JPH11232638A - Magnetic disk and its formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of collision scars between a disk and a head by setting on a substrate a magnetic layer and a protecting layer upper than the magnetic layer to the substrate, and processing a surface of the protecting layer so as to achieve not larger than a specific value at a specific Bearing Depth position of the layer measured by an atomic force microscope. SOLUTION: An upper face of an aluminum alloy disk substrate which is Ni-P plated by electroless plating by a thickness of 10 μm is polished. A Cr undercoat film, a magnetic layer of Co-Cr-Ta alloy and a carbonaceous protecting layer are sequentially formed by sputtering by a thickness of 100-600 Åon the surface of the disk substrate. Thereafter, a surface of the protecting layer is cleansed with the use of an abrasive tape holding abrasive grains to achieve not larger than 7 nm at a position of a Bearing Depth 10% measured by an atomic force microscope. An average occurrence rate of collision scars leading to defective products after abnormal projections present at the surface are removed is greatly lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk and, more particularly, to a high-quality magnetic disk with less occurrence of surface defects in a disk manufacturing process and a method of manufacturing the same.

[0002]

2. Description of the Related Art A magnetic disk is usually provided with a protective layer in order to protect the magnetic layer from deterioration or wear. Although there are various types of protective layers, carbonaceous protective films are most widely used. Currently used magnetic disk devices employ a CSS (contact start top) system in which a magnetic head flies during recording and reproduction and contacts the magnetic disk when the motor is stopped. It must have durability to withstand movement repeatedly. However, as the recording density of the magnetic disk increases, the distance between the magnetic layer and the head needs to be reduced, and the protective layer is also required to be thin. The distance between the magnetic head and the magnetic disk during recording / reproducing, that is, the flying height of the magnetic head has recently been reduced to about 0.10 μm or less.

[0003]

As the flying height of the magnetic head decreases, a finishing and inspection step in the manufacturing process of the magnetic disk, that is, a step of removing protrusions having a predetermined height or more on the surface of the protective layer and an inspection of the flying height. In such cases, there is a problem of a collision mark generated when the inspection (or projection removal) head collides with the magnetic disk. This is because the collision trace is considered to cause a collision with the magnetic head when mounted on the drive, or to cause a component of the magnetic layer to be deposited on the surface from the portion.

[0004]

As a result of intensive studies, the present inventors have found that by providing a protective layer that satisfies predetermined conditions, it is possible to dramatically reduce the collision between the head and the disk in the subsequent finishing and inspection steps. Having found something, they have reached the present invention. That is, the gist of the present invention is to provide a magnetic disk having at least a magnetic layer on a substrate and a protective layer provided above the magnetic layer with respect to the substrate, the Bearin of the protective layer measured by an atomic force microscope (AFM).
The magnetic disk is characterized in that the value of gDepth 10% is 7 nm or less.

Further, another gist of the present invention is to provide a method for manufacturing a magnetic disk in which at least a magnetic layer is provided on a substrate and a protective layer is provided on the substrate above the magnetic layer.
BearingD measured by atomic force microscope (AFM)
A method of manufacturing a magnetic disk, comprising a step of treating the surface of a protective layer so that the value of epth 10% becomes 7 nm or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a substrate,
A substrate that is commercially available, called a substrate,
A base film-forming substrate in which a base film of Ni-P electroless plating is provided on the surface of an Al-Mg alloy substrate, and the base film is mirror-finished (polished) is preferably used. In addition, a substrate made of a material such as copper, titanium, glass, ceramic, carbon, and silicon can be used. Usually, the substrate is processed into a disk shape, the thickness of the substrate itself is about 1 to 3 mm, and the thickness of the underlayer is about 20 mm.
３０30 μm.

[0007] Such a substrate is subjected to a texturing process or the like according to a conventional method, and then used. The texture processing is a mechanical processing performed to provide an extremely minute stripe pattern (groove) or unevenness on the mirror surface of the base film. If necessary, chemical etching or electrolytic etching (electropolishing) can be performed as a finishing process for removing burrs and burrs after the texturing process. By these processes, the attraction between the magnetic disk and the magnetic head is prevented, the contact start / stop (CSS) characteristics are improved, and the magnetic anisotropy is improved.

The underlayer formed on the substrate may be a conventionally known nonmagnetic underlayer, and may be formed of, for example, Cr, Ti, Ni, or the like. The Cr or Ti of the underlayer may be an alloy containing Si, V, Cu, etc. in a range that does not impair the crystallinity thereof, for example, in a range of several atomic%. In the present invention, a Cr-based underlayer is particularly preferable. The thickness of the underlayer is usually 50 to 200.
0 ° range.

The magnetic layer formed on the underlayer of the substrate is generally made of Co-Cr, Co-Ni, Co-Cr-.
It is a cobalt-based alloy thin film layer represented by X, Co-Ni-X, Co-WX or the like. Here, X is Li, S
i, P, Ca, Ti, V, Cr, Ni, As, Y, Z
r, Nb, Mo, Ru, Rh, Ag, Sb, Hf, T
a, W, Re, Os, Ir, Pt, Au, La, Ce,
One or more elements selected from the group consisting of Pr, Nd, Pm, Sm, Eu and B are used. The magnetic layer is usually formed on the base layer of the substrate by means such as sputtering. The thickness of this magnetic layer is usually 1
The range of 00 to 1000 ° is preferred.

The protective layer is provided directly on the magnetic layer or via another layer. Its material is carbon film, hydrogenated carbon film, nitrogenated carbon film, carbonized film such as TiC, SiC,
Nitride film of SiN, TiN, etc., SiO, Al ₂ O ₃ , Zr
It is composed of an oxide film such as O, and is usually formed by sputtering, CVD, or the like. As the protective layer, a carbon film, a hydrogenated carbon film and a nitrogenated carbon film are particularly preferable.

The hydrogenated carbon film is not particularly limited as long as it is a film containing hydrogen and carbon. For example, a sputter gas (usually using an inert gas such as argon) using a carbon target is used. ) And sputtering in a plasma containing hydrogen gas. The content of hydrogen in the sputtering atmosphere is usually 2 to 20% by volume.

The nitrogenated carbon film is not particularly limited as long as it contains nitrogen and carbon. For example, a sputter gas, a nitrogen gas, a nitrogen monoxide gas, a nitrogen dioxide gas, It can be formed by sputtering in a plasma containing a nitrogen-containing gas such as ammonia gas or a nitrogen-containing gas such as air. For example, when air is used, the content of air in the sputtering atmosphere is usually 2 to 20% by volume.
It is. Further, for example, a hydrogenated and nitrogenated carbon film can be formed by simultaneously mixing a hydrogen gas and a nitrogen (containing) gas into a sputtering gas.

The thickness of the protective layer is usually about 50 to 1000
Å, preferably in the range of about 100-600Å. In the present invention, the surface of the protective layer has a bearing depth of 10% by AFM (atomic force microscope) (Bea).
The ring depth curve is set to be 7 nm or less, preferably 6 nm or less (0% to 100% (total height)). The measured value of 7 nm is 7 nm from the highest peak of the protrusion existing within the measurement range.
The horizontal cross-sectional area at the position where
%. Bearing Dep
If the position of th10% is larger than 7 nm (deep), collision marks between the magnetic disk and the magnetic head increase, which is not preferable.

The surface of the protective layer that satisfies such conditions can be realized by, for example, performing tape cleaning after forming the protective layer. As the tape, a polishing tape in which abrasive grains such as alumina particles and SiC particles having a particle size of 0.3 to 3 μm are supported on a film made of polyethylene terephthalate, polyamide, or the like can be used.

As a tape cleaning method, there are a method of blowing air onto the tape to contact the tape with the disk, a method of contacting the tape with the disk with a roll, and the like. Either method may be used to remove minute protrusions on the disk surface. For this purpose, it is necessary to perform a finishing treatment for grinding the protective layer surface by a predetermined amount.

If a surface satisfying the above-mentioned AFM measurement values is obtained, a lubricant layer may be provided on the surface of the protective layer, if necessary. As the lubricant, for example, a fluorine-based liquid lubricant is used, and usually, a dip coating method, a spin coating method,
It is formed on the surface of the protective layer by a spray coating method or the like. The thickness of the lubricant layer is typically in the range of about 5-50 °.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. (Examples and Comparative Examples) A surface of an aluminum alloy disk substrate on which Ni-P plating was applied to a thickness of 10 μm by an electroless plating method was polished, and a Cr base film and a Co—Cr— A magnetic layer made of a Ta alloy and a protective film made of a carbonaceous film were sequentially formed by a sputtering method. In this state, the position where Bearing Depth is 10% was 15 to 20 nm.

Next, the tape was cleaned under the conditions shown in Table 1. The surface of the protective layer was measured under the following conditions. AFM: Scanning probe microscope NanoScopeIIIa (Digita
Unit: Multi-mode unit AFM mode: Tapping Scan size (μm): 10 × 10 Scan angle (deg): 90 Scan rate (Hz): 1.0 Number of samples: 512 Z limit (V): 440 Filter Processing: Lowpass, Flatten Auto (order = 1) Bearing Area: As a result of the measurement, 100 discs with a bearing depth of 10% at 7 nm or less (Example) and 7
About 100 disks larger than nm (comparative example)
Each was coated with a fluorinated liquid lubricant to produce a magnetic disk.

Next, after removing abnormal protrusions present on the surface with a burnishing head, a glide inspection is performed at a head flying height of 25 nm, and the position where the abnormality is detected is observed with an optical microscope to check for the presence of a collision mark. Was. Table 1 shows the average incidence of collision marks.

[0020]

[Table 1]

As described above, according to the magnetic disk of the present invention, since the protective layer having a surface satisfying specific conditions is provided, the occurrence of a collision mark between the disk and the head which causes a defective product is remarkably suppressed. It has the effect that it becomes possible.

Claims (3)

[Claims] 1. A magnetic disk having at least a magnetic layer on a substrate and a protective layer provided above the substrate with respect to the magnetic layer, wherein B of the protective layer measured by an atomic force microscope (AFM).
A magnetic disk, wherein the value of earing Depth 10% is 7 nm or less. 2. The magnetic disk according to claim 1, wherein said protective layer is made of carbonaceous material. 3. A method of manufacturing a magnetic disk, comprising: providing at least a magnetic layer on a substrate and a protective layer above the magnetic layer with respect to the substrate, wherein B of the protective layer is measured by an atomic force microscope (AFM).
A method for manufacturing a magnetic disk, comprising a step of treating the surface of the protective layer so that the value of earing Depth 10% is 7 nm or less.