JP3372101B2 - Magnetic recording medium, magnetic recording / reproducing device, and method of manufacturing magnetic recording medium - Google Patents

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 such as a magnetic drum, a magnetic tape, a magnetic disk and a magnetic card and a magnetic recording / reproducing apparatus, and more particularly to a thin film type magnetic recording medium suitable for an ultra high recording density and The present invention relates to a magnetic recording / reproducing device using the magnetic recording medium.

[0002]

2. Description of the Related Art In recent years, the information-oriented society has advanced due to the remarkable development of information processing devices such as electronic computers, and the amount of information handled by individuals has been increasing. Accordingly, the external storage device of the information processing device is required to have a large capacity and high speed access. In particular, the magnetic disk device is an external storage device suitable for high-density storage, and high speed, small size, and large capacity are strongly demanded.

As a magnetic recording medium used in a magnetic disk device, a coating type magnetic recording medium in which a powder of an oxide magnetic material is coated on a substrate and a thin film type magnetic recording medium in which a thin film of a metal magnetic material is deposited or sputtered on the substrate. A recording medium is known. This thin film type magnetic recording medium is suitable for higher density recording because the density of the magnetic substance in the recording film is higher than that of the coating type magnetic recording medium. Therefore, most of currently manufactured magnetic disk devices use a thin film magnetic recording medium.

As a general structure of a thin film type magnetic recording medium, it is well known that an underlayer, a magnetic layer and a protective layer are sequentially formed on a substrate. In order to increase the storage capacity of the magnetic disk device, it is necessary to increase the coercive force of the thin film magnetic recording medium. Recently, as a method of increasing the coercive force, there is a bias sputtering method in which a negative bias voltage is applied to a substrate during the film formation of an underlayer and a magnetic layer so that Ar, which is a sputtering gas, collides with the substrate surface at the same time as the film formation. Attention has been paid. This method can be used, for example, in "I-E-E-Transaction on Magnetics" 2
Volume 6 (1990), page 1282 [IEEE Transaction o
n Magnetics, Mg26, 1282 (1990)] and "Journal of Japan Applied Magnetics", Vol. 16 (1992), p. 541.

In addition, "Journal of Applied Magnetics of Japan" Vol. 17 (1
993), Supplement, No. S2, page 125 describes a sputtering method using Kr gas. However, in this method, the bias voltage is not applied to the substrate, and the magnetic film is formed by the usual sputtering method.

[0006]

In order to realize a high recording density of 1 gigabit per square inch or more in the future, the remanent magnetization film thickness product of the magnetic recording medium must be reduced in order to reduce the demagnetizing field from the bit boundary. It is thought that it is necessary to make it 150 G · μm or less. At this time, the coercive force is at least 200.
It is necessary to secure 0 Oe. However, it is difficult to meet this criterion by film formation by a normal sputtering method.

As a means for obtaining a high coercive force, as described above, a bias sputtering method is known in which a negative bias voltage is applied to the substrate when the underlayer and the magnetic layer are formed. However, even with the conventional bias sputtering method, a magnetic recording medium having sufficient electromagnetic conversion characteristics (recording / reproducing characteristics) capable of coping with the above high density recording has not yet been obtained. In addition, the medium prepared by the bias sputtering method has not been sufficiently examined for reliability such as corrosion resistance.

The remanent magnetization film thickness product of the magnetic recording medium is 1
When it is 50 G · μm or less, the sensitivity is not always sufficient in the conventional induction type magnetic head and the recording / reproducing separated type head reproducing by using the magnetoresistive effect. Therefore, it is desirable to use a magnetic head having higher reproduction sensitivity, and it is desirable that the signal processing circuit also be adapted to the magnetic head. Further, it is preferable that the signal modulation / demodulation circuit also be compatible with high density recording.

A first object of the present invention is to provide a magnetic recording medium having a high coercive force, good electromagnetic conversion characteristics during high density recording, and excellent reliability such as corrosion resistance. A second object of the present invention is to provide a large-capacity magnetic recording / reproducing apparatus capable of fully utilizing the characteristics of the magnetic recording medium.

[0010]

The first object of the present invention is to manufacture a magnetic recording medium in which a magnetic layer is laminated directly on a non-magnetic substrate or via an underlayer and finally a protective layer is laminated. Kr, Xe or Rn or at least one of these gases as a sputtering gas at the time of forming the layer and A
This is achieved by employing a bias sputtering method in which a gas mixture with r is used and a negative bias voltage is applied to the substrate.

As a bias application method in bias sputtering, either a DC bias or an RF bias may be used. The bias voltage is preferably DC bias or RF bias of −400V or higher and lower than −30V. The bias may be applied only when forming the magnetic layer. In this case, Kr, Xe, R in the underlayer
The concentration of n becomes lower than that in the magnetic layer. On the other hand, if a bias is applied only during the formation of the underlayer, almost no effect can be obtained, which is not preferable. Further, when a bias is applied when forming the protective layer on the magnetic layer, the increase in coercive force is reduced by several tenths. Further, in this case, the corrosion resistance of the medium also decreases, which is not preferable.

When the sputtering gas is a mixed gas with Ar, Ar is mixed with 2 at% or more of Rn, Xe and Kr. The magnetic recording medium according to the present invention contains 100 ppm or more of Kr, Xe or Rn in the magnetic layer,
The magnetic layer is composed of crystal grains containing Co having a substantially hexagonal crystal structure, and has a hexagonal crystal structure (1
The interplanar spacing of the (10) plane is larger than the interplanar spacing of the (110) plane having a hexagonal crystal structure inclined by 20 degrees or more from the film plane.

The remanent magnetization film thickness product is 10 G · μm or more 150
G · μm or less, coercive force of 2000 Oe or more and 4000 Oe
The following is preferable. When the substrate is a non-conductive substrate such as glass, a bias voltage can be effectively applied by forming a conductive film on the substrate in advance.

As the conductive film, C, Ti, V, Cr, C
u, Zn, Nb, Mo, Ru, Rh, Pd, Ag, T
a, W, Pt, Au, Ni-P, and Cr-P are preferable in controlling the crystallinity, crystal orientation, and crystal grain size of the underlayer and the magnetic layer. Moreover, you may use what mixed these elements 2 types or 3 types or more. Further, it is more preferable to form an oxide layer, a nitrogen-containing layer, or a carbon-containing layer on the surface of the conductive film because the coercive force increases by 5 to 20%. The thickness of these oxide layer, nitrogen-containing layer, or carbon-containing layer is preferably 0.1 to 10 nm.

The conductive films 12 and 12 'need not be provided when a conductive substrate is used. However, the conductive film also functions as a control film of the crystal structure of the underlayer, and the coercive force is improved depending on the film configuration and film formation conditions. Therefore, it is preferable to provide the conductive film even when a conductive substrate is used. As the underlayer, Cr, Mo, W, Ta, Nb or Cr-P, Cr-Ti, Cr-V, Cr- containing these as the main components is used.
Mo, Mo-Nb, Mo-Pt, Mo-Ge, WC
An alloy of r, W-Ta, W-Si or the like is preferable in controlling the crystallinity, crystal orientation, and crystal grain size of the magnetic layer. The thickness of the underlayer is preferably in the range of 0.1 to 500 nm in order to improve S / N. The material of the underlayer is determined according to the material of the magnetic layer.

As the magnetic layer, CoCrPt, CoCr
Ta, CoNiPt, CoNiTa, CoSiPt, C
Co such as oSiTa, CoCrPtB, CoCrTaB
It is preferable to use a magnetic alloy containing as a main component from the viewpoint of obtaining high coercive force and recording density characteristics. The thickness of the magnetic layer is 0.2 nm to 50 per layer in consideration of the multilayer medium.
The range of nm is preferable for increasing S / N.

The magnetic layer may be a single layer or a multilayer. When the magnetic layer has a multilayer structure, it is preferable to provide an intermediate layer between the magnetic layers. The intermediate layer preferably has the same composition as the underlayer, but may be an oxide layer, a nitrogen-containing layer or a carbon-containing layer. The thickness of the intermediate layer is 0.1
The thickness of 5 nm is preferable for improving the overwrite characteristic. Even if the intermediate layer is not actually formed by a physical film-forming method, the process of temporarily stopping the film formation of the magnetic layer and then forming the film again is repeated. Therefore, it may be formed by such a method.

As the protective layer, C, WC, (WMo)
C, it can be used _{(ZrNb) N, B 4 C} , a hydrogen-containing carbon. The second purpose is to combine an inductive magnetic head dedicated to recording using a magnetic material having a saturation magnetic flux density of 1.2 T or more in at least a part of the magnetic pole with a magnetoresistive effect head including a giant magnetoresistive effect element. It is achieved by using a magnetic head. The recording / reproducing signal processing means for waveform-processing the input signal and the output signal for the magnetic head includes a signal processing circuit by maximum likelihood decoding and a circuit for correcting the asymmetry of the reproducing signal of the magnetic head utilizing the giant magnetoresistive effect. The flying height of the slider to which the head is fixed is preferably 0.05 μm or less.

[0019]

The function of increasing the coercive force by using the bias sputtering method has not been sufficiently clarified at present, but the following reasons are considered. (1) Sputtering gas elements are taken into the magnetic film, and strain is induced in the magnetic crystal grains. At the same time, the isolation of the magnetic crystal grains is promoted, and the interaction between the crystal grains is cut off. (2) Since the ions collide with the substrate surface at a high speed, the effective temperature of the film surface rises, and segregation of nonmagnetic elements such as Cr to the crystal grain boundaries is promoted. (3) The growth of crystals with weak bonds is suppressed, and the crystal growth proceeds selectively. (4) Clean the laminated surface. (Removal of impurities)

It can be construed that the above action increases the effective anisotropic magnetic field of the magnetic film and increases the coercive force. The energy of the sputter gas has these effects,
That is, the atomic weight is related, and in the present invention, by using Kr, Xe, or Rn gas having a larger atomic weight than Ar gas which has been generally used as a sputtering gas from the past, a larger effect can be obtained. It is considered to be a thing. Further, when Kr, Xe, or Rn is used as the sputtering gas, the excited state of plasma is different from that when Ar is used, and it affects the sputtered particles flying in the plasma and reaching the substrate. Therefore, the crystallinity of the formed film may be improved, and it is better to use Kr, Xe, or Rn as the sputtering gas in addition to the effect of the bias.

However, when 100% pure gas of Kr, Xe or Rn is used as the sputtering gas, the magnetic properties are improved but the manufacturing cost is increased. On the other hand, by using a mixed gas in which Kr, Xe, or Rn is mixed with Ar, the consumption amount of the heavy rare gas can be reduced and the cost can be reduced. Even when a mixed gas is used, the effect of using a heavy rare gas such as Kr, Xe, or Rn is not significantly impaired, and a medium having excellent magnetic characteristics can be manufactured. Here, in particular, the reason why the rare gas is selected as the sputtering gas is that this gas is taken into the film as described above, so that it is stable electrically and chemically so as not to affect the film. This is because gas is desirable.

There are two types of bias sputtering methods, DC bias sputtering method and RF bias sputtering method. The DC bias sputtering method is effective for a conductive substrate, and the RF bias sputtering method is effective for a non-conductive substrate. However, if a conductive film is formed on the substrate in advance and electrical continuity can be secured by providing electrical contact between the conductive film and the substrate electrode, the DC bias sputtering method can be applied to a non-conductive substrate. Can be applied. Furthermore, 0.1 nm or more 10
It is preferable to form an oxide layer, a nitrogen-containing layer, or a carbon-containing layer of about nm or less because the coercive force is further improved. In such thin oxide layer, nitrogen-containing layer, or carbon-containing layer, conduction can be secured by scratches or tunnel phenomenon caused when a jig for applying bias to the substrate is contacted, and sufficient bias can be applied. There is no problem in applying the bias.

According to the bias sputtering method of the present invention, the residual magnetization film thickness product can be set to 150 G · μm or less while maintaining the coercive force of 2000 Oe or more, and high recording density characteristics can be obtained. However, if the remanent magnetization film thickness product is smaller than 10 G · μm, the effect of thermal fluctuation increases, and the coercive force is significantly deteriorated even when the bias sputtering method is used. Moreover, 10G
・ If it is less than μm, the reproduction output becomes too small, which is not preferable. The coercive force is 200
When it is 0 Oe or more, a high reproduction output can be obtained at a high recording density, but when it is higher than 4000 Oe, the writing capability of the magnetic head is far exceeded, and the overwrite characteristic is remarkably deteriorated, which is not preferable.

The structure of the medium produced by this method is not limited to the structure in which the magnetic layer such as the underlayer, the magnetic layer and the protective layer is a single layer, but also the underlayer, the magnetic layer, the intermediate layer, the magnetic layer and the intermediate layer. , ....., may have a multilayer magnetic structure such as a protective layer. In the multi-layer magnetic structure, each magnetic layer is thinned,
By interposing an intermediate layer having a film thickness of 0.1 nm or more between the magnetic layers, the magnetic layers can be stacked while the crystal grains are made finer, and further, the exchange interaction occurs until each layer can be regarded as substantially magnetically independent. It can be reduced. In this case, the magnetic interaction between the magnetic layers can be weakened and the noise can be reduced according to the statistical sum, so that the noise can be further reduced as compared with the single layer medium. Regarding the output, the reproduction output can be increased by stacking a large number of magnetic layers.

A magnetic recording medium of the present invention, an inductive magnetic head dedicated to recording using a magnetic material having a saturation magnetic flux density of 1.2 T or more in at least a part of a magnetic pole, and a reproducing only utilizing a giant magnetoresistive effect. By combining these magnetic heads, a high-quality reproduction signal can be obtained, and
It is possible to realize a large-capacity magnetic disk device that is more than double the capacity.

This is 1.2T at least in a part of the magnetic pole.
A magnetic head dedicated to recording using a magnetic material having the above saturation magnetic flux density has a larger recording magnetic field than a conventional magnetic head having a saturation magnetic flux density of about 1T, and sufficient recording is possible even with a medium having a high coercive force. This is because the overwrite characteristic is remarkably improved, and the recording magnetic field becomes steep, so that the medium noise can be suppressed low. Further, it is one of the major factors that the read-only magnetic head utilizing the giant magnetoresistive effect can obtain a read output more than 5 times that of the conventional induction type magnetic head. In addition to the combination of the magnetic recording medium and the magnetic head, a signal processing circuit by maximum likelihood decoding and a circuit for correcting the asymmetry of the reproduction signal of the magnetic head using the giant magnetoresistive effect are combined.
By setting the flying height of the slider of the magnetic head to be 0.05 μm or less, it is possible to realize a large-capacity magnetic storage device which is three times or more compared with the conventional one.

[0027]

EXAMPLES Examples of the present invention will be described below. [Embodiment 1] FIG. 1 shows a cross section of an embodiment of a magnetic recording medium according to the present invention. Each layer was formed by a sputtering method as described below.

A substrate 11 made of a tempered glass substrate (Corning 0313) having an outer diameter of 95 mmφ is heated at a substrate temperature of 300.
℃, gas pressure 2.5mTorr, input power density 5W
/ Cm ^{2 under} the film forming conditions of DC magnetron sputtering, the conductive films 12, 12 ′ of Cr 2
A 5 nm film was formed. At this time, the sputtering gas is Ar
Was used.

Then, underlayers 13 and 13 were formed by a DC magnetron sputtering method in which a DC bias voltage was applied under film forming conditions of a substrate temperature of 300 ° C., a gas pressure of 2.5 mTorr, and an input power density of 5 W / cm ^2. 'Is Cr of 50 nm and the magnetic layers 14 and 14' is Co-1.
9 at% Cr-8 at% Pt was sequentially formed into a film having a thickness of 25 nm. The DC bias voltage is applied to the conductive films 12, 1
A conductive jig is brought into contact with the surface of 2'to form the base layers 13, 1
The DC bias voltage is applied to the laminated surface of 3'and the magnetic layers 14 and 14 ', and the applied voltage is -100V.
It was changed in the range of -400V. Kr, Xe, and Rn were used as the sputtering gas, respectively.

Finally, as the protective layers 15 and 15 ', Ar is used as a sputtering gas, C is deposited to a thickness of 10 nm without applying a bias voltage, and then 3 nm of perfluoroalkylpolyether-based lubricating layers 16 and 16' are used. Was formed. In the magnetic recording medium of this embodiment, as shown by the circle in FIG. 1, the underlayers 13 and 13 ′, the magnetic layers 14 and 14 ′, and the protective layer 15 are compared with the area of the substrate 11 and the conductive films 12 and 12 ′. 1
The area of 5'is smaller. This is the conductive film 12,1
This is because a jig for applying a DC bias voltage was brought into contact with the outer peripheral portion of 2 ', so that the film after the conductive film could not be laminated on the outer peripheral portion. As a method for ensuring the conduction between the conductive film and the substrate electrode, in addition to this, the inner peripheral portion may be contacted, or the conductive film may be brought into contact with the side surface of the substrate. When the location where the conductive film and the substrate electrode jig are in contact with each other is the inner peripheral portion or the outer peripheral portion of the magnetic recording medium,
This is preferable because the middle part of the disk can be effectively used as a recording area. Also, regarding the contact area, it will be easily understood that point contact is not required to be in contact with the entire circumference of the disk.

COMPARATIVE EXAMPLE 1 Next, for comparison, the same manufacturing conditions as in Example 1 were used except that Ar was used as the sputtering gas, and the bias voltage was changed in the range of −100 to −400V. The magnetic recording medium and the sputtering gas of Ar, Kr, Xe, and Rn are used, and the bias is 0V.
A magnetic recording medium manufactured under the same manufacturing conditions as in Example 1 except for the above was prepared.

FIG. 2 shows the coercive force of the magnetic recording media manufactured as Example 1 and Comparative Example 1. The coercive force is increased by applying a DC bias voltage in any of the media produced using any sputtering gas, and the coercive force shows the maximum value when a bias of -200V is applied. Further, if the bias voltage is set to a negative value and its absolute value is increased, the coercive force becomes lower, and when a bias of -400V is applied, the coercive force is reduced to the same extent as in a medium to which no bias is applied.

Comparing the coercive forces due to the difference in the sputtering gas, the coercive force of the medium made of Rn has the highest coercive force.
It can be seen that the coercive force decreases in the order of e, Kr, and Ar. In the medium using Ar of the comparative example, the maximum coercive force does not reach 2000 Oe. From this, a medium having a higher coercive force can be obtained by using a sputtering gas having a large atomic weight such as Rn, Xe, and Kr. According to the bias sputtering method with Rn, Xe, and Kr selected as the sputtering gas, 2000 Oe or more is obtained. It can be seen that a coercive force can be achieved.

From the above, it is concluded that it is better to apply the bias in the range of -400 V or more and less than -30 V and to use Rn, Xe, Kr as the sputtering gas. The composition of the magnetic film was changed to Co under the same film forming conditions as those of the magnetic recording medium of Example 1.
-16 at% Cr-4 at% Ta, Co-15 at% C
r-12 at% Pt, Co-30 at% Ni-5 at%
Pt, Co-20 at% Ni-10 at% Cr, Co-
16 at% Si-6 at% Ta, Co-20 at% Si
-10 at% Pt, Co-15 at% Cr-4 at% T
a-4 at% B, Co-16 at% Cr-8 at% Pt
Even when the absolute value of the coercive force was slightly different even when changed to -4 at% B, the same result as in FIG. 2 was obtained. That is, as the magnetic layer, CoCrPt, CoCrTa, C
oNiPt, CoNiTa, CoSiPt, CoSiT
Any magnetic layer containing Co as a main component, such as a, CoCrPtB, and CoCrTaB, can be used.

The composition of the conductive films 12 and 12 'is C and T.
i, V, Cu, Zn, Nb, Mo, Ru, Rh, Pd,
Similar results were obtained with Ag, Ta, W, Pt, Au, Ni-P, Cr-P, or a mixture of two or more of these. After forming the conductive films 12 and 12 ′, the vacuum of the film forming apparatus was once broken and exposed to the atmosphere to form a thin oxide layer on the conductive film surface, and the coercive force was improved by about 100 to 400 Oe. In addition,
Even when a thin nitrogen-containing layer or carbon-containing layer was formed on the surface of the conductive film, the phenomenon that the coercive force was similarly improved was observed. The formation of the nitrogen-containing layer was performed by a method of exposing the conductive film to a nitrogen atmosphere or a method of mixing a trace amount of nitrogen into the target. The carbon-containing layer was formed by a method of mixing a trace amount of carbon into the target, a method of forming a thin carbon film on the surface, or an ion implantation.

The DC bias has the effect of improving the coercive force even when applied only during the formation of the magnetic layer. However, when the DC bias is applied only during the formation of the underlayer, the coercive force of the magnetic layer is reduced. It was not improved, and the effect of bias sputtering was hardly seen. Although the tempered glass substrate is used as the substrate in the first embodiment, in addition to the tempered glass substrate, a canasite (crystallized glass) substrate, a ceramic substrate such as SiC, a Ni-P plated Al alloy substrate, a plastic substrate,
A carbon substrate, a boron substrate, a TiO substrate, a Ti alloy substrate or the like can be used.

Before forming the conductive film on the substrate, Ar, Kr, X are added to reduce the influence of impurities on the substrate surface.
Plasma cleaning with e, Rn or the like may be performed. Setting the remanent magnetization film thickness product of the medium to 10 G · μm or more and 150 G · μm or less and the coercive force to 2000 Oe or more and 4000 Oe or less optimizes the substrate temperature, gas pressure, and input power during sputtering depending on the composition and film configuration. To be achieved. The magnetic recording media shown as examples of the present invention all have a residual magnetization film thickness product of 10 G · μm or more and 150 G · μm or less,
The condition that the coercive force was 2000 Oe or more and 4000 Oe or less was satisfied.

In the first embodiment, the sputtering gas is 1
Although Rn, Xe, and Kr of 00% pure gas were used, a mixed gas in which these heavy rare gases were mixed with Ar was also examined. The film structure and film forming conditions of the magnetic recording medium were the same as in Example 1, the DC bias voltage was -200 V, and the composition of the sputtering gas was changed to prepare various magnetic recording media.
The coercive force was measured. The result is shown in FIG.

From FIG. 3, R of 2 at% or more in Ar gas is obtained.
When n, Xe or Kr is mixed, the characteristics are improved as compared with the case where pure Ar is used as the sputtering gas,
It can be seen that a coercive force of e or more can be achieved. Furthermore, R
It is possible to mix three kinds of gases of n, Xe, and Kr. Even when mixing these three kinds of mixed gas and Ar, Rn,
It is desirable to mix a mixed gas of Xe and Kr with Ar at 2 at% or more.

Next, the crystals were evaluated by X-ray diffraction for the magnetic recording medium produced using Ar gas and the magnetic recording medium produced using Rn gas. At this time, the substrate 1
As No. 1, a Ni-P plated Al alloy substrate was used, the same film forming conditions and film constitution as in Example 1 were used, and a medium to which a bias voltage of -200 V was applied was used. The results are shown in Fig. 4. As shown in FIG. 4A, in the medium produced using Ar gas, the diffraction angle of the Co (110) plane parallel to the film surface and the diffraction angle of the Co (110) surface inclined by 60 degrees from the film surface are almost the same. It is the same, and all indicate a surface spacing of 0.1261 nm. On the other hand, as shown in FIG. 4B, in the medium manufactured using Rn gas, the diffraction angle of the Co (110) plane parallel to the film surface is smaller. This is because, in the medium produced by applying a bias to the substrate using Rn gas, Co parallel to the film surface is used.
The (110) plane spacing is 60 degrees (20 degrees or more) from the film surface.
This means that it is larger than the spacing between the inclined Co (110) planes. By the way, the Co (110) plane parallel to the film plane derived from FIG. 4B has a surface spacing of 0.1260 n.
m and Co inclined by 60 degrees (20 degrees or more) from the film surface
The plane spacing of the (110) plane is 0.1250 nm.

Apart from the above embodiment, the conductive film 1 shown in FIG.
X for all layers from 2, 12 'to protective layers 15, 15'
A film is formed by using e gas, and a bias voltage of −200 V is applied when forming the underlayers 13 and 13 ′ and the magnetic layers 14 and 14 ′.
Elemental analysis was performed by SIMS (Secondary Ion Mass Spectroscopy) on the medium produced by applying the voltage. Results are shown in FIG. From FIG. 5, it can be seen that a large amount of Xe is detected in the underlayer and magnetic layer formed by applying a bias.
This means that a large amount of Xe gas was taken into the film by applying the bias, and can be said to be one of the characteristics of performing the bias sputtering.
The film formed by bias sputtering according to the present invention contains Rn, Xe or Kr at a concentration of 100 ppm or more.
Is included.

Next, the medium sputtered with Kr, Xe, and Rn gas was left in an environment of a temperature of 60 ° C. and a humidity of 90%, the attenuation amount of the saturation magnetization of each medium was measured, and the corrosion resistance was compared. The result is shown in FIG. The horizontal axis of FIG. 6 is time,
The vertical axis represents the value of saturation magnetization at each time point normalized by the initial saturation magnetization. From FIG. 6, it can be seen that the corrosion resistance of the medium sputtered with Kr gas is the best, and the corrosion resistance deteriorates in the order of Xe and Rn. Therefore, Rn is most effective for obtaining a high coercive force, but Kr is most effective when high reliability is required.

Example 2 Multilayer magnetic recording medium according to the present invention
A cross section of one embodiment of the body is shown in FIG. Each layer is described below
As described above, a film was formed by the sputtering method. Board 4
2.5 inch diameter canasite (crystallized glass) base
Using a plate, the substrate temperature is 300 ° C., and the Xe gas pressure is 1.7.
mTorr, input power density is 5 W / cm ² Film forming
DC magnetron sputter phosphorus with RF bias applied in some cases
Cr-15 at as the underlayers 42 and 42 'by the coating method.
% Ti is 250 nm, and C is used as the first magnetic layers 43 and 43 '.
o-19at% Cr-8at% Pt 12nm film-forming
It was Further, a Cr film having a thickness of 2 nm is formed as the intermediate layers 44 and 44 '.
Then, as a second magnetic layer 45, 45 ′, Co-16 at
% Cr-4at% Ta 12nm thick, 2 magnetic layers
It has a medium structure. RF bias voltage is -100V ~-
It was changed in the range of 400V.

Finally, as the protective layers 46 and 46 ', a mixed gas of Xe and methane was used as a sputtering gas, a hydrogen-containing carbon film was formed to a thickness of 10 nm without applying a bias voltage, and then a perfluoroalkyl polyether having a thickness of 3 nm was formed. The system lubricating layers 47, 47 'were formed.

[Comparative Example 2] For comparison, magnetic recording having the same multilayer film structure as that of Example 2 under the same conditions as those of Example 2 except that the bias voltage was set to 0V. A medium was prepared. FIG. 8 shows the coercive force of the magnetic recording media produced as Example 2 and Comparative Example 2. As is apparent from FIG. 8, the same results as in Example 1 were obtained also in Example 2 having two magnetic layers, and the medium formed by applying a bias had a higher coercive force. Recognize. The number of magnetic layers may be changed to three layers, four layers, five layers,
Even if the composition of each magnetic layer was the same, the same result as shown in FIG. 8 was obtained.

Further, with the same multilayer film structure as in Example 2,
The same results as shown in FIG. 8 were obtained when a medium was prepared by a DC bias sputtering method using a conductive substrate such as a Ni—P plated Al alloy substrate or a carbon substrate as the substrate.

[Embodiment 3] The electromagnetic conversion characteristics of the magnetic recording media of Embodiments 1 and 2 were measured using a recording / reproducing separated type magnetic head schematically shown in FIG. The recording magnetic head is an inductive thin film magnetic head composed of a pair of recording magnetic poles 51 and 52 and a coil 53 interlinking with the recording magnetic poles 51 and 52. In order to avoid saturation of the magnetic poles, 1.
Magnetic materials 54, 54 'such as CoNiFe having a saturation magnetic flux density of 2T or more are used. The magnetic material having a saturation magnetic flux density of 1.2 T or higher may be provided only on one magnetic pole, or the entire magnetic pole may be made of a magnetic material having a saturation magnetic flux density of 1.2 T or higher. The read-only magnetic head is a magnetoresistive head including a giant magnetoresistive element 55 in which NiO or the like is laminated on NiFe and a conductor layer 56 serving as an electrode, and is sandwiched by a pair of magnetic shield layers 57 and 58. This magnetic head is provided on a magnetic head slider base 59.

As the measurement conditions, the linear recording density is 190 k.
FCI, track width 2 μm, recording head gap length 0.2 μm, reproducing head shield spacing 0.2
μm, flying height of slider of magnetic head is 0.04 μm
And The S / N (signal-to-noise ratio) of the reproduced signal measured under such recording / reproducing conditions is -20 when Rn is used as the sputtering gas in the magnetic recording medium shown in the first embodiment.
The medium having the highest coercive force produced by applying a bias of 0 V was the best, and was 38 dB. 33 dB could be secured for other media.

Further, also in the magnetic recording medium shown in Example 2, the medium produced by applying a bias of -200 V, which had the highest coercive force, was the best, and the value was 37 dB. With other media, 32 dB could be secured. Considering that the S / N required to operate the device normally is about 30 dB, it can be said that the magnetic recording medium of the present invention has sufficient electromagnetic conversion characteristics.

[Embodiment 4] A top view of an example of a magnetic memory device is shown in FIG. 10A, and a sectional view taken along the line AA 'of FIG. 10B.
Shown in. The magnetic recording medium 61 includes a magnetic recording medium driving unit 62.
A magnetic head 63, which is held by a holder connected to the magnetic recording medium 61 and faces each surface of the magnetic recording medium 61, is schematically shown in FIG. The magnetic head 63 is stably floated at a flying height of 0.05 μm or less, and is driven by a magnetic head drive unit 65 to a desired track with a head positioning accuracy of 0.4 μm or less.

The signal reproduced by the magnetic head 63 is
Waveform processing is performed by the recording / reproducing signal processing system 64. The recording / reproducing signal processing system includes an amplifier 81, as shown in FIG.
The analog equalizer 82, the AD converter 83, the digital equalizer 84, and the maximum likelihood decoder 85 are included.
The playback waveform of the head that uses the giant magnetoresistive effect is different from the recording waveform because the positive and negative magnitudes are asymmetrical due to the characteristics of the head, and the frequency characteristics of the recording and playback system affect it. Will end up. The equalizers 82 and 84 have a function of deforming the reproduced waveform and restoring it. The maximum likelihood decoder 85 further constructs a signal processing circuit having an extremely low error rate by passing the restored signal through a signal processing LSI by maximum likelihood decoding. These waveform processing is performed by the recording / reproducing signal processing system 64.
Existing equalizers and maximum likelihood decoders can be used.

With the above device configuration, it was possible to realize a high-density magnetic recording / reproducing device having a storage capacity three times or more that of the conventional magnetic recording / reproducing device. Further, even when the signal processing circuit 85 by maximum likelihood decoding and the circuits 82 and 84 for correcting the asymmetry of the reproduction signal of the magnetic head utilizing the giant magnetoresistive effect are removed from the recording / reproduction signal processing system 64, it is still 2 It was possible to realize a magnetic recording / reproducing device having a storage capacity more than double the storage capacity.

In the recording / reproducing separated type magnetic head shown in FIG. 9, the magnetic shield layer 57 is formed on one recording magnetic pole 52.
One magnetic pole 5 of the recording magnetic head
2 may be omitted. In the above embodiments, examples have been described of the disk-shaped magnetic recording medium and the magnetic storage device using the same, but the present invention is a tape-shaped or card-shaped magnetic recording medium having a magnetic layer only on one side, and the same. It goes without saying that the present invention can also be applied to a magnetic recording / reproducing device using a magnetic recording medium.

[0054]

In the magnetic recording medium of the present invention, a heavy rare gas having a larger atomic weight than Ar such as Kr, Xe, and Rn is used as a sputtering gas, and a magnetic layer is applied directly or through an underlayer while applying a bias voltage. By laminating, it is possible to realize an electromagnetic conversion characteristic that has a high coercive force and is compatible with high density recording.

Further, this magnetic recording medium, a magnetic head dedicated to recording using a magnetic material having a saturation magnetic flux density of 1.2 T or more in at least a part of the magnetic pole, and a magnetic head dedicated to reproduction utilizing the giant magnetoresistive effect. By combining a signal processing circuit by maximum likelihood decoding and a circuit that corrects the asymmetry of the reproduction signal of the magnetic head using the giant magnetoresistive effect, and the flying height of the slider of the magnetic head is set to 0.05 μm or less, A high-quality reproduction output and an extremely low error rate can be obtained, and a magnetic storage device having a large capacity and high density can be obtained as compared with a conventional magnetic storage device.

[Brief description of drawings]

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

FIG. 2 is a diagram comparing the coercive forces of the magnetic recording media of Example 1 and Comparative Example 1.

FIG. 3 is a diagram showing a relationship between a composition of a sputtering gas and a coercive force of a magnetic recording medium.

FIG. 4 is a magnetic recording medium manufactured using Ar gas and Rn.
The X-ray-diffraction-intensity measurement figure about the magnetic recording medium produced using gas.

FIG. 5 shows SIMS (2
The figure which shows the result of secondary ion mass spectrometry.

FIG. 6 is an explanatory diagram of corrosion resistance of a magnetic recording medium.

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

FIG. 8 is a diagram comparing the coercive force of the magnetic recording medium according to the present invention with that of the conventional magnetic recording medium.

FIG. 9 is a schematic diagram of a recording / reproducing separated type magnetic head.

FIG. 10 is a schematic diagram showing the structure of a magnetic recording / reproducing apparatus.

FIG. 11 is a block diagram showing an example of a recording / reproducing signal processing system.

[Explanation of symbols]

11, 41 ... Substrate, 12, 12 '... Conductive film, 13, 1
3 ', 42, 42' ... Underlayer, 14, 14 '... Co-based alloy magnetic layer, 15, 15', 46, 46 '... Protective layer, 1
6, 16 ', 47, 47' ... Lubricating layer, 43, 43 '... First magnetic layer, 44, 44' ... Intermediate layer, 45, 45 '... Second
Magnetic layer, 51, 52 ... Recording magnetic pole, 53 ... Coil, 54,
54 '... magnetic material having large saturation magnetic flux density, 55 ... giant magnetoresistive effect element, 56 ... conductor layer, 57, 58 ... magnetic shield layer, 59 ... slider base, 61 ... magnetic recording medium, 6
2 ... Magnetic recording medium drive unit, 63 ... Magnetic head, 64 ... Recording / reproducing signal processing system, 65 ... Magnetic head drive unit

Front page continued (72) Masaaki Ninomoto, 1-280, Higashi Koigakubo, Kokubunji, Tokyo, Central Research Laboratory, Hitachi, Ltd. (72) Nobuyuki Inaba, 1-280, Higashi Koigakubo, Kokubunji, Tokyo Hitachi, Ltd. Central Research Institute In-house (56) Reference JP 4-123310 (JP, A) JP 2-148417 (JP, A) JP 57-58237 (JP, A) JP 5-274644 (JP, A) JP-A-4-368611 (JP, A) JP-A-4-274001 (JP, A) JP-A-63-80538 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 5/66 G11B 5/85

Claims (7)

(57) [Claims] 1. A non-magnetic substrate, a magnetic layer formed on the non-magnetic substrate, and a protective layer formed on the magnetic layer , the magnetic layer containing Co having a hexagonal crystal structure. Inclusion
In the magnetic layer, 100 ppm or more of at least one element selected from the group consisting of Kr, Xe, and Rn is contained.
A magnetic recording medium characterized by being contained at a concentration of . 2. The residual magnetization film thickness product is 10 G · μm or more 15
0G · μm or less and coercive force of 2000 Oe or more 40
The magnetic recording medium according to claim 1 , wherein the magnetic recording medium has a density of 00 Oe or less. 3. The magnetic recording medium according to claim 1 or 2 ,
A drive unit for driving the magnetic recording medium in the recording direction, a magnetic head arranged so as to face each surface of the magnetic recording medium, and means for moving the magnetic head relative to the magnetic recording medium. A magnetic recording / reproducing apparatus comprising: a recording / reproducing signal processing means for waveform-processing an input signal and an output signal to the magnetic head. 4. The magnetic recording / reproducing apparatus according to claim 3, wherein the magnetic head is a recording / reproducing separated type head including an induction type magnetic recording head and a magnetoresistive effect head. Wherein said inductive magnetic recording head has a magnetic material having a saturation magnetic flux density of more than 1.2T at least a portion of the pole, the magnetoresistive head comprising: a giant magnetoresistive effect element The magnetic recording / reproducing apparatus according to claim 4 . 6. A method of manufacturing a magnetic recording medium, comprising: a step of forming an underlayer on a nonmagnetic substrate; and a step of forming a magnetic layer containing hexagonal Co on the underlayer. The step of forming the layer uses K as a sputtering gas.
Using a gas containing r, Xe or Rn, the non-magnetic substrate is
By sputtering while applying a negative bias voltage
A method of manufacturing a magnetic recording medium characterized by the following. 7. The method of manufacturing a magnetic recording medium according to claim 6, wherein the negative bias voltage is a DC bias or an RF bias of −400 V or more and less than −30 V.