JPH05205241A - Magnetic recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To achieve a magnetic recording medium and its manufacturing method which can reduce a lifting distance of a magnetic head without sacrificing magnetic characteristics by forming recess and projection along a circumferential direction without performing machining. CONSTITUTION:A recessed and projecting parts formation film 7 which is ZrC film in fiber-structure which is formed by sputtering along the circumferential direction is provided on the surface side of a circular plate glass non-magnetic substrate 2 and a magnetic layer 4 is formed while being orientated in the circumferential direction corresponding to the recess and projection of the recess and projection formed film 7. Also, the recess and projection are reflected up to the uppermost surface of a magnetic recording disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and a method for manufacturing the same, and more particularly to a technique for forming irregularities on the surface of the magnetic recording medium.

[0002]

2. Description of the Related Art In recent years, a fixed magnetic disk device has been widely used as an external storage device for an information processing device such as a computer, and a magnetic recording medium used for the fixed magnetic disk device is generally nonmagnetic as shown in FIG. A magnetic recording disk substrate 22 including a substrate 22a and a non-magnetic metal layer 22b, a metal underlayer 23 such as a Cr layer deposited on the surface thereof, a magnetic layer 24 formed on the surface thereof, and an amorphous layer formed on the surface thereof. It is composed of a protective layer 25 such as a carbon layer and a liquid lubricating layer 26 applied on the surface thereof, and the surface state of the outermost layer thereof largely controls the recording density and reliability of the magnetic recording disk 21. In particular, in the CSS (contact start stop) type magnetic recording disk 21, the magnetic head and the surface of the magnetic recording disk 21 are in contact with each other when stopped, and from this state, the magnetic head performs magnetic recording only during operation. Information is read or written while floating slightly above the surface of the disk 21. Therefore, when the surface of the magnetic recording disk 21 is in a mirror surface state, the magnetic head and the magnetic recording disk 21 are
The surface has a large friction coefficient, and the magnetic head may stick to the surface of the magnetic recording disk 21 when stopped.
Further, at the time of starting, the magnetic recording disk 21 of the magnetic head
The magnetic layer 24 may be worn and damaged due to sliding on the surface of the.

Therefore, measures are taken to reduce the friction coefficient by forming fine irregularities on the surface layer of the magnetic recording disk 21 to reduce the contact area between the magnetic head and the surface of the magnetic recording disk 21. The typical concavo-convex forming process is such that a polishing tape or the like is slid on the surface of the nonmagnetic metal layer 22b of the rotating magnetic recording disk substrate 22 to form fine concentric concavities and convexities on the surface. This is a texturing process that reflects even the surface of the magnetic recording disk 21.

[0004]

However, in the conventional magnetic recording disk 21, since the texturing that forms the unevenness of the outermost layer is machining, the unevenness formed on the surface of the nonmagnetic metal layer 22b is rough. It is difficult to control the size. Here, in order to increase the recording density of the magnetic recording disk 21, it is necessary to compress the flying distance of the magnetic head from the surface of the magnetic recording disk 21 to bring the magnetic head and the magnetic layer 24 close to each other. When the roughness of the unevenness reflected on the surface cannot be controlled as in the magnetic recording disk 21 of No. 2, the flying distance must be secured wide so that the unevenness does not collide with the magnetic head.
There is a limit in reducing the flying height of the magnetic head, that is, in increasing the recording density of the magnetic recording disk 21.

Therefore, a new method for forming fine irregularities on the surface of a magnetic recording disk has been studied in place of a mechanical polishing method such as texturing. For example, Japanese Patent Laid-Open No. 3-73419 discloses a non-magnetic substrate. There is disclosed a method in which a low-melting-point metal film such as aluminum is sputter-formed on the surface of to form an island structure, and the unevenness formed by this sputter formation is used. According to this method, the irregularities on the surface of the low-melting-point metal film can be reflected even on the surface of the magnetic recording disk, and the roughness of these irregularities can be regulated to a predetermined roughness by the sputtering formation conditions. Therefore, the flying height of the magnetic head can be reduced.
However, since the unevenness of the magnetic recording disk affects not only the flying distance of the magnetic head but also the magnetic characteristics thereof, the unevenness formed by the low melting point metal film of the island structure is formed on the surface of the magnetic recording disk. On the contrary, in the method of reflecting in (1), there is a problem that the magnetic characteristics are deteriorated and the high recording density of the magnetic recording disk is hindered. That is, in the magnetic characteristics of the magnetic layer shown in FIG. 3, it is important to form the magnetic layer so as to realize high coercive force (high Hc) and high squareness in the direction of the magnetic field generated from the magnetic head. In this, unevenness is formed along the circumferential direction of the magnetic recording disk, which is the direction of the magnetic field generated by the magnetic head, and the hysteresis curve for the circumferential magnetic field (solid line 3
This is because it is important to make 1) higher polygonal than the hysteresis curve for the magnetic field in the radial direction (solid line 32).

In view of the above problems, the object of the present invention is to
By forming fine irregularities on the substrate side without machining, and by giving these irregularities a directionality in the circumferential direction, the low flying distance of the magnetic head can be achieved without sacrificing magnetic characteristics. Object of the present invention is to realize a realizable magnetic recording medium and a manufacturing method thereof.

[0007]

In order to solve the above-mentioned problems, means taken in the magnetic recording medium according to the present invention are as follows:
A fiber-structured concavo-convex forming film is provided on the surface side of a disk-shaped non-magnetic substrate along the circumferential direction, and a magnetic layer is formed on the surface side of the concavo-convex forming film. Is. That is, the surface of the non-magnetic substrate is not machined to form irregularities on the surface thereof, but the surface of the non-magnetic substrate is circumferentially formed along the circumferential direction to form a concavo-convex film having a fibrous structure. It is characterized in that a concavo-convex forming film whose main component is a transition metal carbide is applied in a fibrous structure and the concavities and convexities formed by the concavo-convex forming film having the fibrous structure are utilized.

In order to manufacture the magnetic recording medium having such a structure, in the manufacturing method according to the present invention, the concavo-convex film is formed on the surface side of the non-magnetic substrate by the thermal evaporation method while rotating the non-magnetic substrate in the circumferential direction. It has a physical vapor deposition step of forming it by a physical vapor deposition method such as a sputtering method. Here, the physical vapor deposition is performed with a slit in which the major axis of the opening is aligned from the inner circumference side to the outer circumference side on the surface side of the non-magnetic substrate that rotates in the circumferential direction. Is preferred.

[0009]

In the magnetic recording medium according to the present invention, the non-magnetic substrate is provided on the surface side thereof with a concavo-convex film having a fibrous structure along the circumferential direction thereof. The coefficient of friction between the magnetic recording medium and the magnetic head is reduced by being reflected on the outermost layer of the medium. Here, since the unevenness of the surface of the magnetic recording medium is not formed by machining the non-magnetic substrate, but is formed by the fiber structure-like unevenness forming film deposited by the physical vapor deposition method, Roughness can be controlled by the deposition conditions.
Therefore, the unevenness in roughness is small, and the flying height of the magnetic head can be reduced. Moreover, the concavo-convex forming layer is formed on the front surface side of the non-magnetic substrate along the circumferential direction thereof and has directionality. Therefore, the magnetic layer formed on the surface side of the concavo-convex forming layer is also formed with orientation in the circumferential direction, so that in response to the magnetic field generated in the circumferential direction from the magnetic head,
The magnetic characteristics in the circumferential direction of the magnetic layer can be made high in coercive force and high in prismatic shape. Therefore, the flying height of the magnetic head can be reduced without sacrificing the magnetic characteristics, and the magnetic recording medium can be recorded at high density.

[0010]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a magnetic recording disk of this example.

In the figure, reference numeral 1 is a magnetic recording disk, and the magnetic recording disk 1 has a non-magnetic substrate 2 which is a glass substrate for a metal thin film magnetic disk, which is a base thereof, and a thickness which is formed by sputtering on both sides thereof. A metal underlayer layer 3 which is a 1000 Å Cr layer, and a magnetic layer 4 which is a Co ₈₆ Cr ₁₀ Pt ₄ alloy layer (cobalt-chromium-platinum magnetic thin film layer) having a thickness of about 500 Å sputtered on the surface side thereof; A protective layer 5 which is an amorphous carbon layer having a thickness of about 200Å sputtered on the surface side thereof, and a liquid lubricant layer 6 having a fluorocarbon thickness of about 20Å applied on the surface side thereof.
And have.

Further, in the magnetic recording disk 1 of this example, the unevenness as a ZrC film having a fiber structure is formed between the non-magnetic substrate 2 and the metal underlayer 3 along the circumferential direction of the non-magnetic substrate 2. The film 7 is deposited, and the surface side of the film 7 also has minute irregularities corresponding to the film thickness in the radial direction of the non-magnetic substrate 2. Here, the unevenness on the surface side of the unevenness forming film 7 is not formed by machining the non-magnetic substrate 2, but is formed on the surface side of the non-magnetic substrate 2 along the circumferential direction by Z.
Since the rC film (unevenness forming film 7) is deposited by the reactive sputtering method (physical vapor deposition method), the unevenness forming film 7
In the deposition process of the sputtered particles, the constituent components of the sputtered particles mainly grow around the nuclei formed on the surface of the non-magnetic substrate 2, and the fiber structure (fiber-structure) is formed.
It is in the state where it has been formed. Therefore, the concavo-convex forming film 7 does not cover the surface of the non-magnetic substrate 2 evenly, but forms the adhered areas 7a and the non-adhered areas 7b, and these adhered areas 7a and the non-adhered areas are formed. Corrugations are formed on the surface side of the concavo-convex forming film 7 in correspondence with the step 7b and the step, and the film thickness of the concavo-convex forming film 7. Further, the unevenness forming layer 7 is formed along the circumferential direction of the non-magnetic substrate 2 and has directivity, and these unevennesses are also reflected on the outermost surface of the magnetic recording disk 1. ..

In the magnetic recording disk 1 having such a structure, since the unevenness forming layer 7 has the directionality in the circumferential direction, it is formed on the surface side of the unevenness forming layer 7 via the metal underlayer 5. As a result of the magnetic layer 4 being formed with orientation in the circumferential direction, the magnetic characteristics in the circumferential direction correspond to the magnetic field generated in the circumferential direction from the magnetic head. The magnetic characteristics in the direction are made highly coercive and highly rectangular. Therefore, in the magnetic characteristics measured by applying a magnetic field in the circumferential direction to the magnetic recording disk 1 of this example, the coercive force Hc is 1800 Oe and the squareness ratio S is 0.90.

On the other hand, without forming the concavo-convex forming layer 7, the metal underlayer layer 3, which is a Cr layer 3, Co ₈₆ Cr ₁₀ Pt.
_{4 When a} magnetic layer as an alloy layer 4, a protective layer 5 as an amorphous carbon layer, and a fluorocarbon liquid lubricant layer 6 are formed, the magnetic characteristics measured by applying a magnetic field in the circumferential direction are as follows: Hc is 1200 Oe, squareness ratio S
Is 0.75, and the magnetic recording disk 1 of this example has better magnetic characteristics.

Further, the surface side of the unevenness forming layer 7 has a radius corresponding to the adhered region 7a and the non-adhered region 7b of the unevenness forming film 7 and the film thickness of the unevenness forming film 7. Irregularities are also formed in the direction, and these irregularities are reflected in the outermost layer of the magnetic recording disk 1. Therefore, since the magnetic head slides near the tops of these irregularities, the coefficient of friction between the magnetic head and the magnetic recording disk 1 is as small as 0.4. Moreover, since the unevenness of the unevenness forming film 7 is not formed by machining the surface of the non-magnetic substrate 2, the roughness thereof is controlled by the deposition condition of the unevenness forming film 7, and the size of the unevenness is controlled. The variation is small. Therefore, since the surface roughness of the magnetic recording disk 1 of this example is substantially small, even if the flying distance of the magnetic head with respect to the magnetic recording disk 1 is compressed, the unevenness on the surface side collides with the magnetic head. do not do. Therefore, the flying height of the magnetic head can be reduced, and high density recording of the magnetic recording disk 1 can be realized.

Next, a method of manufacturing the magnetic recording disk 1 having such a structure will be described.

First, the nonmagnetic substrate 2 made of glass having a smooth surface is precisely cleaned, and then the nonmagnetic substrate 2 is placed in the sputtering chamber of the magnetron sputtering apparatus. Then, the sputtering chamber is evacuated to a vacuum degree of about 3 × 10 ⁻⁶ Torr or less, and the nonmagnetic substrate 2 is further heated to about 300 ° C.
Heat to the temperature of.

In this state, as shown in FIG. 2, the major axis of the opening 8a is aligned from the inner peripheral side to the outer peripheral side on the surface side of the non-magnetic substrate 2 arranged in the sputtering chamber. The slit 8 is arranged. In this state, while rotating the non-magnetic substrate 2 in the circumferential direction (shown by the arrow B), Zr was added in an Ar gas atmosphere to which CH ₄ gas was added.
Reactive sputtering is performed using C as a target (physical vapor deposition step). At this time, ZrC (indicated by an arrow B) supplied from the target is with respect to the non-magnetic substrate 2.
It is provided at an angle of about 30 ° to about 60 °. In this way, about 300 Å ZrC is applied to the surface side of the non-magnetic substrate 2.
A film (unevenness forming film 7) is deposited. Here, the unevenness forming film 7
Are formed in a fiber structure by nucleating the constituents in the predetermined direction around the nuclei formed on the surface of the non-magnetic substrate 2 in the deposition process of the sputtered particles. Instead of covering the surface flat,
As shown in FIG. 5, the adhered area 7a and the non-adhered area 7b are formed. As a result, unevenness is formed on the front surface side of the unevenness forming film 7 in correspondence with the deposited area 7a, the non-adhered area 7b, the step, and the film thickness of the unevenness forming film 7. Moreover, since the non-magnetic substrate 2 side is in a state of rotating in the circumferential direction, the unevenness forming film 7 is formed in a state having directivity in the circumferential direction.

Subsequently, the inside of the sputter chamber is set to about 3 × 10 ^-6 To
While evacuating to a vacuum degree of rr or less, the slit 8 is moved to open the surface side of the non-magnetic substrate 2 on which the concavo-convex forming film 7 is deposited, and the temperature of the non-magnetic substrate 2 is set to about Heat to 200 ° C. Next, in an Ar gas atmosphere, the surface of the non-magnetic substrate 2 has a thickness of about 1000Å
Of the metal underlayer 3 which is a Cr layer of Co ₈₆ Cr ₁₀ Pt having a thickness of about 500 Å on the surface side.
_A magnetic layer 4 as a ₄ alloy layer is formed by sputtering, and a protective layer 5 as an amorphous carbon layer having a thickness of about 200 Å is further formed on the surface side thereof by sputtering.

Then, after returning the sputtering chamber to the atmospheric pressure, the unevenness forming film 7, the metal underlayer 3,
The non-magnetic substrate 2 on which the magnetic layer 4 and the protective layer 5 are formed is taken out, and a fluorocarbon liquid lubricant layer 6 is applied to the surface side of the protective layer 5, whereby the magnetic recording disk 1 shown in FIG. 1 is obtained.

As described above, the magnetic recording disk 1 of this example
In the manufacturing method of, in the physical vapor deposition step,
By rotating the magnetic recording disk 1 in the circumferential direction, it is possible to give directionality to the formation direction of the concavo-convex forming film 7, so that it is possible to form the magnetic layer 4 in the circumferential direction on the surface side thereof. The magnetic characteristics of the magnetic layer 4 can be improved. Moreover, since the unevenness forming film 7 is formed on the surface of the non-magnetic substrate 7 made of glass, it is formed as a fiber structure by the crystal axes of ZrC growing in a predetermined direction. The unevenness formed on the surface can be controlled by the surface condition of the non-magnetic substrate 7, which is the underlying side, and the film forming conditions. Therefore, since the unevenness of the roughness formed on the outermost surface of the magnetic recording disk 1 is small, the coefficient of friction with the magnetic head can be reduced, and the magnetic recording disk 1 capable of lowering the flying height of the magnetic head can be formed.

In this example, the fiber structure-like unevenness forming film 7 was formed by reactive sputtering with ZrC as a target in an Ar gas atmosphere to which CH ₄ gas was added. , A method of depositing a small piece of carbon on a Zr target to form a film by sputtering, or by depositing Zr in a plasma atmosphere of Ar gas to which CH ₄ gas is added, a concavo-convex film having a fiber structure is formed. Can be formed. In addition to ZrC, TiC
(Titanium carbide), HfC (hafnium carbide), WC (tungsten carbide), or the like can also be used.

[0024]

As described above, in the present invention, the surface of the non-magnetic substrate is provided with the concavo-convex forming film having a fiber structure formed by physical vapor deposition along the circumferential direction of the non-magnetic substrate. It is characterized in that the magnetic layer is formed on the surface side of the forming film. Therefore, according to the present invention, the unevenness of the unevenness forming film is not formed by machining on the non-magnetic substrate, but is formed by a physical vapor deposition method such as a sputtering method or a thermal evaporation method. Since the variation in roughness is small, the flying height of the magnetic head can be reduced. Moreover, since the unevenness forming layer is formed along the circumferential direction of the non-magnetic substrate, the magnetic characteristics in the circumferential direction of the magnetic layer can be increased in coercive force and polygonal. Therefore, since the flying height of the magnetic head can be reduced without sacrificing the magnetic characteristics, the magnetic recording medium can be highly densely recorded.

[Brief description of drawings]

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

FIG. 2 is a conceptual diagram showing a physical vapor deposition step in the method of manufacturing the magnetic recording disk of FIG.

FIG. 3 is a graph comparing magnetic characteristics in a circumferential direction of a magnetic recording disk with magnetic characteristics in a radial direction thereof.

FIG. 4 is a sectional view of a conventional magnetic recording disk.

[Explanation of symbols]

 1 ... Magnetic recording disk (magnetic recording medium) 2 ... Non-magnetic substrate 3 ... Metal underlayer 4 ... Magnetic layer 5 ... Protective layer 6 ... Liquid lubricant layer 7 ... Unevenness forming film 8 ... Slit

Claims (4)

[Claims] 1. A fiber structure-like unevenness forming film which is to be formed along the circumferential direction of the disk-shaped non-magnetic substrate to form unevenness on the surface side, and the unevenness forming film A magnetic recording medium having a magnetic layer formed on the front surface side. 2. The unevenness forming film according to claim 1,
A magnetic recording medium whose main component is composed of a transition metal carbide. 3. The method of manufacturing a magnetic recording medium as defined in claim 1, wherein the non-magnetic substrate is rotated in the circumferential direction while the concavo-convex film is physically formed on the surface side of the non-magnetic substrate. A method of manufacturing a magnetic recording medium, which comprises a physical vapor deposition step of forming by a vapor deposition method. 4. The physical vapor deposition step according to claim 3, wherein the surface side of the non-magnetic substrate rotating in a circumferential direction is
A method of manufacturing a magnetic recording medium, characterized in that the concave-convex forming film is formed by a physical vapor deposition method with a slit in which the major axis of the opening is aligned from the inner peripheral side toward the outer peripheral side. ..