JPH0261819A - Perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain preferable recording medium without providing a base layer by forming a CoCr film on a specified surface of a substrate. CONSTITUTION:The perpendicularly-oriented CoCr film is formed directly on the substrate the surface of which is (100) or (111) plane of Si. A disk made of this perpendicular magnetic recording medium has good qualities with enhanced magnetic property as well as such a disk having a base layer between a CoCr film and a substrate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a perpendicular magnetic recording medium, and in particular,
The present invention relates to high-density magnetic disk media used in peripheral storage devices.

[Prior Art] Conventionally, there have been the following types of vertical recording media formed by forming a CoCr film on a substrate.

■CoCr film formed directly on the substrate by RF sputtering, EB evaporation, magnetron sputtering, or ion beam sputtering.

■A base film is formed on the substrate to adjust the magnetic properties of the CoCr film, and then the CoCr film is
Formed with a film.

The method of forming a base film on a substrate is very effective as a means of improving the tin characteristics, so conventionally, the method described in
Perpendicular magnetic recording media are common.

Furthermore, Ti was most often used as the material for the base film.

In the perpendicular magnetic recording media of ■ and ■ above, cocrtl
! In the formation process, it is necessary to raise the substrate temperature in order to adjust the magnetic properties of the film, particularly the perpendicular coercive force H8 of the film, to an appropriate value. Therefore, the substrate must have excellent heat resistance. Furthermore, the board has a magnetic head of 0.
．． In order to maintain surface accuracy that allows stable operation even with a low flying height of 1 μm or less, it must have excellent workability.
Furthermore, it must be rigid enough to withstand high-speed rotation.

Conventionally, the substrate material that satisfies these conditions is A.
1 alloy base plate chemically plated with NiP, glass,
St. sea urchin hachihedo is known.

Among these, the one applied to Si Uni8 as a substrate for a perpendicular magnetic recording medium has already been disclosed in Japanese Patent Laid-Open No. 59-96539. This is characterized in that a non-magnetic base film such as Or is formed on a Si substrate, and a magnetic film is applied thereon by sputtering.

[Problems to be Solved by the Invention] Although a perpendicular magnetic recording medium having an underlayer on a substrate has the advantage of being able to improve the magnetic properties of a magnetic film as described above, it also has the following problems. Was.

(2) Since a step of forming an underlayer is required, the cost is higher than that of a perpendicular magnetic recording medium that does not have an underlayer.

■St wafer has a surface precision of R11, (JIS-BO6
01) to a thickness of 10 nm or less has already been established in the field of semiconductor industry, and by using this technology as is for processing substrates, excellent surface precision can be obtained. However, when a base film is formed on the substrate, this excellent surface precision cannot be taken advantage of.
In the end, only the same surface precision as when using other substrate materials was obtained.

Note that in current magnetic disk devices, the flying height (gap) between the magnetic head and the disk is about 0.2 μm, and it will be necessary to reduce it further in the future. Therefore, in order to ensure stable operation of the magnetic head at a low flying height, it is essential to improve the surface precision of the disk substrate.

For the above reasons, there has been a long-awaited desire for a perpendicular magnetic recording medium that can obtain excellent magnetic properties without forming an underlying film on a Si substrate.

[Means for Solving the Problems] The gist of the present invention is to provide a perpendicular recording medium in which a CoCr vertical alignment film is formed on a magnetic disk substrate without an underlayer, in which the substrate surface is St (100) or (111). ) is present in a perpendicular BN recording medium.

[Operation] According to the present invention, the substrate surface is the (100) plane or the (111
) By using an SL substrate having a SL plane, a perpendicular magnetic recording medium having very excellent magnetic properties can be obtained even though a CoCr film is directly formed on the substrate.

[Embodiment] As an embodiment of the present invention, a case will be described in which a CoCr film is formed using a dual ion beam sputtering apparatus.

FIG. 1 is a sectional view showing a dual ion beam sputtering apparatus used in this example. In the figure, 1 is an ion gun for deposition, 2 is a grid, 3 is an ion beam, and 4
．． 5 is a target, 6 is a substrate holder, and 7 is a chamber.
8 is an exhaust device, 9 is a target holder, 10 is a substrate, 1
Reference numeral 1 denotes an assisting ion gun for directly injecting an ion beam into the substrate.

Next, a method for forming a CoCr film on a substrate using this apparatus will be explained.

(1) First, an St substrate is mounted on the substrate holder 6, and a CoCr is mounted as the target 4.

(2) Exhaust the inside of the chamber using the exhaust device 8.

(2) Start the rotation of the substrate holder 6 and generate ions with the ion gun 1 for deposition.

(2) Ions extracted from the grid 2 become an ion beam 3 and hit the target 4.

(2) Particles of the sputtered target 4 are deposited on the substrate 10 on the substrate holder 6 to form a CoCr film. At this time, the ion beam is incident on the substrate 10 by the assisting ion gun 11. Note that the assist ion gun 11 is controlled independently of the deposition ion gun 1.

Incidentally, after carrying out the above steps (1) to (2) using Ti as the target 4 and CoCr as the target 5 (however, at this time, the ion beam is not incident on the substrate 10 by the assisting ion gun 11), the target holder 9 target 5 by rotating target 4
If the worker is moved to the position shown in FIG. 2 and the ion beam 3 is directed to the target 5 (at this time, the ion beam is incident on the substrate 10 by the assisting ion gun 11), the perpendicular magnetic recording medium having the base film Ti is formed. (i.e., a conventional perpendicular magnetic recording medium).

In this example, Si with plane orientations (100), (110), and (111) was prepared using the method described above.
Substrates with an underlayer (conventional perpendicular magnetic recording medium) and without an underlayer (perpendicular magnetic recording medium according to the present invention) were prepared, and pieces of 6 mm x 4 mm were taken out from these substrates. It was used as a sample. Note that a CoCr target having a composition of 22 at % Cr was used.

For each sample, the sputtering conditions for forming the CoCr film were: substrate temperature 160°C, substrate holder rotation speed 4.
rpm, ion beam acceleration voltage 1 kV, target current density 0.3 mA/crn', assist ion beam acceleration voltage 1 kV, assist ion beam substrate current density 0.13 mA/c rri'', and the thickness of the CoCr film is The sputtering conditions for forming the Ti base layer in the conventional sample were: substrate temperature 160°C, substrate holder rotation speed 4 rpm, ion beam acceleration voltage 1 kV, target current density 0.13 mA/
crn', and the film thickness was 10 mm. Note that the assist ion beam is used to improve the magnetic properties of cocr[ and to flatten the surface.

The magnetic properties of the 6 fffi sample thus prepared were measured using a vibrating sample magnetometer (VSM).

The results are shown in Table 1. HC□ is the vertical holding force of the membrane, and it needs to be high to some extent in order to preserve the recorded signal. HC/ is the horizontal coercive force of the film, and when recording and reproducing a vertical medium with a ring head, it is desirable that it be small so that the horizontal component of the head field is not emphasized. SQ/ is the BH left curve squareness ratio in the horizontal direction of the film, and is a measure of the thickness of the initial deposited layer on the substrate side where the hexagonal crystal system of CoCr1li is difficult to organize; the smaller this value is, the better the orientation is. ing. Hk represents an anisotropic magnetic field, and in order to obtain high reproduction output in high frequency recording, it is desirable that this value be high. From the table, it can be seen that for samples with a Ti base, the HC finish is 8000 for any surface orientation.
e, and Sq//, which is a measure of vertical orientation, is sufficiently small, indicating that the crystal is good with few initial deposited layers. That is, by providing a thin Ti underlayer in this way, an excellent medium can be obtained regardless of the plane orientation of the Si substrate. On the other hand, among the samples without a Ti underlayer, those with a Si substrate orientation of (110) are considerably inferior in both properties;
It can be seen that all samples No. 11) (that is, samples according to the present invention) have magnetic properties that are four levels higher than those provided with a Ti underlayer.

From the above, it was found that if Si (100) is used in a recording medium, a medium having magnetic properties equivalent to that of a Ti base can be obtained without providing an underlayer.

CoCr film vertical Note) 1
〜3.5 Comparative example 4.6 Example of the present invention [Effects of the invention] As explained above, according to the present invention, even if a CoCr film is directly formed without providing a base film, , it is possible to obtain a medium having magnetic properties equivalent to those obtained by forming a Ti base and forming a CoCr film thereon. Therefore, the perpendicular magnetic recording medium of the present invention enables stable operation of a magnetic disk device using a floating head at a low flying height.
Moreover, excellent recording and reproducing characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a dual ion beam sputtering apparatus used in an embodiment of the present invention. 1... Ion gun for deposition, 2... Grid, 3...
...Ion beam, 4.5...Target, 6...
Substrate holder, 7...chamber 8...exhaust device,
9...Target holder, 10...Substrate, 11...
・Ion gun for assisting in directly injecting the ion beam into the substrate.

Claims (1)

[Scope of Claims] In a perpendicular magnetic recording medium in which a CoCr vertically aligned film is formed on a magnetic disk substrate without an underlying layer, the substrate surface is formed from the (100) or (111) plane of Si. A perpendicular magnetic recording medium characterized by: