JPH08129738A - Magnetic recording medium and magnetic recording-reproducing device - Google Patents

Abstract

PURPOSE: To obtain a magnetic recording medium having superior low noise characteristics at the time of magnetic recording and reproduction and fit for ultrahigh density recording. CONSTITUTION: When an underlayer 2, a magnetic film 3 and a protective layer 4 are laminated on a nonmagnetic substrate 1 to obtain a magnetic recording medium, an ion implanted region 5 is formed in at least one among the underlayer 2, the magnetic film 3 and the protective layer 4. The region 5 is formed in concentric circles or in a spiral shape or it is radially formed from the center toward the periphery. The magnetic film 3 may be formed as a multilayered film consisting of magnetic layers laminated with a nonmagnetic middle layer in-between and an ion implanted region may be formed in the entire surface of at least one layer of the multilayered film. The crystal orientation or magnetic anisotropy of the magnetic film or the interaction between magnetic particles can be controlled without forming a texture groove on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium suitable for high density magnetic recording and a magnetic recording apparatus using the same.

[0002]

2. Description of the Related Art Currently, the magnetic recording method practically used is parallel to the surface of a magnetic recording medium and has N and N poles.
This is an in-plane magnetic recording method in which magnetic recording is performed by magnetizing the poles, the S poles, and the S poles in a direction to abut each other. In order to increase the recording density with this method, the thickness of the recording magnetic film is reduced to reduce the influence of the demagnetizing field during recording, and the coercive force is set to about 3 kOe.
(Kilo-Oersted), but it is considered to be one of the promising recording methods for high density magnetic recording of the order of several Gb / in ² in the future.

Further, the perpendicular magnetic recording system is a recording system in which magnetic domains are formed in a direction perpendicular to the surface of a recording medium and so that adjacent recording bits are antiparallel to each other. Since the demagnetizing field is small, sharp recording magnetic domains are formed, which is one of the promising means for high density magnetic recording. Co-Cr, Co-Ni, Co-V, Co-Mo are used as magnetic films for in-plane magnetic recording and perpendicular magnetic recording media.
Co-based alloy thin films such as Ta, Pt, Mo, Ru, Re, F are used for alloys containing Co-Cr as a main component.
An alloy containing e, Rh, O, etc. is used. These Co-based alloys have a hexagonal close-packed structure (hcp structure),
The easy axis of magnetization is in the <001> direction of the c-axis of this crystal.

The longitudinal magnetic recording medium is made of Al coated with NiP.
The Co alloy thin film is formed on a non-magnetic substrate such as a substrate, a glass substrate, or a plastic film such as polyimide or polyethylene terephthalate.
In the in-plane recording, it is necessary to highly orient the c-axis of the Co alloy magnetic crystal in the plane of the substrate. For this purpose, an underlayer such as Cr having a body-centered cubic (bcc) lattice structure is formed on the substrate,
A method of forming the above Co alloy magnetic thin film on this has been proposed. A method is also known in which a textured groove is provided on a substrate in order to impart magnetic orientation to a magnetic thin film, and different magnetic anisotropy is added in a direction along the groove and a direction orthogonal to the direction. .

The perpendicular magnetic recording medium is composed of Al coated with NiP.
The Co alloy thin film is formed on a non-magnetic substrate such as a substrate, a glass substrate, or a plastic film such as polyimide or polyethylene terephthalate.
In perpendicular recording, the c-axis of the Co alloy magnetic crystal needs to be highly oriented perpendicular to the substrate surface in order to improve magnetic recording characteristics such as recording density, reproduction output and reproduction noise characteristics when magnetically recording. For this purpose, a method has been proposed in which an underlayer having an hcp structure such as Ti or an amorphous underlayer such as Si or Ge is formed on the substrate and the Co alloy magnetic thin film is formed on the underlayer. In addition, a method of providing a soft magnetic material thin film such as permalloy under the Co alloy magnetic thin film in order to increase the reproduction sensitivity is IEEE Trans. Magnetics,
MAG-15, 1456 (1979) “Perpendicular Magnetic Recording with Composit
e Anisotropy Film) ”.

The medium noise in the reproduced signal is closely related to the structure of the boundary (magnetization transition region) of the recording magnetic domain and the magnetic domain structure inside the recording bit, and this is due to the magnetic interaction between particles forming the magnetic film. Strength and dispersion of magnetic anisotropy are related. As a conventional method for reducing the medium noise, (1) a method in which the non-magnetic Cr in the CoCr-based alloy is biased to the grain boundaries to reduce the magnetic interaction between the magnetic particles, ( 2) There is a method of controlling the pressure of the sputtering gas to morphologically isolate the underlayer and the magnetic film for structure control. Further, a method of reducing the interaction between the magnetic grains not only in the plane direction of the magnetic film but also in the film thickness direction, for example, Cr between CoCr-based alloy magnetic films
A method of providing such a non-magnetic intermediate film has been proposed.

[0007]

In an ultra-high density magnetic recording device of several Gb / in ² or more, the spacing between the medium and the magnetic head approaches tens of nm or less. As a result, the substrate with textured grooves as in the past has poor surface smoothness, making it difficult to bring the spacing between the medium and the magnetic head close enough, and the medium and magnetic head collide during operation and are destroyed. Cause of.

Further, when a non-magnetic intermediate film is simply provided between the magnetic films to reduce the medium noise, the coercive force is lower than that of a single-layer magnetic film of the same thickness, which is necessary for super high density recording. It is difficult to realize a high coercive force of 2 kOe or more. A first object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for imparting magnetic anisotropy to a magnetic film without forming textured grooves in a substrate. A second object of the present invention is to provide excellent low noise characteristics during magnetic recording and reproduction by controlling the crystal orientation and magnetic anisotropy of the magnetic film formed on the substrate, or the interaction between magnetic particles. Another object of the present invention is to provide a magnetic recording medium suitable for ultra high density recording.

[0009]

According to the present invention, a magnetic layer is formed by forming an underlayer for controlling the structure of a magnetic film on a non-magnetic substrate, and forming one or more magnetic films and a protective layer on the underlayer. In the recording medium, the first object is achieved by providing an ion-implanted region in at least one selected region of the substrate, the underlayer and the magnetic film. The selected ion-implanted regions are conveniently set concentrically, spirally, or radially from the center of the substrate to the periphery.

Further, according to the present invention, in a magnetic recording medium comprising a non-magnetic substrate, a base layer, a plurality of magnetic films with the non-magnetic layer interposed therebetween, and a protective layer, at least one magnetic layer other than the uppermost layer is magnetic. The second object is achieved by forming an ion-implanted region on the entire surface of the film. The ion-implanted region may be formed in a selected region of the magnetic film other than the magnetic film having the ion-implanted region formed on the entire surface, for example, concentrically, spirally, or radially from the center toward the outer peripheral portion.

Ions to be implanted in the ion implantation region are
Cr, Mo, V, Ta, Pt, Si, B, Ir, W, H
At least one element selected from the elements f, Nb, Ru, Ti, O, Ar, Kr, and Xe can be used, and the thickness of the ion implantation region is one atomic layer or more, the underlayer or the magnetic film. It can be set arbitrarily within the range of thickness. The magnetic film contains Co as a main component, and Cr, Fe, Mo,
V, Ta, Pt, Si, B, Ir, W, Hf, Nb, T
It has a hexagonal close-packed structure made of a material containing at least one element or compound selected from i, Ni, CoO and rare earth elements. The magnetic film is a thin film epitaxially grown on a base layer for structure control. When the magnetic films are laminated in multiple layers, the magnetic films may have the same composition or different compositions.

The easy axis of magnetization of the magnetic film is parallel or perpendicular to the substrate surface, or in the case of a multi-layer magnetic film, the easy axis of magnetization of the magnetic film of the first layer and the second and subsequent layers is relative to the substrate surface. All of them are composed of parallel films or a combination of parallel films and vertical films. The direction of the easy axis of magnetization can be arbitrarily controlled by selecting an underlayer or a nonmagnetic layer provided below the magnetic film. Further, in the multilayer magnetic film, by providing an ion-implanted region between the magnetic films of the first layer and the second layer and thereafter, the easy axes of magnetization of the magnetic films of the first layer and the second layer and thereafter can be independently controlled. You can

For the underlayer and the non-magnetic layer for controlling the structure, a material having a good lattice matching with the magnetic film formed thereon is selected. For example, Cr, V, W, Mo, Pt, Pd, S
a material having a face-centered cubic structure, a body-centered cubic structure, or an amorphous structure containing at least one selected from i, Ge, and B, or Co, Ti, Ru, Hf, Ta, Cr, V, W,
A material having a hexagonal close-packed lattice structure containing at least one selected from Mo, Pt, Pd, Si, Ge, and B or an amorphous structure is selected. A physical vapor deposition method such as a vacuum vapor deposition method, a high frequency sputtering method, an ion beam sputtering method or an electron cyclotron resonance sputtering method can be used for forming the thin film.

[0014]

The Co-based alloy having a hexagonal close-packed lattice (hcp) structure has a large crystal magnetic anisotropy in the c-axis direction, and the in-plane magnetic recording medium has the c-axis oriented in the plane of the substrate and also has a perpendicular magnetic field. The recording medium has the c-axis oriented vertically to the substrate surface. The underlayer and the non-magnetic layer for structure control are used to highly orient the c-axis. For example, an underlayer having a body-centered cubic lattice (bcc) structure such as a Cr alloy functions to control the in-plane orientation and the crystal grain size of the Co-based alloy magnetic film crystal formed on the underlayer.
An underlayer having an hcp structure such as an alloy is formed on this C layer.
It acts to control the vertical orientation and crystal grain size of the o-based alloy magnetic film crystal. The underlayer and non-magnetic layer for structure control are
By using an alloy thin film, the crystal grain size can be made smaller than in the case of a thin film using a single material, and therefore the crystal grain size of the magnetic film formed on this can also be made smaller, and recording density, reproduction noise, etc. Magnetic recording characteristics can be improved.

The ion implantation serves to apply local stress to the implanted region. Therefore, by providing a circumferentially or radially ion-implanted region in a selected region of the substrate, underlayer or magnetic film, magnetic anisotropy is imparted to the magnetic film in the circumferential or radial direction. be able to. The magnetic thin film grows epitaxially on the underlying layer or non-magnetic layer provided in the lower layer, and the c-axis of the Co-based alloy magnetic film reflects the property of the material of the underlying underlying layer or non-magnetic layer to be in-plane or Orient vertically.

The magnetic film can be used by being laminated in multiple layers with a non-magnetic layer interposed therebetween, whereby the strength of interaction between magnetic particles is controlled in the in-plane direction as well as in the film thickness direction. A function can be added and reproduction noise can be reduced. Further, when the second and subsequent magnetic films are formed on the first magnetic film via the non-magnetic layer, the ion-implanted region is formed on the entire surface of the first magnetic film. The second and subsequent magnetic films can be formed over the non-magnetic layer. The thickness of the ion-implanted region is preferably a monoatomic layer or more and 10 nm or less, and the in-plane orientation of the crystals of the magnetic films of the second and subsequent layers stacked on the ion-implanted region is formed by the formation of the ion-implanted region. It can be formed by changing the orientation of the film. This can weaken the magnetostatic coupling between the magnetic film of the first layer and the magnetic films of the second and subsequent layers,
The effect of reducing the reproduction noise is further enhanced as compared with the multilayer magnetic film medium in which the first magnetic film and the second magnetic film and thereafter are epitaxially grown through the non-magnetic layer.

Further, by implanting ions on the entire surface of the lower magnetic layer oriented in-plane, and laminating the magnetic layer on it through a non-magnetic layer for controlling crystal orientation, the crystals of the two magnetic layers are formed. The orientation can be controlled independently. According to this method, it is possible to easily manufacture a multilayer magnetic film in which the lower magnetic layer is in-plane oriented and the magnetic layer thereabove is vertically oriented and which is suitable for high reproduction output.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings. In the figure, the parts with the same reference numerals represent the parts having the same function. [Example 1] The washed glass substrate 1 was placed in a sputtering apparatus and evacuated to a vacuum degree of 2 x 10 ^-7 Torr. Subsequently, the substrate was heated to 250 ° C. to form an underlayer 2 having a thickness of 50 nm for controlling the structure of the magnetic film. Here, an example in which Cr is used as the underlayer 2 will be described. However, with Cr as the main component, V, W, Mo, Pt, Pd, Si,
Ge, B, Ru, Hf, Ir, Re, Ti, Ta, Zr
It is also possible to add and use such elements as 0 to 20 at%. When measured by an X-ray diffraction method, the underlayer 2 had a body-centered cubic lattice (bcc) structure, and its growth orientation was <110> or <100> orientation. A magnetic film 3 was formed on this underlayer, and a carbon film having a film thickness of 10 nm was further formed thereon as a protective layer 4.

In this example, the following four types of media were prepared in order to investigate the effect of ion implantation. First, as shown in the schematic sectional view in FIG.
As described above, the medium A is formed by concentrically forming the ion-implanted regions 5 and then forming the underlying layer 2, the magnetic film 3, and the protective layer 4 in this order. As for the second medium, as shown in the schematic sectional view of FIG. 1B, after forming the underlayer 2 on the substrate 1, a concentric ion implantation region 5 is formed on the surface of the underlayer 2 as shown in FIG. Then, the magnetic film 3 and the protective layer 4 are formed in this order on the medium B. The third medium is shown in FIG.
As shown in the schematic sectional view in FIG. 2, after forming the underlayer 2 and the magnetic film 3 on the substrate 1, the ion implantation region 5 is concentrically formed on the surface of the magnetic film 3 as shown in FIG. Four
It is the medium C which formed. For comparison, a medium having no ion-implanted region on any of the substrate, the underlayer, and the magnetic film was prepared.

In the ion implantation area shown in FIG. 2, an ion beam converged to a line width of 0.1 to 1 μm is irradiated to a predetermined position of the disk-shaped medium, and the medium is rotated around the central axis. Can be formed. The interval between the concentric ion implantation regions adjacent to each other in the radial direction is 0.2.
˜2 μm. The depth of the ion-implanted region and the amount of implantation can be controlled by adjusting the acceleration voltage and the beam current at the time of ion beam irradiation, or the rotation speed of the disk. In this embodiment, the acceleration voltage is 100V to 30kV,
The experiment was conducted in the range of the beam current of 1 μA to 10 mA. When the accelerating voltage was 500 V or less, the effect of ion implantation was small, and when the accelerating voltage was 20 kV or more, the sample surface was processed and unevenness was sometimes formed.

In Table 1, B ions are used as the implanted ions, the acceleration voltage of the ion beam is 10 kV, and the beam current is 5
Coercive force Hc (θ) in the circumferential direction and coercive force H in the radial direction of each medium when the ion-implanted region is formed under the condition of 0 μA
It is shown by c (R). The magnetic film 3 contains Co as a main component, and contains Cr, Fe, Mo, V, Ta, Pt, Si, B, and I.
A material to which at least one of r, W, Hf, Nb, Ti, Ni, CoO, and a rare earth element is added can be used. Here, CoCr ₁₆ Ta ₆ , CoCr ₂₀ Pt ₁₂ ,
And CoCr ₂₀ Pt ₁₂ Ta ₆ are used and the film thickness is 20 nm.

[0022]

[Table 1]

As is clear from Table 1, by forming ion-implanted regions in the substrate, the underlayer or the magnetic film along the circumferential direction, the underlayer or the magnetic film crystal formed on the substrate is strained. As a result, it was possible to obtain an in-plane magnetic recording medium having so-called magnetic anisotropy, in which the coercive force in the circumferential direction was larger than the coercive force in the radial direction. Other than B, Cr, Mo,
V, Ta, Pt, Si, B, Ir, W, Hf, Nb, R
Elements such as u, Ti, Ga, O, Ar, Kr, and Xe, or two or more of these elements can be used at the same time, and the same effect can be obtained in any case. When two or more elements are used as the implanting ion species, a gaseous ion species is mixed to create a focused ion beam for use. Further, the same effect can be obtained even if the ion-implanted region has a spiral shape.

Example 2 Using the same sputtering apparatus as in Example 1, a disk-shaped medium was prepared in which ion-implanted regions 5 were radially formed from the center toward the outer periphery as shown in FIG. In order to investigate the effect of ion implantation, the following four types of media were created. One is Figure 1
As shown in FIG. 3A, a medium in which ion implantation regions 5 are radially formed on the surface of a substrate 1 and an underlayer 2, a magnetic film 3 and a protective layer 4 are formed in this order on the region 5. It is AA. As for the second medium, as shown in the schematic sectional view of FIG. 1B, after forming the underlayer 2 on the substrate 1, ion implantation regions 5 are formed radially on the surface of the underlayer 2 as shown in FIG. , The medium BB on which the magnetic film 3 and the protective layer 4 are formed. As for the third medium, as shown in the schematic sectional view in FIG. 1C, after forming the underlayer 2 and the magnetic film 3 on the substrate 1, the surface of the magnetic film 3 is radially ion-implanted as shown in FIG. 5 is a medium CC on which the protective layer 4 is formed. For comparison, a medium having no ion-implanted region on any of the substrate, the underlayer, and the magnetic film was prepared.

In the ion implantation area 5 shown in FIG. 3, an ion beam converged to a line width of 0.1 to 1 μm is applied to a predetermined position on the disk-shaped medium to scan the ion beam in the radial direction. It can be formed by rotating the disc around the rotation center of the disc. It is also possible to simultaneously irradiate with a plurality of ion beams. Ion implantation area 5
Can be controlled by arbitrarily setting the line width of the ion beam and the feed interval within a range of 1 time or more of the line width of the ion beam.

Table 2 shows, by way of example, super smooth NiP on the substrate 1.
Using a coated Al substrate, Cr-15 at% as the underlayer 2
Ti is 50 nm thick, and the same C as in Example 1 was used as the magnetic film 3.
oCr ₁₆ Ta ₆ , CoCr ₂₀ Pt ₁₂ , and CoCr ₂₀ P
t ₁₂ Ta ₆ is formed to a film thickness of 20 nm, and Ca is used as an ion species.
The magnetic characteristics of each medium in the case of using are shown.

[0027]

[Table 2]

As is clear from Table 2, by forming radially ion-implanted regions in the radial direction of the substrate, the underlayer, or the magnetic film, strain is applied to the underlayer and the magnetic film crystal formed on the substrate. As a result, an in-plane magnetic recording medium having so-called magnetic anisotropy, which has a larger coercive force in the radial direction than the coercive force in the circumferential direction, can be obtained.

Example 3 Using the same sputtering apparatus as in Example 1, as shown in FIG. 4A, a medium D having a magnetic film laminated in multiple layers with a non-magnetic layer interposed was produced. For the production of medium D, ultra-smoothed NiP
An underlying layer 2 for controlling the structure of the magnetic film is formed on the coated Al substrate 1.
As a Cr-15 at% Ti alloy underlayer 2 with a film thickness of 50 n
m formed. As a result of measurement by an X-ray diffraction method, this underlayer 2
Had a bcc structure, and the (100) plane was oriented parallel to the substrate surface. Ion-implanted regions 5 having a depth of about 5 nm were formed concentrically on the surface of the underlayer 2 as shown in FIG. A film thickness of 15 is formed as a first magnetic film 31 on the underlayer 2.
nm, a CoCr ₁₈ Pt ₁₂ alloy film having a thickness of 2 nm was formed, and subsequently, a nonmagnetic layer 6 having a film thickness of 2 nm and made of a Cr-15 at% Ti alloy film having the same composition as the underlayer was formed. Subsequently, a CoCr ₁₈ Pt ₁₂ alloy film having the same composition as that of the first magnetic film 31 was formed as the second magnetic film 32 on the non-magnetic layer 6 to a thickness of 15 nm.
The first and second magnetic films and the nonmagnetic layer were epitaxially grown on the underlayer. Further, a film thickness of 10n
m carbon protective layer 4 was formed.

For comparison, as shown in FIG. 4B, a medium E in which two layers of magnetic films were laminated with the non-magnetic layer 6 in between without forming an ion-implanted region on the surface of the underlayer 2 was produced. In this medium, the underlayer 2, the first magnetic film 31, the nonmagnetic layer 6, the second magnetic film 32, and the protective layer 4 have the same material composition and film thickness as in FIG. The first and second magnetic films and the nonmagnetic layer were epitaxially grown on the underlayer.

For further comparison, ultra-smoothed NiP is used.
An underlying layer 2 for controlling the structure of the magnetic film is formed on the coated Al substrate 1.
As a Cr-15 at% Ti alloy underlayer 2 with a film thickness of 50 n
m, and a single-layer magnetic film 31 made of a CoCr ₁₈ Pt ₁₂ alloy film having the same composition as that of the first magnetic film shown in FIGS. A medium F having the carbon protective layer 4 formed thereon was produced. Magnetic film 31
Were epitaxially grown on the underlayer 2.

Table 3 shows a comparison of the relative values of the coercive force of the above-mentioned three types of media D, E and F and the reproduction noise when recording / reproducing the linear recording density of 20 kFCI (FCI: Flux Change per Inc).
The results of h), 100 kFCI and 250 kFCI are shown. The smaller the relative value of the reproduction noise is, the smaller the noise generated from the medium is.

[0033]

[Table 3]

As is clear from Table 3, the medium D in which ion-implanted regions are provided in the circumferential direction of the medium and the magnetic film is divided by the non-magnetic layer to be laminated in multiple layers has a circumferential direction as compared with the radial direction. Has a large coercive force, that is, magnetic anisotropy is imparted in the so-called circumferential direction, and the noise value in the magnetic recording / reproducing characteristics is smaller than that of the other comparative media, resulting in improved performance.

Here, the case where the magnetic film has two layers has been described as an example, but the same effect can be obtained even when the magnetic film has three or more layers. The non-magnetic layer 6 is made of Cr, V, W, M.
The same effect can be obtained by using bcc, fcc or a material having an amorphous structure containing at least one material selected from o, Pt, Pd, Si, Ge and B.

[Embodiment 4] Using a sputtering apparatus similar to that of Embodiment 1, a medium G having a multilayer film structure whose cross-sectional schematic view is shown in FIG. In producing the medium G,
On the glass substrate 1, a structure controlling underlayer 2 having a film thickness of 50 nm and a first magnetic film 31 having a film thickness of 15 nm were sequentially formed. Next, an ion irradiation layer 55 of several atomic layers was uniformly formed on the surface of the first magnetic film 31 by the reverse sputtering method. Ion species are Cr, Mo, V, Ta, Pt, Si, B, Ir,
W, Hf, Nb, Ru, Ti, O, Ar, Kr, Xe or the like can be used. Here, the entire surface of the first magnetic film 31 was irradiated with Ar ions accelerated to 1 keV. Subsequently, a nonmagnetic layer 6 having a film thickness of 2 nm, a second magnetic film 32 having a film thickness of 15 nm, and a carbon protective layer 4 having a film thickness of 10 nm were sequentially formed on the ion irradiation layer 55.

Here, Cr-10 at is used as the underlayer 2.
% V alloy thin film as the first magnetic film 31 of CoCr ₁₈ Ta.
_{The 6} alloy thin film is used as the second magnetic film 32 for CoCr ₂₀ Pt ₁₂
The alloy thin film is further used as the non-magnetic layer 6 in the same C as the underlayer 2.
An example using a r-10 at% V alloy thin film will be described.
As a result of examining the structure of the medium G by an X-ray diffraction method and a transmission electron microscope, the first magnetic film 31 is epitaxially grown on the underlayer 2, and the second magnetic film 32 is the nonmagnetic layer 6. It was confirmed that the film was epitaxially grown on top of. However, the magnetic crystal of the first magnetic film 31 and the magnetic crystal of the second magnetic film 32 did not grow epitaxially. That is, the easy axis of magnetization of the magnetic crystal of the second magnetic film 32 is parallel to the easy axis of the magnetic crystal of the first magnetic film 31 and random in the plane, and is isotropic in the plane. .

For comparison, a similar sputtering apparatus was used, and as shown in the schematic sectional view of FIG. 5 (b), Cr-10a for controlling the structure having a film thickness of 50 nm was formed on the glass substrate 1.
t% V alloy underlayer 2, 15 nm thick CoCr ₁₈ Ta ₆
First magnetic film 31 made of an alloy thin film, Cr-having a thickness of 2 nm
10 at% V alloy non-magnetic layer 6, 15 nm thick CoCr
₂₀ Pt ₁₂ alloy thin film second magnetic film 32 and film thickness 10
A medium H having a multilayer magnetic film structure in which a carbon protective layer 4 having a thickness of 10 nm was sequentially formed was prepared. As a result of examining the medium H by an X-ray diffraction method and a transmission electron microscope, the first magnetic film 31 and the second magnetic film 32 are epitaxially grown on the underlayer 2 via the nonmagnetic layer 6, Furthermore, the axes of easy magnetization of both magnetic films 31 and 32 are aligned in the same direction in the plane. Table 4 shows a comparison of the relative values of the coercive force of the two types of media G and H and the reproduction noise when recording / reproducing the linear recording density of 20 kFCI, 10
The results obtained for 0 kFCI and 250 kFCI are shown.

[0039]

[Table 4]

As is clear from Table 4, the ion irradiation layer is provided between the first magnetic film and the non-magnetic layer, and the magnetic film is divided by the non-magnetic layer to magnetize the first magnetic film and the second magnetic film. The medium G having a multilayer structure in which the easy axis is isotropically oriented in the plane to weaken the magnetostatic interaction even in the film thickness direction of the magnetic film has a noise value in the magnetic recording / reproducing characteristics which is comparable to that of the comparative medium H. Smaller and improved performance. Here, the case where the magnetic film has two layers has been described as an example, but it has been confirmed that there is a similar tendency even when the magnetic film has three or more layers.

[Embodiment 5] Using a sputtering apparatus similar to that of Embodiment 4, a medium I having a multilayer magnetic film structure whose cross-sectional schematic view is shown in FIG. 6 was produced. In producing the medium I, the underlayer 2 for controlling the structure having a film thickness of 50 nm made of a Cr-10 at% V alloy thin film was formed on the glass substrate 1. Then, a focused B (boron) ion beam is applied to the surface of the underlayer to form an ion implantation region 5 having a depth of about 2 nm.
Were formed concentrically as shown in FIG. A 15 nm-thick CoCr ₁₈ Ta ₆ film having a thickness of 15 nm is formed on the underlayer as the first magnetic film 31.
An alloy thin film was formed. Next, an ion irradiation layer 55 of several atomic layers was uniformly formed on the surface of the first magnetic film 31 by the reverse sputtering method. The ion species is Ar accelerated to 1 keV.
The entire surface of the first magnetic film 31 was irradiated with ions. Then, Cr-10a having a film thickness of 2 nm is formed on the ion irradiation layer 55.
Non-magnetic layer 6 made of t% V alloy thin film, CoCr ₂₀ Pt ₁₂
A 15-nm-thick second magnetic film 32 made of an alloy thin film and a 10-nm-thick carbon protective layer 4 were sequentially formed.

For comparison, the materials and thicknesses of the substrate 1, the underlayer 2, the first magnetic film 31, the second magnetic film 32, the non-magnetic layer 6, and the ion irradiation layer 55 are set to be the same, Figure 5 (a)
A medium J having the same structure as that of was prepared. Table 5 shows the coercive force of the two types of mediums I and J and the medium H shown in FIG.
The results of relative value comparison of reproduction noise when recording and reproducing are shown for linear recording densities of 20 kFCI, 100 kFCI and 250 kFCI.

[0043]

[Table 5]

As is clear from Table 5, the ion irradiation layer is provided between the first magnetic film and the non-magnetic layer, and the magnetic film is divided by the non-magnetic layer to magnetize the first magnetic film and the second magnetic film. The medium J having a multilayer structure in which the easy axis is oriented isotropically in the plane and the magnetostatic interaction is weakened even in the film thickness direction of the magnetic film is a comparative medium having a noise value in the magnetic recording / reproducing characteristics. It is smaller than H and has improved performance. Further, the medium I is provided with an ion-implanted region in the circumferential direction of the medium, and the magnetic film is divided into an ion irradiation layer and a non-magnetic layer to form a multilayer structure.
Has a larger coercive force in the circumferential direction than in the radial direction, that is, magnetic anisotropy is imparted in the so-called circumferential direction, and the effect of improving performance such as recording / reproducing characteristics is clear. Here, the case where the magnetic film has two layers has been described as an example, but it has been confirmed that the same effect can be obtained even when the magnetic film has three or more layers.

[Embodiment 6] Using a sputtering apparatus similar to that of Embodiment 1, a medium K having a multilayer magnetic film structure whose cross-sectional schematic view is shown in FIG. 7A was produced. In producing the medium K, the structure controlling underlayer 2 having a film thickness of 30 nm and the first magnetic film 33 having a film thickness of 50 nm were sequentially formed on the glass substrate 1. A Ti-10 at% Cr alloy thin film having an hcp structure was used for the underlayer 2, but Co, Ti, Ru, Hf, Ta, C were used.
It is also possible to use a material having a hexagonal close-packed structure or an amorphous structure containing at least one selected from r, V, W, Mo, Pt, Pd, Si, Ge, and B. First magnetic film 33
As the thin film, a Co-based alloy thin film having an hcp structure containing Co as a main component was used, and a CoCr ₁₈ Ta ₆ alloy thin film was used in this example. Next, an ion irradiation layer 55 of several atomic layers was uniformly formed on the surface of the first magnetic film 33 by the reverse sputtering method. Ion species include Cr, Mo, V, Ta, Pt, S
i, B, Ir, W, Hf, Nb, Ru, Ti, O, A
r, Kr, Xe, etc. can be used. Here, the entire surface of the first magnetic film 33 was irradiated with Kr ions accelerated to 0.5 keV.

Subsequently, a nonmagnetic layer 6 having a film thickness of 2 nm, a second magnetic film 34 having a film thickness of 50 nm, and a carbon protective layer 4 having a film thickness of 10 nm were sequentially formed on the ion irradiation layer 55. As the non-magnetic layer 6, Co, Ti, Ru, Hf, Ta, C
A material having a hexagonal close-packed structure or an amorphous structure containing at least one selected from r, V, W, Mo, Pt, Pd, Si, Ge, and B is used. Here, Ti of hcp structure
An example using a -10 at% Cr alloy thin film will be described.
The second magnetic film 34 may be made of a material having a composition different from that of the first magnetic film 33. Here, an example using the same CoCr ₁₈ Ta ₆ alloy thin film as the first magnetic film 33 will be described.

As a result of X-ray diffraction and transmission electron microscope observation of the medium cross section, the first magnetic film 33 was epitaxially grown on the underlayer 2, and the second magnetic film 34 was epitaxially grown on the nonmagnetic layer 6. Therefore, the c-axes of the easy axes of the first and second magnetic films having the hcp structure were oriented perpendicular to the substrate surface.
In addition, as a result of observing the medium thin film from the plane direction, the first magnetic film and the second magnetic film had independent crystal orientations in the in-plane direction.

For comparison, as shown in FIG. 7B, an underlayer 2 for controlling the structure having a thickness of 30 nm is formed on the glass substrate 1.
A medium L having a multilayer magnetic film structure in which a first magnetic film 33 having a film thickness of 50 nm, a nonmagnetic layer 6 having a film thickness of 2 nm, a second magnetic film 34 having a film thickness of 50 nm, and a carbon protective layer 4 having a film thickness of 10 nm are sequentially formed is manufactured. did. The material composition of the underlayer, the first and second magnetic films, and the nonmagnetic layer was the same as that of the medium K.

As a result of examining the structure of the medium L by X-ray diffraction and observing the cross section of the medium with a transmission electron microscope, the first magnetic film 3 is obtained.
3 and the second magnetic film 34 are epitaxially grown on the underlayer 2 via the non-magnetic layer 6, and the c-axis of the easy axis of magnetization of the magnetic film of the hcp structure is oriented perpendicular to the substrate surface. Was there. In addition, as a result of observing the thin film of the medium from the plane direction, it was confirmed that the first magnetic film 33 and the second magnetic film 34 had the same crystal axis even in the in-plane direction.

For further comparison, as shown in FIG.
A single-layer magnetic film in which a 30 nm-thickness underlayer 2 for structure control is formed on a glass substrate 1, and a 100 nm-thickness magnetic film 33 and a 10 nm-thickness carbon protective layer 4 are sequentially formed on the underlying layer 2. A medium M was prepared. The underlayer of this medium was made of the same material as the non-magnetic layer of the medium K, and the magnetic film was made of the same CoCr ₁₈ Ta ₆ alloy thin film as the first magnetic film of the medium K.

As a result of examining the structure of the medium M by an X-ray diffraction method or observing the cross section of the medium by a transmission electron microscope, the magnetic film 33 is epitaxially grown on the underlayer 2, and hc
The c axis of the easy magnetization axis of the magnetic film 33 having the p structure was oriented perpendicular to the substrate surface. Table 6 shows the above three types of media K, L, and M.
The relative values of the coercive force Hc (perpendicular) in the direction perpendicular to the film surface, the average particle diameter of the magnetic particles, and the reproduction noise when recording / reproducing were compared.
The results obtained for 0 kFCI are shown. The average particle size of the magnetic particles was determined by observation with a scanning electron microscope.

[0052]

[Table 6]

As is clear from Table 6, the ion irradiation layer is provided between the first magnetic film and the non-magnetic layer, and the magnetic film is divided by the non-magnetic layer to magnetize the first magnetic film and the second magnetic film. The medium K having a multilayer structure in which the easy axis is independently oriented in the plane and the magnetostatic interaction is weakened also in the film thickness direction of the magnetic film is a multilayer film medium L in which a magnetic film is simply divided by a non-magnetic layer. Noise in the magnetic recording / reproducing characteristics can be reduced as compared with the single-layer magnetic film medium M. It is considered that this is because the average particle size of the magnetic particles can be reduced and the magnetic domain size when magnetized can be reduced. Here, the case where the magnetic film has two layers has been described as an example, but the same effect can be obtained even when the magnetic film has three or more layers.

[Embodiment 7] Using the same sputtering apparatus as in Embodiment 1, a medium N having a multi-layer magnetic film structure whose cross-sectional schematic view is shown in FIG. 8A was produced. In producing the medium N, the structure controlling underlayer 2 having a film thickness of 50 nm and the first magnetic film 31 having a film thickness of 15 nm were sequentially formed on the glass substrate 1.
The Cr-15 at% Ti alloy underlayer 2 was used as the underlayer 2. This underlayer had a bcc structure, and the (100) plane was oriented parallel to the substrate surface. Co as the first magnetic film 31
A Cr ₁₈ Ta ₆ alloy thin film was used. The easy axis of magnetization of this magnetic film was oriented parallel to the substrate surface. Next, the ion irradiation layer 55 of several atomic layers was formed uniformly on the surface of the first magnetic film 31. Ion species include Cr, Mo, V, Ta, Pt,
Si, B, Ir, W, Hf, Nb, Ru, Ti, O, A
r, Kr, Xe, etc. can be used. Here, the entire surface of the first magnetic film 31 was irradiated with Ar ions accelerated to 0.5 keV.

Subsequently, a nonmagnetic layer 6 having a film thickness of 2 nm, a second magnetic film 34 having a film thickness of 70 nm, and a carbon protective layer 4 having a film thickness of 10 nm were successively formed on the ion irradiation layer 55. As the non-magnetic layer 6, Co, Ti, Ru, Hf, Ta, C
A material having a hexagonal close-packed structure or an amorphous structure containing at least one selected from r, V, W, Mo, Pt, Pd, Si, Ge, and B is used. Here, Ti of hcp structure
A -10 at% Ru alloy thin film was used. As the second magnetic film 34, a CoCr ₁₈ Pt ₁₂ Ta ₅ alloy film was used.

When examined by X-ray diffractometry and a transmission electron microscope observation of the cross section of the thin film, the nonmagnetic layer 6 was found to have the c axis of the hcp structure oriented in the direction perpendicular to the substrate surface.
No. 4 was epitaxially grown on this nonmagnetic layer, and its easy axis of magnetization was oriented in the direction perpendicular to the film surface.
That is, the medium N has a multilayer film structure in which the easy axis of magnetization of the first magnetic film is oriented parallel to the substrate surface, and the easy axis of the second magnetic film is oriented perpendicular to the substrate surface.

For comparison, as shown in FIG. 8B, a 50 nm-thick underlayer 2 made of a Ti-10 at% Ru alloy thin film having an hcp structure is formed on a substrate 1 and CoC is formed thereon.
The first magnetic film 33 having a film thickness of 15 nm made of an r ₁₈ Ta ₆ alloy thin film and the film thickness 2n made of a Ti-10 at% Ru alloy thin film.
m nonmagnetic layer 6, a second magnetic film 34 of CoCr ₁₈ Pt ₁₂ Ta ₅ alloy thin film having a film thickness of 70 nm, and a film thickness of 10 n.
A medium O having a multilayer magnetic film structure in which the m carbon protective layer 4 was sequentially formed was prepared. In this medium O, the first magnetic film 33 and the second magnetic film 34 are epitaxially grown on the underlayer 2 via the non-magnetic layer 6, and the first magnetic film 33 is also the second magnetic film 33.
The easy axis of magnetization of the magnetic film 34 was also oriented in the direction perpendicular to the film surface.

For comparison, as shown in FIG. 8C, a 50 nm-thick underlayer 2 made of a Ti-10 at% Ru alloy thin film having an hcp structure is formed on a substrate 1 and CoCr ₁₈ Ta is formed thereon. A medium P having a single-layer magnetic film structure in which a magnetic film 33 of a _6- alloy thin film having a film thickness of 70 nm and a carbon protective layer 4 having a film thickness of 10 nm were sequentially formed was prepared. The magnetic film 33 of the medium P was epitaxially grown on the underlayer 2, and the easy axis of magnetization was oriented in the direction perpendicular to the film surface.

Table 7 shows the coercive force Hc (perpendicular) of the above three types of media N, O and P in the direction perpendicular to the film surface and the linear recording density 10
The reproduction output at 0 kFCI (relative comparison by the voltage of the signal amplitude) and the relative value comparison of the reproduction noise at the time of recording and reproduction are compared with the linear recording density of 20 kFCI, 100 kFCI and 25.
The results obtained for 0 kFCI are shown.

[0060]

[Table 7]

As is clear from Table 7, the ion irradiation layer is provided between the first magnetic film and the nonmagnetic layer, the magnetic film is divided by the nonmagnetic layer, and the easy axis of magnetization of the first magnetic film is set to the substrate surface. The medium N in which the magnetic film is simply divided into non-magnetic layers is a multi-layer medium O or a single-layer magnetic film medium, in which the magnetic film is divided into non-magnetic layers. Compared with a comparative medium such as P, the reproduction output can be greatly increased, and the magnetic domain size when magnetized can be made smaller than other comparative media. Therefore, the noise value in the magnetic recording / reproducing characteristics is different from that of other comparative media. Compared to the above, the effect of performance improvement is clear. Here, the case where the magnetic film has two layers has been described as an example, but the same effect can be obtained even when the magnetic film has three or more layers.

[Embodiment 8] FIG. 9 shows a schematic view of a magnetic recording / reproducing apparatus incorporating the in-plane and perpendicular magnetic recording media according to the present invention described in the embodiments 1 to 7. The magnetic disk 61 is held by a holder rotated by a motor, and a magnetoresistive effect element reproducing composite head 62 for writing and reading information is arranged corresponding to each magnetic film. The position of the composite magnetoresistive element reproducing head 62 with respect to the magnetic disk 61 is determined by the actuator 63.
And the voice coil motor 64. Further, in order to control these, the recording / reproducing circuit 65 and the positioning circuit 6
6. An interface control circuit 67 is provided.

[0063]

As described in detail above, according to the magnetic recording medium of the present invention, the ion-implanted region is formed at any selected position on the substrate, the underlayer for controlling the structure of the magnetic film, or the magnetic film. And a perpendicular magnetic recording film formed by laminating magnetic films having the same or different compositions in multiple layers, and by using a perpendicular magnetic recording film A magnetic recording / reproducing device can be provided, and its industrial utility value is extremely high.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a magnetic recording medium provided with an ion-implanted region.

FIG. 2 is an explanatory view of an embodiment of an ion implantation area forming method.

FIG. 3 is an explanatory view of another embodiment of the ion implantation area forming method.

FIG. 4 is a schematic cross-sectional view of an example and a comparative example of a multilayer in-plane magnetic recording medium provided with an ion-implanted region.

FIG. 5 is a schematic cross-sectional view of an example and a comparative example of a multilayer in-plane magnetic recording medium provided with an ion-implanted region.

FIG. 6 is a schematic cross-sectional view of an example of a multilayer in-plane magnetic recording medium provided with an ion-implanted region.

FIG. 7 is a schematic cross-sectional view of an example and a comparative example of a multilayer perpendicular magnetic recording medium provided with an ion-implanted region.

FIG. 8 is a schematic cross-sectional view of an example and a comparative example of a multilayer perpendicular magnetic recording medium having an ion-implanted region.

FIG. 9 is a schematic diagram of a magnetic recording / reproducing device.

[Explanation of symbols]

1 ... Substrate, 2 ... Underlayer, 3 ... Magnetic film, 4 ... Protective layer, 5 ...
Ion-implanted region, 6 ... Nonmagnetic layer, 31, 33 ... First
Magnetic film, 32, 34 ... Second magnetic film, 55 ... Ion irradiation layer, 61 ... Magnetic disk, 62 ... Magnetoresistive element reproducing composite head, 63 ... Actuator, 64 ... Voice coil motor, 65 ... Recording / reproducing circuit, 66 ... positioning circuit,
67 ... Interface control circuit

Claims (20)

[Claims] 1. A magnetic recording medium comprising a non-magnetic substrate, an underlayer, a magnetic film and a protective layer laminated on the non-magnetic substrate, and at least one selected region of the non-magnetic substrate, the underlayer or the magnetic film is ion-implanted. A magnetic recording medium having a region formed therein. 2. A magnetic recording medium comprising a non-magnetic substrate, a base layer, a magnetic film formed by laminating a plurality of layers via a non-magnetic layer, and a protective layer, wherein the non-magnetic substrate, the base layer or the plurality of layers are provided. A magnetic recording medium, wherein an ion-implanted region is formed in at least one selected region of the individual magnetic films in the stacked magnetic films. 3. The magnetic recording medium according to claim 1, wherein the ion-implanted region has a concentric circular shape or a spiral shape. 4. The magnetic recording medium according to claim 1, wherein the ion-implanted region is radial from the center toward the outer peripheral portion. 5. A magnetic recording medium comprising a non-magnetic substrate, a base layer, a plurality of magnetic films with a non-magnetic layer interposed therebetween, and a protective layer, wherein ions are formed on the entire surface of at least one magnetic film other than the uppermost layer. A magnetic recording medium having a drive region formed therein. 6. The magnetic recording medium according to claim 5, wherein an ion-implanted region is formed in a selected region of the magnetic film other than the magnetic film having the ion-implanted region formed on the entire surface. 7. The magnetic recording medium according to claim 6, wherein the ion-implanted region has a concentric circular shape or a spiral shape. 8. The ion implantation region is made of Cr, Mo,
V, Ta, Pt, Si, B, Ir, W, Hf, Nb, R
8. The magnetic recording medium according to claim 1, comprising at least one element selected from the elements u, Ti, O, Ar, Kr, and Xe. 9. The magnetic film contains Co as a main component, and Cr, Fe, Mo, V, Ta, Pt, Si, B, Ir,
9. A material containing at least one element or compound selected from W, Hf, Nb, Ti, Ni, CoO and rare earth elements, and having a hexagonal close-packed structure. The magnetic recording medium according to item 1. 10. The magnetic recording medium according to claim 2, wherein the underlayer and the nonmagnetic layer have a face-centered cubic structure, a body-centered cubic structure, or an amorphous structure. 11. The underlayer and the non-magnetic layer are made of Cr, V,
The magnetic recording according to claim 2, 5, 6, or 7, which is made of a material containing at least one selected from W, Mo, Pt, Pd, Si, Ge, and B, or an alloy material containing the same. Medium. 12. The underlayer has a face-centered cubic structure, a body-centered cubic structure, or an amorphous structure, and the non-magnetic layer has a hexagonal close-packed structure or an amorphous structure. ,
The magnetic recording medium according to 5, 6, or 7. 13. The nonmagnetic layer contains Ti, Ru, and Co as main components, and contains Co, Ti, Ru, Hf, Ta, and C.
13. The magnetic recording according to claim 12, which is made of a material having a hexagonal close-packed structure or an amorphous structure containing at least one selected from r, V, W, Mo, Pt, Pd, Si, Ge and B. Medium. 14. The magnetic recording medium according to claim 2, wherein the underlayer and the nonmagnetic layer have a hexagonal close-packed structure or an amorphous structure. 15. The underlayer and the non-magnetic layer are Co, T
i, Ru, Hf, Ta, Cr, V, W, Mo, Pt, P
15. The magnetic recording medium according to claim 14, which is made of a material containing at least one selected from d, Si, Ge, and B, or an alloy material containing the same. 16. A magnetic film comprises at least two layers of a first magnetic film on a side closer to a non-magnetic substrate and a second magnetic film on a side farther from the substrate, and an easy axis of magnetization of the first magnetic film and the second magnetic film. 8. The magnetic recording medium according to claim 2, 5, 6 or 7, characterized in that is oriented in the in-plane direction of the substrate. 17. The magnetic recording medium according to claim 16, wherein the easy axis of magnetization of the second magnetic film is isotropic in the plane of the substrate with respect to the easy axis of the first magnetic film. . 18. The magnetic film comprises at least two layers, a first magnetic film on the side closer to the non-magnetic substrate and a second magnetic film on the side farther from the substrate, and the first magnetic film has an easy axis of magnetization in the in-plane direction of the substrate. 9. The magnetic recording medium according to claim 2, wherein the second magnetic film has an easy axis of magnetization in a direction perpendicular to the substrate surface. 19. The magnetic film comprises at least two layers, a first magnetic film on the side closer to the non-magnetic substrate and a second magnetic film on the side farther from the substrate, and the first magnetic film and the second magnetic film are on the surface of the substrate. 3. Having a perpendicular easy axis.
The magnetic recording medium according to 5, 6, or 7. 20. A magnetic recording medium according to claim 1, a magnetic head for recording / reproducing magnetic information on / from the magnetic recording medium, and the magnetic recording medium and the magnetic head are arranged relative to each other. A magnetic recording / reproducing apparatus comprising: a driving mechanism for moving the magnetic head; and an actuator for positioning the magnetic head at an appropriate position on the magnetic recording medium.