JPH0963046A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain very low levitation of a magnetic head as well as to improve CSS(contact start stop) resistance by making the height of protrusions formed in a CSS region equal to or lower than the plane of a part which becomes a data region. SOLUTION: This magnetic recording medium has a magnetic layer on the substrate made of amorphous carbon and has a CSS region in which contact with a magnetic head is caused chiefly at the time of stopping the magnetic recording medium and a data region in which contact with the head is not caused and magnetic recording is chiefly performed on the substrate. The surface roughness of the CSS region is made higher than that of the data region and the center line average height of the CSS region is made equal to or lower than that of the data region within the range of 10-500Å. A magnetic head does not collide against the protrusions in the CSS region at the time of start and stop, CSS resistance is improved and very low levitation of the head can be attained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a magnetic recording medium and a method for manufacturing the same. More specifically, the present invention relates to a magnetic recording medium such as a magnetic disk which realizes a low flying height of a magnetic head and has excellent CSS durability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk used in a hard disk drive employs a so-called contact start stop (hereinafter referred to as CSS) system in which a magnetic head stops and starts at an arbitrary position on the disk. However, in this method, the magnetic head slides on the disk at the time of stopping and starting, so that problems such as damage to the disk and data destruction occur. Therefore, today, a magnetic head has a C
The mainstream method is to prevent data destruction and mechanical damage to the magnetic disk by forming an area for performing SS (hereinafter referred to as CSS area) and a data area where data is magnetically recorded and the magnetic head does not slide. Has become.

In this method, the surface of the data area is made as smooth as possible in order to reduce the flying height of the magnetic head and achieve high density recording. On the other hand, since the CSS area has a function of attaching and detaching the magnetic head, it is necessary to prevent faster detachment of the magnetic head and agglomeration of liquid components (lubricant, water, etc.) when the head is moored. The surface roughness of the CSS area is roughened by an appropriate method to make the surface roughness rougher than the surface roughness of the data area. Such roughening is performed by forming protrusions on a target surface by various methods generally called texture.

[0004]

However, by increasing the surface roughness of the CSS area as described above,
Many protrusions higher than the data area are formed in the CSS area. The presence of such protrusions is a major obstacle to reducing the flying height of magnetic heads required today. That is, the disturbance of the flying posture of the magnetic head caused by the difference in the surface shape of the magnetic disk when the magnetic head slides in the CSS zone and floats to move to the data zone causes contact between the magnetic disk and the magnetic head at high speed. As a result, damage to the magnetic head, crash of the magnetic disk, burst destruction of digital data, etc. occur.

A method of lowering the protrusions of the CSS zone by polishing or the like can be considered, but in this case, the surface area of the upper portion of the protrusions becomes large, so that the contact area with the magnetic head also becomes large, and when operating from the time of stopping. The coefficient of friction also increases, power consumption increases, and the life of the CSS region shortens, leading to a decrease in so-called CSS durability.

[0006]

In view of the above points, the inventors of the present invention have made earnest studies to further improve the floating stability of the magnetic head, and as a result, the CSS of the substrate for forming the magnetic recording medium.
The magnetic head is formed by digging in the area that is to be the area and then subjecting the area that becomes the CSS area to texture processing so that the height of the protrusions formed in the CSS area is the same as or lower than the surface of the area that becomes the data area. Found that the magnetic head does not collide with protrusions during start-up / berthing and CSS durability is improved, and an ultra-low flying height of the magnetic head can be realized.

That is, according to the present invention, in a magnetic recording medium having a substrate and a magnetic layer formed on the substrate, a CSS region and a data region are formed on the substrate, and the C
The surface roughness of the SS area is larger than the surface roughness of the data area, and the center line average height (Rp) of the CSS area.
Is the same as or lower than the center line average height of the data area. For such a magnetic recording medium, a substrate whose surface serving as the CSS area is processed to be lower than the surface serving as the data area is used, and the surface of the substrate serving as the CSS area is subjected to a texture treatment to reduce the surface roughness of the CSS area. It can be manufactured by a method including a step of making the center line average height (Rp) of the CSS region larger than the surface roughness of the data region equal to or lower than the center line average height of the data region.

In the present invention, the CSS area is an area which mainly comes into contact with the magnetic head when the magnetic recording medium is stopped, and the data area does not come into contact with the magnetic head when the magnetic recording medium is stopped or started. Although the area is mainly used for magnetic recording, the CSS area can be used as an area for magnetic recording as required.

The substrate used in the present invention is a non-magnetic support used for ordinary magnetic disks and the like. For example, carbon such as glassy carbon material, tempered glass, crystallized glass, aluminum and aluminum alloys, titanium and A substrate made of titanium alloy, ceramics, resin, or a composite material thereof is used.

Among these, the substrate made of a glassy carbon material is particularly excellent in heat resistance and light weight and can be particularly preferably used in the present invention. Here, the “glassy carbon material” includes not only glassy carbon alone but also a composite material containing glassy carbon as a base material.

In the present invention, it is also possible to use an aggregate of glassy carbon materials, or a composite material aggregate containing a glassy carbon material and a synthetic resin and / or a carbonaceous filler. These are molded by various well-known molding methods such as casting, compression, extrusion, etc., which are dried and cured, and then carbonized at a high temperature, or directly on the surface of the substrate by a sputtering method or a vapor deposition method. It is in the form of a precipitate formed by depositing a carbonaceous material, and specifically,
It is preferable to use the materials described in JP-A-60-35333.

The disk substrate of the present invention is a glassy carbon material aggregate having as few pores as possible, or
It is preferable to manufacture the composite material aggregate containing a glassy carbon material, but in order to obtain such an aggregate, in the case of a casting method, for example, a precursor of a carbon material (a thermosetting resin and a curing agent are used). Alternatively, in the step of obtaining a state of being cured by heat), the curing agent is uniformly dispersed or uniformly heated, and the curing rate is adjusted so as not to become too fast. In the case of the compression or extrusion molding method, it can be obtained, for example, by wetting a carbon material or the above composite material with a thermosetting resin to reduce voids as much as possible and molding.

Further, by subjecting the vitreous carbon to ultra-high temperature HIP (hot isostatic pressing) treatment or the like, pores are almost eliminated to increase the density, and a high-density amorphous carbon whose characteristics are close to those of graphite is obtained. Can also be used,
Specifically, the glassy carbon described in JP-A 1-230471 and the like can be used.

In the magnetic recording medium of the present invention, the CSS area of the substrate as described above is dug lower than the data area, and then the CSS area is powder beam texture, sputter texture, tape texture, etc. The surface-roughened material is used by a suitable method. The method for digging into the CSS area is not limited,
This can be performed by, for example, a method of masking the data area of the substrate and etching the CSS area by anodic oxidation. For texture processing,
A powder beam texture is particularly preferable. The powder beam texture is a method in which fine particles having an average particle size of several microns or less are jetted together with a gas onto the surface of a workpiece to be processed. In this method, the shape can be changed by forming minute unevenness on the surface of the work piece or by cutting the work piece. The material of the fine particles used for powder beam texture is this processing method suitable size, hardness,
There is no particular limitation as long as it has a shape, and, for example, diamond particles, metal or metal oxide particles, ceramic particles or the like generally used as abrasive particles can be used. Preferably, silicon carbide type abrasive grains and alumina type abrasive grains are used.

As the texture treatment, sputter texture can be used. The sputter texture is to form protrusions by depositing sputtered particles from an appropriate sputter source on a portion which becomes a CSS region on the substrate. The sputter source used for the sputter texture is a metal, among which Si, Cr, Ta, Ti, Zr, Y, Mo, which can form carbide,
One or more metals selected from W and V or alloys thereof can be mentioned. In the present invention, the term “sputtering” is a concept including PVD (physical vapor deposition) means such as vacuum deposition and ion plating in addition to sputtering.

Further, a tape texture can be used for the texture processing. The tape texture is a method of roughening the CSS area by bringing the surface of the substrate into contact with a polishing tape in which suitable polishing abrasives are carried on a synthetic resin tape, and the abrasives usually used in the present invention, Tape can be used.

The Rp of the CSS region of the textured substrate is preferably 10 to 500Å, more preferably 100 to 300Å. In addition, an appropriate texturing method can be applied to the data area of the board, but Rp
Is preferably about 10 to 50Å. Ra of the CSS area of the substrate after texture is 10 to 30Å,
Ra of the data area is preferably 1 to 10 Å.

In the present invention, CS after texture
The centerline average height (Rp) of the S area needs to be equal to or lower than the centerline average height of the data area. The height difference is preferably 200 Å or less, more preferably 100
It is preferable for it to be less than Å because the flying stability of the head is improved. Incidentally, the processing step of digging the portion to be the CSS region on the substrate as described above may be incorporated in the manufacturing step of the magnetic recording medium, or a substrate processed into a desired shape in advance may be used.

A magnetic layer, a protective layer, a lubricating layer and the like are appropriately formed on the substrate having such characteristics by a conventional method.

Examples of the magnetic layer include a metal thin film type magnetic layer formed by PVD means. As the material for forming the metal thin film type magnetic layer, for example, CoCr, CoNi, CoCrX, CoNiX,
CoWX (where X is Ta, Pt, Au, Ti,
V, Cr, Ni, W, La, Ce, Pr, Nd, Pm,
Sm, Eu, Li, Si, B, Ca, As, Y, Zr,
Nb, Mo, Ru, Rh, Ag, Sb, Hf, and the like) is preferably selected from the group consisting of 1 or 2 or more) and the like, and a Co-based magnetic alloy containing Co as a main component is preferably cited. When used, they can be used alone or as a mixture of two or more kinds. The thickness of the magnetic layer is preferably 20 to 50 nm.

In a recording medium having a metal thin film type magnetic layer, a protective layer is generally provided on the magnetic layer from the viewpoint of protecting the magnetic layer. As this protective layer, a material having high hardness is selected from the viewpoint of abrasion resistance. For example,
Al, Si, Ti, Cr, Zr, Nb, Mo, Ta, W
Examples thereof include oxides, nitrides and carbides of metals such as carbon, boron nitride and the like. In addition to this, for example, JP-A-5-217154 and JP-A-5-21
7156, JP-A-5-225555, JP-A-5-225557, JP-A-5-282661, JP-A-6-25840, and Japanese Patent Application No. 4-268.
Those disclosed in Japanese Patent Application No. 952, Japanese Patent Application No. 5-1720, Japanese Patent Application No. 5-217156, and Japanese Patent Application No. 5-40142 can be used. Of these, preferred is carbon, silicon carbide, tungsten carbide, silicon oxide, zirconium oxide, boron nitride, or a composite of these materials. Particularly preferred is carbon, especially diamond-like carbon. This protective layer preferably has a thickness of 5 to 25 nm.
The protective layer can be formed by PVD means such as sputtering.

In order to improve the running property, the magnetic layer or the protective layer may have a thickness of 5 to 100Å,
Preferably, a lubricant layer of about 10 to 50Å may be provided. As the lubricant, a lubricant having a polar group and a lubricant having no polar group may be used alone, but it is preferable to use them in combination. For example, after applying a lubricant solution with a polar group, apply a lubricant solution without a polar group at the end, or apply a mixed solution of a lubricant with a polar group and a lubricant without a polar group. Alternatively, a lubricant having a polar group may be present mainly on the lower layer side close to the protective layer side, and a lubricant having no polar group may be present on the upper layer side. The polar group-containing lubricant used is a perfluoropolyether type having a molecular weight of 2000 to 4000, and preferably has an aromatic ring at the end. _{That, - (CF 2 CF 2 O} ) n - (CF 2 O) m
-Having a skeleton, an aromatic ring at the end, and a molecular weight of 20
It is preferably from 00 to 4000. As a specific example, Fomblin AM2001 (made by Montecatini)
And Demnum SP (manufactured by Daikin Industries, Ltd.) and the like.
A lubricant having no polar group has a molecular weight of 2000 to 100.
A perfluoropolyether type of No. 00 is preferable. _{That, CF 3 - (CF 2 CF} 2 O) n - (CF 2 O) m -CF 3
And a molecular weight of 2,000 to 10,000 is preferable. Specific examples include Foblin Z03 (manufactured by Montecatini). The coating method is not limited, and examples thereof include a dip coating method and a spin coating method which are commonly used.

The lubricant layer can also be formed by gas phase polymerization. Specifically, a lubricant is formed by synthesizing a lubricant by vapor phase polymerization of a fluorocarbon compound, and depositing it on the surface of an object to be deposited that has been erected vertically or laid horizontally, to form a lubricant layer. To be done. That is,
The fluorine-based compound (lubricant composition) polymerized in the gas phase reaches and adheres to the surface by diffusion, reacts with the surface by the radicals remaining in the fluorine-based compound, and is fixed. This forms a lubricant layer. Since this polymerization reaction proceeds in the gas phase, it is not affected by the non-uniformity of the disk surface, and there is no need to cool the disk to promote surface condensation, resulting in excellent productivity. The gas phase polymerization is, for example, plasma polymerization or CVD (especially, photo CV
D). In the case of performing the photo-CVD, it is preferable that the surface of the object to be precipitated is not directly irradiated with the laser light but is irradiated only in the source gas.

Since the shape of the texture is reflected in the finally obtained magnetic recording medium of the present invention, Rp of the CSS area is equal to or less than Rp of the data area. Specifically, the finally obtained magnetic recording medium of the present invention is
Ra of the CSS area is preferably 10 to 50Å,
Particularly preferably, it is 15 to 30 Å. The Rp of the CSS region is preferably 10 to 500Å, particularly preferably 100 to 300Å. On the other hand, in the finally obtained magnetic recording medium of the present invention, Ra of the data area is 3 to 15
Å and Rp are preferably 10 to 50Å.

[0025]

According to the present invention, it is possible to obtain a magnetic recording medium such as a magnetic disk which can realize a low flying height of a magnetic head and is excellent in CSS durability.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Amorphous carbon substrate (Ra = 10 Å or less, Rp =
Mask the data area of 40 Å or less) and anodize (50 mA / c in 10% NaOH aqueous solution).
m ² anode voltage) and unmasked CS
A groove having a width of 2.8 mm and a depth of 25 nm was provided in the portion to be S. Then, fine particles (average particle size 1.0
Powder beam texturing was performed by spraying (μm alumina). Ra and Rp of the CSS area and the data area after the texture are as shown in Table 1. After that, a Ti film (50 nm) and C are sputtered on the substrate.
r film (40 nm), CoCr ₁₀ Pt ₁₂ film (30 nm),
C films (15 nm) were sequentially formed, and a lubricant [Fomblin AM2001 (manufactured by Aojimont Co.)] was applied to a film thickness of 2 nm. The sputtering conditions are as follows. -Ar gas pressure in vacuum 5 mTorr-Substrate temperature 240 ° C-Substrate bias voltage -100 V Ra and Rp of the finally obtained magnetic disk were measured by a stylus type roughness meter (manufactured by TENCOR, model P2) as follows. It was measured under the conditions. Stylus diameter: 0.6 μm (needle curvature radius) Stylus pressing pressure: 7 mg Measurement length: 250 μm × 8 places Trace speed: 2.5 μm / sec Cutoff: 1.25 μm (low pass filter).

Regarding the obtained disc substrate,
The CSS test and the glide height test (GHT) were performed by the following methods. Table 1 also shows the results. * CSS test; using a Yamaha thin film head, head load 3.5g, head flying height 2.8μ inch, 450
A cycle of running at 0 rpm for 5 seconds and stopping for 5 seconds was repeated, and the number of times until the static friction coefficient (μs) reached 0.6 was examined. The CSS test was performed at a position 12 mm from the center when the disk was regarded as a circle. * GHT: 50% using PROQUIP tester
This was done using a slider head. Ten sample substrates are used, "◎" when the passing rate of the flying height of 0.025 µm is 100%, "○" when the passing rate is 80 to less than 100%, and "x" when the passing rate is less than 80%. Was displayed.

Example 2 In the substrate of Example 1, the groove depth of the portion to be the CSS region was set to 35 nm, and then the tape texture was applied to the groove portion under the following conditions to prepare a disk substrate. A magnetic disk is manufactured in the same manner as in the above, and the Ra, Rp, GHT, C of the CSS area and the data area of the magnetic disk are manufactured.
SS was evaluated. Table 1 shows the results. <Tape texture conditions> -Tape: Nippon Micro Coating Co. # 4000-
# 8000 Tape feed speed: 300 to 500 mm / min · indenter load: 2-3 kg / cm ² · substrate rotation speed: 40 to 100 rpm Tape swing: 200 to 500 reciprocations / min, Yuradohaba 1 mm-indenter hardness: Shore hardness 60 degrees-Processing time: 2 seconds to 10 seconds.

Example 3 A disk substrate was prepared in the same manner as in Example 1 except that the groove of the CSS region was formed by polishing under the following conditions. Was prepared, and Ra, Rp, GHT, and CSS of the CSS area and the data area of the magnetic disk were evaluated. Table 1 shows the results. <Polishing conditions> -Tape: Nippon Micro Coating Co. # 4000-
# 6000 Tape feed speed: 300 to 500 mm / min · indenter load: 4~5kg / cm ² · substrate rotation speed: 100 rpm - indenter hardness Shore hardness of 60 degrees and processing time: 10 seconds to 20 seconds.

Example 4 In Example 1, the depth of the groove in the portion to be the CSS region was set to 30 nm, and the Ti layer and A were formed by the sputtering method under the following conditions.
A substrate on which the 1Si layer and the C layer were formed was produced, a magnetic disk was produced in the same manner as in Example 1, and Ra, Rp, GHT, and CSS of the CSS area and the data area of the magnetic disk were evaluated. Table 1 shows the results. <Sputtering conditions> After setting the substrate in the sputtering apparatus, the chamber is evacuated to a vacuum degree of 3 × 10 ⁻⁷ ,
Then, Ar gas was introduced to obtain 5 mTorr. After that, the substrate was heated to 200 ° C. by a heater and a bias voltage of −100 V was applied to the substrate to form the following layers in this order.・ Ti layer (50 nm) ・ AlSi (Al: Si = 90: 10 atomic ratio) layer (30 n
m) (texture layer) -C layer (20 nm) Comparative Example 1 In Example 2, a tape texture (conditions are the same as those in Example 2) was applied to the entire substrate without forming a groove in a portion to be a CSS region of the substrate. Example 2
Create a magnetic disk in the same manner as in
Ra, Rp, GHT, and CSS of the area and the data area were evaluated. Table 1 shows the results.

Comparative Example 2 Protrusions in the CSS region of the substrate produced in Comparative Example 1 were ground by polishing under the following conditions to produce a disc substrate with a uniform protrusion height. Ra, Rp, GHT and CSS of the data area were evaluated. Table 1 shows the results. <Polishing conditions> -Tape: Nippon Micro Coating Co. # 6000-
# 10000 Tape feed speed: 300 to 500 mm / min indenter load: 2-3 kg / cm ² · substrate rotation speed: 40 to 100 rpm Tape oscillation speed: 200 to 500 reciprocations / min · indenter hardness Shore hardness of 60 degrees・ Processing time: 15 to 150 seconds

[0033]

[Table 1]

Claims (5)

[Claims] 1. In a magnetic recording medium having a substrate and a magnetic layer formed on the substrate, a CSS region and a data region are formed on the substrate, and the surface roughness of the CSS region is the data region. And a centerline average height (Rp) of the CSS area is equal to or lower than the centerline average height of the data area. 2. The center line average height (R) of the CSS region
The magnetic recording medium according to claim 1, wherein p) is 10 to 500 Å. 3. The magnetic recording medium according to claim 1, wherein the substrate is made of amorphous carbon. 4. In manufacturing a magnetic recording medium having a CSS area and a data area formed on a substrate, the CS
A surface of the data area is roughened by using a substrate whose surface serving as the S area is processed to be lower than the surface serving as the data area and subjecting the surface of the substrate serving as the CSS area to a texture treatment. Larger than the above, and the CSS
A method of manufacturing a magnetic recording medium, comprising the step of making the centerline average height (Rp) of the area equal to or lower than the centerline average height of the data area. 5. The method for manufacturing a magnetic recording medium according to claim 4, wherein the texture treatment is performed by powder beam texture.