JPH09265619A - Magnetic recording medium, its production and magnetic storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium with which recording and reproducing of high-density information is possible and which has high coercive force, low noise, high S' and high reliability. SOLUTION: This magnetic recording medium is constituted by arranging information recording layers 15, 15' consisting of magnetic films of a Co-based alloy system via at least two layers of nonmagnetic ground surface layers 13, 14, 13', 14' on a substrate 11. The first nonmagnetic ground surface films 13, 13' arranged on the extreme substrate side among the nonmagnetic ground surface layers 13, 14, 13', 14' consist of composite films essentially consisting of Cr and contg. at least one kind of the elements in the group consisting of Zr, Si, Al, Ti, V, Ta and Y and oxygen. The concn. of the elements described above is specified to >=1 to <=20atm.% and the concn. of the oxygen to >=1 to <=30atm.%.

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 for recording information such as a magnetic disk, a method of manufacturing the same, and a magnetic storage device, and more particularly, a magnetic recording medium having a high surface recording density, a method of manufacturing the same, and a magnetic storage device. Regarding

[0002]

2. Description of the Related Art Conventionally, a medium for in-plane magnetic recording in which magnetization is reversed in the in-plane direction for recording is a Co-based alloy magnetic thin film containing a ferromagnetic metal such as Co as a main component as an information recording layer. There is. In order to enable high density information recording of 1 gigabit per square inch or more, it is required to increase the coercive force of this recording layer and reduce the medium noise.

In general, in order to increase the coercive force (Hc), the amount of Pt added in the CoCrPt alloy magnetic film is increased, and the amount of Pt is added to the body-centered cubic structure (bcc) of Cr or an alloy based non-magnetic alloy containing Cr as the main component. A method of epitaxially growing on a formation is disclosed in, for example, Journal of Applied Physics, 73 (1993), pages 5569-5571 (J. Appl. Phys., Vol. 73, No. 1).
0, (1993) p. 5569-5571).

Further, as an effective method for reducing the medium noise, when the medium is formed by sputtering, the Ar pressure is increased to 10 mTorr or more to spatially separate the crystal grains of the recording layer, and thereby the magnetic crystal is formed. A method of magnetically isolating grains (for example, I E E E)
Transaction on Magnetics, Volume 26 (1
990) pp. 1578-1580 (IEEE Tra
ns. on Magn. , Vol. 26, no. 5 (1
990) p. 1578-1580)) are known.
Further, the concentration of Cr in the CoCrPt magnetic film is increased to increase the Cr content.
Segregate at the grain boundaries (for example, I-E-E-Transaction-on-Magnetics,
Volume 29 (1993) pp. 3667-3669 (IEEE)
E Trans. on Magn. , Vol. 29, N
o. 6 (1993) p. 3667-3669)) are known.

Further, as a method for reducing the medium noise, a non-magnetic underlayer film containing Cr as a main component is formed into two layers, and the first underlayer film disposed on the substrate side is used as a body-centered cubic film in X-ray diffraction. A nonmagnetic underlayer having a crystalline structure mainly composed of (110) orientation is formed to a thickness of 0.5 to 8 nm, and a second nonmagnetic material mainly composed of (200) orientation of body-centered cubic structure is formed thereon. A method of forming a base film having a film thickness of 20 to 300 nm is
It is described in JP-A-7-57238. Further, as a method for improving the magnetostatic characteristics and the electromagnetic conversion characteristics, JP-A-1-290118 describes a method of improving the crystal orientation by adding oxygen to a non-magnetic underlayer film containing Cr as a main component. .

Further, in order to realize high density recording,
In order to maintain the magnetization in the recording direction by overcoming the demagnetizing field from the magnetization at the bit boundary, the coercive force is increased, and at the same time, the product of the film thickness t of the recording layer and the residual magnetic flux density Br.
It is necessary to reduce t to reduce the demagnetizing field (for example, I-E-E-Transaction on Magnetics, Vol. 29 (1993) No. 3670-3).
Page 672 (IEEE Trans. On Magn.,
Vol. 29, No. 6 (1993) p. 3670-3
672)).

[0007]

The above-mentioned conventional technique, namely, the increase in the coercive force by increasing the Pt concentration in the magnetic film has a problem that the precious metal Pt is expensive and the manufacturing cost is increased. Therefore, there has been a demand for a technique for improving the coercive force by another method. Further, the method of separating the crystal grains of the magnetic film or increasing the Cr concentration to reduce the noise has a problem that the value of the coercive force squareness ratio (S ^* ) is lowered and, as a result, the reproduction output is lowered. . Further, when the medium noise is reduced by the above method, the value obtained by normalizing the change rate of the coercive force with respect to the ambient temperature by the coercive force at room temperature (25 ° C.) (hereinafter referred to as the normalized coercive force temperature change rate) increases, and In this case, the coercive force increased and it became difficult to overwrite, and at high temperature, the coercive force decreased and the reproduction output decreased.
Heretofore, there has been no known method for realizing both low noise and a low coercive force temperature change rate.

Further, according to the method described in Japanese Patent Application Laid-Open No. 7-57238, the first underlayer film disposed on the substrate side is 0.5 to 8.
nm, preferably 0.5 to 1.5 nm, which is an extremely thin film thickness of 1/10 or less as compared with other films, and it is necessary to control the film thickness distribution in the disk surface and to perform a mass production process. It has been difficult to manufacture a large amount of magnetic recording media with constant quality. Further, the effect of improving the coercive force or reducing the coercive force temperature change rate is not described.

The method described in Japanese Patent Laid-Open No. 1-290118 can improve the coercive force and S ^* , but it does not describe the effect of reducing the medium noise or the temperature change rate of the coercive force.

As described above, in order to realize a higher density, the coercive force is improved without increasing the Pt concentration in the magnetic film, and the S ^* value is not lowered to maintain the standardization. It is necessary to reduce the medium noise without increasing the temperature change rate of the magnetic force.

Further, it has been sufficiently studied how the recording / reproducing separated head using the magnetoresistive element and the above magnetic recording medium are combined to realize a magnetic disk device having a high recording density. Was not done. It has been found that Hc exceeding 2.0 kOe is required to achieve the above-mentioned recording density of 1 Gbit / in 2 or more.

It is a first object of the present invention to provide a magnetic recording medium having a high coercive force, a high S ^* , a low noise and a high reliability, which can record and reproduce high density information. A second object of the present invention is to provide a method of manufacturing a magnetic recording medium having high coercive force, high S ^* and low noise as described above.
A third object of the present invention is to provide a highly reliable magnetic storage device using the magnetic recording medium having high coercive force, high S ^* and low noise as described above.

[0013]

In order to achieve the above-mentioned first object, a magnetic recording medium of the present invention comprises a Co-based alloy-based magnetic film on a substrate with at least two layers of non-magnetic underlayers interposed therebetween. The first nonmagnetic underlayer film, which is disposed on the most substrate side among the above nonmagnetic underlayer films, is composed of Cr as a main component and Zr, Si, Al, Ti, V, Ta. And Y
A composite film containing at least one element selected from the group consisting of and oxygen, wherein the concentration of the element is 1 atom% or more and 20 atom% or less, and the concentration of oxygen is 1 atom% or more, 30
It is made to be not more than atomic%.

The second nonmagnetic undercoating film, which is disposed closest to the information recording layer among the above nonmagnetic undercoating films, contains Cr as a main component and is at least selected from the group consisting of Ti, Mo, W and V. It is preferable to use an alloy containing one kind of element in a concentration of 5 atomic% or more and 50 atomic% or less, and to have a crystal structure mainly having a (110) orientation of a body-centered cubic structure in X-ray diffraction.

Further, the first non-magnetic underlayer film is made amorphous by X-ray diffraction and has a film thickness of 10 nm or more and 100 n.
m or less, the thickness of the second non-magnetic underlayer film is 2 nm or more and 15 nm or less, and the magnetic film has a hexagonal close-packed (10.0) -oriented crystal structure in X-ray diffraction. It is preferable because it has the effect of improving the magnetic force and reducing the temperature change rate. In particular, when the average particle size of the first nonmagnetic underlayer film is 2 nm or more and 30 nm or less, the medium noise can be kept low. Further, when the thickness of the non-magnetic underlayer film is 10 nm or more, the mass production process can be easily controlled, and when the thickness is 100 nm or less, the particle size can be kept within a desired range.

Zr, Si, Al, Ti, V, Ta,
The element of the group consisting of Y has a property of easily bonding with oxygen as compared with Cr, and exists mainly in an oxide state in the composite film. In this way, the non-magnetic underlayer is formed of Zr, Si, Al,
By forming a composite film of Cr and an oxide of an element of the group consisting of Ti, V, Ta, and Y, the grain size can be made small and uniform, and an amorphous film can be obtained by X-ray diffraction. This is because the oxide of the element group consisting of Zr, Si, Al, Ti, V, Ta, and Y has the effect of suppressing the crystal growth of Cr crystal grains. It is preferable that these oxides are segregated and present in the film because the coercive force can be improved and the temperature change rate of the coercive force can be reduced.

Zr, Si, Al,
The addition concentration of the oxide of the element of the group consisting of Ti, V, Ta and Y is such that the total concentration of the above element group is 1 atom% or more and 20 atom% or less, and the oxygen concentration is 1 atom% or more and 30 atom% or less. Then, an amorphous structure can be obtained by X-ray diffraction. Such a composite film includes Zr, Si, Al, Ti,
It can be easily formed by sputtering using a target made of Cr and an oxide of an element of the group consisting of V, Ta, and Y. Further, similar characteristics can be improved when two or more kinds of oxides of the above elements are added.

Further, the non-magnetic underlayer is composed of at least two layers, and the first layer is arranged closest to the substrate.
The non-magnetic underlayer film of the above-mentioned composite film is composed of the above-mentioned composite film, and the second nonmagnetic underlayer film disposed closest to the information recording layer of the nonmagnetic underlayer film contains Cr of the body-centered cubic structure (bcc) as a main component. And the size of its (110) crystal lattice is
Hexagonal close-packed structure (hcp) Co alloy magnetic film (1
0.1) When formed so as to substantially match the size of the crystal lattice, Hc can be kept high at 2 kOe or more and 5 kOe or less, and S ^* can be kept high at 0.7 or more and 0.95 or less, and 1G
It is preferable because a sufficient reproduction output can be obtained even at a high recording density of b / in ² or more. Here, the size of the crystal lattice of the second non-magnetic underlayer being substantially matched with the size of the crystal lattice of the magnetic film means that the difference in the size of the crystal lattice is within ± 5%. Means that there is to be.
In particular, the second non-magnetic underlayer film is formed of Cr-Ti or Cr-
Mo-based alloy with Ti or Mo addition concentration of 10-20
When the atomic percentage is set, the matching of the crystal lattice with the Co—Cr—Pt-based alloy magnetic film is increased, and the crystal grain size can be reduced, so that the medium noise can be reduced, which is preferable.

Further, when the non-magnetic undercoat film made of the above composite film is formed, the ratio of crystal grains oriented and grown so that the (10.0) plane is parallel to the substrate in the crystal grains of the magnetic film is increased. You can As a result, c, which is the easy axis of magnetization of the magnetic film,
The axis becomes parallel to the substrate surface, and the values of coercive force and remanent magnetization squareness ratio (S) are improved. As a result, a sufficient reproduction output can be obtained even at a high recording density of 1 Gb / in ² or more.

As a result of the improvement of the crystal structure, crystal orientation, and lattice matching as described above, the coercive force and the temperature change rate of the coercive force can be improved. In particular, when the thickness of the second non-magnetic underlayer film is 5 nm or more and 15 nm or less, the rate of change in coercive force with temperature is significantly reduced. As a result, change in coercive force is reduced in the temperature range of 5 ° C. to 55 ° C., and overwrite and reproduction output fluctuation can be reduced, which is preferable.

Further, in the above magnetic recording medium, when the total magnetic film thickness t is set to 10 nm or 30 nm or less and the coercive force Hc is set to 2.0 kOe or more, the disorder of the magnetization in the magnetization transition region is reduced and the width of the magnetization transition region is reduced. Is reduced, and a high output can be obtained even in a high recording density region, which is preferable. Especially Br
When t is 30 Gμm or more and 100 Gμm or less, medium noise is reduced and a high medium S / N can be obtained, which is preferable. Further, in order to ensure good overwrite characteristics, the coercive force Hc is preferably 4 kOe or less.

Further, in the above magnetic recording medium, when the center line average roughness Ra of the surface of the medium protective film measured in the direction perpendicular to the head running direction is 0.3 nm or more and 3 nm or less, the head flying height is 0.02 μm. As described above, even if the thickness is 0.1 μm or less, it is possible to float stably, which is preferable. In addition, R on the medium surface
When a is smaller than the conventional value, the adhesion of the magnetic head during CSS operation can be controlled by forming a protective film on the magnetic film and performing plasma etching using a mask so that the height of the surface is 20 nm or less. Forming fine unevenness of
A low melting point metal compound such as Al or a mixture target is used to form fine projections on the surface of the protective film,
Alternatively, if minute unevenness is formed on the surface by heat treatment, C
It is preferable because the frictional force between the head and the medium can be reduced during the SS operation, and the problem of the head sticking to the medium can be avoided.

Further, Cr, Mo, W, V, Ta, N
b, Zr, Ti, B, Be, C, Ni-P, Ni-B as a main component and a film thickness of 0.5 nm
As described above, it is preferable that the nonmagnetic intermediate layer having a thickness of 5 nm or less makes the magnetic film multi-layered into two or more layers because the medium noise is further reduced as compared with the single-layer magnetic film.

Further, carbon is used as a protective layer for the magnetic film,
A nonmagnetic material containing hydrogenated carbon or carbon as a main component is formed to a film thickness of 5 to 20 nm, and a lubricating layer such as an adsorbent perfluoroalkyl polyether is formed to a film thickness of 3 to 1
By providing 0 nm, a highly reliable magnetic recording medium capable of high density recording can be obtained. WC, (W-
Mo) -C and the like carbide, (Zr-Nb) -N, Si 3 N 4
Such as nitrides, oxides such as SiO ₂ and ZrO ₂ , or B, B
_It is preferable to use ₄ C, MoS ₂ , Rh or the like because the sliding resistance and the corrosion resistance can be improved. The surface of these protective films is etched using a mask, and projections having an area ratio of 1 to 20% are provided, or film formation conditions, compositions, and the like are adjusted to deposit projections having different phases in the protective films. Thus, it is more preferable that the protective film has a larger surface roughness than the surface of the magnetic film.

In order to achieve the above second object,
A method of manufacturing a magnetic recording medium according to the present invention comprises forming at least two layers of a non-magnetic underlayer film on a substrate, and then forming an information recording layer composed of a Co-based alloy-based magnetic film. Of the first non-magnetic underlayer film disposed closest to the substrate among Cr, Zr, Si, Al, Ti, V, T
a mixture with an oxide of at least one element selected from the group consisting of a and Y, and the addition concentration of the above element is
The target is 1 at% or more and 20 at% or less, and sputtering is performed in pure Ar without using oxygen gas.

If the first nonmagnetic underlayer film is formed at room temperature and then the substrate is heated to 150 ° C. or higher and 400 ° C. or lower before the second nonmagnetic underlayer film is formed, the coercive force is improved. However, the temperature change rate is reduced, which is preferable. Further, in forming the medium, it is preferable to set the substrate temperature at the time of forming the magnetic film to 200 ° C. or higher and 400 ° C. or lower because segregation of Cr in the magnetic film is promoted and Hc is improved.

Further, in order to achieve the third object, the magnetic storage device of the present invention comprises any one of the above magnetic recording medium and a magnetic head for recording / reproducing information on / from this magnetic recording medium. It was done like this.

The magnetic head for combining with the above magnetic storage medium to form a magnetic storage device is preferably a recording / reproducing separated head using a magnetoresistive effect element as a reproducing element. The above-described magnetic recording medium has a sufficient S / N ratio even when recording / reproducing at a recording density of 1 gigabits per square inch or more, for example, in combination with the high reproducing sensitivity characteristic of the magnetoresistive element. can get.

Further, the reproducing portion of the magnetic head is arranged between a plurality of conductive magnetic layers which cause a large resistance change due to the mutual change of their magnetization directions by an external magnetic field, and the conductive magnetic layer. And a thickness t of the magnetic layer.
And the product Br · t of Br measured by applying a magnetic field in the traveling direction of the magnetic head relative to the magnetic recording medium during recording are set to 30 Gμm or more and 80 Gμm or less, and the magnetic field is applied in the above direction for measurement. By setting the coercive force Hc of the magnetic recording medium to be 2.2 kilo Oersted or more, it is possible to record and reproduce high density information of 2 gigabits or more per square inch.

[0030]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic view of a sectional structure of an in-plane magnetic recording medium of the present invention. In the figure, 11 is a substrate made of Al-Mg alloy, chemically strengthened glass, crystallized glass, titanium, silicon, carbon or ceramics, and 12 and 12 'are Ni-P and Ni-W formed on both sides of the substrate 11. It is a non-magnetic plating layer made of -P or the like. When an Al-Mg alloy is used as the substrate, one having such a plating layer is used as the substrate.
In addition, when Si single crystal, glass, carbon or the like is used for the substrate, the nonmagnetic plating layer may not be formed.

Reference numerals 13 and 13 'are first composite films containing Cr as a main component and containing at least one element of the group consisting of Zr, Si, Al, Ti, V, Ta, and Y and oxygen. Of non-magnetic underlayer, 14 and 14 'are Cr, M
o, W, V, Nb, Ta, Cu, Ag, Mn, Zr, H
metal consisting of f or Si or Cr, Mo, W, V,
Nb, Ta, Cu, Ag, Mn, Zr, Hf or S
This is a second non-magnetic underlayer film made of an alloy containing any one of i as a main component. In addition, when the non-magnetic underlayer film has three layers,
The same material as above is used for the intermediate layer.

Further, 15 and 15 'are Co-Sm, Co-Ni-Cr, Co- formed on the non-magnetic underlayer.
Ni-Pt, Co-Ni-P, Co-Cr-Ta, Co
-Cr-Pt, Co-Cr-W, Co-Cr-Si, C
The information recording layers 16 and 16 'made of an alloy magnetic film made of o-Cr-Ta-Pt or the like are non-magnetic protective films made of carbon, boron, SiO ₂ , ZrO ₂ or the like formed on the information recording layer. is there.

Such an in-plane magnetic recording medium was manufactured as follows. Tempered glass substrate, crystallized glass substrate,
A single-wafer system in which various magnetic disk substrates, such as Al alloy substrates whose surfaces are mirror-polished with Ni-P, are mirror-polished, and the respective films constituting the magnetic recording medium are formed in separate film forming chambers. Each film was formed by the DC magnetron sputtering method by sequentially feeding one by one with a tact time of 10 seconds using a sputtering device. Here, the film forming conditions are: back pressure of the main vacuum chamber: 5
× 10 ^-8 Torr or less, substrate heating temperature: 100 to 300
C, Ar gas pressure: 5 to 30 mTorr, input power: 1 to 4 kW for a target size of 6 inches. On one or more of the above-mentioned various substrates, one or more non-magnetic underlayer films containing Cr as a main component are formed, and the film thickness is continuously 10 to 30 n.
Various alloy compositions of m of Co, Cr and Ta or alloy magnetic films containing Co, Cr and Pt as main components were formed, and a carbon protective film was formed thereon. Then, magnetic properties, crystallographic properties, etc. of these films were evaluated.

2A and 2B are a schematic plan view and a schematic sectional view taken along the line AA 'of the magnetic memory device of the present invention. This magnetic storage device includes one or a plurality of magnetic disks 21, a magnetic head 23 corresponding to the information recording surface of the magnetic disks, and a drive unit 22 for rotationally driving the magnetic disks.
And a magnetic head driving means 24 and a signal processing section 25. It is preferable to use a composite head (MR head) for reproducing an electromagnetic induction type magnetoresistive effect element as a magnetic head in combination with the magnetic recording medium.

[0035]

【Example】

<Example 1> Outer diameter 65 mm, inner diameter 20 mm, thickness 0.6
A stain such as an abrasive adhered to the mm-mm glass disk substrate was washed and dried.

This substrate was loaded into a substrate preparation chamber of a single-wafer type DC magnetron sputtering apparatus and evacuated to a vacuum, and then the substrate was heated, a non-magnetic underlayer forming chamber, a magnetic film forming chamber,
Vacuum degree 5 × in the order of non-magnetic protective film forming chamber and take-out chamber
It was conveyed through a main exhaust tank at 10 ^-8 Torr or less, and each film was formed in each chamber.

First, under an argon pressure of 8 mTorr, a power of 1 kW was applied to Cr-ZrO ₂ targets having different Zr addition concentrations to produce a Cr- film having a thickness of 10 to 100 nm.
The Zr-O nonmagnetic underlayer film was formed as the first nonmagnetic underlayer film. Then, heat to 270 ° C in the heating chamber and set to 8 mTorr.
Under the Argon pressure, a Cr-20 atom% Ti target is applied with an electric power of 4 kW to form a Cr-T film having a thickness of 2 to 15 nm.
The i base film was formed as a second non-magnetic base film. On this underlayer film, a target of 1.5 kW was applied under an argon pressure of 8 mTorr to produce Co-20 atom% C.
An alloy magnetic film having a film thickness of 20 nm made of r-6 atom% Pt was laminated. Further, a power of 1.5 kW was applied to the target on the magnetic film under an argon pressure of 10 mTorr to form a carbon protective film having a film thickness of 10 nm. Then, a lubricating layer such as an adsorbent perfluoroalkylpolyether was formed on the protective film to obtain a 2.5-inch magnetic disk.

The magnetostatic properties (coercive force Hc, squareness ratio S ^* ) and recording / reproducing properties of the magnetic disk thus formed were evaluated by the following methods. For the magnetostatic characteristics, the magnetic disk was cut into a substantially square shape of 8 mm × 8 mm from the position of the radius of 20 mm, and a sample in which the magnetic film on one side was scraped off was prepared, and a vibrating sample magnetometer (VSM) was used. With the maximum applied magnetic field of 13 kOe, the in-plane static magnetic property was determined. For evaluation of the recording / reproducing characteristics, a magnetic head was used for recording, with a gap length of 0.4 μm and a track width of 3.5.
A recording / reproducing separated type head having a thin film type head having a winding number of 17 μm and a winding number of 17 and an MR head having a shield interval of 0.25 μm and a track width of 2.3 μm is used, and a linear recording density of 18
The value of S / N at 0 kBPI was obtained.

No diffraction peak was detected in the X-ray diffraction of the non-magnetic composite film containing ZrO ₂ . Z in the above non-magnetic composite underlayer film measured by Auger electron spectroscopy
FIG. 3 shows the relationship between the concentration of r and Hc of the magnetic film. Zr
The Hc could be improved by setting the concentration of 1 atomic% or more and 20 atomic% or less. In addition, the medium noise of the same sample
FIG. 4 shows the relationship between the normalized medium noise and the Zr concentration in the composite underlayer film, which is normalized by the value of the sample to which Zr is not added. By setting the Zr concentration to be 1 atomic% or more and 20 atomic% or less, the medium noise could be reduced. Further, in these samples, the product of Br and the magnetic film thickness t has a Brt of 80 G.
It was confirmed that μm and S ^* were constant at about 0.8 regardless of the Zr addition concentration, and the medium noise could be reduced without reducing S ^* . In addition, it was confirmed that the oxygen concentration measured by Auger electron spectroscopy in the composite underlayer film at this time increased as the Zr concentration increased and was 1 atom% or more and 30 atom% or less.

Further, FIG. 5 shows the relationship between the normalized coercive force temperature change rate (normalized by the coercive force at room temperature) and the Zr addition concentration measured while changing the ambient temperature from 5 ° C. to 100 ° C. The normalized coercive force temperature change rate could be reduced by setting the Zr concentration to 1 atom% or more and 20 atom% or less. On the other hand, when the thickness of the Cr—Ti alloy underlayer film, which is the second non-magnetic underlayer film, is 20 nm or more, the effect of reducing the coercive force temperature change rate decreases.

Further, the linear recording density of the same sample is 180 kB.
The relationship between the S / N value at PI and the Zr concentration in the composite underlayer is shown in FIG. By setting the Zr concentration to be 1 atom% or more and 20 atom% or less, the S / N could be improved. As a result of X-ray diffraction analysis of the magnetic recording medium formed by the above method, as the Zr was added to the non-magnetic composite underlayer, the orientation of the magnetic film changed from (10.1) orientation of the hexagonal structure to (10. The orientation changed to 0) and the easy magnetization axis (c-axis) was oriented in the in-plane direction of the substrate. Along with this, the value of the remanent magnetization squareness ratio (S) was improved from 0.8 to 0.9. On the other hand, the (110) X-ray diffraction intensity of the Cr-Ti base film decreased as the Zr addition concentration increased. This represents the refinement of crystal grains.

Example 2 A magnetic disk was prepared in which Si, Al, Ti, V, Ta, and Y were added in an amount of 10 atomic% instead of Zr in Example 1, and the Hc, normalized noise, and linear recording density of the magnetic disk were manufactured. The S / N and the normalized coercive force temperature change rate at 180 kBPI were evaluated. The values are shown in Table 1. The comparative example shows the characteristics when the above element group is not added.

[0043]

[Table 1]

In each case, it was confirmed that the characteristics were improved as compared with the sample without addition. Also, when the addition concentration of each element is changed, the addition concentration is 1 atom% or more, 20 atom% or more, and the oxygen concentration is 1 atom% as in Example 1.
As described above, the characteristics have been improved by setting the content to 30 atomic% or less. Furthermore, it has been confirmed that similar characteristics can be improved when two or more of the above elements are added.

Further, as the second non-magnetic underlayer film in Example 1, instead of Cr-Ti, Cr-20 atom% M was used.
Magnetic disks using o, Cr-20 atomic% W, and Cr-20 atomic% V were manufactured and their characteristics were evaluated. Also in this case, substantially the same result as that of the magnetic disk of Example 1 was obtained.

Example 3 A magnetic disk having the same characteristics as those of Examples 1 and 2 was used, CoTaZr alloy was used as a recording magnetic pole material, and an MR head was used, as shown in FIGS. 2 (a) and 2 (b). The magnetic recording device shown in was prototyped. As described above, by combining the magnetic recording medium with the MR head and the high-accuracy head positioning device, the following characteristics of the recording / reproducing error rate of 10 ⁻⁸ at an areal recording density of 1.5 gigabits per square inch are obtained. was gotten.

In this embodiment, the case of using the composite type magnetic head using CoTaZr alloy as the magnetic pole material has been described, but also in the case of using the composite type magnetic head using NiFe, FeC alloy or the like as the recording magnetic pole material. Similar effects are obtained.
Further, the reproducing portion of the magnetic head is composed of a magnetoresistive sensor utilizing a giant magnetoresistive effect which is significantly larger than the conventional magnetoresistive effect, thereby recording at a high areal recording density of 2 gigabits or more per square inch. Characteristics with a reproduction error rate of 10 ⁻⁸ or less were obtained.

[0048]

According to the present invention, an in-plane magnetic recording medium having a small coercive force temperature change rate and capable of recording with an extremely high areal recording density of 1 gigabit per square inch or more was obtained. Further, the magnetic storage device combined with this magnetic recording medium has an extremely high areal recording density of 1 gigabit per square inch or more, and shows high reliability.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional structural view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a magnetic memory device according to an embodiment of the present invention and a vertical cross-sectional view taken along the line AA ′.

FIG. 3 shows Zr in a non-magnetic composite underlayer film according to an embodiment of the present invention.
FIG. 6 is a diagram showing the relationship between the concentration of H and the magnetic film Hc.

FIG. 4 is a graph showing Zr in a non-magnetic composite underlayer of one embodiment of the present invention.
FIG. 5 is a diagram showing the relationship between the density of the image and the standardized medium noise.

FIG. 5 is a graph showing Zr in a non-magnetic composite underlayer of one embodiment of the present invention.
FIG. 6 is a diagram showing the relationship between the concentration of γ and the normalized coercive force temperature change rate.

FIG. 6 is a graph showing Zr in a non-magnetic composite underlayer of one embodiment of the present invention.
FIG. 5 is a diagram showing the relationship between the density of γ and the S / N when the linear recording density is 180 kBPI.

[Explanation of symbols]

 11 ... Substrate 12, 12 '... Nonmagnetic plating film 13, 13' ... First nonmagnetic underlayer film 14, 14 '... Second nonmagnetic underlayer film 15, 15' ... Information recording layer 16, 16 '... Non Magnetic protection film 21 ... Magnetic disk 22 ... Drive unit 23 ... Magnetic head 24 ... Magnetic head drive means 25 ... Signal processing unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Ishikawa 2880 Kozu, Odawara-shi, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (9)

[Claims] 1. In a magnetic recording medium in which an information recording layer made of a Co-based alloy magnetic film is arranged on a substrate with at least two nonmagnetic underlayer films interposed therebetween, most of the nonmagnetic underlayer films are formed. The first non-magnetic underlayer film disposed on the substrate side is Cr
A composite film containing at least one element selected from the group consisting of Zr, Si, Al, Ti, V, Ta and Y and oxygen as a main component, and the concentration of the above element is 1 atomic% or more, 20 A magnetic recording medium, characterized in that the concentration of oxygen is 1 atomic% or less and the oxygen concentration is 1 atomic% or more and 30 atomic% or less. 2. The second non-magnetic undercoating film of the non-magnetic undercoating film disposed closest to the information recording layer is composed mainly of Cr and is selected from the group consisting of Ti, Mo, W and V. And an alloy containing at least one element in a concentration of 5 atomic% or more and 50 atomic% or less and having a crystal structure mainly composed of a (110) orientation of a body-centered cubic structure. Item 1. The magnetic recording medium according to item 1. 3. The magnetic recording medium according to claim 1, wherein the first non-magnetic underlayer film is amorphous and has a film thickness of 10 nm or more and 100 nm or less. 4. The film thickness of the second nonmagnetic underlayer film is 2 nm.
3. The magnetic recording medium according to claim 2, wherein the thickness is 15 nm or less. 5. The magnetic film has a hexagonal close-packed structure (1
The magnetic recording medium according to any one of claims 1 to 4, which has a crystal structure mainly composed of (0.0) orientation. 6. The magnetic recording medium according to claim 1, wherein the element in the first non-magnetic underlayer is bound to oxygen and segregated. 7. The magnetic according to claim 1, wherein at least two non-magnetic underlayer films are formed on the substrate, and then an information recording layer made of a Co-based alloy-based magnetic film is formed. In the method of manufacturing a recording medium, the first nonmagnetic underlayer film is formed by using Cr, Zr, Si, Al, Ti, V, and T.
It is composed of a mixture with an oxide of at least one element selected from the group consisting of a and Y, and the addition concentration of the above element is 1
Using a target of at least 20 atomic% and at least 20 atomic%,
A method for forming a magnetic recording medium, characterized by performing sputtering in pure Ar without using oxygen gas. 8. The first non-magnetic underlayer film is formed at room temperature,
8. The method for forming a magnetic recording medium according to claim 7, wherein the substrate is heated to 150 ° C. or higher and 400 ° C. or lower before the second nonmagnetic underlayer film is formed. 9. A magnetic storage device comprising the magnetic recording medium according to claim 1 and a magnetic head for recording / reproducing information on / from the magnetic recording medium.