reproduction output changes when the head sequentially passes through points A, B, 0, and D, which are concentric points on the disk-shaped medium 8, and performs recording and reproduction. The horizontal axis shows the passage of time, and the vertical axis shows the output, which is called an output envelope. In the figure, A, B, C, and D correspond to points A, B, 0, and D on the disk-shaped medium 8, respectively. At points A and 0, the head is parallel to the direction of low initial magnetic permeability μl of the soft magnetic underlayer, and at points B and D, μi is the opposite direction.
Run parallel to the higher direction. As a result, as shown in FIG. 9, the output is low at points A and 0, and high at points B and L1. Such output fluctuations are inconvenient for disk-shaped media, and an improvement is needed.

To eliminate output fluctuations, the soft magnetic underlayer must be made isotropic. Deposition in a magnetic field is one such method. This occurs in the soft magnetic under layer forming part during vapor deposition or sputtering of the soft magnetic under layer, and in the absence of a magnetic field, the direction K becomes the axis of difficult magnetization, and when magnets with different poles facing each other are placed, it tends to become isotropic. It is something. It is sufficient that the magnetic field is 200 e or more on the nonmagnetic substrate 1 on which the soft magnetic underlayer is formed.

Problems to be Solved by the Invention When a soft magnetic material, which is easily influenced by the magnetic field, is used as the good-strike layer of a two-layer film medium by deposition in a magnetic field, the above method usually results in the hard magnetization axis of the soft magnetic backing layer being The axes of easy magnetization were swapped, and it was difficult to obtain an isotropic film before the swapping.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a soft magnetic underlayer, which makes it possible to obtain a two-layer perpendicular magnetic recording medium with excellent recording and reproducing efficiency and with little variation in reproduction output.

Means for Solving the Problems In the step of continuously forming a soft magnetic backing layer on a long substrate by a vapor deposition method or a sputtering method, a soft magnetic backing layer is formed near the soft magnetic backing layer forming portion in a substantially longitudinal direction of the long substrate. It is characterized by arranging one or more pairs of magnets with the same polarity facing each other.

Since the applied magnetic field is perpendicular to the substrate, the soft magnetic layer will not be anisotropic due to the in-plane component of the magnetic field.

Embodiment FIG. 1 shows the arrangement of magnets on a shielding plate 6 during deposition or sputtering of a soft magnetic underlayer to explain an embodiment of the present invention.

In FIG. 1, the board 1 is traveling along the circumferential surface of the cylindrical can 2, and on the way, a shielding plate 6 is placed on the surface of the plate 1.
A vapor deposited film of soft magnetic material flying from the evaporation source 5 through the gap is formed. During sputtering, a soft magnetic target is placed at 5, and sputtered with ions such as Ar+. 9 is a magnet placed on the A drawing board 6, and the arrow indicates its magnetization direction; in FIG.
(MD direction), that is, in parallel to the running direction of the substrate, opposing magnets with the same polarity are arranged during deposition or sputtering of the soft magnetic underlayer. Note that the direction of magnetization of the magnet may be reversed. Furthermore, the same effect can be achieved even if a method other than a permanent magnet is used to generate the magnetic field, such as passing a current through a coil.

When a soft magnetic underlayer is deposited using a vacuum evaporation apparatus as shown in FIG. ing.

Next, the reason why the present invention is effective when a soft magnetic material that is medium-deposited and easily influenced by a magnetic field is used as the soft magnetic underlayer will be explained. FIG. 2 shows the flow of magnetic flux in a conventional magnet arrangement in which different poles face each other, and FIG. 3 shows the flow in magnetic flux in a magnet arrangement in which the same poles face each other according to the present invention. The magnetic field that influences magnetic field deposition or sputtering is a component in the in-plane direction of the soft magnetic underlayer where the soft magnetic underlayer is formed. In the conventional example shown in Fig. 2, most of the magnetic flux enters the soft magnetic underlayer in the in-plane direction, so if a material that is easily influenced by the magnetic field is used as the soft magnetic material by deposition in a magnetic field as described above, it is easy to change the direction in which the magnetic flux flows. is the axis of easy magnetization and cannot be an isotropic film. In FIG. 3 of the present invention, most of the magnetic flux enters the normal direction of the soft magnetic underlayer, and only a small amount of magnetic flux enters the in-plane direction of the soft magnetic underlayer near the magnetic poles of the magnet. Therefore, even if a material that is easily affected by the magnetic field is used as a soft magnetic material by deposition in a magnetic field as described above, the direction in which the magnetic field is applied will not be the axis of easy magnetization, making it difficult to obtain the isotropic film shown in Figure 4. becomes possible.

Specific examples of soft magnetic materials that are easily affected by the magnetic field when deposited in a magnetic field include those whose main components are Co, Fe, and Ni. Also, specifically, being susceptible to the magnetic field during deposition in a magnetic field means that the uniaxial anisotropy constant Ku induced by deposition in a magnetic field at a substrate temperature of 250°C is 3 x 10 erq/c.
rd or higher.

Thus, the two-layer film medium 7 in which the Co--Cr perpendicular anisotropic film is formed on the isotropic soft magnetic backing layer according to the present invention is punched out into a disk shape as shown in FIG.

FIG. 5 shows changes in the reproduction output when the head sequentially passes through points A, B, 0, and D, which are concentric points on the disk-shaped medium 8, and performs recording and reproduction. The horizontal axis shows the passage of time, and the vertical axis shows the output, which is called an output envelope. A, B, and C in the diagram.

D corresponds to point A, point B, point 0, and point D on the disk-shaped medium 8, respectively. Looking at FIG. 5, almost no output fluctuation is seen, and the effect of the uniform force ratio of the soft magnetic underlayer is recognized.

Next, a specific example will be described. CO1sF @ 1e Nl s 9 was used as the soft magnetic backing layer, and evaporation was performed in a magnetic field as shown in FIG. 1 to form 8,000 soft magnetic backing holes. A Co--Cr vertically anisotropic film was continuously formed thereon to a thickness of 200 μm. As a result, the B- and loops of the soft magnetic backing layer as shown in Figure 4 were obtained, the coercive force was 66e, and the output envelope was as shown in Figure 5. Good vertical centering with extremely small output fluctuations was obtained. A two-layer recording medium was obtained.

Effects of the Invention According to the method of the present invention, fluctuations in reproduction output of a double-layer film medium for perpendicular magnetic recording, which were conventionally large, can be suppressed to a small level.

[Brief explanation of drawings]

FIG. 1 is a partial diagram of the inside of a vapor deposition apparatus for explaining the present invention, FIG. 2 is a diagram showing the flow of magnetic flux in the conventional magnetic field vapor deposition or sputtering section, and FIG. 3 is a diagram showing the magnetic flux vapor deposition or sputtering part of the present invention. FIG. 4 is a graph showing the magnetic flux flow in the sputtering part, FIG. 4 is a graph showing the magnetic properties of the soft magnetic underlayer obtained by the present invention, and FIG. 5 is a graph showing the output fluctuation of the two-layer film medium obtained by the present invention. Figure 6 is a front view of the inside of a conventional vacuum evaporation apparatus used to produce a soft magnetic backing layer, Figure 7 is a graph showing the magnetic properties of only the conventional soft magnetic backing layer, and Figure 8 is a graph showing the magnetic properties of only the conventional soft magnetic backing layer. Diagram explaining the problems of double-layer membrane media, No. 9
The figure is a graph showing output fluctuations of a conventional two-layer, one-layer media. 1... Non-magnetic substrate, 2... Cylindrical can, 3... Board entry roller, 4... Board exit roller, 5...・Evaporation source, 6...Brush plate, 7...Long double-layer film medium for perpendicular magnetic recording,
8... Disk-shaped medium, 9... Magnet. Name of agent: Patent attorney Toshio Nakao and one other person
Fig. 2 Fig. 4 (Longitudinal direction (100) of soft magnetic film main film (100) B-H loose (b) Soft magnetic film vertical direction (TO) f3-H 0 Fig. 5 Fig. 6 Figure 7 (a-) Longitudinal direction (r'tD) of soft membrane 1 B-Fl/Ti-
7'(b) δ B-Hl Rede of the ↑ crystal direction (D) of the soft five-dimensional film Fig. 8 Fig. 9

Claims (5)

[Claims] (1) In the step of continuously forming a soft magnetic backing layer on a long substrate by vapor deposition or sputtering, the same polarity is placed near the soft magnetic backing layer forming part in the substantially longitudinal direction of the long substrate. 1. A method for manufacturing a double-layer perpendicular magnetic recording medium, comprising arranging one or more pairs of magnets with a diameter of 1. (2) The method for manufacturing a double-layer perpendicular magnetic recording medium according to claim 1, wherein the soft magnetic underlayer is a soft magnetic material containing Co, Fe, and Ni as main components. (3) The method for manufacturing a double-layer perpendicular magnetic recording medium according to claim 2, wherein the soft magnetic material contains 5 to 32% by weight of Co. (4) The method for manufacturing a two-layer perpendicular magnetic recording medium according to claim 2, wherein the soft magnetic material contains 10 to 25% by weight of Co. (5) The soft magnetic underlayer lowers the substrate temperature to 250°C.
The uniaxial anisotropy constant Ku induced by deposition in a magnetic field when
2. The method for manufacturing a double-layer perpendicular magnetic recording medium according to claim 1, wherein the soft magnetic material has an erg/cm^3 or more.