WO1999045537A1

WO1999045537A1 - Magnetic recording medium, process for fabricating the same, and magnetic storage apparatus made by using the same

Info

Publication number: WO1999045537A1
Application number: PCT/JP1998/000886
Authority: WO
Inventors: Yoshinori Honda; Yuuichi Kokaku; Mitsuhiro Shoda; Toshinori Ono
Original assignee: Hitachi, Ltd.
Priority date: 1998-03-04
Filing date: 1998-03-04
Publication date: 1999-09-10
Also published as: WO1999045536A1

Abstract

A process for plasma-treating the surface of the substrate of a magnetic recording medium to have a uniform and arbitrary surface roughness over the whole surface without allowing ions or radicals in the plasma to erode main elements constituting the surface. This process can provide the advantages of prevention of adhesion of the magnetic head to the magnetic recording medium, adhesion to a magnetic high reliability, low flying height, high TPI thanks to isotropy of magnetic characteristics, and low noise. Further, it can provide a magnetic storage apparatus having a high recording density and a high reliability.

Description

Details

Magnetic recording medium, method of manufacturing the same, and magnetic storage device using the same

The present invention relates to a magnetic storage device such as a magnetic disk device, and more particularly to a magnetic recording medium used for a head disk assembly (HDA) of a magnetic storage device and a method of manufacturing the same. In particular, the present invention relates to an inexpensive and high-quality magnetic recording medium capable of high-density recording, a manufacturing method thereof, and an HDD using the magnetic recording medium.

In recent years, as the amount of information has increased and the transmission speed has increased, the importance of higher density and higher speed of magnetic storage devices used as external storage devices in computers has been increasing.

In general, a magnetic disk drive mainly includes a magnetic disk 1 and a magnetic head 2 that levitates above the magnetic disk 1 and performs recording and reproduction, as shown in FIG. 12, and also rotates the magnetic disk 1 Rotating mechanism 3, Magnetic head 2 Positioning head on rotating magnetic disk 1, Head positioning mechanism (servo mechanism) 4, RZW signal circuit 5 for recording and reproducing from magnetic disk using magnetic head Consists of Here, the floating gap between the magnetic disk 1 and the magnetic head 2 has become less than 0.05 m with the increase in recording density. It is desired to guarantee the sliding reliability at the time of contact.

Conventionally, a configuration of a magnetic recording medium and a method of manufacturing the same have been proposed for these measures. Various proposals have been made for the purpose. The magnetic recording medium is composed of a substrate and a layered structure such as a magnetic film and a protective film formed on the substrate.Fine abrasive grains are applied to the surface of the substrate to prevent the magnetic head and the magnetic disk from attracting. The method of forming fine grooves by circumferential or non-directional polishing called texture by the used machining method has been generally adopted. Other methods include a so-called deposition texture in which fine projections are formed on the surface of a substrate or a magnetic film by sputtering, and a method in which a surface is coated with teflon particles after forming a protective film, and then a DRY etch is performed. There is a so-called etching texture method for forming irregularities on the surface of the protective film by etching with a polishing method. Examples of these methods are disclosed in Japanese Patent Application Laid-Open Nos. Sho 61-19695 and Sho 61-2. 0 2 3 2 4 and Japanese Patent Application Laid-Open No. 58-53 0 26.

In either method, the purpose is to prevent adhesion between the magnetic head and the magnetic disk and to ensure reliability by contact start / stop (hereinafter referred to as CS / S). Requires a certain height. Therefore, the flying height of the magnetic head cannot be reduced below the height of the unevenness, and the low flying height of the magnetic head required to achieve the high recording density required at present is required. There was a problem that I could not do it. In other words, the flying characteristics of the conventional magnetic head depend on the height at which the contact between the magnetic head and the magnetic recording medium starts (hereinafter referred to as H to), the protective film thickness on the magnetic film, and the lubricating film thickness. Defined. As a result, conventionally, the limit of H to was about 2 O rnn. This is because it is difficult to reduce the surface roughness of the magnetic recording medium to a certain value or less, and the burrs that occur when processing the substrate cause the center line average roughness (R a) to be small even if the center line average roughness (R a) can be reduced. The reason is that the peak height (R p) and the maximum peak height (R max) have abnormally high values, and the uniformity of the surface shape of the entire substrate cannot be controlled. This phenomenon is The same applies to the texture and the etching texture. In the case of the depot texture, since the projections are formed by sputtering, there is a high possibility that the projections will grow abnormally, and it is difficult to make the sizes uniform. In the case of the etching texture, the height of the hill and the film thickness of the etched surface for etching the protective film cannot be absolutely reduced in terms of adhesion and strength, and the roughness of the substrate cannot be reduced. Since the hills are transferred to the surface of the protective film and appear, the height of the hills is limited to about 10 nm, and the remaining film thickness needs to be about 10 nm or about 15 nm, making it difficult to improve the flying characteristics. Regarding the uniformity of the hills, secondary and tertiary agglomeration cannot be avoided because the fine particles are applied and masked. This will inevitably cause thermal aspiration (TA) due to contact between the magnetic head and the large hills.

As described above, in the prior art, since consideration has not been given to the uniformity of the entire surface of the substrate, the anti-adhesion between the magnetic head and the magnetic disk, which has been increasingly required in recent years, has been improved. It is difficult to achieve high recording density by ensuring the reliability and lowering the flying height of the magnetic head. Disclosure of the invention

An object of the present invention is to solve the problems of the prior art, and to achieve extremely low levitation, high sliding resistance, high TPI and high TPI due to the disappearance of magnetic anisotropy, and reliability with low noise. Another object of the present invention is to provide a magnetic recording medium and a magnetic storage device having high performance. For this purpose, as described above, it is essential to supply a process capable of making the surface of the magnetic disk uneven and uniform in the disk surface and selecting an arbitrary surface roughness.

In the present invention, the basic concept for obtaining a uniform surface is that the height of the concaves and convexes can be controlled uniformly in the plane, and the number of irregularities and the pitch of the irregularities are controlled. The above-mentioned problems of the prior art are solved based on controllability, non-directionality such as machining, improvement of mechanical properties of the surface by processing only the surface, and the present invention. It achieves its purpose.

In the method of forming a medium by sputtering, tracing the surface roughness of the substrate as it is is a basic phenomenon.

There are roughly two processing methods. One is a chemical treatment method using a jet, and the other is a dry method using vacuum and plasma. In wet methods, methods such as etching and plating are the main methods, so control is difficult, there is no stability, and there are significant effects such as contamination of the substrate and necessity of cleaning after processing. As a method of forming the surface shape by a dry method, a physical method using plasma was considered to be easy to control and suitable for arbitrary process construction. Therefore, when the substrate surface was treated with Ar gas using a parallel plate RF etching device, the surface of the substrate was shaved. As shown in the upper part of Fig. 1, the average center of the surface roughness of the substrate before the treatment was obtained. The position of the average center line of the surface roughness after processing is lower than the position of the line. In other words, it was found that under the conditions that would cause etching, the surface would not be uniform in height of the projections, but only roughened. Thus, by selecting the processing conditions, the present inventors did not change the average center line of the surface roughness of the substrate even after plasma processing, as shown in the lower part of Fig. 1, and changed the surface shape minutely. I found something that could be done. This can be achieved by treating the main constituent elements on the surface of the substrate without erosion by ions or radicals in the plasma.

Further, the present inventors, as shown in FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. The height depends on the processing time and the energy of the plasma to be processed. Tsuchi was found to be dependent on the type of gas being processed and the pressure of the gas. Therefore, it is found that the magnetic recording medium required for the present invention can be obtained by appropriately selecting the processing conditions such as the processing time, the energy of the plasma to be processed, the gas type and the gas pressure, and performing the plasma processing. Was.

This makes it possible to make the pitch finer than was possible with the prior art, and to control very fine irregularities with good reproducibility.

Furthermore, the hardness and Young's modulus of the surface treated by the present invention were measured with a thin film hardness tester manufactured by Nanoindenter, and as shown in Fig. 9, the hardness and Young's modulus were clearly improved as compared to before the treatment. Therefore, the effect of reducing the impact at the time of contact between the magnetic disk and the magnetic head can be greatly expected. Therefore, improvement of scratch resistance and crash resistance can be expected. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a roughness curve in the etching mode and the process of the present invention. FIG. 2 is a diagram showing the relationship between plasma power and surface roughness.

FIG. 3 is a diagram showing the relationship between the plasma power and the pitch of the minute projections. FIG. 4 is a diagram showing the relationship between plasma processing time and surface roughness.

FIG. 5 is a diagram showing the relationship between the plasma processing time and the pitch of the minute projections. FIG. 6 is a diagram showing the relationship between the processing gas pressure and the surface roughness.

FIG. 7 is a diagram showing the relationship between the processing gas pressure and the pitch of the fine projections. FIG. 8 is a diagram showing the relationship of surface roughness.

FIG. 9 is a diagram showing hardness and Young's modulus before and after the treatment of the present invention. FIG. 10 is a diagram showing a manufacturing flowchart of this embodiment and a conventional example. FIG. 11 is a diagram showing AFM images of the substrate surface of the present embodiment and the conventional example. FIG. 12 is a schematic diagram of a magnetic disk drive.

FIG. 13 is a diagram showing processing conditions of the present example and a comparative example. FIG. 14 is a diagram showing evaluation results for the present example and the comparative example.

FIG. 15 is a schematic view showing a magnetic recording medium according to this embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

First, we prepared two types of substrates: a Ni-P plating on aluminum, followed by a machined flat surface, and a chemically strengthened glass substrate. The substrate size is 3.5 inches for the aluminum / Ni-P substrate and 2.5 inches for the glass substrate.

After cleaning the substrate with pure water, treatment is performed under the processing conditions shown in Fig. 13 to treat the substrate surface without eroding the main constituent elements on the substrate surface by ions or radicals in the plasma. Was. As a result, the substrates of Examples Nos. 1 to 10 having the mechanical properties and surface states shown in FIG. As a comparative example, as shown in Comparative Examples 1 to 4 in FIG. 13, a substrate (aluminum ZN i-P substrate) on which a texture was formed by a conventional technique and an untreated glass substrate were prepared. The mechanical properties and surface condition of the substrate were examined. The processing steps after the re-cleaning were the same for the substrate as the comparative example. FIG. 10 is a flowchart comparing the manufacturing process of the present invention with the manufacturing process of the prior art.

From FIG. 13, it can be seen that the mechanical properties of the substrate of this example, the hardness and Young's modulus, are higher than those of the comparative example, and that the surface modification is performed in this example. Here, both properties are improved by 10% or more in this example as compared with the hardness and Young's modulus of the comparative example not treated in the present invention.

Further, it refinement to the number of projections is also formed on the surface of the substrate Izure In this embodiment IX 10 ⁸ pieces / mm ² or more (7 x 10 ⁹ cells / mm ² or less).

Here, in order to achieve the object of the present invention, the center line average roughness (R a) Is preferably 0.15 nm or more and lOnm or less, and the center line peak height (Rp) is preferably 0.3 or more and 20 ηm or less.

As shown in FIG. 13, in this embodiment, although the processing conditions differ depending on the processing method, the ultimate pressure of the vacuum exhaust was set to IE-4 Pa or less.

In addition, the processing of the substrate surface is not limited to the processing method of the present embodiment, but includes a plasma etching method, a reactive ion etching method, a reactive ion beam etching method, a chemical assist ion beam etching method, an ion beam etching method, and a sputtering etching method. Method or an induced plasma method such as ERC or ICP can be used.

Next, as shown in FIG. 15, a magnetic recording medium 1 was obtained by sequentially forming a base film 12, a magnetic film 13 and a protective film 14 on the substrate 11 of this example by a sputtering apparatus.

The underlayer 12 is sputtered to 30 nm in an Ar gas atmosphere using a Cr target, and the magnetic film 13 is sputtered in an Ar gas atmosphere using a CoCrPt target. The sputter was set to 25 nm. The protective film 14 was sputtered in an Ar gas atmosphere using a graphite target to a thickness of 15 nm. After film formation, the surface of the magnetic recording medium was rubbed and dust was removed while rotating the substrate with a tape with abrasive grains to clean the surface. Thereafter, a fluorine-based lubricant was applied by DiP to a thickness of 15 A, and cured at 80 ° C. in a clean oven to form a lubricant film 15. The magnetic recording media of Examples 1 to 10 were evaluated as described below, and the results are shown in FIG.

The evaluation methods include tangential force, CSS resistance, frequency of scratches caused by random seek, levitation of magnetic head (H to), T.A frequency of occurrence, and magnetostatic properties (Hc, S *, B rt ) And magnetic anisotropy. From FIG. 14, it is clear that this example is superior in any of the evaluation results as compared with the comparative example, and it can be seen that the object of the present invention is sufficiently satisfied.

In addition to this embodiment, any other manufacturing method can be used as long as it is a surface treatment method using a plasma in a vacuum, and the latitude in equipment is increased.

Further, according to the present invention, there is no need for the conventional substrate processing, cleaning process and DEPO-TEX formation at the time of film formation, etching by applying particles after forming the protective film, and the cleaning process. You can check. In addition, it has an excellent cost performance.

Further, with respect to the substrate of the present example (No. 5) and the substrate of the comparative example (No. 2), the surface condition was measured using an AFM (Atomic Force Microscope) to cover an area of 10 μm ² . It was measured. The result is shown in Fig. 11 as an image of unevenness. As can be seen from the figure, it is clear that the substrate surface has been subjected to a uniform surface treatment and has extremely fine irregularities due to the treatment in this embodiment.

The underlying film, magnetic film, protective film, and lubricating film of the magnetic recording medium are not limited to those of the present embodiment, but include a two-layer underlying film, an alloy underlying film, a Co-based magnetic film, It is also possible to use any combination of a protective film for the layer, reactive sputtered carbon (carbon film containing H2, N2, etc.), and PCVD carbon film. In particular, the combination with a high-strength H 2, N 2 -containing carbon protective film results in even better results.

In addition, when combined with LZT (laser zone texture), the CSS zone is LZT, and the data surface can be processed with the processing method of the present invention to achieve a very low flying height and easy high recording density surface. It is clear that high-density recording media with high performance can be produced. Further, by subjecting the substrate to the surface treatment of the present invention, the in-plane magnetic anisotropy of the magnetic layer disappears, and a magnetic recording medium having isotropic magnetic characteristics is obtained.

For this reason, the magnetic recording medium has high reliability and high TPI due to disappearance of magnetic anisotropy and low noise. Industrial applicability

According to the present invention, it is possible to realize a magnetic disk medium capable of achieving extremely low flying height and to supply a sufficiently clean substrate without using an unstable and special cleaning technique such as machining. Thus, a cheaper and higher quality magnetic recording medium can be obtained. Therefore, not only can the reliability of the HDD be ensured, but also a system such as a high-density HDD with a high recording density and a high capacity can be supplied.

Further, according to the present invention, the total amount of investment in manufacturing equipment itself is reduced by eliminating the process of machining such as machining in the manufacturing process, and the manufacturing yield power is significantly increased, so that the cost of magnetic disks is reduced. In addition, the cost of HDDs can be greatly reduced.

Further, by subjecting the substrate to the surface treatment of the present invention, the in-plane magnetic anisotropy of the magnetic layer disappears, and a magnetic recording medium having isotropic magnetic characteristics is obtained.

For this reason, a highly reliable magnetic recording medium and magnetic storage device with extremely low flying height, high sliding resistance, high T.A. compatibility, high TPI by eliminating magnetic anisotropy, and low noise have been developed. Can be provided.

Claims

The scope of the claims

1. In a magnetic recording medium having a base film, a magnetic film, a protective film, and a lubricating film on a non-magnetic substrate, the surface of the substrate is treated with ions or radicals in the plasma using plasma. A magnetic recording medium characterized in that minute projections are formed by treating the main constituent elements of the present invention without erosion.

2. The surface of the substrate has a center line average roughness (R a) force of 0.15 nm or more and 10 nm or less, a center line peak height (R p) force of 0.3 or more and 20 nm or less. raising the number is not less IX 10 ⁸ pieces / mm ² or more, a magnetic recording medium according to claim 1, feature in that it has isotropic magnetic properties.

3. Forming fine projections on the surface of the non-magnetic substrate by using plasma and treating the main constituent elements on the surface of the substrate without erosion by ions or radicals in the plasma;

A method for manufacturing a magnetic recording medium, comprising sequentially forming a base film, a magnetic film, and a protective film on the substrate by sputtering, and further forming a lubricating film.

4. The surface of the substrate is treated so that both the hardness and the Young's modulus of the surface of the substrate are improved by 10% or more compared to the hardness and the Young's modulus of the surface of the substrate before the treatment. A method for manufacturing a magnetic recording medium.

5. The method of manufacturing a magnetic recording medium according to claim 3, wherein an average centerline position of the surface roughness of the substrate is substantially equal to an average centerline position of the surface roughness before the processing.

6.The treatment of the surface of the substrate uses a gas of at least one of H2, He, N, 0, F, Ne, Ar, Kr, and Xe. 6. The method for producing a magnetic recording medium according to 3 to 5.

7. The surface treatment of the substrate is performed by plasma etching, 4. The method according to claim 3, wherein the etching is performed by any one of an etching method, a reactive ion beam etching method, a chemical assist ion beam etching method, an ion beam etching method, a sputtering etching method, and an induction plasma method. 8. The method for producing a magnetic recording medium according to 7.

8. Magnetic recording medium, rotating mechanism for rotating the magnetic recording medium, magnetic head for performing recording and reproduction by floating on the magnetic recording medium, and positioning the magnetic head on the rotating magnetic recording medium In a magnetic storage device composed of a head positioning mechanism,

The magnetic recording medium is composed of a base film, a magnetic film, a protective film and a lubricating film on a non-magnetic substrate, and the surface of the substrate is exposed to plasma by using ions or radicals in the plasma. A magnetic storage device characterized in that fine projections are formed on the surface of the substrate by processing without erosion of the main constituent elements of the present invention, and that the magnetic storage apparatus has isotropic magnetic characteristics.