JPS6267726A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a vertically magnetized film having a broad width and uniformly high coercive force at a high speed by depositing Cr by evaporation by induction heating and Co by electron beam heating. CONSTITUTION:The secondary electrons generated in a large quantity by heating of Co are made to act with Cr vapor for a long period by the effect of the magnetic field of induction heating; therefore Cr is brought into the large energy state and the crystal orientation of a Co-Cr film is improved. The large coercive force is thereby obtd. even if the temp. of a high-polymer film 1 is low. There is no need for using a glow discharge and the uniformity in the transverse direction is stably assured simply by using a broad vapor source.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium, and particularly to a method of manufacturing a magnetic recording medium suitable for perpendicular magnetization recording.

BACKGROUND ART Conventionally, as a method for magnetic recording, a method using magnetization in a substantially longitudinal direction of a recording medium has been exclusively employed.

However, in such a system that uses magnetization in the in-plane longitudinal direction, if an attempt is made to increase the recording density, the demagnetizing field within the recording medium increases, so there is a limit to the increase in the recording density.

Therefore, in order to eliminate such problems, magnetization in a direction perpendicular to the surface of the recording medium is used.

A so-called perpendicular magnetization recording method is being considered. If this perpendicular magnetization recording method is adopted, the magnetic field within the medium decreases as the recording density increases, making it possible to achieve high-density recording.

By the way, in order to employ the perpendicular magnetization recording method, a recording medium having an axis of easy magnetization in a direction orthogonal to the recording medium is required.

A typical example of such a recording medium is C containing about 20 wt% of Cr f on a polymer film such as polyimide.
It is known that an O alloy thin film is formed to a thickness of 0.1 μm to 0.3 μm.

Sputtering method, electron beam evaporation method, ion blating method, etc. are being considered for forming the Co-0r thin film.

Among them, the electron beam evaporation method and the ion blating method are attracting attention from a practical standpoint because they have a high thin film formation rate.

[For example, IEICE journal Volt, Iee-
C, pp. 55-61 (1983)] Problems to be Solved by the Invention However, in the electron beam evaporation method, in order to obtain a large coercive force, it is necessary to heat the polymer film to a high temperature, which causes wrinkles during winding. This often occurs, and if an extremely expensive film such as polyimide is used to avoid this, there is a problem in that it is not practical.

On the other hand, ion blating has the potential to lower the temperature of polymer films compared to electron beam evaporation, but it has some drawbacks in terms of equipment. That is, in order to obtain a uniform perpendicularly magnetized film on a wide polymer film, it is necessary to configure the glow discharge region uniformly and widely, but it is difficult to maintain this state stably for a long time.

For example, if the evaporation source is configured so that a high-frequency coil is included, the high-frequency coil will be deposited and the conditions will not be stabilized.To avoid this, it is necessary to make the coil larger. When this occurs and the influence of the magnetic field weakens, the electron beam is affected and the evaporation source cannot be stably heated.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a manufacturing method that can form a wide, uniform, and perpendicularly magnetized film with high coercive force at high speed without raising the polymer film to high temperatures. be.

Means for Solving the Problems In order to solve the above-mentioned problems, the method for manufacturing a magnetic recording medium of the present invention involves vapor deposition using Crf induction heating and Cof electron beam heating.

Function The present invention has the following configuration as described above, so that secondary electrons generated in large quantities by heating CO interact with Cr vapor for a long time due to the effect of the magnetic field of induction heating, so Cr is high in energy. Since the crystal orientation of the co-Cr film is improved, a large coercive force can be obtained even at low temperatures of the polymer film, and a glow discharge can be avoided simply by using a wide evaporation source. Therefore, uniformity in the width direction can be stably ensured.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. The figure shows an example of a magnetic recording medium manufacturing apparatus used in carrying out the present invention. In the figure, 1 is a polymer film, 2
is a sending shaft, 3 is a winding shaft, 4 is a cylindrical can, 6 is a first evaporation source container, 6 is a heating coil, 11 is Co, 12 is Cr
, 13 is a mask, 14 is a slit, 16 is a vacuum container, 1
6 is a vacuum pump.

In the apparatus shown in the figure, the diameter of the cylindrical can 4 is FzOcm + the position of the mask 13 is 28 cm from the center of the can, the slit width is 6.2 cWt in the film running direction, and the evaporation surface of the evaporation source is 48 cr:L from the center of the can. , CO evaporation source center and C
The distance from the center of the r evaporation source is 10 cm. The induction heating coil had 16 turns and was heated by a variable frequency power source, and two types of electron beams were used: a 270 degree deflection type and a straight gun (30KV x 2A).

For comparison, a magnetic recording medium was manufactured by simultaneously evaporating both elements Co and Cr from an electron beam evaporation source.

The polymer films used were polyethylene terephthalate and polyamide filters, each having a constant thickness of 15 μm.

We also tried manufacturing by ion blating, but at that time, the high frequency coil had 3 turns, 29ctn from the can center to the top of the coil, and 36ctn to the bottom, and the film was moved using a closed coil with a rectangular coil. One with 11 crns in the direction and 69 crns in the direction perpendicular to it was used.

First, the main manufacturing conditions for the magnetic recording medium A of the present invention are as follows. Vacuum degree: 1X1O-6 (Torr)
, induction heating: 10) Ji 24KW, electron beam conditions: 5oKV 1. sA, the conditions of medium B are the same as A except for induction heating: 100 k) h, 26 KW, and the conditions of medium C are the same except that the electron beam condition is 4 270 degree deflection type with 10 KV 1.6 A arranged in the width direction. adapted to the conditions.

The ion brating conditions were 1001. [1,1KW
7. causing a high frequency glow discharge; θx 10-”T
It was deposited at orr.

Other conditions and the uniformity of the obtained magnetic properties in the width direction.

The results of examining the uniformity in the longitudinal direction are shown in the table below.

From the table above, according to the present invention, a large coercive force can be obtained without increasing the temperature of the cylindrical can. Therefore, a polyethylene terephthalate film can be used.

It also has excellent uniformity of magnetic properties.

These are thought to be based on the induction heating method and probably the generation of a large amount of secondary electrons from the electron beam evaporation source. This effect is thought to be a combination of the effect of significantly increasing the activity of Cr, and the same effect can be obtained with other polymer films.

Effect of the invention As described above, according to the present invention, C has a high coercive force.

-Or It has an excellent effect of being able to uniformly obtain a perpendicularly magnetized film at high speed without heating the polymer film.

[Brief explanation of drawings]

The figure is a configuration diagram of essential parts of an example of a vapor deposition apparatus used to carry out the present invention. 1...Polymer film, 4...Cylindrical can, 8...Secondary electron beam, 10...
・Induction heating coil.

Claims (1)

[Claims] 1. A method of manufacturing a magnetic recording medium, characterized in that when forming a perpendicularly magnetized film made of Co--Cr, Cr is evaporated by induction heating and Co is evaporated by electron beam heating.