JP3217012B2 - Magnetic recording media - 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 storage device, and more particularly to a magnetic storage device having a recording density of 1 gigabit per square inch or more and a low-noise thin-film magnetic recording medium for realizing the same. It is.

[0002]

2. Description of the Related Art A demand for a large capacity of a magnetic storage device is increasing at present. Conventional magnetic heads use an electromagnetic induction type magnetic head that utilizes a voltage change accompanying a temporal change in magnetic flux. This is to perform both recording and reproduction with one head. On the other hand, in recent years, a composite head using a magnetoresistive head, which has a high sensitivity as a reproducing head, separately from a recording head and a reproducing head, has been rapidly adopted. The magnetoresistive head utilizes the fact that the electric resistance of the head element changes with the change of the magnetic flux leaking from the medium. Further, the development of a more sensitive head utilizing an extremely large magnetoresistance change (giant magnetoresistance effect or spin valve effect) generated in a magnetic layer of a type in which a plurality of magnetic layers are stacked via a nonmagnetic layer has been advanced. It is getting. This effect is an effect in which the relative directions of the magnetizations of the plurality of magnetic layers via the non-magnetic layer change due to the leakage magnetic field from the medium, thereby changing the electric resistance.

At present, in a magnetic recording medium put into practical use, an alloy containing Co as a main component, such as CoCrPt, CoCrTa, or CoNiCr, is used as a magnetic layer. Since these Co alloys have a hexagonal close-packed structure (hcp structure) having an easy axis of magnetization in the c-axis direction, a crystal orientation in which the c-axis is in the in-plane direction is desirable for an in-plane magnetic recording medium. However, such an orientation is unstable and generally does not occur even when Co is directly formed on a substrate. Therefore, Cr with a body-centered cubic structure (bcc structure)
Utilizing that the (100) plane has good consistency with the Co (11.0) plane,
0) An oriented Cr underlayer is first formed on the substrate, and
A method has been used in which a Co alloy layer is epitaxially grown so that the Co alloy layer has a (11.0) orientation in which the c-axis is in the in-plane direction. In order to further improve the crystal lattice matching at the interface between the Co alloy magnetic layer and the Cr underlayer, a method of adding a second element to Cr to increase the lattice spacing of the Cr underlayer has been used. As a result, the Co (11.0) orientation is further increased, and the coercive force can be increased. Examples of such technology include JP-A-62-257618 and JP-A-63-257618.
As shown in 197018, those to which V, Ti and the like are added can be mentioned. Elements required for high recording density include low noise as well as high coercive force of the recording medium. In order to reduce the medium noise, it is known that it is effective to make the crystal grains in the magnetic layer fine and to make the crystal grain size uniform.

[0004] An important requirement for magnetic disk media is improvement in impact resistance. In particular, in recent years, magnetic disk devices have been mounted on portable information devices such as notebook personal computers, and from the viewpoint of improving reliability, this impact resistance improvement has become a very important issue. The impact resistance of the magnetic disk medium can be improved by using a glass substrate having a reinforced surface or a crystallized glass substrate instead of the conventional Al alloy substrate having NiP plating on the surface. Glass substrate is made of conventional NiP plated Al
Since the surface is smoother than the alloy substrate, it is advantageous in reducing the floating spacing between the magnetic head and the medium,
Suitable for high recording density. However, when a glass substrate is used, problems such as poor adhesion to the substrate, impurity ions from the substrate, or adsorbed gas on the substrate surface penetrating into the Cr alloy base layer occur. In particular, regarding the adhesion of the film, as described in J. Vac. Sci. Technol. A4 (3), 532 to 535 of 1986, it has been reported that the adhesion deteriorates when the glass substrate is heated. I have. For these, various measures such as forming various metal films, alloy films, and oxide films between the glass substrate and the Cr alloy underlayer have been taken (Japanese Patent Application Laid-Open Nos. 62-293512 and 62-293512). -29923, Japanese Patent Laid-Open No. 5-
No. 135343). Further, Japanese Patent Application Laid-Open No.
By forming an amorphous film composed of Y, i, Zr, Hf, V, Nb, Ta, Cr, Mo, W, etc. between the glass substrate and the underlayer, the crystal grain size of the magnetic layer is prevented from increasing. It is shown that the magnetic properties are improved.

[0005]

SUMMARY OF THE INVENTION
The effect type head has an extremely high reproduction sensitivity and is suitable for high-density recording. However, the sensitivity to noise as well as the reproduction signal from the magnetic recording medium also increases. For this reason, the recording medium is required to have lower noise than before. It is known that miniaturization and uniformization of crystal grains in the magnetic layer are effective for reducing the medium noise as described above. However, when a magnetic disk drive was trial-produced by combining such a magnetic recording medium and a high-sensitivity magnetic three-effect type head, sufficient electromagnetic conversion characteristics could not be obtained. In particular, when a glass substrate was used as the substrate of the magnetic recording medium, the result that the electromagnetic conversion characteristics in a high linear recording density region were poor was obtained. Upon examining the cause, the Cr alloy base layer formed directly on the glass substrate or through the various metals found in the known examples, or their alloys, was formed on the NiP plated Al alloy substrate. It was not as strongly (100) oriented as it was. For this reason, the crystal plane other than (11.0) of the Co alloy magnetic layer grew parallel to the substrate, and the degree of in-plane orientation of the c-axis, which is the axis of easy magnetization, was small. As a result, the coercive force was reduced, and the reproduction output at a high linear recording density was reduced.
When a glass substrate was used, the crystal grains of the magnetic layer were enlarged as compared with the case where the Al alloy substrate was used, and the particle size distribution of the crystal grains was also increased by about 20 to 30%. . For this reason, the medium noise increases and the electromagnetic conversion characteristics deteriorate. Further, even if an amorphous or microcrystalline film described in JP-A-4-153910 is formed between the glass substrate and the base layer, the crystal grain size of the magnetic layer may be reduced to some extent, Was not. Further, there was almost no effect on the reduction of the particle size distribution, and good electromagnetic conversion characteristics could not be obtained.

As described above, a magnetic head, a magnetic recording medium, and a substrate for a magnetic recording medium suitable for increasing the recording density have been separately developed. Until now, whether to implement a disk device has not been sufficiently considered. An object of the present invention is to solve the above problems and provide a highly reliable magnetic storage device having a recording density of 1 gigabit per square inch or more, and a low-noise magnetic recording medium suitable for a high recording density. It is to be.

Another object of the present invention is to improve the poor adhesion that tends to occur when a film is formed after heating a glass substrate. This not only broadens the range of film formation conditions for noise reduction of the recording medium, but also enables substrate heating immediately before film formation, thereby desorbing impurity gas adsorbed on the substrate surface, and The reproducibility of the magnetic film characteristics can be improved.

[0008]

An object of the present invention is to provide a magnetic recording medium having a magnetic layer formed on a substrate through a multilayer underlayer in which a plurality of underlayers are stacked, and at least one of the multilayer ground layers contains Co. This is achieved by using a magnetic recording medium made of an amorphous or microcrystalline material.

As described above, when the glass substrate is used, the degree of in-plane orientation of the c-axis, which is the axis of easy magnetization, of the Co alloy magnetic layer is smaller than when the conventional NiP-plated Al alloy substrate is used. The characteristics were degraded because the crystal grains were large. The crystal grains of the magnetic layer are epitaxially grown on the crystal grains of the underlayer. Generally, the orientation and size of the crystal grains of the magnetic layer are greatly affected by the crystal grain size and surface shape of the underlayer. Based on such findings, the present inventors,
Various types of magnetic recording media with different underlayer materials, layer configurations, film thicknesses, film forming conditions, etc. were manufactured, and a composite magnetic field using an electromagnetic induction head for the recording section and a magnetoresistive head for the reproducing section The relationship with the recording / reproducing characteristics was examined by combining with a head. As a result, a new underlayer made of an amorphous or microcrystalline material containing Co is provided between the substrate and the bcc structure underlayer such as a Cr alloy for increasing the crystal lattice matching with the magnetic layer by increasing the number of layers of the underlayer. It has been found that the characteristics can be improved by inserting a proper underlayer (hereinafter referred to as a first underlayer). Hereinafter, the detailed means will be described.

Here, in the case of amorphous, a clear peak due to X-ray diffraction is not observed, or a clear diffraction spot or diffraction ring due to electron beam diffraction is not observed, but a halo-shaped diffraction ring is observed. Say that. Further, the term “microcrystal” means that the crystal grain has a crystal grain size smaller than the crystal grain size of the magnetic layer, and preferably has an average grain size of 8 nm or less.

The material constituting the layer composed of the amorphous or microcrystalline material containing Co which constitutes the above-mentioned multilayer underlayer is a material containing an element forming amorphous or microcrystal with Co. If so, its composition is not particularly limited. When a first underlayer made of an amorphous or microcrystalline material containing Co is formed on a glass substrate, a Cr layer formed on the first underlayer is formed.
At the same time as the crystal grains of a base layer having a bcc structure such as an alloy (hereinafter referred to as a second base layer) are refined, bcc
The (100) plane of the structure easily grows parallel to the film plane. As a result, the crystal grains having the hcp structure of the Co alloy magnetic film grow so that the axis of easy magnetization points in the film plane, and the grain size becomes small. Therefore, coercive force is improved and noise is reduced. Even when an amorphous material containing no Co or a microcrystalline material is used, the crystal grain size of the magnetic layer may be reduced to some extent, but as shown in Example 6, the amorphous material containing Co, Alternatively, when a microcrystalline material is used, the crystal grain size is remarkably reduced, and the dispersion of the crystal grain size is reduced. This is because fine irregularities are uniformly formed on the surface of an amorphous or microcrystalline material containing Co, and the crystal grains of the second underlayer grow using the nuclei as the nuclei.

The fine structure of the first underlayer is desirably amorphous, but good characteristics can be obtained even if the fine structure has an average crystal grain size of 8 nm or less. In the case of the amorphous structure, since the crystal grains of the second underlayer and the magnetic layer are finer, a medium with lower noise can be obtained. In the case of a microcrystalline structure, noise is slightly increased, but the reproduction output at a high recording density is increased. Therefore, it is suitable for combination with a head having relatively high head noise.

As a specific material of the first underlayer, T
i, Y, Zr, Nb, Mo, Hf, Ta, W, Si, an alloy of Co with at least one first additive element selected from the first group consisting of B, or a first alloy thereof; Oxides of Co and Co
Are preferred. The concentration of the first additive element is 5at
% Is preferably in the range of 70 at% or less. When the concentration of the first additive element is less than 5 at%, the crystal grains of the magnetic layer become larger than when the second underlayer is formed directly on the glass substrate, and when the concentration is more than 70 at%, the magnetic film becomes larger. of
The component whose c-axis rises from the film surface increases, which is not preferable. As the first additive element, Zr in the first group,
The use of Ta or W is particularly preferable because the in-plane orientation component of the easy axis is strong.

Since the magnetization of the first underlayer has some influence on the recording / reproducing characteristics, it is desirable that the first underlayer is non-magnetic. However, as a result of examination, it was confirmed that there is no practical problem if the product of the residual magnetic flux density and the layer thickness of the first underlayer is 20% or less of the product of the residual magnetic flux density and the layer thickness of the magnetic layer. Was. The product of the residual magnetic flux density of the first underlayer and the layer thickness is
When the product exceeds 20% of the product of the residual magnetic flux density and the layer thickness of the magnetic layer, MR
Fluctuations appear in the baseline of the output signal of the head, and low-frequency noise increases, which is not preferable. To eliminate such an effect, it is effective to reduce the thickness of the first underlayer, increase the concentration of the first additive element, or add a second additive element. When Cr, V, Mn, or the like is used as the second additive element, the magnetization is greatly reduced, and this is effective.

As the second underlayer, it is preferable to use an alloy of at least one element selected from Ti, Mo, and V and Cr, or Cr. Further, the second underlayer may be constituted by two layers having a bcc structure.

The magnetic layer is made of CoCrPt, CoCrPtTa, CoCrPtT
i, CoCrTa, CoNiCr, and other alloys containing Co as the main component can be used, but in order to obtain a high coercive force, Pt is contained.
It is particularly preferable to use a Co alloy. Also, SmCo, FeSm
A magnetic alloy containing a rare earth element such as N can also be used. It is known that SmCo alloy films consist of very small crystal grains. However, because of the strong magnetic interaction between the crystal grains, each crystal grain is not an independent magnetic particle. It is thought that the aggregate of SmCo alloy grains formed on the layer acts as one magnetic unit. When the first underlayer made of the amorphous or microcrystalline material containing Co of the present invention is formed, the crystal grains of the second underlayer having the bcc structure are refined. The unit is miniaturized, and the medium noise can be reduced. Further, the magnetic layer may be composed of a single layer or a plurality of layers via a non-magnetic intermediate layer. In this case, the thickness t of the magnetic layer in Br × t of claim 8 represents the total thickness of each magnetic layer.

The magnetic properties of the magnetic layer are as follows: the coercive force measured by applying a magnetic field in the recording direction is 1.8 kOe or more, and the product Br × t of the residual magnetic flux density Br and the film thickness t is 20 gauss microns. As described above, it is preferable that the thickness be 140 gauss / micron or less because good recording / reproducing characteristics can be obtained in a recording density region of 1 gigabit / square inch or more. If the coercive force is smaller than 1.8 kOe, the output at a high recording density (200 kFCI or more) becomes undesirably small. Further, when Br × t is larger than 140 Gauss / micron, the resolution is reduced, and when it is smaller than 20 Gauss / micron, the reproduction output is undesirably reduced.

Further, by forming carbon as a protective layer of a magnetic layer with a thickness of 10 nm to 30 nm and further providing a lubricating layer of an adsorbent perfluoroalkyl polyether or the like with a thickness of 2 nm to 20 nm, high reliability and high density can be achieved. A recordable magnetic recording medium is obtained. Further, a carbon film to which hydrogen is added as a protective layer, or silicon carbide, tungsten carbide, (W
-Mo) -C, (Zr-Nb) -N and the like, or a film composed of a compound of these compounds and carbon, sliding resistance,
It is preferable because the corrosion resistance can be improved. In addition, after forming these protective layers, plasma etching is performed using a fine mask or the like to form fine irregularities on the surface, or a heterogeneous projection is formed on the surface of the protective layer using a compound or mixture target. Or, by forming irregularities on the surface by heat treatment, the contact area between the head and the medium can be reduced, and CSS
This is preferable because the problem that the head sticks to the medium surface during operation is avoided.

When the first underlayer made of the amorphous or microcrystalline material containing Co of the present invention is used, the same effect as when the glass substrate is heated after the substrate is formed but not heated. Was found to have good adhesion. This is presumed to be because cobalt, which is a main component element of the base film, has a strong bonding force with silicon or oxygen on the glass substrate. The use of the above-mentioned compound of the oxide of the first additional element and Co further improves the adhesion to the glass substrate, and particularly reduces the flying height of the magnetic head slider (the spacing between the magnetic head and the medium). Suitable when contact is likely to occur.
As described above, when the present invention is used, it is not necessary to particularly provide a layer for improving adhesion. However, in order to form irregularities on the surface of the medium and improve CSS characteristics,
A low melting point metal such as l or Ag, an alloy layer, or an intermetallic compound layer may be formed between the substrate and the first underlayer.

Also, when an Al alloy substrate plated with Ni-P was used as the substrate, the effect of making the crystal grains of the magnetic layer finer was confirmed as in the case of using a glass substrate.

The magnetic recording medium, a driving unit for driving the magnetic recording medium in a recording direction, a magnetic head including a recording unit and a reproducing unit, a unit for moving the magnetic head relative to the magnetic recording medium, in the magnetic storage device having a recording and reproduction signal processing means for performing an output signal reproduced from the signal input and the magnetic head to the magnetic head, by constituting the reproduction unit of the magnetic head with a magnetoresistive head, Sufficient signal strength at a high recording density can be obtained, and a highly reliable magnetic storage device having a recording density of 1 gigabit per square inch or more can be realized.

Further, the magnetic recording apparatus of the present invention is used in the present invention.
2 sandwiching the magnetoresistive sensor unit of the magnetoresistive head
The interval between the shield layers (shield interval) is 0.35 μm
The following is preferred. This means that the shield spacing is 0.35 μm
This is because the resolution is reduced and the phase jitter of the signal is increased.

Further, the magneto-resistance effect type magnetic head includes a plurality of conductive magnetic layers which generate a large resistance change when their magnetization directions are relatively changed by an external magnetic field;
It is composed of a magnetoresistive sensor including a conductive non-magnetic layer arranged between the conductive magnetic layers, and has a giant magnetoresistive effect,
Alternatively, by utilizing the spin valve effect, the signal strength can be further increased, and a highly reliable magnetic storage device having a recording density of 2 gigabits per square inch or more can be realized.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> An embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. FIGS. 1 (a) and 1 (b) show a schematic plan view and a schematic sectional view of the magnetic storage device of this embodiment. This apparatus comprises a magnetic head 1, a driving unit 2, a recording / reproducing signal processing means 3 for the magnetic head, a magnetic recording medium 4, and a driving unit 5 for rotating the magnetic recording medium.
This is a magnetic storage device having a known structure comprising:

FIG. 2 shows the structure of the magnetic head. The magnetic head is a composite head having both a magnetoresistive head for reproducing an electromagnetic induction type magnetic head for recording formed on the base 6. The recording head is a coil 7
The upper recording magnetic pole 8 and the lower recording magnetic pole / upper shield layer 9 sandwiching the magnetic recording medium and the gap layer thickness between the recording magnetic poles was 0.3 μm. Cu having a thickness of 3 μm was used for the coil. The reproducing head comprises a magnetoresistive sensor 10 and electrode patterns 11 at both ends thereof. Both magnetoresistive sensors are sandwiched between a lower recording magnetic pole / upper shield layer and a lower shield layer 12 each having a thickness of 1 μm. 25 μm.
In FIG. 2, the gap layer between the recording magnetic poles and the gap layer between the shield layer and the magnetoresistive sensor are omitted.

FIG. 3 shows a sectional structure of the magnetoresistive sensor.
The signal detection region 13 of the magnetic sensor includes a portion in which a lateral bias layer 15, a separation layer 16, and a magnetoresistive ferromagnetic layer 17 are sequentially formed on a gap layer 14 of Al oxide. A 20 nm NiFe alloy was used for the magnetoresistive ferromagnetic layer. NiFeNb of 25 nm was used for the lateral bias layer.
Any ferromagnetic alloy such as Rh or the like having a relatively high electric resistance and good soft magnetic properties may be used. The lateral bias layer is magnetized in an in-plane direction (lateral direction) perpendicular to the current by a magnetic field generated by a sense current flowing through the magnetoresistive ferromagnetic layer, and applies a lateral bias magnetic field to the magnetoresistive ferromagnetic layer. As a result, a magnetic sensor showing a linear reproduction output with respect to the leakage magnetic field from the medium can be obtained. The separation layer for preventing the shunt of the sense current from the magnetoresistive ferromagnetic layer has a relatively high electric resistance of T.
a, and the film thickness was 5 nm.

At both ends of the signal detection area, there are tapered portions 18 formed into a tapered shape. The taper is
It comprises a permanent magnet layer 19 for converting the ferromagnetic layer into a single magnetic domain, and a pair of electrodes 11 formed thereon for extracting signals. The permanent magnet layer needs to have a large coercive force and the magnetization direction does not easily change, and CoCr, CoCrPt alloy, or the like is used.

FIG. 4 shows the layer structure of the magnetic recording medium of this embodiment. As the substrate 20, soda lime glass that has been chemically strengthened was used. The first underlayer 21 made of Co-30at% Cr-10% Zr alloy is 50 nm thereon, and the second underlayer 22 made of Cr-15at% Ti alloy is 30 nm, Co-20at% Cr-12at% Pt. 20 nm for the alloy magnetic layer 23,
Further, a carbon protective film 24 of 10 nm was formed by DC sputtering. The first underlayer is formed without heating the substrate,
Then, it heated to 250 degreeC with the lamp heater, and formed each layer on it. After forming the film, a material obtained by diluting a perfluoroalkylpolyether-based material with a fluorocarbon material was applied as a lubricant 25. Further, a medium using Cr-15at% Ti for the first underlayer was produced under the same conditions as above, and this was used as a comparative example.

The coercive force of the medium of the present example was 2620 Oe and about 400 Oe higher than that of the medium of the comparative example, and the product Br × t of the residual magnetic flux density and the thickness of the magnetic layer was 85 Gauss / micron. Incorporated in the magnetic storage device, the linear recording density 210 kBP
When the recording and reproducing characteristics were evaluated under the conditions of I and track density of 9.6 kTPI, the S / N was about 15% higher than that of the comparative medium.
It was 1.8.

When a single layer film of only the CoCrZr alloy as the first underlayer was formed on a glass substrate under the same conditions at a thickness of 50 nm, and X-ray diffraction was measured, no clear diffraction peak was observed. When the structure of the CoCrZr alloy film was examined using a transmission electron microscope (TEM), a TEM image and a selected area diffraction pattern as shown in FIG. 5 were obtained. The white spot and ring at the upper right corner of the figure are the selected area diffraction patterns. The selected area diffraction pattern was obtained from a region having a diameter of about 0.5 μm. The TEM image shows no lattice image indicating the existence of the crystal structure, and the selected area diffraction pattern shows a halo-shaped diffraction ring unique to amorphous. From this, it is considered that the CoCrZr alloy of the first underlayer has an amorphous structure. In the TEM image, shading reflecting fine irregularities on the surface of the first underlayer was observed. These irregularities are formed quite uniformly at a pitch of several nm.

As a result of measuring the X-ray diffraction of the medium of this example and the medium of the comparative example in which the carbon protective film was formed, FIG.
Was obtained. In the diffraction pattern of the medium of the comparative example, since the first underlayer and the second underlayer have the same composition, the diffraction peaks of the two cannot be distinguished. In addition, since the (110) peak of the body-centered cubic structure (bcc structure) of the underlayer overlaps the (00.2) peak of the hexagonal close-packed structure (hcp structure) from the magnetic layer, it is impossible to discriminate between the two. is there. However, in any case, the second underlayer is as strong as the working medium (100)
It is not oriented and is a mixed phase of a plurality of crystal grains having different orientations. Therefore, the CoCrPt alloy crystal in the magnetic layer also has various crystal orientations, and a plurality of diffraction peaks are observed from the CoCrPt magnetic layer. On the other hand, in the example medium, since the CoCrZr alloy of the first underlayer does not show a diffraction peak as described above, the diffraction peak in the drawing is bcc (200) from the second underlayer.
The peak and the hcp (11.0) peak from the CoCrPt magnetic layer. From this, the CrTi alloy of the second underlayer formed on the CoCrZr alloy layer having the amorphous structure has a (100) orientation, and the CoCrPt magnetic layer thereon is epitaxially grown (11.
0) It turns out that it has taken the orientation. For this reason, the component in the in-plane direction of the c-axis, which is the axis of easy magnetization of the CoCrPt alloy, increases, and good magnetic properties can be obtained. Furthermore, the TEM of the magnetic layer
As a result of observation, the average crystal grain size of the CoCrPt alloy of this example was about 16.1 nm, which was about 3 nm finer than the comparative example. In addition, when the magnetization of the single-layer CoCrZr alloy single-layer film was measured, no clear hysteresis curve was obtained, so the alloy film is considered to be nonmagnetic.

<Embodiment 2> In the same magnetic storage device as in Embodiment 1, a magnetic recording medium using a CoMnTa alloy for the first underlayer was used.

The film configuration of the medium is the same as in the first embodiment. After heating the tempered glass substrate to 150 ° C, the C
o-36at% Mn-10% Ta alloy, 10mTorr argon with 5% nitrogen
A 30 nm film was formed in the mixed gas atmosphere. Thereafter, the substrate was heated again so that the substrate temperature became 250 ° C., and the CrV alloy of the second underlayer was formed to 30 nm, the CoCrNiPt alloy magnetic layer was formed to 30 nm, and the carbon protective film was formed to 10 nm in order. Each layer after the second underlayer was formed under a pure argon gas pressure of 5 mTorr. The coercive force of the obtained medium was 2560 Oersted. To study the magnetization of the single-layer film of the Co-36at% Mn-10% Ta alloy of the first underlayer, and the film structure, the single-layer film
m, formed on a tempered glass substrate under the same conditions as above. When the magnetization of this single layer film was measured, the saturation magnetic flux density was about
It was about 80G. When the particle size was observed by TEM,
The average crystal grain size of the CoMnTa alloy single layer film was about 3 nm or less. As a result of X-ray diffraction measurement of the medium formed up to the carbon protective film, the CrV alloy of the second underlayer was (100) as in Example 1.
It was found that the CoCrNiPt alloy was oriented (11.0) by epitaxial growth. Furthermore, when the CoCrNiPt alloy of the magnetic layer was observed by TEM, the average crystal grain size was about 19 nm. In this embodiment, the film formation is all
Although the sputtering was performed by the DC sputtering method, the same effect can be obtained by an ion beam sputtering method, an ECR sputtering method, or the like.

After applying the lubricant, a linear recording density of 210 kBP
As a result of performing recording and reproduction characteristics under the conditions of I and track density of 9.6 kTPI, a high device S / N of 1.8 was obtained. When a CSS test (contact start / stop test) was performed, the coefficient of friction was less than 0.3 even after 30,000 times of CSS. Also, head seek test from the inner circumference to the outer circumference of the medium
The number of bit errors after 50,000 times was less than 10 bits / plane, and an average failure interval of 300,000 hours or more was achieved.

Example 3 In order to examine the adhesion of the film,
Each single-layer film of the following first underlayer was formed on a glass substrate, and a peeling test was performed.

The CoCrZr alloy, CoMnTa alloy and Co-30at% Cr alloy, Co-20at% Cr-10at% of Examples 1 and 2
An SiO2 alloy was used. A single layer film of a CoCrZr alloy and a CoMnTa alloy was formed on a glass substrate under the same conditions as described above. The CoCr alloy and the CoCrSiO2 alloy formed a single-layer film under the same conditions as in Example 2. For comparison, Cr was used for the first underlayer,
A single-layer film was formed under the same conditions as in Example 2. In the peeling test, a 3 mm x 3 mm mesh was cut on the membrane surface with a cutter knife.
After individual injury, a tape was applied, and peeling was performed 40 to 48 hours later. The adhesion was evaluated by the area ratio of the peeled portion. FIG. 7 shows the results of the peeling test. C for the first underlayer
All systems using the alloy consisting of o showed good adhesion. In the case where the compound of oxide and Co was used,
The first underlayer of No. 2 was better than the underlayer of Example 1.

<Embodiment 4> In the same magnetic storage device as in Embodiment 1, a magnetic recording medium using a CoCrW alloy for the first underlayer was used.

In the same manner as in Example 1, Co-
A 25 at% Cr-12 at% W alloy was formed to a thickness of 25 nm. However, at this time,
Substrate heating is not performed, and argon gas pressure during film formation is 5 to 30 m
Changed to Torr. After the formation of the underlayer, the substrate was heated to 220 ° C., and the CrMo underlayer 50 nm, the CoCrPtTa magnetic layer
25 nm and a carbon protective film of 10 nm were sequentially formed.

First, as in the case of Examples 1 and 2, only the CoCrW alloy of the first underlayer was formed on a glass substrate under an argon gas pressure of 5 to 25 mTorr, and the X-ray diffraction was measured. went. As a result, the argon gas pressure during film formation is 5 to 10 mTorr
Is relatively low, a strong hcp from the CoCrW single layer film
A (20.2) peak was observed, indicating that the film had an (00.1) oriented hcp structure. However, as the argon gas pressure increased (20.2), the peak intensity decreased sharply, and the gas pressure decreased to 15m.
Above Torr, no clear diffraction peak was observed. Next, the medium formed up to the carbon protective film was measured for X-ray diffraction. From the obtained diffraction pattern, the intensity ratio between the (200) peak and the (110) peak from the second underlayer CrMo alloy and the intensity ratio between the (11.0) peak and the (00.2) peak from the magnetic layer And the relationship with the argon gas pressure during the formation of the first underlayer was examined. FIG. 8 shows the results. The symbol in the figure, for example, ICo11.0 represents the (11.0) diffraction peak intensity from the CoCrPtTa layer, and the same notation is used for other peak intensities. When the argon gas pressure at the time of forming the first underlayer is 10 mTorr or less, the CrMo alloy of the second underlayer has a bcc (110) orientation, and the CoCrPtTa magnetic layer has an hcp (10.1) orientation. On the other hand, when the argon gas pressure becomes 15 mTorr or more, the intensity of the (110) peak from the second underlayer rapidly decreases, and instead, the (200) peak increases. Accompanying this, the peak intensity ratio from the CoCrPtTa alloy magnetic layer also sharply changes, and the (11.0) peak sharply increases. FIG. 9 shows the relationship between the coercive force of the medium and the gas pressure during the formation of the CoCrW alloy. The coercive force is an argon gas pressure of 10 to 15 mTor where the crystal orientation changes rapidly.
It has increased sharply beyond the border. From the above, the CoC of the first underlayer was formed at an argon gas pressure of 15 mTorr or more.
By forming the rW alloy shape, the underlayer becomes amorphous,
Alternatively, it was found that the CrMo underlayer had a (100) orientation and the CoCrPtTa magnetic layer had a (11.0) orientation, and the coercive force was increased.

A similar tendency is observed when the second underlayer is made of, for example, Cr
When other Cr alloys such as Ti and CrV are used, or CoC
This was also observed when other Co alloys such as rPt and CoCrTa were used.

After applying the lubricant, a linear recording density of 210 kBP
Recording characteristics were performed under the conditions of I and track density of 9.6 kTPI. The apparatus S / N improved with the increase of the argon gas pressure during the formation of the CoCrW alloy, and a value of 1.6 or more was obtained at 15 mTorr or more. Also, a head seek test from the inner circumference to the outer circumference of the medium
The number of bit errors after 50,000 times was less than 10 bits / plane, and an average failure interval of 300,000 hours or more was achieved.

Fifth Embodiment In a magnetic storage device similar to that of the first embodiment, a sensor shown in FIG. 10 was used for a reproducing magnetic head. This sensor has a 5 nm Ta buffer layer 26, 7n on the gap layer 14.
m first magnetic layer 27, 1.5 nm Cu intermediate layer 28,
3 nm second magnetic layer 29, 10 nm Fe-50 at
% Mn antiferromagnetic alloy layer 30 is sequentially formed. A Ni-20 at% Fe alloy was used for the first magnetic layer, and Co was used for the second magnetic layer. The magnetization of the second magnetic layer is fixed in one direction by the exchange magnetic field from the antiferromagnetic layer. On the other hand, the direction of magnetization of the first magnetic layer, which is in contact with the second magnetic layer via the non-magnetic layer, changes due to the leakage magnetic field from the magnetic recording medium, so that a resistance change occurs. Such a change in resistance due to a change in the relative direction of magnetization of the two magnetic layers is called a spin valve effect. In this embodiment, a spin valve magnetic head utilizing this effect is used as a reproducing head. The tapered portion has the same configuration as the magnetic sensor of the first embodiment.

In the magnetic recording medium, a first underlayer, a second underlayer, a magnetic layer, and a carbon protective film were formed on a glass substrate.
Those formed sequentially in the same process as 1 were used. For the first underlayer, a 20nm Co-40at% V-12at% M alloy (M = Ti,
Y, Zr, Nb, Mo, Hf, Ta, W, B) were used, a 50 nm CrTi alloy was used for the second underlayer, and a 22 nm CoCrPt alloy was used for the magnetic layer.

As a result of TEM observation, the first underlayer had an amorphous or microcrystalline structure similar thereto. As a result of X-ray diffraction measurement, it was found that the CrTi alloy of the second underlayer was (100) oriented and the CoCrPt magnetic layer was (11.0) oriented. This tendency was the same when any of the above-mentioned Co-VM alloys was used for the first underlayer. Coercive force, coercive force squareness ratio of a recording medium using each alloy material for the first underlayer,
Table 1 shows the intensity ratio between the (11.0) peak and the (10.1) peak from the CoCrPt magnetic layer (referred to as ICo11.0 / ICo10. 1).

[0045]

[Table 1]

As a comparative example, this table shows that the first underlayer
The values when Cr is used are also shown. In the medium of the comparative example, the CrTi of the second underlayer is strongly (110) oriented, so that CoC
The rPt magnetic layer is oriented (10.1), and the (1
1.0) No peak is observed. On the other hand, in the medium of the present embodiment, as described above, the CoCrPt magnetic alloy is strong in all cases (11.
0) Because it is oriented, c is the axis of easy magnetization of the magnetic alloy
The in-plane component of the shaft is large, and a high coercive force and a high coercive force squareness ratio can be obtained. In particular, when M = Zr, Ta, W, (1) of the CoCrPt magnetic layer
1.0) Diffraction is strong, and the in-plane orientation component of the easy axis is large.

After the lubricant was applied, the recording / reproducing characteristics were measured under the condition of a recording density of 2 gigabits per inch.
A high S / N value of 1.6 or more was obtained. Further, the medium of this example had a coefficient of friction of 0.2 or less even after performing 30,000 times of CSS, and exhibited better CSS characteristics than the medium of Example 2.

<Embodiment 6> In the magnetic recording medium of the embodiment, instead of the Co-30at% Cr-10% Zr alloy layer, T was added to Co-30at% Cr.
Using a magnetic recording medium using a layer to which oxides of i, Y, Zr, Nb, Mo, Hf, Ta, W and B were added as a first underlayer, a magnetic storage device similar to that of Example 1 was used. Configured.

As a result of TEM observation, the underlayer was amorphous,
Or a microcrystalline structure close to it. Also, as a result of X-ray diffraction measurement, the CrTi alloy of the second underlayer was (100) oriented, C
The oCrPt magnetic layer was found to be (11.0) oriented. table
2, the coercive force, coercive force squareness ratio when each underlayer is used,
Also, the X-ray diffraction peak intensity ratio ICo11.0 / ICo10.1.

[0050]

[Table 2]

In particular, when an oxide of Zr, Ta, or W is added, the (11.0) diffraction of the CoCrPt magnetic layer becomes strong, and the in-plane orientation component of the easy axis of magnetization increases.

After the lubricant was applied, the recording / reproducing characteristics were measured under the condition of a recording density of 2 gigabits per inch.
A high S / N value of 1.6 or more was obtained. Further, the medium of this example had a coefficient of friction of 0.2 or less even after performing 30,000 times of CSS, and exhibited better CSS characteristics than the medium of Example 2.

When a magnetic layer was formed directly on the first Co alloy underlayer of the present invention having an amorphous structure or a microcrystalline structure similar thereto, the magnetic layer showed a strong (00.1) orientation. This is an orientation in which the c-axis of the Co alloy crystal of the magnetic layer is perpendicular to the film surface and cannot be used as an in-plane magnetic recording medium, but is suitable for a perpendicular magnetic recording medium.

<Embodiment 7> In a magnetic recording medium having the same film configuration as that of Embodiment 1, the second underlayer was made of a 10 nm layer of Cr and a Cr-15at% Ti alloy formed thereon. 20nm
The magnetic recording medium composed of the two layers was manufactured. Other film configurations and film forming processes are the same as those in the first embodiment. As a comparative example, in the above magnetic recording medium, a Y (yttrium) -M alloy (M = Ti, Nb, V,
Ta) and a magnetic recording medium using Cr were produced.

The coercive force of the medium of this embodiment was 2710 Oersted. On the other hand, the coercive force of the medium of the comparative example using the first underlayer where M of the YM alloy is V is 2030 Oe, which is smaller than the medium of the present example. T as M
Almost the same results were obtained when i, Nb, and Ta were used. This is due to the difference in the strength of the (11.0) orientation of the magnetic layer. That is, when a YM alloy is used for the first underlayer,
Since the magnetic layer is not strongly (11.0) oriented unlike the medium of Example 1, good magnetic properties cannot be obtained. FIG. 11 (a) shows the plane T
4 shows the distribution of the crystal grain size of the magnetic layer of the medium of the present example determined from the EM image. Also, FIG. 11 (b) is based on the data of FIG. 11 (a),
It is a figure which shows the particle size accumulation curve which took the area percentage of the crystal grain below a certain crystal grain size on the vertical axis. The average crystal grain size obtained from this data was 17.5 nm, and the particle size distribution was 10.1 nm. Here, the average crystal grain diameter <D> is a crystal grain diameter at which the value on the vertical axis in FIG. 11 (b) is 50%, and the particle diameter dispersion width ΔD is 75% on the vertical axis.
The difference in the crystal grain size was 25%. Table 3 shows a comparison between the average crystal grain size and the grain size dispersion width of the media of this example and the comparative example.

[0056]

[Table 3]

The crystal grain size of the magnetic layer is about 10 to 20% finer when the Co alloy is used than when the YV alloy or Cr is used for the first underlayer. The dispersion width of the crystal grain size was about 25-30% smaller. This is the first underlayer C
o It is considered that the distribution of crystal nucleation sites on the alloy surface is more uniform.

When the recording and reproducing characteristics were evaluated under the same conditions as in Example 1, the medium of this example was 1.9,
In the case of the comparative example using the M alloy for the first underlayer, 0.8 to
Only about 1.1 S / N was obtained. This is considered to be due to the decrease in the reproduction output due to the decrease in the orientation and the increase in the medium noise due to the non-uniform grain size of the Co alloy crystal grains in the magnetic layer as described above. Such a tendency was also observed when another Co alloy was used for the magnetic layer. From the above, it can be seen that the use of the Co alloy of the present invention for the first underlayer provides more excellent characteristics than the use of the YM alloy for the first underlayer.

The medium of this embodiment using two layers of Cr and CrTi as the second underlayer has higher coercive force and higher S / N than the medium of the first embodiment. This is the first C
o This is because Cr on the alloy underlayer has a stronger (100) orientation than CrTi.

[0060]

The magnetic recording medium of the present invention has effects such as a reduction in medium noise and an increase in coercive force. By using the magnetic recording medium and the magnetoresistive head of the present invention, a magnetic storage device having a recording density of 2 gigabits per square inch and an average number of failures of 300,000 hours or more can be realized.

[Brief description of the drawings]

FIGS. 1A and 1B are a schematic plan view of a magnetic storage device according to an embodiment of the present invention and an AA ′ line thereof, respectively.
It is sectional drawing.

FIG. 2 is a perspective view showing an example of a sectional structure of a magnetic head in the magnetic storage device of the present invention.

FIG. 3 is a diagram showing a magnetic head of the magnetic storage device according to the present invention;
It is a schematic diagram which shows an example of the cross-sectional structure of a magnetoresistive sensor part.

FIG. 4 is a schematic diagram illustrating an example of a cross-sectional structure of a magnetic recording medium according to the present invention.

FIG. 5 is a schematic diagram of a plane transmission electron microscope image and a selected area diffraction pattern of a first underlayer containing Co used in an embodiment of the magnetic recording medium of the present invention.

FIG. 6 is an X-ray diffraction pattern of a magnetic recording medium according to an example of the present invention and a medium according to a comparative example.

FIG. 7 is a diagram showing film adhesion of a first underlayer.

FIG. 8 shows argon gas pressure and CrM during formation of a first underlayer.
FIG. 9 is a diagram showing a relationship between intensity ratios of diffraction peaks from an underlayer and a CoCrPtTa magnetic layer.

FIG. 9 is a diagram showing a relationship between an argon gas pressure and a coercive force when a first underlayer is formed.

FIG. 10 is a schematic diagram showing an example of a cross-sectional structure of a magnetic resistance sensor section of a magnetic head in the magnetic storage device of the present invention.

FIGS. 11A and 11B are diagrams showing a crystal grain size distribution of a magnetic layer in a magnetic recording medium according to one embodiment of the present invention, and a grain size accumulation curve thereof.

[Explanation of symbols]

1. . . 1. magnetic head; . . Magnetic head drive,
3. . . 3. recording / playback signal processing system; . . Magnetic recording media,
5. . . 5. magnetic recording medium drive; . . Substrate, 7. . .
Coil, 8. . . 8. upper recording pole; . . 10. lower recording pole and upper shield layer; . . Magnetoresistive sensor, 1
1. . . 11. conductor layer; . . Lower shield layer, 1
3. . . 13. signal detection area; . . 14. gap layer between shield layer and magnetoresistive sensor; . . Lateral bias layer,
16. . . Separation layer, 17. . . Magnetoresistive ferromagnetic layer, 1
8. . . Tapered portion, 19. . . 20. permanent magnet layer, .
Substrate, 21. . . First underlayer, 22. . . Second underlayer, 23. . . Magnetic layer, 24. . . Protective film, 25. . .
Lubrication film, 26. . . Buffer layer, 27. . . First magnetic layer, 28. . . Middle layer, 29. . . Second magnetic layer, 3
0. . . Antiferromagnetic layer.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Fukaya 2880 Kozu, Kodahara, Kanagawa Prefecture Storage Systems Division, Hitachi, Ltd. (72) Inventor Ichiro Tamai 1-280, Higashi Koikebo, Kokubunji, Tokyo In the laboratory (72) Inventor Yasuo Yakuo 2880 Kozu, Odawara-shi, Kanagawa Prefecture Hitachi, Ltd.Storage Systems Division (72) Inventor Joe Hosoe 1-280, Higashi-Koikekubo, Kokubunji-shi, Tokyo Within the Hitachi, Ltd. ) Inventor Kazu Tanahashi 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (72) Inventor Yoshifumi Matsuda 2880 Kozu, Kokuzu, Odawara-shi, Kanagawa Pref. Hiroyuki Kataoka 2880 Kozu, Kozuhara-shi, Odawara-shi, Kanagawa Pref.Hitachi, Ltd. Storage Systems Division (72) Inventor Toshinori Ohno 2880 Kotsu, Kokutsu, Odawara-shi, Kanagawa Pref. 2880 Kozu, Hitachi, Ltd. Storage Systems Division, Hitachi, Ltd. (72) Inventor Kazuhiro Ura 2880 Kofu, Odawara, Kanagawa Prefecture, Hitachi, Ltd. Storage Systems Division, Hitachi, Ltd. (56) References JP-A-5-128481 (JP, A) Kaihei 7-14144 (JP, A) JP-A-4-153910 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/738 G11B 5/64-5/65 H01F 10/16 H01F 10/30

Claims (8)

(57) [Claims] And 1. A first under layer amorphous or microcrystalline containing Co which is formed on the substrate, a body-centered cubic structure containing Cr which is formed on the first underlayer 2. An in-plane magnetic recording medium, comprising: a second underlayer; and a magnetic layer having a hexagonal close-packed structure containing Co formed on the second underlayer. 2. The method according to claim 1, wherein the first underlayer is made of Ti, Y, Zr, Nb, Mo, Hf, Ta, W, S as a first additive element.
2. The longitudinal magnetic recording medium according to claim 1, wherein the medium contains at least one element selected from the group consisting of i and B. 3. The method according to claim 2, wherein the first underlayer further contains at least one element selected from the group consisting of Cr, V and Mn as a second additive element. In-plane magnetic recording medium. Wherein the concentration of the first additive element, 5at% or more in-plane magnetic recording medium according to claim 3, characterized in that not more than 70 at%. Wherein said first underlayer plane magnetic recording medium according to claim 1, any one of 4, which is a Co-Cr-Zr alloy. 6. A product according to claim 1 , wherein a product of a residual magnetic flux density and a film thickness of said first underlayer is 20% or less of a product of a residual magnetic flux density and a film thickness of said magnetic layer. Any one of
Item 6. The longitudinal magnetic recording medium according to item 1. 7. The first underlayer having an average crystal grain size of 8 nm.
The in-plane magnetic recording medium according to any one of claims 1 to 6, wherein: 8. A longitudinal magnetic recording medium according to any one of claims 1 to 7 (11.0) plane of the magnetic layer is characterized by being oriented parallel to the substrate surface.