JP2001023141A - Perpendicular magnetic recording medium and magnetic memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a recording medium have a low-noise characteristic for high-density recording by separating a perpendicular magnetization film set via a nonmagnetic undercoat layer or backing magnetic film layer onto a nonmagnetic substrate to a plurality of layers by at least one Al film or Al alloy film. SOLUTION: At least one Al film or Al alloy film is introduced in the middle of a perpendicular magnetization film to accelerate to make magnetic crystal particles fine and magnetically separated. The structure is effective both to a single layer perpendicular magnetic recording medium having a perpendicular magnetization film and a protecting film formed on a nonmagnetic substrate via a nonmagnetic undercoat layer, and to a double layer perpendicular magnetic recording medium having a perpendicular magnetization film and a protecting film formed on a nonmagnetic substrate via a backing magnetic film layer. Moreover, the effect is further increased when an Al alloy added with an element such as B, C, Cr, Cu, Ge, Hf, Ir, Mg, Mn, Si or the like to is used.

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 having a magnetic film suitable for high-density magnetic recording and a magnetic storage device using the same.

[0002]

2. Description of the Related Art Magnetic disk drives currently in practical use employ an in-plane magnetic recording system. In the in-plane magnetic recording method, it is a technical problem to form in-plane magnetic domains parallel to the substrate at high density on an in-plane magnetic recording medium which is easily magnetized in a direction parallel to the disk substrate surface. In the in-plane recording, since the magnetizations are adjacent to each other in opposite directions, it is necessary to increase the coercive force of the recording film and decrease the film thickness in order to increase the linear recording density. When the thickness of the recording film is reduced, the recording magnetization intensity is reduced due to thermal fluctuation, and in extreme cases, there is a problem that recorded information is lost. In the longitudinal recording method, it is difficult to achieve a planar recording density of ²⁰ Gb / in ² or more when a conventionally used Co alloy recording film is used.

[0003] The perpendicular magnetic recording system is a system in which magnetization is formed perpendicularly to the film surface of a thin-film medium. The recording principle and medium noise generation mechanism are different from those of the conventional longitudinal magnetic recording medium.
Since the adjacent magnetizations do not face each other, attention has been paid to a method suitable for high-density magnetic recording, and a medium structure suitable for perpendicular magnetic recording has been proposed. In order to improve the vertical orientation of a perpendicular magnetic film made of a Co alloy material, a method of providing a nonmagnetic material base between the perpendicular magnetic film and the substrate has been studied. For example, JP-A-58-77025,
JP-A-58-141435 discloses a method of forming a Ti film as a base layer of a Co-Cr magnetic film.
Japanese Patent No. 214417 discloses a method of using a Ge or Si material as an underlayer, and Japanese Patent Application Laid-Open No.
An oxide underlayer material such as oO or NiO is disclosed.

As a perpendicular magnetic recording medium used in combination with a single-pole type recording head, a medium provided with a soft magnetic film layer such as permalloy between a substrate and a perpendicular magnetic film has been studied. As means for reducing the noise of the perpendicular magnetic recording medium and improving the recording resolution, a nonmagnetic CoCr film or T
It is effective to introduce an i-film. Such technology is
For example, the 5th perpendicular magnetic recording symposium meeting materials (1
(October 23-25, 996) A paper entitled "Improving S / N of Single-Layer Perpendicular Magnetic Disk Medium", pp. 95-100.

[0005]

As a perpendicular magnetic recording medium capable of high-density magnetic recording of ²⁰ Gb / in ² or more,
It is necessary that medium noise be low in addition to high linear recording density resolution. For this purpose, as described above, a non-magnetic Co—Cr underlayer is introduced between the perpendicular magnetization film and the substrate, or a non-magnetic element such as Ta is added as an additive element to the Co alloy magnetic film. It is known that reducing the diameter is effective. By taking such measures, the medium noise can be considerably reduced, but if the noise can be further reduced, the recording density of the magnetic recording device can be more easily increased.

An object of the present invention is to provide a perpendicular magnetic recording medium having low noise characteristics for realizing a high recording density of 30 Gb / in ² or more, and to facilitate realization of a high-density recording / reproducing apparatus. .

[0007]

As a result of examining the recording magnetization state of a perpendicular magnetic recording medium using a magnetic force microscope or a scanning spin electron detection microscope, most of the noise is caused by microscopic fluctuations of the magnetization existing on the medium surface. Was found to be the cause. Micro-fluctuations in magnetization indicate that the intensity of magnetization on the surface of the medium varies from place to place at the micron (μm) level. In order to reduce the medium noise, it is necessary to reduce the fluctuation of microscopic magnetization existing on the surface of the medium. To this end, it is effective to reduce the size of the magnetic crystal grains constituting the perpendicular magnetization film and to promote magnetic separation.

In order to achieve the above object, the present invention provides at least one Al film or Al film in the middle of a perpendicular magnetization film.
The introduction of an alloy film promotes miniaturization and magnetic separation of magnetic crystal grains. This structure is suitable for a single-layer perpendicular magnetic recording medium in which a perpendicular magnetization film and a protective film are formed on a non-magnetic substrate via a non-magnetic underlayer, and a perpendicular magnetization via a backing magnetic film layer on the non-magnetic substrate. This is also effective for a two-layer perpendicular magnetic recording medium having a film and a protective film formed thereon.

The interatomic distance of Al is 0.286 nm, which is close to the average interatomic distance of 0.25 to 0.27 nm of the Co—Cr alloy used for the perpendicular magnetization film, and the atomic arrangement of the densest surface is small. Since it is similar to the atomic arrangement of a Co-Cr alloy, an ultra-thin film of about 0.5 nm to several nm is coated with Co-
Even when formed on a Cr alloy film, it has the property of easily growing as a continuous film having a uniform thickness. Further, Al is a non-magnetic element, and the Co-Cr alloy film is vertically divided by the interposition of this layer, and Al is easily diffused to the crystal grain boundaries of the Co-Cr alloy film. Miniaturization and magnetic separation can be promoted.

Further, B, C, Cr, Cu, G
The above effect is further enhanced by using an Al alloy to which elements such as e, Hf, Ir, Mg, Mn, and Si are added.
This is because the ability of Al or the additional element to diffuse to the crystal grain boundary is amplified as compared with pure Al by the addition of the additional element, and Co-C
This is due to the effect of adjusting the mismatch of the lattice constant with the r alloy magnetic film. The amount of the element added to Al needs to be at least 0.5 at% or more and less than 25 at%. If the addition amount is less than 0.5 at%, the effect of the added element is not remarkable, and if it exceeds 25 at%, the interposition ratio of the second phase having a structure different from the crystal structure of the Al-based alloy increases. This is because it is greatly reduced.

In order to realize a recording density of 30 Gb / in ² or more, the maximum linear recording density needs to be 300 kFCI or more. At this time, the bit length becomes 80 nm or less, and for this purpose, the diameter of the magnetic crystal grains of the perpendicular magnetization film constituting the perpendicular magnetic recording medium is 20 nm or less, preferably 15 nm or less.
nm or less. According to experiments by the present inventors, it has been found that for this purpose, the total thickness of the perpendicular magnetization film needs to be less than 40 nm. However, if the film thickness is 1
It has been clarified that when the thickness is less than 0 nm, a problem that the recording magnetization intensity in the low recording density region decreases due to thermal fluctuation also occurs. Therefore, the desired total thickness of the perpendicular magnetization film is 10 nm.
Not less than 40 nm. Here, the total thickness of the perpendicular magnetization film is the total thickness of the Co—Cr alloy-based perpendicular magnetization film, and does not include the thickness of the Al film or the Al alloy film in which at least one layer is introduced.

A Co-Cr alloy-based perpendicular magnetization film having a different composition between the protective film and the Co-Cr perpendicular magnetization film or Pt /
It is also possible to further reduce noise by providing a Co multilayer film, a Fe—Pt ferromagnetic film, or the like.

In order to achieve the above object, according to the present invention, at least one layer of Cr, Au,
Cu, Hf, Ir, Pd, Pt, Ru, Re, Rh, T
By introducing a layer having a thickness of 0.3 nm or more and less than 5 nm made of i, V, Zr, or an alloy containing any of these elements as a main component, miniaturization and magnetic separation of magnetic crystal grains are promoted. It is characterized by doing. This structure is suitable for a single-layer perpendicular magnetic recording medium in which a perpendicular magnetization film and a protective film are formed on a non-magnetic substrate via a non-magnetic underlayer, and a perpendicular magnetization via a backing magnetic film layer on the non-magnetic substrate. This is also effective for a two-layer perpendicular magnetic recording medium having a film and a protective film formed thereon.

In this case, a Co-based alloy is suitable for the perpendicular magnetization film. In a Co-based alloy film with perpendicular magnetic anisotropy, a hexagonal close-packed structure (Hexagonal Closed-Packed St
The (0001) plane, which is the densest surface of the ructure (HCP), is parallel to the substrate, and the growth direction of the film is [0001]. In the process of growing a Co-based alloy having an HCP structure, A
face-centered cubic structures such as u, Cu, Ir, Pd, Pt (Face
When a metal film of Centered Cubic Structure (FCC) is formed, the atomic arrangement of the (111) plane, which is the closest dense plane of the FCC structure, is the same as the atomic arrangement of the (0001) plane of the HCP structure. The heteroepitaxial growth that progresses is realized. Such growth is unlikely to occur when the lattice constants of the two materials are significantly different from each other.
When it is small, such as m or less, the lattice is distorted, and the epitaxial growth is secured. In the case of a material having the same HCP structure as a Co-based alloy, such as Ru, Re, and Rh, epitaxial growth is ensured even if there is a large difference in lattice constant as compared with a material having an FCC structure. Also, Cr, V,
Body Centered Cubic Structures such as Zr, Hf
In the case of Structure (BCC), when the film thickness to be formed is as small as 5 nm or less, the film can be grown while maintaining a heteroepitaxial relationship with the HCP structure of the Co-based alloy.

FCC, H made of such a nonmagnetic metal
When a material made of a Co-based alloy is formed again after forming an ultrathin film of the CP and BCC materials, the epitaxial growth continues and the growth direction can be set to [0001]. The [0001] direction of the Co-based alloy having the HCP structure is the axis of easy magnetization, and in order to obtain good perpendicular magnetic characteristics, it is necessary to form a film so that this axis is perpendicular to the substrate. When the Co-based alloy film is separated by such an extremely thin film of nonmagnetic metal, it is also separated magnetically, and the unit of the magnetic crystal grains becomes finer, and the noise of the medium can be reduced. The thickness of the nonmagnetic metal film is preferably in the range of 0.3 nm to 5 nm, more preferably in the range of 0.5 nm to 3 nm.

In order to reduce the noise of the medium, it is necessary to promote not only the magnetic separation in the growth direction of the film but also the separation in the in-plane direction of the film. The Co alloy perpendicular magnetization film is a polycrystalline film and has crystal grain boundaries. In order to promote magnetic separation in the in-plane direction of the film, it is necessary to form a thin film made of a nonmagnetic element by segregating the nonmagnetic element at a crystal grain boundary. When an ultra-thin film of a non-magnetic metal element as described above is formed during the growth process of the Co-based alloy, if the substrate temperature during film formation is high, the non-magnetic element diffuses to crystal grain boundaries and segregates at the grain boundaries. The effect occurs. Further, such an effect can be promoted by using a material in which an element which easily diffuses into the metal element is added in the process of forming a film.

The elements to be added to the above metal elements and the amounts thereof are basically the same as those of FCC, HCP, B
It is desirable not to destroy the CC structure. B, C, Si, Mn, and Al are effective as additional elements.
In the case of C and Si, if the addition amount is several at% or more, the alloy becomes amorphous or the crystal structure changes, so Mn or Al to which a larger amount can be added is desirable.
In the case of Mn, if the maximum amount that can be added is shown for each nonmagnetic element, Au (10 at%), Cr (45 at%), Cu
(48 at%), Hf (3 at%), Ir (35 at%)
%), Pd (28 at%), Pt (38 at%), Ru
(10 at%), Rh (10 at%), Re (2 at%)
%), Ti (2 at%), V (45 at%), Zr (1
3 at%). In the case of Al, Au (15 at
%), Cr (48 at%), Cu (20 at%), Hf
(30 at%), Ir (10 at%), Pd (20 at%)
%), Pt (12 at%), Ru (4 at%), Rh
(3 at%), Re (3 at%), Ti (20 at%)
%), V (49 at%), and Zr (21 at%).
At least 0.5 at% is required as a minimum addition amount for effectively exerting the effect of promoting the segregation of the nonmagnetic element to the crystal grain boundary of the magnetic film by adding the additional element.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. [Embodiment 1] A perpendicular magnetic recording medium having a sectional structure shown in FIG. 1 was manufactured by a DC magnetron sputtering method using a glass substrate having a diameter of 2.5 inches. Substrate 11
After forming a nonmagnetic underlayer 12 thereon, the perpendicular magnetization film 1 is formed.
3. A non-magnetic film 14, a perpendicular magnetization film 15, and a protective film 16 were formed. Ti-10.2at% Cr for non-magnetic underlayer 12
Co-16 at% C for the target and perpendicular magnetization film 13
r-4 at% Ta target, Al for nonmagnetic film 14
Co-20 at% Cr for target and perpendicular magnetization film 15
A -10 at% Pt-1.5 at% Ta target and a carbon target for the protective film 16 were used. A of spatter
r gas pressure 3 mTorr, sputtering power 10 W / c
m ² and a substrate temperature of 280 ° C.
nm, the Co—Cr—Ta film is 30 nm, and the nonmagnetic film is 1. nm.
5 nm, Co-Cr-Pt-Ta perpendicular magnetization film
A carbon film was formed to a thickness of 5 nm.

Under the same conditions, Al-2 at% B, Al-1.5 at% C, A
1-2.5 at% Cr, Al-3.6 at% Cu, Al
-3 at% Ge, Al-2 at% Hf, Al-1.8 a
t% Ir, Al-24at% Mg, Al-3at% M
A perpendicular medium similar to the above was prepared except that n, Al-4 at% Si was used.

As a result of observing the cross-sectional structure of a perpendicular medium sample using Al-3.6 at% Cu as the nonmagnetic film with a transmission electron microscope, it was confirmed that the structure shown in FIG. 2 was realized. Co-Cr having a [0001] direction as a growth direction is formed on a Ti-Cr non-magnetic underlayer 22 formed on a substrate 21.
-Ta crystal grains 23 grow, and an Al-Cu layer 24 having a similar crystal diameter is formed thereon.
[001] Co-Cr-Pt-Ta having a growth direction
In the crystal grains, the carbon protective film 26 was further formed. Further, Cr, A
Nonmagnetic elements such as l and Cu were precipitated in a larger amount than in the crystal grains.

As a comparative sample, a perpendicular magnetic recording medium without a nonmagnetic film was manufactured. The recording / reproducing characteristics of these magnetic recording media were evaluated using a recording / reproducing separated magnetic head. The recording head had a gap length of 0.2 μm, the giant magnetoresistive (GMR) head for reproduction had a shield interval of 0.15 μm, and the measurement spacing was 0.02 μm. The recording density was determined by measuring the output half-reduced recording density (D ₅₀ ) which is half of the low-frequency reproduction output, and the S / N when magnetic recording at 20 kFCI was performed was shown as a relative value to the S / N of the comparative sample. . Table 1 shows the results.

[0022]

[Table 1]

[0023] From Table 1, the magnetic recording medium of the present embodiment, improved D ₅₀ compared to Comparative Examples, moreover has improved the medium S / N, it has been found that desirable as a high-density magnetic recording medium . Using the magnetic recording medium having a diameter of 2.5 inches produced in the present embodiment, a magnetic recording / reproducing apparatus using a GMR head as a reproducing element was produced. Surface recording density 30G
It was confirmed that an error rate of 10 ^-9 could be ensured under the condition of b / in ^{2 and that} the device operated as an ultra-high density recording / reproducing apparatus.

[Second Embodiment] A perpendicular magnetic recording medium having the same cross-sectional structure as that of the first embodiment was prepared in the same procedure. Here, using an Al-Mg alloy as the non-magnetic film, a sample was prepared in which the film thickness and the alloy composition were changed. Al-Mg
Al-8 at% Mg is used as the alloy to form a film having a thickness of 0-10.
Samples were prepared in the range of nm, and the recording resolution (D ₅₀ ) and the medium S / N were compared with those of the comparative example prepared in the first embodiment. The results are shown in FIGS.

As shown in FIG. 3, the resolution was improved and then decreased as the thickness of the Al—Mg alloy nonmagnetic film was increased. When the film thickness was more than 5 nm, it was confirmed that the resolution was lower than that of the comparative sample. On the other hand, as shown in FIG. 4, the S / N increased as the film thickness increased. From these results, it was confirmed that the range of the film thickness at which high resolution and high S / N were obtained was 5 nm or less. When the film thickness is less than 0.5 nm, the resolution and S / N of the sample hardly differ from those of the comparative sample, and a film thickness of at least 0.5 nm is necessary to obtain a remarkable improvement effect. Do you get it.

Next, the composition of the Al—Mg alloy is adjusted to the addition amount of Mg of 0 to 5 while maintaining the nonmagnetic film thickness at a constant value of 1.5 nm.
A sample was prepared in the range of 0 at%, and the resolution and S / N were measured under the same conditions. The results are shown in FIGS. As shown in FIG. 5, the resolution was improved as the amount of added Mg was increased, but when the added amount of Mg exceeded 25 at%, the resolution tended to be lower than that of the comparative sample. On the other hand, as shown in FIG.
/ N was found to be improved over the comparative sample. When the addition amount is less than 0.5 at%, the resolution of the sample and S
/ N almost did not differ from the comparative sample, and it was found that at least 0.5 at% of the added amount was necessary to obtain a remarkable improvement effect.

A magnetic recording medium having a thickness of 1.5 nm
A magnetic recording / reproducing apparatus was manufactured using a perpendicular magnetic recording medium having a diameter of 2.5 inches on which a 1-20 at% Mg nonmagnetic film was formed and a GMR head as a reproducing element. It was confirmed that an error rate of 10 ^-9 could be secured under the condition of a surface recording density of 45 Gb / in ² , and that the device operated as an ultra-high density recording / reproducing apparatus.

[Third Embodiment] A perpendicular magnetic recording medium having a sectional structure shown in FIG. 7 was manufactured by a DC magnetron sputtering method using a glass substrate having a diameter of 2.5 inches. This medium has a backing magnetic film, an intermediate layer,
A so-called 2 in which a multilayer perpendicular magnetization film and a protective film are sequentially formed.
This is a layered perpendicular magnetic recording medium. Here, the backing magnetic film is a seed layer 32 made of Hf with a thickness of 5 nm, a ferromagnetic layer 33 made of Fe-45 at% Pt with a thickness of 10 nm, and a thickness of 3 nm.
Non-magnetic layer 34 made of Si with a thickness of 150 nm and a thickness of 150 n
The soft magnetic film 35 was made of m-5 Co-5 at% Nb-3 at% Zr. Before forming the perpendicular magnetization film, a 5 nm-thick Si film was formed as the intermediate layer 36.

The perpendicular magnetization film was composed of a lower perpendicular magnetization film 37, a non-magnetic film 38, a middle perpendicular magnetization film 39, a non-magnetic film 40, and an upper perpendicular magnetization film 41. Co-17 at% Cr-4a was used as a target for forming each film.
t% Nb, Al-2at% Mn, Co-19at% Cr
-7at% Pt-3at% Ta-1.5at% B, Al
-2 at% Mn and Fe-50 at% Pt were used. The film thicknesses are 15 nm, 1 nm, 5 nm, 0.8 nm,
3 nm. A protective film 42 having a thickness of 5 nm was formed on the perpendicular magnetized film using a carbon target, thereby producing a perpendicular magnetic recording medium. Each film has a sputtering gas pressure of 3 mT.
orr, sputter power 20 W / cm ² , substrate temperature 25
It was formed under the condition of 0 ° C.

For this perpendicular magnetic recording medium, a single pole type recording head having a track width of 0.4 μm for recording, a track width of 0.35 μm and a shield interval of 0.1 for reproduction.
A recording / reproducing experiment was performed using a 2 μm GMR head at a spacing of 15 nm between the head and the medium. As a result, the recording resolution (D ₅₀ ) was 380 kFCI and 300 kFC.
A value of 32 dB was obtained as the medium S / N when the I signal was recorded. The error rate of the reproduced waveform of the signal was evaluated through an EEPR4 type signal processing circuit. As a result, it was confirmed that an error rate of 10 ^-8 could be secured under the condition of an areal recording density of 60 Gb / in ² , and that the device operates as an ultra-high density recording / reproducing apparatus. did.

[Embodiment 4] A perpendicular magnetic recording medium prototyped in Embodiment 3 and a tunnel type magnetoresistance effect (TMR)
A magnetic storage device shown in FIG. 8 was manufactured using a recording / reproducing separation head having a high-sensitivity reproducing element using the same. FIG. 8A is a schematic plan view of the magnetic storage device, and FIG.
As shown in the A 'cross-sectional view, a magnetic recording medium 51 rotated by a magnetic recording medium driving unit 52, a magnetic head 53 driven by a magnetic head driving unit 54 to perform recording and reproduction on the magnetic recording medium 51, This is an apparatus having a known configuration including a signal processing unit 55 that processes a recording signal and a reproduction signal of the magnetic head 53.

The track width of the recording head is 0.3 μm, the track width of the TMR head element for reproduction is 0.26 μm,
The spacing between the magnetic head 53 and the magnetic recording medium 51 is reduced by one.
05 nm. When the EEPR4 system was adopted as the signal processing system and the apparatus was operated under the condition of a surface recording density of 75 Gb / in ² , an error rate of 10 ⁻⁸ or less was obtained.

[Embodiment 5] A perpendicular magnetic recording medium having a sectional structure shown in FIG. 9 was manufactured by a DC magnetron sputtering method using a glass substrate having a diameter of 2.5 inches. After forming the nonmagnetic underlayer 62 on the substrate 61,
A perpendicular magnetization film 63, a non-magnetic film 64, a perpendicular magnetization film 65, and a protective film 66 were formed. Ti-10a for non-magnetic underlayer 62
t-17% Cr target, Co-17 for perpendicular magnetization film 63
at% Cr-3.2 at% Ta target, non-magnetic film 6
4 for Au target, and Co-1 for perpendicular magnetization film 65.
A 9 at% Cr-8 at% Pt-2 at% Ta target and a carbon target for the protective film 66 were used. Cr-T under the conditions of a sputtering Ar gas pressure of 2.8 mTorr, a sputtering power of 12 W / cm ² , and a substrate temperature of 275 ° C.
An i film was formed to a thickness of 30 nm, a Co—Cr—Ta film was formed to a thickness of 25 nm, a nonmagnetic film was formed to a thickness of 0.5 nm, a Co—Cr—Pt—Ta perpendicular magnetization film was formed to a thickness of 5 nm, and a carbon film was formed to a thickness of 5 nm.

Under the same conditions, as targets of the nonmagnetic film 64, Cr, Cu, Hf, Ir, Pd, Pt, Ru,
A perpendicular medium having the same structure as described above was prepared except that Rh, Re, Ti, V, and Zr were used. Also, as a comparative sample,
A perpendicular magnetic recording medium without a non-magnetic film was manufactured.

The recording / reproducing characteristics of these magnetic recording media are as follows:
The evaluation was performed using a recording / reproducing separation type magnetic head. The gap length of the recording thin film head was 0.22 μm, the shield spacing of the reproducing giant magnetoresistive (GMR) head was 0.16 μm, and the spacing at the time of measurement was 0.02 μm. The recording density was determined by measuring the output half-reduced recording density (D ₅₀ ), which is half of the low-frequency reproduction output, and the S / N when magnetic recording at 200 kFCI was performed was shown as a relative value to the S / N of the comparative sample. . Table 2 shows the results.

[0036]

[Table 2]

As shown in Table 2, the magnetic recording medium of the present embodiment, improved D ₅₀ compared to Comparative Examples, moreover medium S
/ N has been improved, indicating that it is desirable as a high-density magnetic recording medium. 2.5 diameter produced in this embodiment
When a magnetic recording / reproducing apparatus was manufactured using an inch magnetic recording medium and a GMR head as a reproducing element, an error rate of 10 ^-9 could be secured under the condition of a surface recording density of 30 Gb / in ² , and an ultra-high density recording / reproducing apparatus was obtained. Confirmed to work as.

[Embodiment 6] A perpendicular magnetic recording medium having a cross-sectional structure similar to that of Embodiment 5 was prepared in the same procedure. Here, using a Cu-Mn alloy as the non-magnetic film, a sample was prepared in which the thickness and alloy composition were changed. Cu-Mn
Using Cu-10 at% Mn as an alloy, the film thickness is set to 0 to 1
A sample was prepared in the range of 0 nm, and its recording resolution (D ₅₀ ) and medium S / N were compared with those of the comparative example prepared in the fifth embodiment. The results are shown in FIGS.

As shown in FIG. 10, the resolution is Cu-Mn.
As the thickness of the alloy non-magnetic film increased, it improved and then decreased. When the film thickness was more than 5 nm, it was confirmed that the resolution was lower than that of the comparative sample. On the other hand, as shown in FIG. 11, the S / N increased as the film thickness increased.
From these results, it was confirmed that the range of the film thickness at which a high resolution and a high S / N were obtained was less than 5 nm, and a more desirable range was 0.5 nm or more and 3 nm or less. Cu
-When the thickness of the non-magnetic film of the Mn alloy is less than 0.3 nm, the resolution and S / N hardly differ from those of the comparative sample, and a thickness of at least 0.3 nm is necessary to obtain a remarkable improvement effect. I found it.

Then, the composition of the Cu—Mn alloy was adjusted to the addition amount of Mn of 0 to 6 while maintaining the nonmagnetic film thickness at a constant value of 1.2 nm.
A sample was prepared in the range of 0 at%, and the resolution and S / N were measured under the same conditions. The results are shown in FIGS. As shown in FIG. 12, the resolution was improved when Mn was added, but the resolution tended to be lower as compared with the comparative sample when the added amount of Mn exceeded 50 at%. Further, it was found that the effect of Mn addition became remarkable when the addition amount was 0.5 at% or more. Further, as shown in FIG. 13, it was found that the addition of Mn improved the S / N as compared with the comparative sample.

As a magnetic recording medium, C having a thickness of 1.2 nm
A magnetic recording / reproducing apparatus was manufactured using a perpendicular magnetic recording medium having a diameter of 2.5 inches on which a u-12 at% Mn nonmagnetic film was formed and using a GMR head as a reproducing element. It was confirmed that an error rate of 10 ^-8 could be secured under the condition of a surface recording density of 30 Gb / in ² , and that the device operated as an ultra-high density recording / reproducing apparatus.

[Embodiment 7] A perpendicular magnetic recording medium having a sectional structure shown in FIG. 14 was manufactured by a DC magnetron sputtering method using a glass substrate having a diameter of 2.5 inches. This medium is a so-called two-layer perpendicular magnetic recording medium in which a backing magnetic film, an intermediate layer, a multilayer perpendicular magnetic film, and a protective film are sequentially formed on a substrate 71. Here, the backing magnetic film is a seed layer 72 made of Cr having a thickness of 5 nm, and a thickness of 8 nm.
Ferromagnetic layer 73 of Fe-45 at% Pt, non-magnetic layer 74 of 3 nm in thickness of Si, and thickness of 200
The soft magnetic film 75 was made of Co-5 at% Nb-4 at% Zr of nm. Before forming the perpendicular magnetization film, a 3 nm thick Si-15 at% Ge film was formed as the intermediate layer 76.

The perpendicular magnetization film was composed of a lower perpendicular magnetization film 77, a nonmagnetic film 78, a middle perpendicular magnetization film 79, a nonmagnetic film 80, and an upper perpendicular magnetization film 81. Co-17 at% Cr-4 at% T was used as a target for forming the lower perpendicular magnetic film, the middle perpendicular magnetic film, and the upper perpendicular magnetic film, respectively.
a, Co-19at% Cr-8at% Pt-3at% T
a-2at% B, Co-17at% Cr-12at% P
t was used. The thickness of each perpendicular magnetization film is 15 nm,
5 nm and 3 nm.

As the non-magnetic films 78 and 80, Au-7at
% Mn, Cr-35at% Mn, Cu-43at% M
n, Hf-2at% Mn, Ir-18at% Mn, Pd
-27at% Mn, Pt-28at% Mn, Ru-9a
t% Mn, Rh-7at% Mn, Re-1.5at% M
n, Ti-2at% Mn, V-45at% Mn, Zr-
12at% Mn, Au-12at% Al, Cr-25a
t% Al, Cu-17at% Al, Hf-22at% A
1, Ir-10at% Al, Pd-17at% Al, P
t-11at% Al, Ru-3at% Al, Rh-2a
t% Al, Re-1.5at% Al, Ti-18at%
Al, V-46 at% Al, Zr-16 at% Al, C
r-10at% Mn-5at% Al, Cu-25at%
Mn-8at% Al, Pt-20at% Mn-5at%
Al, Ti-1 at% Mn-5 at% Al, Cr-1a
t% B, Cu-0.8at% C, Cu-1.4at% S
Films were formed using i-1 at% B, respectively. The thickness of these nonmagnetic films was 0.8 nm.

The protective film 82 was formed to a thickness of 5 nm by using a carbon target, and a perpendicular magnetic recording medium was prepared. Each film was formed under the conditions of a sputtering Ar gas pressure of 3 mTorr, a sputtering power of 20 W / cm ² , and a substrate temperature of 250 ° C. As a comparative sample, a perpendicular magnetic recording medium having the same structure except that the nonmagnetic films 78 and 80 were not provided was prepared. The resolution of these perpendicular magnetic recording media and the media S / N
Was measured under the same conditions as in the fifth embodiment. Table 3 shows the results
Shown in

[0046]

[Table 3]

Further, a single pole type thin film recording head having a track width of 0.4 μm for recording the perpendicular magnetic recording medium and a GMR head having a track width of 0.35 μm and a shield interval of 0.12 μm for reproduction are used. A recording / reproducing experiment was performed with the spacing between the head and the medium being 15 nm. When the error rate of the reproduced waveform of the signal was evaluated through an EEPR4-type signal processing circuit, the perpendicular magnetic recording media according to the present invention all showed a surface recording density of 50 Gb / in ^2.
An error rate value of 10 ⁻⁸ or less was obtained under the condition of (1).

[Embodiment 8] A perpendicular magnetic recording medium prototyped in Embodiment 7 and a tunnel type magnetoresistive effect (TMR)
A magnetic recording / reproducing apparatus shown in FIG. 8 was produced using a recording / reproducing separation head having a high-sensitivity reproducing element using the same. Track width of recording head 0.3 μm, track width of TMR head element for reproduction 0.26 μm, spacing between head and medium 1
It was set to 0 nm. When the EEPR4 system was adopted as the signal processing and the apparatus was operated under the condition of a surface recording density of 75 Gb / in ² , an error rate of 10 ⁻⁸ or less was obtained.

[0049]

According to the present invention, the noise of the perpendicular magnetic recording medium can be reduced, and as a result a high S / N ratio can be obtained, so that the density of the magnetic disk drive can be increased, especially at 30 Gb. / In ² or higher density magnetic recording becomes possible, making it easier to reduce the size and capacity of the device.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a magnetic recording medium according to the present invention.

FIG. 2 is a sectional view showing an example of a magnetic recording medium according to the present invention.

FIG. 3 is a view showing characteristics evaluation results of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 4 is a view showing characteristics evaluation results of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 5 is a diagram showing a result of evaluating characteristics of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 6 is a diagram showing characteristics evaluation results of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 7 is a sectional view showing another example of the magnetic recording medium according to the present invention.

FIG. 8 is a configuration diagram of a magnetic storage device.

FIG. 9 is a sectional view showing another example of the magnetic recording medium according to the present invention.

FIG. 10 is a view showing a result of characteristic evaluation of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 11 is a diagram showing characteristics evaluation results of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 12 is a diagram showing characteristics evaluation results of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 13 is a view showing a result of characteristic evaluation of an example of a perpendicular magnetic recording medium according to the present invention.

FIG. 14 is a sectional view showing another example of the magnetic recording medium according to the present invention.

[Explanation of symbols]

11: substrate, 12: non-magnetic underlayer, 13: perpendicular magnetization film,
14: non-magnetic film, 15: perpendicular magnetization film, 16: protective film, 2
DESCRIPTION OF SYMBOLS 1 ... Substrate, 22 ... Nonmagnetic underlayer, 23 ... Perpendicular magnetization film, 2
4: Non-magnetic film, 25: perpendicular magnetization film, 26: protective film, 31
... substrate, 32 ... seed layer, 33 ... ferromagnetic film, 34 ... nonmagnetic layer, 35 ... soft magnetic film, 36 ... intermediate layer, 37 ... lower perpendicular magnetization film, 38 ... nonmagnetic film, 39 ... middle perpendicular magnetization film , 40
... nonmagnetic film, 41 ... upper perpendicular magnetization film, 42 ... protective film, 5
DESCRIPTION OF SYMBOLS 1 ... Magnetic recording medium, 52 ... Magnetic recording medium drive part, 53 ...
Magnetic head, 54: magnetic head drive unit, 55: signal processing unit 61: substrate, 62: non-magnetic underlayer, 63: perpendicular magnetization film,
64: non-magnetic film, 65: perpendicular magnetization film, 66: protective film, 7
DESCRIPTION OF SYMBOLS 1 ... Substrate, 72 ... Seed layer, 73 ... Ferromagnetic film, 74 ... Non-magnetic layer, 75 ... Soft magnetic film, 76 ... Intermediate layer, 77 ... Lower perpendicular magnetization film, 78 ... Non-magnetic film, 79 ... Middle perpendicular magnetization Membrane, 8
0: non-magnetic film, 81: upper perpendicular magnetization film, 82: protective film

Continued on the front page (72) Inventor Yukio Honda 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Atsushi Kikukawa 1-280 Higashi Koigabo-ku, Kokubunji-shi, Tokyo Hitachi, Ltd. In-house F term (reference) 5D006 BB01 BB08 CA01 CA05 CA06 DA03 FA09

Claims (9)

[Claims] 1. A perpendicular magnetic recording medium in which a perpendicular magnetic film is provided on a nonmagnetic substrate via a nonmagnetic underlayer or a backing magnetic film layer, wherein the perpendicular magnetic film has at least one A layer.
1. A perpendicular magnetic recording medium characterized by being separated into a plurality of layers by an l film or an Al alloy film. 2. The perpendicular magnetic recording medium according to claim 1, wherein the Al alloy is Al-B, Al-C, Al-Cu, Al
-Cr, Al-Ge, Al-Hf, Al-Ir, Al-
Made of any of Si, Al-Mn and Al-Mg;
The amount of addition of alloying element to 1 is at least 0.5 at% and 25 a
perpendicular magnetic recording medium characterized by being less than t%. 3. The perpendicular magnetic recording medium according to claim 1, wherein the perpendicular magnetic film is made of a Co-based alloy. 4. The magnetic recording medium according to claim 1, wherein the thickness of one of the Al film and the Al alloy film is 0.5 nm or more and less than 5 nm, excluding the Al film or the Al alloy film. A perpendicular magnetic recording medium, wherein the total thickness of the perpendicular magnetization film is 10 nm or more and less than 40 nm. 5. A perpendicular magnetic recording medium having a perpendicular magnetic film provided on a nonmagnetic substrate via a nonmagnetic underlayer or a backing magnetic film layer, wherein the perpendicular magnetic film is made of Cr, Au, Cu,
Hf, Ir, Pd, Pt, Ru, Rh, Re, Ti, V
A perpendicular magnetic field, wherein the perpendicular magnetic field is separated into a plurality of layers by at least one material film having a film thickness of 0.3 nm or more and less than 5 nm made of Zr or an alloy mainly containing any of these elements. recoding media. 6. The perpendicular magnetic recording medium according to claim 5, wherein the alloy contains Mn and the amount of Mn is 0.5 at% or more and less than 50 at%. 7. The perpendicular magnetic recording medium according to claim 5, wherein the alloy contains Al and the additive amount thereof is 0.5 at% or more.
A perpendicular magnetic recording medium characterized by being less than 0 at%. 8. The perpendicular magnetic recording medium according to claim 5, wherein the perpendicular magnetization film is made of a Co-based alloy. 9. A magnetic recording medium, a magnetic recording medium driving unit for driving the magnetic recording medium, a magnetic head for recording and reproducing on and from the magnetic recording medium, and a magnetic head driving unit for driving the magnetic head And a recording / reproducing signal processing system for processing a recording signal and a reproducing signal of the magnetic head, wherein the perpendicular magnetic recording medium according to claim 1 is used as the magnetic recording medium. The magnetic head includes a thin-film type recording head and a reproducing element using a giant magnetoresistance effect or a magnetic tunnel effect, and has a surface recording density of 30 Gb.
A magnetic storage device which performs magnetic recording and reproduction at / in ² or more.