JP2006099813A - Method for manufacturing magnetic recording medium substrate, and method for manufacturing magnetic recording medium using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly processing a substrate surface and to suppress the formation of abnormal projections by improving slurry wetting on the surface of a substrate to be subjected to texture processing, and uniformly spreading a slurry to be supplied to the surface of the substrate during the texture processing to the surface of the substrate. <P>SOLUTION: The method includes the wetting improving liquid application step 40 of applying a wetting improving liquid for improving the wetting of a slurry containing abrasive grains on the surface of a substrate to be subjected to texture processing before the texture processing is executed, and the texture processing step 50 of executing the texture processing by rotating the substrate wet by the wetting improving liquid to supply a slurry to the surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a substrate for a magnetic recording medium and a method for manufacturing a magnetic recording medium using the manufacturing method, and is particularly suitable for a magnetic recording medium mounted on a hard disk drive (HDD).

In recent years, hard disk drives (HDDs) are often used as storage devices for personal computers and digital home appliances.
A magnetic disk (HD) as a magnetic recording medium mounted on the HDD is generally a non-magnetic substrate made of a Ni-P film by electroless plating on the surface of a disk-like nonmagnetic substrate, for example, a substrate made of aluminum alloy or glass. A magnetic metal film is formed and a surface is textured to produce a substrate. On the substrate, a nonmagnetic metal underlayer made of a Cr film, a magnetic recording layer made of a Co alloy magnetic film, amorphous carbon, etc. A protective layer made of a film or the like is sequentially formed by sputtering or the like, and a lubricating layer is formed by applying a liquid lubricant thereon.
The texture processing described above gives magnetic anisotropy to the magnetic recording layer to improve the magnetic characteristics, and concentric circles on the surface of the substrate in order to improve the friction / adsorption characteristics (CSS characteristics) with the magnetic head. This is a processing technology for forming streak, which is done by pressing the polishing tape while supplying slurry to the surface of the rotating substrate. To increase the recording capacity of the magnetic disk, the surface of the magnetic head and magnetic disk Therefore, in the texturing process, it is necessary to reduce the grain size of the abrasive grains contained in the slurry of the processing liquid to make it finer.

At that time, if there are abnormal protrusions on the surface of the textured substrate, they will appear as protrusions as they are on the surface of the magnetic disk formed with a magnetic recording layer on the surface. A texture processing technique for reducing the height as much as possible is desired.
As an example of solving the problem when reducing the particle size of the abrasive grains contained in the slurry, Patent Document 1, for example, reduces the particle size of the abrasive grains by increasing the hydrophilicity of the surface of the substrate. Furthermore, it is described that a sufficient and uniform texture can be formed in a short time.
Japanese Patent Laid-Open No. 2003-30821 Japanese Patent Laid-Open No. 2001-341058 JP-A-10-188273

In recent years, with the spread of digital home appliances and the like, there has been a demand for further increase in the recording capacity of the magnetic disk, and hence further reduction in the flying height of the magnetic head. There is a demand for stable flying of the head.
As described above, since the flying height of the magnetic head is extremely low, an abnormal protrusion on the surface of the magnetic disk may cause a head crash and damage the surface of the magnetic disk. Even a small protrusion that does not lead to a head crash is likely to cause various errors when reading and writing information.
For this reason, in texture processing, it is necessary to eliminate the formation of abnormal protrusions on the substrate surface or to reduce the height thereof as much as possible, but the slurry supplied to the substrate surface during texture processing is applied to the substrate surface in a short time. If it does not spread uniformly, the amount of dispersion of diamond or other abrasive particles suspended in the slurry will be different on the substrate (the dispersion state is not uniform), so that the substrate surface cannot be processed uniformly and abnormal projections will occur. There is a risk of being easily formed.

  In view of the above-mentioned points, the present invention improves the wettability of the slurry on the surface of the substrate to be textured, so that the slurry supplied to the surface of the substrate during texturing spreads uniformly on the surface of the substrate. Another object of the present invention is to provide a method for manufacturing a substrate for a magnetic recording medium that enables uniform processing of the substrate surface and can suppress the formation of abnormal protrusions, and a method for manufacturing a magnetic recording medium using the manufacturing method.

In order to achieve the above-described object, the method for manufacturing a magnetic recording medium substrate according to the present invention comprises subjecting a wettability improving liquid to improve the wettability of a slurry containing abrasive grains on the surface of the substrate to be textured. A wettability improving liquid coating step to be applied before applying the coating, and a texture processing step of rotating the substrate wet with the wettability improving liquid and applying texture processing to the surface while supplying the slurry. Features.
Here, the wettability improving liquid is preferably composed of a liquid whose contact angle to the surface of the substrate to be textured is smaller than that of the slurry, and is composed of a liquid of components obtained by removing abrasive grains from the slurry. The wettability improving liquid can be applied by a dip coating method or a spin coating method.
The method for producing a magnetic recording medium of the present invention comprises forming a magnetic recording layer comprising at least a Co alloy magnetic film on the magnetic recording medium substrate produced by the method for producing a magnetic recording medium substrate of the present invention. It is characterized by including a film forming step.

  In the present invention, the wettability improving liquid for improving the wettability of the slurry is applied to the surface of the substrate before texturing, so that the wettability of the slurry on the substrate surface is improved. The slurry supplied to the surface of the rotating substrate while wetted with the improvement liquid is spread uniformly on the surface of the substrate in a short time by the rotation of the substrate.

  According to the present invention, the wettability improving liquid for improving the wettability of the slurry is applied to the surface of the substrate before the texturing, so that the slurry supplied at the time of texturing spreads uniformly on the surface of the substrate. Since it did in this way, the uniform process without distribution in the dispersion state of an abrasive grain is attained, and formation of an abnormal protrusion can be suppressed. Therefore, the height of the abnormal protrusion can be reduced to enable stable flying of the magnetic head with a low flying height, thereby increasing the recording capacity.

Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing an embodiment of a magnetic recording medium manufactured according to the present invention.
As shown in FIG. 1, a magnetic recording medium 100 according to an embodiment manufactured according to the present invention has a nonmagnetic metal underlayer 11, a magnetic recording layer 12, and a magnetic recording medium substrate 10 according to an embodiment manufactured according to the present invention. A protective layer 13 and a lubricating layer 14 are sequentially laminated.
The magnetic recording medium substrate 10 is preferably provided with a nonmagnetic metal film 2 on a disk-shaped nonmagnetic substrate 1. When a glass substrate or the like is used as the nonmagnetic substrate 1, the nonmagnetic metal film 2 can be eliminated using the nonmagnetic substrate 1 itself as the substrate 10.
Although not shown, the nonmagnetic metal film 2, the nonmagnetic metal underlayer 11, the magnetic recording layer 12, the protective layer 13, and the lubricating layer 14 can be similarly provided on the other surface side of the nonmagnetic substrate 1. .

As shown in FIG. 2, the manufacturing method of the magnetic recording medium 100 of this embodiment includes a plating step 20 for electroless plating a nonmagnetic metal film 2 on a disk-shaped nonmagnetic substrate 1, and the plated nonmagnetic material. Polishing step 30 for polishing the surface of the metal film 2 and application of a wettability improving liquid for applying a wettability improving liquid for improving the wettability of the slurry containing abrasive grains to the surface of the polished nonmagnetic metal film 2 A substrate manufacturing process 200 including a process 40 and a texture processing process 50 for rotating the substrate 10 in a state wetted with the wettability improving liquid and supplying a slurry to the surface thereof, and the substrate manufacturing process 200. A film forming step 60 for sequentially forming the nonmagnetic metal underlayer 11, the magnetic recording layer 12, the protective layer 13 and the lubricating layer 14 on the magnetic recording medium substrate 10 manufactured by the above method.
[Description of Substrate Manufacturing Process 200]
In the plating step 20, an aluminum alloy substrate or glass substrate having a nominal diameter of 2.5 inches, 3 inches, 3.3 inches, 3.5 inches, 5 inches, etc. is used as the disk-shaped nonmagnetic substrate 1 on both sides. The substrate 10 is preferably formed by forming a Ni—P film or the like as the nonmagnetic metal film 2 by electroless plating.

In addition, when the nonmagnetic base | substrate 1 itself which consists of glass substrates etc. is used as the board | substrate 10, this plating process 20 is unnecessary.
As the polishing step 30, it is preferable that both surfaces of the substrate 10 are mirror-polished simultaneously using a well-known double-side polishing apparatus. The polished substrate 10 is cleaned and dried to prepare for texture processing.
In the wettability improving liquid application step 40, it is preferable to apply uniformly the liquid of the component excluding the abrasive grains from the slurry used for texture processing as the wettability improving liquid on the surface of the substrate 10 by dip coating or spin coating. 10 on both sides.
This coating is performed by adding a dip tank for dip coating the wettability improving liquid, a vertical mechanism of the substrate 10 into the dip tank, and a coating nozzle for the wettability improving liquid for spin coating to the texture processing apparatus. Can do. In the case of adding a wettability improving liquid application nozzle, it is preferable because the wettability improving liquid can be spin-coated using the substrate rotation mechanism of the texture processing apparatus.

As the texture processing step 50, using a known texture processing apparatus, the substrate 10 is rotated to bring a polishing cloth (preferably a polishing tape) into contact therewith, and abrasive grains such as diamond are dispersed and suspended at the contact portion. The slurry can be dropped by dropping from the slurry supply nozzle.
By uniformly applying the liquid of the component excluding the abrasive grains from the slurry used for texturing in the wettability improving liquid application step 40 as the wettability improving liquid, the affinity of the slurry on the substrate 10 is improved. Therefore, the slurry can be spread uniformly in a short time during texturing, and the dispersed state of the abrasive grains such as diamond suspended in the slurry with respect to the substrate becomes uniform. Therefore, the substrate can be uniformly processed without texture irregularity, and the formation of abnormal protrusions is suppressed.
[Description of Film Formation Step 60]
In the film forming step 60, after the texture processing in the texture processing step 50, the nonmagnetic metal underlayer 11, the magnetic recording layer 12, the protective layer 13, and the lubricating layer 14 are sequentially formed on the cleaned and dried substrate 10. Each film forming step.

The nonmagnetic metal underlayer 11 is preferably formed by sputtering, and the composition may be conventional and is not particularly limited. For example, Cr, Cr—W, Cr—V, Cr—Mo, Cr It is made of -Si, Ni-Al, Co-Cr, Mo, W, Pt, etc., and may have a multilayer structure. The film thickness is 20 nm or less, preferably 10 to 20 nm.
The magnetic recording layer 12 is preferably formed by a sputtering method, comprising the ferromagnetic metal can be used as a recording layer, for _{example, CoCrTaPt, CoCrTaPt-Cr 2 O} 3, CoCrTaPt-SiO 2, CoCrTaPt-ZrO 2, CoCrTaPt It is made of a Co alloy magnetic film containing -TiO ₂ , CoCrTaPt-Al ₂ O ₃ or the like as a component, and may have a multilayer structure. The film thickness is 20 nm or less, preferably 10 to 20 nm.
The protective layer 13 is preferably formed by sputtering or plasma CVD, and has a function of protecting the magnetic recording layer 12 from the impact of the magnetic head and corrosion of corrosive substances in the outside world. A carbon protective film made of carbon, nitrogen-added amorphous carbon, or the like is preferable. The film thickness is 5.0 nm or less, preferably 2.0 to 4.0 nm.

The lubricating layer 14 is preferably formed by applying a liquid lubricant, and the liquid lubricant is preferably a perfluoro-polyether, such as Z-dol, Z-tetraol, Z-dol TX, AM ( Any liquid lubricant such as a trade name of Augmont) may be used. The film thickness is 2.0 nm or less, preferably 1.0 to 1.5 nm.
When the flying height that can guarantee the stable flight of the magnetic head is measured for the magnetic recording medium manufactured as described above, the conventional wettability improving liquid coating process 40 is not provided by providing the wettability improving liquid coating process 40. Compared to that, uniform processing with no distribution of abrasive grains is performed to suppress the formation of abnormal projections, and the height of abnormal projections can be reduced, so the magnetic head is stable even at low flying height Can fly.

It is a cross-sectional schematic diagram which shows the structure of embodiment of the magnetic recording medium manufactured by this invention. It is process drawing which shows the structure of embodiment of the manufacturing method of the magnetic recording medium using the manufacturing method of the board | substrate for magnetic recording media which concerns on this invention.

Explanation of symbols

1 Nonmagnetic Base 2 Nonmagnetic Metal Film 10 Magnetic Recording Medium Substrate 11 Nonmagnetic Metal Underlayer 12 Magnetic Recording Layer 13 Protective Layer 14 Lubricating Layer 100 Magnetic Recording Medium 200 Substrate Manufacturing Process

Claims (5)

A wettability improving liquid application step for applying a wettability improving liquid for improving the wettability of the slurry containing abrasive grains on the surface of the substrate to be textured before applying the texture process;
A method of manufacturing a substrate for a magnetic recording medium, comprising: a texture processing step of rotating a substrate wetted with the wettability improving liquid and performing texture processing while supplying the slurry to the surface of the substrate.   2. The method of manufacturing a substrate for a magnetic recording medium according to claim 1, wherein the wettability improving liquid comprises a liquid having a contact angle to the surface of the substrate to be textured smaller than that of the slurry.   The method for manufacturing a substrate for a magnetic recording medium according to claim 1, wherein the wettability improving liquid comprises a liquid having a component obtained by removing abrasive grains from the slurry.   4. The method of manufacturing a magnetic recording medium substrate according to claim 1, wherein the wettability improving liquid is applied in the wettability improving liquid application step by a dip coating method or a spin coating method.   A method of manufacturing a magnetic recording medium, comprising: a film forming step of forming at least a magnetic recording layer on the magnetic recording medium substrate manufactured according to claim 1.

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