JPH08147683A - Magnetic disk - Google Patents

Abstract

PURPOSE: To prevent the lowering of a lubrication effect, to provide excellent wear resistance, durability and protection against corrosion and also to prevent the stain or the like of a head by forming a lubricant layer of a fluorine-based solid lubricant layer and using a liquid lubricant. CONSTITUTION: A NiP-plated backing layer 12 is formed in both faces of a non-magnetic disk 11, and a Cr backing layer 13 and a magnetic film 14 are formed thereon in order. A fluorine-based solid lubricant layer 16' is formed immediately on the magnetic film 14 without forming a carbon film. The lubricant layer 16' is formed by instantly evaporating and depositing a fluororesin material by plasma and therefore the change is made uniform, and the formed thin film is made fine. By using a fluorine-based solid lubricant layer, a uniform and fine film of not less than 5Å can be made and a low floating can be made since carbon is not essential. It has an antifriction characteristic without having a carbon layer underneath and has better protection against corrosion than carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk using a metal magnetic layer made of Co alloy and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 4 is a plan view showing the entire internal structure of a magnetic disk device. When a magnetic disk D is rotating at a high speed, a magnetic head 1 moves in the radial direction of the magnetic disk D to perform a seek operation. Information recording / reproduction is performed. 2 in the figure
Is a spindle, 3 is a suspension, 4 is a drive arm,
5 is a voice coil motor. When the magnetic disk D is cut and enlarged at the position of the magnetic head 1, it becomes as shown in FIG.

In the thin film type magnetic disk D, reference numeral 11 is a substrate made of a non-magnetic material such as aluminum or glass. A NiP plating layer 12 is formed on the surface of the substrate to increase the mechanical strength of the Co alloy. The Cr underlayer 13 for enhancing the horizontal orientation is formed by sputtering about 1000Å. And CoCrTa or CoNiCr
Sputter magnetic material such as 500 Å for thin magnetic film 1
After forming 4, the protective film 15 is made of carbon 30 or the like.
About 0Å is sputtered, and finally, a fluorine-based lubricating layer (liquid) 16 such as perfluoropolyether is applied on the order of several tens ofÅ to complete the process.

Information is recorded / reproduced on / from the magnetic disk D by the head element section 18 while the magnetic disk D is rotated at a high speed in the direction of arrow a ₁ and the magnetic head slider 1 is slightly floated by the wind force. The slider 1 of the magnetic head is attached to a suspension (spring arm) 3 via a gimbal 20, and a seek operation is performed by a drive arm 4 of a carriage 22. As described above, due to the simplicity of the mechanism, the core slider does not float and slides into contact with the CSS (Cactact Start) when the apparatus is started and stopped.
The Stop method has become popular.

The magnetic head of FIG. 6 is an MR type head,
The head element portion 24 is formed by thin film technology and is made of Al ₂ O.
It is covered with a protective film such as ₃ . The slider 1 has levitation rails 25 and 26 on the left and right of the sliding surface, and on the side opposite to the head element portion 24, the inflow slope 2 for taking in the air flow.
5s and 26s are formed. FIG. 7 shows an explanatory view when a composite thin film magnetic head is used. FIG. 7A is a cutaway oblique view, and FIG. 7B is a cross-sectional view (taken along line XX).

FIGS. 7A and 7B show a composite thin film magnetic head 40 of an electromagnetic conversion head (recording head) and a magnetoresistive (MR) head (reproducing head). Resistance effect head (MR head) 41
Is composed of a rectangular magnetoresistive effect element (MR element) 43 formed on the non-magnetic substrate 42, a lead conductor layer 44 of the MR element 43, and upper and lower magnetic shield layers 45a and 45b.

The lead conductor layer 44 is cut to a predetermined width in the longitudinal direction of the MR element 43 and connected to both ends of an MR layer (described later) of the MR element 43. The MR element 33 and the lead conductor layer 44 are between the magnetic shield element layer 45b and electrically connected by the non-magnetic insulating layer 36.
On the other hand, the electromagnetic conversion type head (inductive head) for recording information on the magnetic disk D is the MR head 4
1 upper magnetic shield element 45a to the lower magnetic pole (first magnetic pole)
And an interlayer insulating layer 49 made of a thermosetting resin, a thin-film coil conductor layer (Cu) 50, and an upper magnetic pole 51 through a recording gap with alumina (Al ₂ O ₃ ) interposed in order on the upper surface thereof.
Are stacked, and information is horizontally recorded by a recording gap 48 formed by an upper magnetic pole (second magnetic pole) 51 and a lower magnetic pole (upper magnetic shield layer) 45a. Further, a protective insulating layer 52 is formed on the upper magnetic pole 51. These are formed by sputtering, vacuum deposition plating, or the like.

In the figure, 6 is a protective layer consisting of a hydrogen-containing carbon (diamond-like carbon) layer, on which a fluoride layer 17 is optionally formed as a lubricating protective layer and applied.

[0009]

In order to cope with the recent increase in density, the following measures have been taken for magnetic disks. The flying height of the magnetic head (physical head-disk spacing) is reduced to about 0.05 to 0.10 μm.

Effective spacing (magnetic head
250 Å → 15 to reduce the disk space)
The film is made extremely thin from 0Å to 100Å. The disk surface is flat and smooth in order to enable The surface of the disk has become flat with the recent increase in density of disks.
It is expected that smoothing will make problems such as head crashes and stick slips even more serious. However, despite the problems mentioned above, contact recording must also be possible.

At present, the following items are considered as problems between the head and the disk. Touch Noise Problem In the related art, there is touch noise (discharge noise) that occurs when the head collides with an abnormal protrusion on the disk surface. As a countermeasure for this conventional technique, the texture processing is changed from the tape polishing method to the slurry polishing method in order to eliminate abnormal protrusions on the disk surface, but many minute defects still occur.

Further, in order to increase the electric resistance of the solid lubricant on the surface of the disk, the protective film is changed from carbon to diamond-like carbon and further to SiC, but it is difficult to control the conditions for sputtering film formation, and variations in production and in-plane are caused. However, it is impossible to increase the electric resistance. Friction property (adsorption) / migration / durability problem In the conventional method, the free layer (m
The presence of an obi layer), the surface energy of the disk surface is increased due to the interaction of the carbon head material and the gas, and the friction characteristics are deteriorated.

Further, there is a bonding layer / free layer (immobil layer / mobile layer) in the film thickness of the fluorine-based liquid lubricant, and the free layer causes migration due to disk rotation, deteriorating durability. Therefore, in the conventional technology, as a countermeasure, in order to strengthen the bond with the carbon of the fluorine-based liquid lubricant, after applying the lubricant, ultraviolet rays or near infrared rays are irradiated to activate the surface to enhance the bond,
After forming the carbon layer, the surface is rapidly activated by irradiation with ultraviolet rays or near infrared rays to enhance the bond. However, even in these lubricating layers, since the free layer is present, the problem that the surface energy of the disk surface is increased and the friction characteristics are deteriorated as described above cannot be solved.

[0014]

In the present invention, it has been found that the above problems can be solved by changing from a liquid to a solid fluorine-based lubricant, which has been used as a lubricant for hard disks for many years, on the magnetic layer. That is, according to the present invention, in a magnetic disk having a lubricating layer on a magnetic disk substrate including a magnetic Co alloy layer, the lubricating layer is made of a fluorine-based solid lubricant layer and no liquid lubricant is used. Provided is a CCS magnetic disk, and a method of manufacturing a magnetic disk characterized by forming a fluorine-based solid lubricant layer on a CCS magnetic disk substrate having a magnetic Co alloy layer.

The magnetic disk of the present invention is used in the CCS system. In particular, the magnetic layer is CoCrTa, CoCrP
This is a metal magnetic layer made of a Co alloy such as t, CoNiCr. The present invention, particularly in the CCS method using a metal magnetic layer, cannot conventionally reduce the flying height of the magnetic head when carbon is used as a solid lubricant (and a liquid lubricant is further used thereon), and This is aimed at solving the problem that corrosion resistance and durability cannot be improved.

Although a fluorine-based solid lubricant layer can be formed on the Co alloy magnetic layer, a protective layer made of carbon, diamond-like carbon, silicon carbide or the like may be provided if necessary. A fluorine-based solid lubricant layer is formed on the Co alloy magnetic layer or the protective layer according to the present invention. As the fluorine-based solid lubricant, for example, a fluororesin such as polytetrafluoroethylene or polytrichlorotrifluoroethylene can be used. A preferred fluorine-based solid lubricant is a fluororesin as described above to which a hydroxyl group or a benzene group is added (at the terminal).

As the method for forming the fluorine-based solid lubricant layer, methods such as a dipping method, a spin method and a sputtering method can be applied. The preferred method of formation is plasma polymerization. Specifically, the fluororesin is plasmatized in a vacuum atmosphere and deposited on the substrate, and a uniform film without fluctuation and a dense film can be formed. Although the film thickness of the fluorine-based solid lubricant layer is not limited, it is generally 0.001 to 0.
01 μm, more preferably 0.001 to 0.002 μm
Is preferred. Although not limited to, 0.001 μm
If it is thinner, sufficient lubrication performance cannot be obtained, and wear resistance is insufficient. It is not a problem that the film thickness is large, and the film thickness is substantially sufficient.

The magnetic disk of the present invention is characterized in that the solid lubricant layer is used as the uppermost layer without coating the liquid lubricant layer on the fluorine-based solid lubricant layer. When the lubricating layer is a fluorine-based solid, the following effects can be obtained. Since the solid lubricant layer also serves as a protective layer in the magnetic disk of the present invention, description will be made from the viewpoint of both the lubricant layer and the protective layer.

Touch Noise When a liquid lubricant is used as in the prior art, the electrical resistance of the protective layer (carbon-based) thereunder becomes a problem with respect to touch noise, but the electrical resistance is as high as 1 × 10 ⁶ Ω. On the contrary, in the case of the present invention, the electric resistance of the solid lubricant layer is 1 × 10 5.
Since it is as high as ¹⁵ Ω, the insulation resistance between the magnetic layer (metal layer) and the disk is large, and discharge noise does not occur even if the head collides with the abnormal protrusion of the disk.

Friction characteristics / adsorption / durability Conventional liquid lubricants have a free layer, so that friction and adsorption are poor. However, in the present invention, since there is no free layer, friction and adsorption are good. In particular, when there is water on the disk due to humidity, etc., unlike liquid lubricants, there is no interaction between the free layer and water, so water acts as a lubricant, and the fluorine-based solid is used for friction characteristics and adsorption. The lubricant has a smaller intermolecular force than the carbon-based solid protective layer, and the present invention is superior in low friction / self-lubricating property.

Durability The carbon-based protective layer, which has the durability of the conventional magnetic disk, shifts from carbon to diamond-like carbon and further to SiC aiming at the diamond structure (SP ³ hybrid orbit). Although C and Si can have an SP ³ structure, argon gas is used for film formation by sputtering.
In other words, in the case of SiC, SP of SiC + Ar
(Referred to as diamond-like) ² structure, SP ³ structure is a manufacturing variation is large production difficult. In the present invention, particularly in the case of film formation by plasma polymerization, the crosslink density is high and the film is hard. The so-called H1s ¹ F2S ² 2p ⁵ has a transformer structure and is stable.

Corrosion Resistance In conventional discs, the carbon-based protective layer plays a role in corrosion resistance.
The film is thinning from 50Å → 150Å → 100Å. For example, sacrificial acid is water with an ionization constant of 2.05 × 10 ⁻⁴ (18 ° C.),
Although it is a very strong acid mixed with alcohol at an arbitrary ratio, sacrificial acid molecules (ions) penetrate between the metal bonds of the carbon-based protective layer and corrode the magnetic layer. However, in the present invention,
Since the magnetic layer is coated with a so-called fluororesin, there is no penetration of formic acid molecules (ions), so there is no corrosion.
Since the carbon-based protective layer can be omitted in the present invention, the present invention is superior in corrosion resistance in the tendency that the protective layer (solid lubricant) on the magnetic layer becomes thin.

Lubricant migration In the conventional method, a fluorine-based liquid lubricant is used and a free layer is present, so that a macroglation occurs. Liquid lubricants are classified into two layers, a bonding layer / free layer, but the free layer moves due to disk rotation. As a countermeasure for the conventional technology, in order to strengthen the bond with the carbon of the fluorinated liquid lubricant, after applying the lubricant, the surface is activated by irradiating ultraviolet rays or near infrared rays to enhance the bond, or the carbon layer is formed. After that, a method has been proposed in which ultraviolet rays or near infrared rays are rapidly irradiated to activate the surface to enhance the bond, but since the free layer is present at nearly 50%, migration occurs and the lubricant decreases. By doing so, durability and friction characteristics (adsorption) are caused.

On the other hand, in the present invention, the fluorine-based solid lubricant is used, the free layer does not exist, and all the binder layers are used. Since the lubricant is not reduced, the durability and friction characteristics (adsorption) are improved. It is good. Head contamination Conventionally, since a fluorine-based liquid lubricant is used, CS
S There is dirt on the head due to sliding. However, in the present invention, since the fluorine-based solid lubricant is used, there is no head contamination due to CSS sliding or the like. Further, since the fluorine-based solid lubricant has a smaller surface energy than the fluorine-based solid lubricant, the non-adhesiveness of the present invention is stronger, so that dust, gas, etc. do not adhere to the surface.

[0025]

FIG. 8 is a sectional view showing a method of manufacturing a conventional thin film magnetic disk in the order of steps, which is also disclosed in Japanese Patent Application No. 3-336495 filed by the applicant of the present invention. In step (1), 11 is a doughnut-shaped substrate made of a non-magnetic material such as aluminum, and is formed in the same size as the magnetic disk to be manufactured.
For example, when manufacturing a 2.5-inch small-diameter magnetic disk, the non-magnetic disc 11 is also 2.5-inch.

Then, in step (2), NiP-plated underlayers 12 are formed on both sides of the nonmagnetic disk 11, and in step (3), the plate surface of the rotating nonmagnetic substrate is polished. The tape is pressed to form a fine texture T in the circumferential direction. Next, in the step (4), a Cr underlayer 3 for enhancing the horizontal orientation of the Co alloy is formed on the texture T to a thickness of about 1000Å, and in the step (5), for example, from a Co alloy or the like. Composed magnetic film 1
4 is formed into a film of about 500Å. On this magnetic film 14,
As in step (6), the hydrogen-containing carbon film 15 is used as a protective film.
Is formed to a thickness of about 300Å, and the fluorine-based lubricating layer 16 is finally applied. The Cr layer 13, the thin film type magnetic film 14 and the carbon film 15 are formed by a thin film technique such as sputtering.

The texture T formed in the step (3) is
It is for imparting magnetic anisotropy so that the electromagnetic conversion characteristics at the time of recording / reproducing information are improved. Further, since the carbon film 15 also becomes uneven along the texture T, it is possible to suppress the magnetic head from being attracted to the magnetic disk surface by the lubricant, and to reduce the friction between the magnetic head and the magnetic disk surface. You can

As described above, the conventional magnetic recording medium is Ni
A structure in which an underlayer (Cr) of about several thousand liters, a recording layer of several hundred liters, and a carbon protective layer are sequentially formed on an aluminum substrate or a glass substrate that has been subjected to -P plating treatment. However, in recent years, a diamond-like carbon film (DLC) has been developed as a high hardness protective film.

On the other hand, referring to FIGS. 1 and 2, in the present invention, the formation of the magnetic film 14 can be performed in a conventional manner, and then the carbon film 15 can be formed (FIG. 1). In a preferred embodiment, the fluorine-based solid lubricant layer 16 'is immediately formed on the magnetic film 14 without forming the carbon film 15 (FIG. 2). The formation of the fluorine-based solid lubricant will be specifically described.

FIG. 3 shows an outline of the structure of an apparatus used for forming the fluorine solid lubricant of the present magnetic disk. In FIG. 3, 61 is a vacuum container, 62 is a supply unit for a fluororesin material and a plasma forming material provided on the upper part of the vacuum container 61, 6
Reference numeral 3 is a high-frequency coil, 64 is a holding table provided below the vacuum container 61, and 65 is an exhaust unit. The holding table 64 is rotated by being driven by a driving source (not shown) provided outside the vacuum container 61. The exhaust unit 65 is
It is a thing for keeping the inside of the vacuum container 61 at a predetermined pressure, and is connected to an external exhaust pump (not shown) through a valve or the like.

The fluororesin is formed by using this apparatus as follows.
Done in steps. When forming the fluororesin,
The non-magnetic support 101 on which the magnetic layer is formed is mounted on the holding table 64.
, And energize the high frequency coil 63,
Plasma gas (Ar) and sheath gas from the supply port 66
(O₂) Supply. The supplied gas is supplied from the supply unit 62.
Inside the vacuum container 61 as shown by the dotted arrow line from the bottom
Excited by the magnetic field generated by the high-frequency coil 63
It becomes plasma. This plasma is above the support 101.
Is formed in a space parallel to the support 101. This state
Then, the support 101 is rotated, and the supply above the supply unit 62 is performed.
A fluororesin material is supplied through the mouth 67. Fluororesin material
As a carrier gas (N ₂)inside
Dispersed powder or fluororesin powder is used as carrier gas.
Use the one dispersed in the space. Fluororesin material supplied
The charge is indicated by the solid arrow line from the lower center of the supply unit 62.
Is blown into the vacuum chamber 61, and the temperature of the plasma changes
It evaporates in an instant. Note that the plasma generated
The peripheral wall of the vacuum container 61 to be heated flows in from the cooling water inlet 68.
And is cooled by the cooling water flowing out from the cooling water outlet 69.
Be done.

As described above, since the fluorine solid lubricant layer of the present invention is formed by evaporating the fluorine resin material by plasma in an instant and depositing it, it becomes uniform without variation. Further, the plasma generation space is the support 10
1 and on the support 101 and parallel to the support 101, the formed thin film is dense.

The magnetic disk of the present invention is characterized in that the lubricant layer is composed of a fluorine-based solid lubricant, and in a preferred embodiment, the fluorine-based solid lubricant layer is directly formed on the recording layer without a carbon layer. . Further, no liquid lubricant is used on the fluorine-based solid lubricant layer. By using the fluorine-based solid lubricant layer, a uniform and dense film can be formed with a thickness of 5 liters or more, and carbon can be omitted, so that low levitation can be achieved.
Further, it has anti-friction properties even if it does not have a carbon layer underneath, and is superior in corrosion resistance to carbon. On the other hand, when a conventional liquid lubricant is used, a carbon layer is indispensable underneath, and it is difficult to reduce the flying height. Further, even if carbon is present, migration occurs, so that the amount of lubricant is reduced, the friction resistance is poor, and the corrosion resistance is also low.

[0034]

The CSS type magnetic disk having the metal magnetic layer of the present invention has a low flying height of the magnetic head and a thinning of the protective layer. It has the effects of preventing deterioration and being excellent in touch noise, abrasion resistance, durability, corrosion resistance, head contamination, and the like.

[Brief description of drawings]

FIG. 1 shows a magnetic disk of an embodiment.

FIG. 2 shows a magnetic disk of an embodiment.

FIG. 3 shows a plasma polymerization apparatus of an example.

FIG. 4 shows an overview of a magnetic disk device.

FIG. 5 shows a magnetic head on a magnetic disk.

FIG. 6 shows an overview of a magnetic head.

7A and 7B show the content structure of a composite magnetic head.

8 (1) to (6) show manufacturing steps of a magnetic disk.

[Explanation of symbols]

 11 ... (Al) substrate 12 ... NiP 13 ... Cr underlayer 14 ... (Co alloy) magnetic film 15 ... Protective film 16 ... Liquid lubricant layer 16 '... Solid lubricant layer

Claims (6)

[Claims] 1. A magnetic disk having a lubricating layer on a magnetic disk substrate including a magnetic Co alloy layer, wherein the lubricating layer comprises a fluorine-based solid lubricant layer and no liquid lubricant is used. disk. 2. The magnetic disk according to claim 1, wherein the fluorine-based solid lubricant layer is directly provided on the magnetic layer without a protective layer. 3. The magnetic disk according to claim 1, wherein the fluorine-based solid lubricant has an OH group or a benzene group. 4. The magnetic disk according to claim 1, wherein the fluorine-based solid lubricant layer is formed by a plasma polymerization method. 5. A method of manufacturing a CCS type magnetic disk, comprising forming a fluorine-based solid lubricant layer on a CCS type magnetic disk substrate having a magnetic Co alloy layer. 6. The method according to claim 5, wherein the fluorine-based solid lubricant layer is formed by a plasma polymerization method.