JPS58164030A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the crushing of a head and the stripping, breaking and other trouble of a ferromagnetic layer of Co-Cr or the like by forming a boron nitride-base protective film on the ferromagnetic layer. CONSTITUTION:A magnetic recording medium 1 such as a magnetic disk obtd. by forming a ferromagnetic layer such as a vertically magnetizable film of Co-Cr on a nonmagnetic substrate by a sputtering method is placed on an electrode 3 in a vacuum vessel 2. While heating the medium 1 with a heater 4, gaseous H2 in a cylinder 5 is introduced into the vessel 2, and gaseous B2H6 in a cylinder 6 and gaseous NH3 in a cylinder 7 are mixed through a mixer 8 and introduced into the vessel 2 from holes 10 pierced in an electrode 9. High frequency is then applied between the electrodes 3, 9 from an RF power source 11 to cause plasma discharge, and by the discharge a protective film of boron nitride BNx is formed on the medium 1. The preferred value of x is 0.5-1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and by forming a protective film containing boron nitride BNM as a main component on a ferromagnetic layer, the head crash prevention effect is extremely large and the durability is improved. The purpose is to provide an excellent magnetic recording medium.

In recent years, unlike conventional coating-type magnetic recording media, methods of manufacturing magnetic recording media have been studied that involve directly forming a ferromagnetic layer on a nonmagnetic substrate, such as by sputtering or vapor deposition. The magnetic recording medium 1 obtained in this way, for example, a magnetic disk, has a high recording density (-50KBPI) that is incomparable to conventional coated magnetic disks.
It is possible to achieve the following. However, in this type of magnetic disk, the problem of so-called head crash, in which the magnetic film is destroyed due to contact between the magnetic recording medium and the magnetic head, is more likely to occur than in coated magnetic disks.
This is a problem in commercialization.

Additionally, as the recording density increases, it is necessary to reduce the spacing between the magnetic recording medium and the magnetic head, but on the other hand, as the spacing becomes smaller, the problem of head crashing becomes more likely to occur. Therefore, solving the head crush problem will be very important in increasing the recording density of magnetic recording media in the future.

In order to solve the head crash problem mentioned above,
fsi02, TlO2, Si3N4, WC, TiC
A method of forming a protective film made of a hard material such as , SiC, or B+C cap on a magnetic layer (Japanese Patent Publication No. 54-34602,
Japanese Patent Publication No. 55-39047, Japanese Patent Application Publication No. 53-21901, Japanese Patent Application Publication No. 53'-21902, etc.) have been proposed.

However, as a result of studies conducted by the present inventors, the above-mentioned material has high hardness but poor lubricity, so if there is even a slight protrusion on the protective film, the protrusion will cause a connection between the magnetic recording medium and the magnetic field. ii # II
In many cases, I was peeled off and even the magnetic layer was destroyed from there.

Therefore, the inventors of the present invention have conducted intensive studies to solve the conventional problems described in (a), and found that it is not so much that the material that forms the protective film has a high hardness, but that it is familiar with its lubricity. It was discovered that -1- is more important in preventing head crashes, and the present invention was completed.

That is, the magnetic recording medium according to the present invention is characterized in that a ferromagnetic layer is provided on a nonmagnetic substrate, and a protective film containing boron nitride BNx as a main component is formed on the ferromagnetic layer. .

A protective film containing boron nitride BNM as a main component not only has high hardness, but also has particularly excellent lubricity. Therefore, the contact between the magnetic recording medium and the magnetic head is very smooth, and peeling and destruction of the protective film and magnetic layer due to head crash are very effectively prevented. Moreover, the protective film made of boron nitride BNR can be easily formed using a dry process called plasma CVD method.
It is also an excellent domestic product.

X in the boron nitride BNx is plasma CVD
if, 4, +: O+t 6 If fee, 7 (
7) it$1. f ;t 4f B2Hb k NH
When using 3', it is adjusted by the ratio with NH5 such as B, H6, etc. When the range of X is 0.5 to 1.5, it exhibits good lubricity and can be used as a protective film. When x is in the range of 0.8 to 1.2, particularly good lubricity is exhibited and the effect of preventing head crashes is extremely large, so it is desirable to adjust the value within this range.

In addition, in order to adjust the hardness of the protective film, Si, C, AI
, P, etc., to an extent that does not impair the lubricity of the protective film, the effects of the present invention will not be lost.

Possible methods for forming the protective film include vapor deposition, sputtering, and CVD. However, in the case of the vapor deposition method or the sputtering method, a matrix of boron nitride BNII must be created once, which has the drawback of increasing the production cost. Further, in the case of the CVD method, the surface to be formed must be heated to about 1000° C., and the crystal grains of the magnetic layer of the magnetic recording medium may be deformed in the process, making it unsuitable. On the other hand, the plasma CVD method uses temperatures ranging from room temperature to 300°C.
Since it is possible to form a protective film in a relatively low temperature range of about 00° C., great advantages can be obtained in terms of both productivity and production cost.

The present invention will be explained in more detail below based on Examples.

Example 1 In FIG. 1, Co was deposited on a nonmagnetic substrate by sputtering.
A magnetic disk 1 on which a -Cr perpendicular magnetization film is formed with a thickness of 0.51 Lm is placed on an electrode 3 -L in a vacuum container 2 .

The electrode 3 is heated to about 100° C. by the heater 4.

Hz gas is supplied from the cylinder 5 into the vacuum container 2, and B2)1. gas and N
H and gas were introduced respectively. B2 H6 gas and N
A mixed gas of H and gas is blown into the vacuum container 2 through a hole IO provided in the electrode 9.

1 between the electrode 3 and the electrode 9 by the RF power source 11.
A high frequency of 3.58 MHz is applied to generate plasma discharge, and a protective film of boron nitride BNM is formed on the magnetic disk 1. The thickness of this protective film is adjusted to 500 mm.

According to the above procedure, X of boron nitride BNx is set to X=0.
82 H, gas and NH so that it is in the range of 5 to 1.5
A magnetic disk l having a protective rotor of boron nitride BNx on a ferromagnetic layer was fabricated while changing the mixing ratio of E gas. This magnetic disk l was tested with a dropout tester for 8-inch floppy disks to
Durability tests were conducted for up to 10,000 passes. The results are shown in FIG. In FIG. 2, the horizontal axis shows the number of passes up to 10 million, and the vertical axis shows the number of sectors without drop-out. Note that the initial state is 27 sectors.

Boron nitride BNM in the range x = 0.8-1.2
Regarding the magnetic disk with the protective film, no dropout was observed up to 10 million passes, as shown by line Ll in FIG. In addition, boron nitride BN1 in the range of 0.5<x<0°8 and 1.2<x≦1.5
Regarding the magnetic disk having the protective film No. 1, one or two sectors with dropout occurred after 1 million passes or more, as shown by line L2 in FIG.

Comparative Example 1 B2. Example 1 except that H6 gas was changed to SIH+ gas
A protective film of 5 iqN4 was formed on the magnetic disk 1 in the same manner as in Example 1, and the same durability test as in Example 1 was conducted. The results are shown as gland L3 in FIG. As is clear from the results, in Comparative Example 1, sectors with dropouts began to occur after 1000 passes or more, indicating that the durability of the protective film was inferior to that of Example 1.

Comparative Example 2 A durability test similar to that in Section t was conducted on a magnetic disk without a protective film. As shown by the line L4 in Figure 2, after about 10 passes, the number of sectors without dropouts decreased to less than half of the initial number of 27.
Dropouts were seen in all sectors before reaching 10,000 passes.

υAs mentioned above, the magnetic recording medium according to the present invention is characterized in that a ferromagnetic layer is provided on a nonmagnetic substrate, and a protective film containing boron nitride as a main component is formed on the ferromagnetic layer. Therefore, a protective film with high hardness and excellent lubricity is formed on the ferromagnetic layer, and a magnetic recording medium with extremely high head crash prevention effect and excellent durability can be provided. .

[Brief explanation of drawings]

FIG. 1 is a diagram showing a plasma CVD apparatus for manufacturing a magnetic recording medium according to the present invention, and FIG. 2 is a diagram showing the results of a durability test of the magnetic recording medium. Figure 1

Claims (4)

[Claims] (1) A magnetic recording medium characterized in that a ferromagnetic layer is provided on a nonmagnetic substrate, and a protective film containing boron nitride as a main component is formed on the ferromagnetic layer. (2) The magnetic recording medium according to claim 1, wherein the boron nitride has a chemical formula of BNx, where x is in the range of 0.5 to 1.5. (3) The magnetic recording medium according to claim 1, wherein the boron nitride has a chemical formula of BNg, where x=o, in the range of 8 to 1.2. (4) The magnetic recording medium according to claim 1, 2, or 3, wherein the protective film is formed by a plasma CVD method.