JPH04278219A - Magnetic recording medium and magnetic memory device - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium which is excellent in sliding resistance and proper to high-density recording and to provide a high-reliability large-capacity magnetic memory device. CONSTITUTION:In a magnetic recording medium having at least one layer of a protective covering layer 14 and 14' on a magnetic layer 13 and 13', the absolute value of an internal stress remaining in the magnetic recording medium 14 and 14' is less than 1GPa. According to the invention, further a magnetic memory device having the magnetic recording medium surface can be provided. The application of the protective covering layer in which the absolute value of the stress remaining inside is less than 1GPa, enhances the adhesion of the magnetic layer and the protection covering layer, which makes it possible to enhance sliding resistance and hence provide a high-reliability and large-capacity magnetic memory device.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to magnetic recording media used in flexible magnetic disk devices, drum-type magnetic storage devices, tape-type magnetic storage devices, card-type magnetic storage devices, rigid-type magnetic disk devices, etc. Related to magnetic storage devices.

0002

2. Description of the Related Art In order to cope with the increasing density of magnetic recording, research and development is progressing on magnetic recording media having thin magnetic layers such as iron oxide thin films, iron nitride thin films, and magnetic alloy thin films as recording layers. These thin film media are often formed on nonmagnetic substrates by sputtering, vacuum evaporation, plating, ion plating, or other techniques. These materials are suitable for high recording density because of their small film thickness, large coercive force, and large magnetization. However, magnetic recording media using the magnetic thin film described above have the problem of being easily damaged by sliding of the magnetic head and having poor sliding resistance. Since magnetic recording media used as magnetic files are particularly required to have a high degree of reliability, overcoming the above problems is extremely important in realizing high recording density.

In order to solve the above-mentioned problems in conventional magnetic recording media using continuous thin films, a method of forming a C-based protective coating layer on the magnetic film (Japanese Unexamined Patent Publication No. 61-54017, Japanese Unexamined Patent Publication No. 61-61) has been proposed. -54019), a method of further forming an organic liquid lubricant on the C-based protective coating layer (Japanese Patent Laid-Open No. 61-9
6512), a method for forming a WC protective coating layer (JP-A-49-20081, JP-A-53-21901)
(Japanese Patent Application Laid-Open No. 53-21902), Si, Zr
, Hf, Ti, Ta, Nb, W forming a nitride or carbide protective coating layer (US Patent No. Re.3246)
4), a method of forming a protective coating layer of oxides, nitrides, carbides, and borides of Zr, Ti, Ta, and Hf (Japanese Unexamined Patent Publication No. 6)
3-66722) etc. have been proposed.

0004

[Problems to be Solved by the Invention] However, according to the studies of the present inventors, in the case of the prior art having the above-mentioned protective coating layer, although the hardness of the protective coating layer is relatively high, the magnetic layer The problem is that the adhesion between the magnetic recording medium and the protective coating layer is low, causing rapid damage to the magnetic recording medium such as cracking and peeling, and insufficient sliding resistance when vibrations are applied to the device. Ta. The present invention has been made in view of the above points, and is based on a magnetic layer made of metal, oxide, nitride, etc.
By forming a highly hard and tough protective coating layer with excellent adhesion to the magnetic layer, we are able to create magnetic recording media with excellent abrasion resistance and suitable for high-density recording, as well as highly reliable large-capacity magnetic storage devices. The purpose is to provide.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides at least one protective coating layer on a magnetic layer, and reduces the absolute value of internal stress remaining in the protective coating layer to 1.
GPa or less. In addition, by combining such a magnetic recording medium with a magnetic head that contains at least a metal magnetic alloy in a part of the magnetic core and whose magnetic core is substantially made of zirconia or ferrite, the storage capacity can be increased compared to conventional ones. A magnetic storage device that is 1.5 times larger can be manufactured. Here, it is more preferable to provide a lubricant layer having at least one adsorbent end group on the protective coating layer, since the sliding resistance and corrosion resistance can be significantly improved. It is more desirable that the absolute value of the internal stress remaining in the protective coating layer is 0.5 GPa or less,
A pressure of 0.3 GPa or less is particularly desirable because it further improves sliding resistance. Furthermore, the thickness of the above protective coating layer was increased to 3 nm.
60 nm or more, more preferably 3 nm or more and 40 nm
The thickness is more preferably 5 nm or more and 30 nm or less, which is particularly desirable because it keeps the sliding resistance high and also improves the recording and reproducing characteristics.

Furthermore, the magnetic head used in the magnetic storage device includes a metal magnetic alloy as at least a part of the magnetic core, and by making zirconia or ferrite the main component of the magnetic core, the reliability of the magnetic storage device is improved. It is particularly desirable because it can significantly improve the performance.

[0007]

[Action] The above effect is due to the following action. When a C-based protective coating layer is used, when WC is used as a protective coating layer, or when nitrides or carbides of Si, Zr, Hf, Ti, Ta, Nb, and W are used as a protective coating layer, Furthermore, when oxides, nitrides, carbides, and borides of Zr, Ti, Ta, and Hf are used as the protective coating layer, these materials exhibit high hardness, so in principle, the thin film protective coating layer of the magnetic recording medium can be used. It can be used as However, as a result of examining the sliding resistance of magnetic recording media formed with the above-mentioned materials as a protective coating layer, it was found that these magnetic recording media do not exhibit sufficient sliding resistance in some cases when subjected to high loads such as impacts. It became clear that there is. This is because the protective coating layer is brittle, and the internal stress that remains in the protective coating layer is generally large, so the adhesion force with the magnetic layer is also small. Cracks occur inside the magnetic layer and at the interface between the magnetic layer and the protective coating layer.
This is because it is easy to peel off and break.

On the other hand, according to the studies of the present inventors, using a protective coating layer in which the absolute value of internal stress is 1 GPa or less results in excellent adhesion between the magnetic layer and the protective coating layer. Therefore, it has become clear that the sliding resistance can be improved.

[0009] Here, further, taking Example 1 of the present invention as an example,
The range of the above internal stress will be explained. As shown in Figure 2, when the absolute value of internal stress is 1 GPa or less,
When the flaw width after sliding was 40 μm or less and 0.5 GPa or less, the flaw width was 25 μm or less, and when it was 0.3 GPa or less, the flaw width was 20 μm or less. According to the inventors' study, the scratch width was 40 μm, 25 μm, and 20 μm.
m corresponds to approximately 10,000 times, 50,000 times, and 100,000 times or more of CSS (contact, start, stop) characteristics, respectively. Therefore, it is preferable that the absolute value of the internal stress is 1 GPa or less because it is possible to ensure practically sufficient sliding resistance of 10,000 CSS cycles or more. It is more desirable that the absolute value of the internal stress is 0.5 GPa or less, as this further improves the sliding resistance.
A pressure of 0.3 GPa or less is particularly desirable because high sliding resistance of 100,000 CSS cycles or more can be ensured.

Next, the preferred range of the thickness of the protective coating layer will be explained. The thickness of the above protective coating layer is 3 nm or more 60
It is desirable that it be less than nm. This is because the film thickness is 3
A protective coating layer with a thickness of less than 60 nm cannot make a sufficient contribution to improving the sliding resistance of a magnetic recording medium, and conversely, a protective coating layer with a thickness of more than 60 nm unnecessarily separates the distance between the magnetic layer and the magnetic head. This is because the recording and reproducing characteristics will deteriorate. In order to improve recording/reproducing characteristics and maintain practical sliding resistance, the thickness of the protective coating layer is preferably 3 nm or more and 40 nm or less, more preferably 5 nm or more and 30 nm or less.

When a material having a thermal conductivity of about 0.005 cal/sec/cm/deg or more is used as the core material of a magnetic head, such as zirconia, ferrite, or alumina, thermal distortion occurs less, and lubricant It is particularly preferred because it has less thermal volatilization and improves sliding resistance.

0012

Embodiments Embodiment 1 FIG. 1 is a block diagram of a magnetic recording medium according to Embodiment 1 of the present invention.

[0013] 130 plated with NiP and provided with unevenness approximately in the circumferential direction on the surface with a center line average surface roughness of 10 nm.
The substrate temperature was 300°C and the argon gas pressure was 2 m on an Al-Mg alloy substrate 11 with a diameter of mm by RF magnetron sputtering.
Torr, input power 10W/cm2, film thickness 50nm C
r Nonmagnetic underlayers 12, 12', Co0.
After forming the 86Cr0.12Ta0.02 magnetic layers 13, 13', (W0.9Co0.1)0.5C0.5 protective coating layers 14, 14' are formed by DC magnetron sputtering.
Same conditions as non-magnetic underlayer and magnetic layer, or substrate temperature 2
The film forming conditions were changed from those of the non-magnetic underlayer and magnetic layer to form a 30 nm thick film at 50° C., argon gas pressure of 2 to 15 mTorr, and input power of 0.5 to 5 W/cm2, and it also had an adsorbent ester group at the end. Perfluoroalkyl polyester
A magnetic disk was prepared by providing a 4 nm thick lubrication layer. The residual internal stress in the protective coating layer can be evaluated by measuring the position of the X-ray diffraction peak in the protective coating layer in detail, or by separately fabricating a sample on a silicon wafer with the same configuration as the above-mentioned magnetic disk. A method of measuring the amount of deflection of a silicon wafer with and without a protective coating layer was adopted. To evaluate the sliding resistance, a zirconia spherical slider with a curvature of 30 mm was pressed against the surface of the magnetic disk with a load of 10 gf, and the magnetic disk was rotated at a relative speed of 10 m/s with the slider for 3600 sliding movements. A method was adopted to measure the width of scratches that occurred on the surface of magnetic disks. FIG. 2 shows the relationship between the absolute value of residual internal stress in the protective coating layer and the sliding resistance.

Generally, the absolute value of the internal stress remaining in the protective coating layer can be reduced by increasing the gas pressure during film formation or by forming the film at a relatively low temperature. In the case of a protective coating layer with an absolute value of internal stress of 1 GPa or more, if the non-magnetic underlayer and magnetic layer are removed by etching etc. and the protective coating layer insoluble in the etching solution is released, the protective coating layer will be able to absorb the large internal stress. Therefore, it was curled into a fine string. On the other hand, the protective coating layer whose absolute value of internal stress was 0.5 GPa or less hardly curled. From this, it can be understood that if the internal stress is small, the protective coating layer will remain stable even against minute scratches on the surface caused by sliding. Conversely, the residual internal stress in the protective coating layer can also be determined by this method.

Embodiment 2 Next, another embodiment of the magnetic disk having the structure shown in FIG. 1 will be described. NiP is plated on the surface,
A film was formed by RF magnetron sputtering on a 130 mmφ Al-Mg alloy substrate 11 with irregularities of 10 nm in centerline average surface roughness in the circumferential direction at a substrate temperature of 300° C., an argon gas pressure of 3 mTorr, and an input power of 5 W/cm2. Thickness 60nm
After forming Cr0.9Ti0.1 nonmagnetic underlayers 12, 12' and Co0.83Cr0.12Pt0.05 magnetic layers 13, 13' with a film thickness of 40 nm, a carbon protective coating layer 1 is formed.
4 and 14' by DC magnetron sputtering, substrate temperature 100°C, argon gas pressure 15 mTorr, input power 1.
A perfluoroalkyl polyether lubricating layer having a terminal ester group was formed to a thickness of 30 nm at W/cm2 and a thickness of 4 nm.
It was installed as a magnetic disk.

Embodiment 3 Next, another embodiment of the magnetic disk having the structure shown in FIG. 1 will be described. NiP is plated on the surface,
A 63.5 mmφ Al-Mg alloy substrate 11 with unevenness of 10 nm in centerline average surface roughness in the circumferential direction was coated by RF magnetron sputtering at a substrate temperature of 250° C., an argon gas pressure of 5 mTorr, and an input power of 5 W/cm 2 . film thickness 100
nm Cr nonmagnetic underlayer 12, 12', 50 nm thick Co0.85Cr0.10Pt0.05 magnetic layer 13,1
After forming 3', (W0.6Mo0.3Co0.1)
The 0.5C0.5 protective coating layers 14 and 14' were formed to a thickness of 20 nm by DC magnetron sputtering at a substrate temperature of 200°C, an argon gas pressure of 15 mTorr, and an input power of 1 W/cm2, and were made of perfluoroalkyl polyester having an OH group at the end. - A magnetic disk was prepared by providing a 5 nm thick Teru-based lubricating layer.

Embodiment 4 Next, another embodiment of the magnetic disk having the structure shown in FIG. 1 will be described. The substrate temperature was 300° C. and the argon gas pressure was 1 mTorr using the DC magnetron sputtering method on a reinforced glass substrate 11 of 89 mm diameter whose surface was roughly disordered and had irregularities of 5 nm in centerline average surface roughness by chemical etching. Film thickness 50nm at power 10W/cm2
Cr nonmagnetic underlayers 12, 12', 60 nm thick Co
0.84Cr0.13Ta0.03 magnetic layer 13, 13'
After forming (Zr0.45Nb0.45Co0.1
) 0.5O0.5 protective coating layers 14, 14' were formed by RF magnetron sputtering at a substrate temperature of 150°C and 50% argon.
vol% oxygen 50vol% mixed gas pressure 13mTorr,
A magnetic disk was prepared by forming a 20 nm thick layer using an input power of 1 W/cm 2 and providing a 7 nm thick perfluoroalkyl polyether lubricating layer having an adsorptive polar group containing CN.

Comparative Example 1 Next, a comparative example using a magnetic disk having the structure shown in FIG. 1 will be explained.

[0019] NiP was plated, and the surface was uneven with a center line average surface roughness of 10 nm in the circumferential direction.
mφ Al-Mg alloy substrate 11 was sputtered by RF magnetron sputtering at a substrate temperature of 200°C and an argon gas pressure of 1.5.
mTorr, input power of 1 W/cm2, 300 nm thick Cr nonmagnetic underlayer 12, 12', 70 nm thick Co0
．． After forming the 60Ni0.35Zr0.05 magnetic layers 13, 13', the carbon protective coating layers 14, 14' were formed by DC magnetron sputtering at a substrate temperature of 150°C, an argon gas pressure of 2 mTorr, and an input power of 15 W/cm2 for 30 nm.
A magnetic disk was prepared by forming a perfluoroalkyl polyether lubricant layer having a thickness of 4 nm and having an ester group at the end.

Comparative Example 2 Next, another comparative example using the magnetic disk having the structure shown in FIG. 1 will be described. An 89 mm diameter tempered glass substrate 11 whose surface has been chemically etched to be roughly disordered and has unevenness of 5 nm in centerline average surface roughness is heated by RF magnetron sputtering at a substrate temperature of 350° C. and an argon gas pressure of 1 mTorr. Film thickness 250nm with power 3W/cm2
Cr nonmagnetic underlayers 12, 12', 50 nm thick Co
0.87Cr0.10Ta0.03 magnetic layer 13, 13'
After forming Ti0.5C0.5 protective coating layer 14,1
4' by DC magnetron sputtering at a substrate temperature of 250
°C, argon gas pressure 5mTorr, input power 10W/c
A magnetic disk was prepared by forming a 30 nm thick perfluoroalkyl polyether lubricant layer having a benzene ring-containing adsorption group at the end.

The sliding resistance of the magnetic disks of Examples 2 to 4 and Comparative Examples 1 and 2 was evaluated by CSS. The results are shown in Table 1.

[0022]

[Table 1]

As shown in Table 1, the CSS resistance of the magnetic disk of this example was much superior to that of the comparative example, and showed good wear resistance.

Here, the substrate 11 is made of NiP-plated Al alloy, tempered glass, crystallized glass, plastic, ceramics, surface glass coated ceramics, etc., and the non-magnetic underlayers 12 and 12' are made of Cr, Mo, W, Cr, etc. -Ti, Cr
-Si, Cr-W, etc., and Co-N for the magnetic layers 13 and 13'.
i, Co-Ni-Cr, Co-Ni-Zr, Co-Ni
-Pt, Co-Cr, Co-Cr-Ta, Co-Cr-
Carbon, carbide, nitride, oxide, boride, etc., such as Pt, can be used for the protective coating layers 14, 14', and similar effects can be obtained with any combination. It is preferable to further provide an adsorbent organic lubricant layer thereon, since this significantly improves the sliding resistance.

Example 5 Using 2, 4 to 8 magnetic disks of Example 2,
A metal-in-gap magnetic head in which CoTaZr, FeAlSi alloy, etc. is provided in the gap part and the core part is made of polycrystalline or single crystal ferrite, or NiFe, C
A magnetic disk device was manufactured by combining a thin film magnetic head with a magnetic pole material made of oFe, CoTaZr alloy, etc. and a core made of a nonmagnetic material containing zirconia as a main component. The average device lifespan until an error occurred was determined, and in all cases the lifespan was 2 to 10 times longer than that of devices using conventional magnetic disks, and high reliability was obtained. When the magnetic core was made of ferrite, particularly excellent characteristics were obtained when single crystal ferrite was used. Compared to a magnetic disk device combined with a conventional Mn-Zn ferrite ring head, the ability to erase unnecessary information in the track width direction is higher, so the magnetic disk device of the present invention has a wider phase margin and a higher storage capacity. We were able to increase this by more than 1.5 times.

[0026]

Effects of the Invention: The magnetic recording medium provided with the protective coating layer of the present invention has excellent sliding resistance, making it suitable for high-density recording, and magnetic recording media and magnetic storage devices having sufficient sliding resistance for practical use. can get.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetic disk in Example 1 of the present invention.

FIG. 2 is a diagram showing the relationship between the absolute value of residual internal stress in a protective coating layer and sliding resistance.

[Explanation of symbols]

11...Substrate, 12, 12'...Nonmagnetic underlayer, 13, 13
'...Magnetic layer, 14,14'...Protective coating layer.

Claims (9)

[Claims] 1. A magnetic recording medium having at least one protective coating layer on a magnetic layer, wherein the absolute value of internal stress remaining in the protective coating layer is 1 GPa or less. 2. The magnetic recording medium of claim 1, wherein a lubricant layer having at least one adsorbent end group is present on the protective coating layer. 3. The magnetic recording medium according to claim 1, wherein the absolute value of internal stress remaining in the protective coating layer is 0.5 GPa or less. 4. The magnetic recording medium according to claim 3, wherein the absolute value of internal stress remaining in the protective coating layer is 0.3 GPa or less. 5. The thickness of the protective coating layer is 3 nm or more and 60 nm.
5. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is less than or equal to m. 6. The protective coating layer has a thickness of 3 nm or more and 40 nm.
The magnetic recording medium according to claim 5, wherein the magnetic recording medium is less than or equal to m. 7. The thickness of the protective coating layer is 5 nm or more and 30 nm.
7. The magnetic recording medium according to claim 6, wherein the magnetic recording medium is less than or equal to m. 8. A magnetic recording medium comprising at least one magnetic recording medium according to any one of claims 1 to 7, and a magnetic head containing a metal magnetic alloy as at least a part of the magnetic core. Features of magnetic storage device. 9. The magnetic storage device according to claim 8, wherein the core material of the magnetic head consists essentially of zirconia or ferrite.