JP2898184B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial application] Computer external storage device,
In particular, the present invention relates to a magnetic recording medium useful for a magnetic hard disk.

[0002]

2. Description of the Related Art Along with the progress of the information society, a recording medium capable of recording and reproducing data at a high speed with a large capacity is required. In particular, a magnetic recording medium which plays a central role as an external memory of a computer has been increasing year by year. Although both recording densities are increasing, developments are being made to perform higher density recording. To improve the recording density, the distance between the recording medium and the magnetic head that records and reproduces information (flying height)
, But for that purpose the surface of the recording medium must be as smooth as possible. The surface shape of the recording medium after film formation is determined by the surface shape of the substrate. Also,
With the downsizing of notebook and palm-top type computers, thinner magnetic recording devices are required, and thus thinner magnetic recording media are required. Since most of the thickness of the magnetic recording medium is the thickness of the substrate, a thinner substrate that is not easily deformed by an external force is required.

[0003] A substrate of a magnetic recording medium conventionally used is an Al-M substrate in which a base plating layer of a magnetic layer is coated with Ni-P.
Although it is a g alloy substrate, the Al-Mg alloy has a drawback that it is difficult to smooth its surface because of its softness, and that if it is thin, it will be easily distorted during the manufacture of a magnetic recording apparatus. Therefore, a silicon substrate used as a substrate for a semiconductor device which is harder and can smooth the substrate surface has been proposed [Japanese Patent Laid-Open No. 57-105826 (Silicon
JP-A-59-8141 (substrate in which an oxide film is formed on the surface of a single-crystal Si wafer), JP-A-59-96539 (silicon substrate having substantially no irregularities on the surface) See]. On the other hand, in a magnetic recording device, especially a magnetic hard disk, generally, a magnetic recording medium and a magnetic head for writing and reproducing information on and from the recording medium are lifted by a buoyancy generated by an air flow caused by rotation of the recording medium, and the operation is performed. At times, the magnetic head and the recording medium are separated from each other, but the contact start / stop method (abbreviated CSS method) is used in which the magnetic head and the recording medium are in contact when not operating. For this reason, there is a disadvantage that a smooth silicon substrate used for a semiconductor is attracted between a magnetic head and a recording medium, and is not suitable for the CSS method.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic recording medium which solves these disadvantages, has excellent smoothness, and is compatible with the CSS system.

[0005]

Means for Solving the Problems The present inventors have solved the above-mentioned problem by providing a magnetic recording medium comprising:
After examining the silicon material in detail, it was found that the polycrystalline silicon plate, a polycrystalline silicon film deposited on a non-magnetic substrate, or a polycrystalline silicon film deposited on a monocrystalline silicon plate became smooth. It has been found that the present invention is excellent in that it can be applied to the CSS method, and various conditions are established to complete the present invention. That is, in the magnetic recording medium, at least the surface portion of the substrate constituting the magnetic recording medium, which becomes the load / unload portion when incorporated in the magnetic recording device, is made of polycrystalline silicon. The entire substrate may be polycrystalline silicon. The surface portion of the substrate other than the surface portion may be a non-magnetic substrate, and a polycrystalline silicon film may be formed on the surface portion of the substrate.
Further, the substrate may be a single-crystal silicon substrate other than the surface portion, and a polycrystalline silicon film may be formed on the surface portion on the substrate. It is preferable that the polycrystalline silicon on the surface has a crystal grain size of 0.05 to 300 μm.

Hereinafter, the present invention will be described in detail.

The most important feature of the present invention is that a polycrystalline silicon is used for a magnetic recording medium substrate in a magnetic recording medium using silicon as a substrate. In a polycrystalline silicon plate, the polishing rate and the etching rate are different between the inside of the crystal grain (grain) and the boundary between the crystal grains (grain boundary). In a polycrystalline plate, the crystal orientation of each grain is different, so that the crystal orientation of the polished surface is different for each grain.
For this reason, even if the polycrystalline silicon plate is polished, it does not become a perfect mirror surface, and moderate irregularities remain. The smoothness is Rmax, for example, 10
5050 nm. By using a polycrystalline silicon plate as described above, the surface of the substrate can be easily roughened. It is said that the magnetic recording medium and the magnetic head attract each other in proportion to the true contact area of each other.
SS characteristics can be improved.

The method of using polycrystalline silicon may be to cut a polycrystalline silicon wafer into a substrate shape, or to convert polycrystalline silicon into Al, Al-Mg by a method such as CVD or sputtering.
Alternatively, a film may be formed on a non-magnetic substrate such as glass, or the non-magnetic substrate may be a single-crystal silicon plate, and polycrystalline silicon may be formed on the single-crystal silicon plate to form a substrate on which a magnetic recording medium is formed. In the case of a non-magnetic substrate on which a polycrystalline silicon film is formed, the polycrystalline silicon film may be formed only on the load / unload portion (for example, the inner peripheral portion of the disk) contacted by the magnetic head during non-operation. In the case of a polycrystalline silicon film single-crystal silicon substrate, a polycrystalline silicon film is formed only on the load / unload portion, and then this is etched or polished, so that the load / unload portion has appropriate irregularities. In addition, a portion for recording information can have a surface as smooth as a semiconductor wafer, and a magnetic recording medium substrate capable of high recording density can be obtained.

The smaller the crystal grain size of the polycrystalline silicon used in the present invention is, the more desirable it is. Particularly, the crystal grains are smaller than the width of the slider (the shorter one of the width and the length) of the magnetic head. When a rail is provided, it is preferable that the width is smaller than the rail width (the shorter one of the width and the length).
The thickness is 300 μm, preferably 0.05 to 50 μm. The thickness of the substrate used in the present invention is not particularly limited. For example, about 0.2 to 1.5 mm generally used for a magnetic recording medium is sufficient, but is preferably 0.5 mm or less. There is no particular limitation on the size of the magnetic recording medium substrate. For example, a polycrystalline ingot larger than 95 mmφ, which is currently most commonly used for magnetic disks, can be easily obtained. Also, when forming polycrystalline silicon on a single crystal silicon plate,
The above single crystal silicon plate can be easily obtained.

The polycrystalline silicon is formed by a CVD method or a sputtering method. In the case of the CVD method, for example, a heating temperature of 6
Set to 50 ° C and use monosilane as the reaction gas.

The magnetic recording medium of the present invention may be formed by forming an underlayer, a magnetic recording layer, a protective layer, and a lubricating layer in this order on the polycrystalline silicon substrate and the polycrystalline silicon film-formed substrate.
Conventionally known materials, film forming methods, and film forming apparatuses may be used for each layer. As for the material, for example, a Cr layer is formed as a base layer, a Co-Cr-Ta layer is formed as a magnetic recording layer, a C layer is formed as a protective layer, and a perfluoropolyether-based lubricant is applied to the lubricating layer. An RF or DC sputtering method can be used as a film forming method.
And a film formation temperature of 250 ° C.
The film may be formed by sputtering argon at 20 mTorr.

[0011]

EXAMPLES Hereinafter, embodiments of the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. (Example 1) Polycrystalline silicon was sliced and wrapped, and then cut with a core drill to obtain an outer diameter of 48 mm, an inner diameter of 12 mm, and a thickness of 0.38.
After preparing a substrate of mmt and chamfering, polish,
After washing, a magnetic recording medium substrate was manufactured. At this time, the size of the grains was about 50 μm. On this magnetic recording medium substrate, a Cr layer was 100 nm as an underlayer, and Co-C
RF sputtering was performed in an argon gas atmosphere at a substrate temperature of 250 ° C. in the order of an r-Ta layer of 60 nm and a C layer of 30 nm as a protective layer. Lubricant was applied to this magnetic recording medium, and a CSS test (magnetic head: slider width; 1.5 mm, rail width; 0.3 mm) was performed on the inner surface of the substrate whose surface was roughened. No change was observed in the friction force.

Example 2 A substrate made of single-crystal silicon having an outer diameter of 48 mmφ, an inner diameter of 12 mmφ, and a thickness of 0.38 mmt was prepared, and a polycrystalline silicon film was formed on the entire surface of the substrate by a CVD method. This was polished and washed to produce a film-formed substrate. At this time, the crystal grain size of the polycrystalline silicon was about 0.5 μm. An underlayer, a magnetic recording layer, a protective layer, and a lubricating layer were formed on this film-formed substrate in the same manner as in Example 1, and a CSS test was performed on the inner peripheral portion of the substrate whose surface was roughened. Did not change.

Example 3 A substrate made of single-crystal silicon having an outer diameter of 48 mmφ, an inner diameter of 12 mmφ, and a thickness of 0.38 mmt was prepared, and a polycrystalline silicon film was formed on the entire surface of the substrate by a CVD method. After that, only the outer peripheral portion was etched to form a single crystal plane, which was polished and washed to prepare a film-formed substrate.
An underlayer, a magnetic recording layer,
A protective layer and a lubricating layer were formed, and a CSS test was performed on the inner peripheral portion of the substrate whose surface was roughened. As a result, no change was observed in the frictional force up to 10,000 cycles.

(Example 4) A substrate made of single-crystal silicon having an outer diameter of 48 mmφ, an inner diameter of 12 mmφ, and a thickness of 0.38 mmt was prepared, and a mask was applied to the outer peripheral portion. Crystalline silicon was formed. This was polished and washed to produce a film-formed substrate. An underlayer, a magnetic recording layer, a protective layer, and a lubricating layer were formed on this film-formed substrate in the same manner as in Example 1, and a CSS test was performed on the inner peripheral portion of the substrate whose surface was roughened. Did not change.

(Comparative Example) After slicing and wrapping single-crystal silicon, cutting was performed with a core drill, and the outer diameter was 48 mm.
A substrate having a diameter φ of 12 mmφ and a thickness of 0.38 mmt was prepared, etched, polished and washed to prepare a single crystal silicon substrate. An underlayer, a magnetic recording layer, a protective layer, and a lubricating layer were formed on this substrate in the same manner as in Example 1, and a CSS test was performed. As a result, the frictional force doubled after 1,000 cycles.

[0016]

According to the present invention, it is possible to provide a magnetic recording medium which is excellent in smoothness and conforms to the CSS system, and its industrial value is extremely high.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshio Tawara 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa KSP Building Shin-Etsu Chemical Co., Ltd. Corporate Research Center (58) Field surveyed (Int.Cl. ⁶ G11B 5/82 G11B 5/704 G11B 5/66

Claims (5)

(57) [Claims] 1. A magnetic recording medium, of the board constituting the magnetic recording medium, incorporated into at least a magnetic recording apparatus
The surface of the part that becomes the load / unload part when
The magnetic recording medium which is a polycrystalline silicon down. 2. The magnetic recording medium according to claim 1, wherein
Magnetic recording medium the entire plate is a multi-crystal silicon down. 3. The magnetic recording medium according to claim 1, wherein
Other than the surface portion of the plate is non-magnetic substrate, and the substrate on the
Magnetic recording medium which polycrystalline silicon film on the surface portion of is deposited. 4. The magnetic recording medium according to claim 1, wherein
Other than the surface portion of the plate is a single crystal silicon substrate, and polycrystalline silicon film is deposited on the surface portion of the substrate
Magnetic recording media it is. 5. The polycrystalline silicon on the surface has a crystal grain size of
5. The magnetic recording medium according to claim 1 , wherein the thickness is 0.05 to 300 [mu] m .