JPS60201531A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a vertical magnetization film with excellent C axis orientation in a speed higher than one digit order of the speed of the sputtering method by using an electron beam evaporating source and irradiating an electron beam nearly perpendicularly to an evaporated plane under a special power density condition so as to form the vertical magnetization film. CONSTITUTION:The base 1 is made run toward the arrow A along a cylindrical can 2. The evaporation source 6 consists of an evaporation source tank 8 and an evaporating material 7, the heating of the evaporation material 7 is conducted by the electron beam 9 and the beam is irradiated nearly perpendicularly to the evaporation plane L. The irradiating conditiin of the electron beam is kept to a value of 50kW/cm<2> or over by focusing. Thus, the C axis orientation in a speed as high as 60 times that of the conventional sputtering method and the same degree obtained as the sputtering method is obtained.

Description

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

Conventional Structure and Problems There is a perpendicular recording method as a recording method with excellent short wavelength recording characteristics. This method requires a perpendicular recording medium whose axis of easy magnetization is perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented perpendicularly to the film surface of the medium, and therefore, the shorter the signal wavelength, the smaller the demagnetizing field within the medium, and the better the reproduced output.

Currently used perpendicular recording media are made by recording C on a non-magnetic substrate directly or through a soft magnetic thin film such as permalloy.
A magnetic layer containing O and Or as main components and having an axis of easy magnetization in the perpendicular direction is formed by a sputtering method.

However, since the sputtering method has a slow rate of forming a magnetic thin film, it is difficult to obtain a perpendicularly magnetized film at low cost. (including methods that ionize some of the evaporated atoms, such as the brating method) are progressing, and Go-Or can be formed at a fast formation rate of several thousand angstroms in 7 seconds.
It is known and expected that perpendicularly magnetized films can be obtained. However, in the range currently known, it is inferior to films obtained by sputtering in terms of C-axis orientation, which is a measure of performance as a perpendicularly magnetized film, and improvements are desired.

This C-axis orientation is determined by the value of the half-width Δθ50 of the X-ray rocking curve of the (002) plane of the X-ray diffraction pattern of the hexagonal close-packed structure, and with high density digital recording, sufficient signal can be obtained. This is because Δθ60 needs to be 10 degrees or less, more preferably 5 degrees or less to obtain noise-resistant discharge, but a perpendicularly magnetized film with such performance cannot be obtained by vacuum evaporation.

OBJECTS OF THE INVENTION The present invention provides a method for forming a perpendicularly magnetized film with good C-axis orientation on a substrate moving along a rotating support at high speed by vacuum evaporation.

Structure of the Invention In the present invention, when a perpendicularly magnetized film is vacuum-deposited on a substrate moving along a rotating support, the evaporation source is an electron beam evaporation source, and the electron beam from this evaporation source is 60 KW/c.
The beam is focused at 7 J or more and is irradiated almost perpendicularly to the evaporation surface, making it possible to obtain a perpendicularly magnetized film with good C-axis orientation at high speed.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the basic configuration of a magnetic recording medium manufacturing apparatus used to carry out the present invention.

The substrate 1 runs along the cylindrical can 2 in the direction of arrow A. A mask 6 is placed between the evaporation source 6 and the cylindrical can 2, and evaporates atoms (sometimes containing ions).
passes through the slit S and adheres to the substrate 1. 3 and 4 are a supply roll and a take-up roll for the substrate 1, respectively.

The evaporation source 6 consists of an evaporation source container 8 and an evaporation material 7, and the evaporation material 7 is heated by an electron beam 9.
As shown in the figure, the evaporation surface is irradiated almost perpendicularly.

Actually, the irradiation part V is not a plane, but it is defined as schematically shown in FIG. 2.

The present invention is characterized in that the electron beam irradiation conditions are as described above at the irradiation angle, and that the electron beam is maintained in a focused state such that it is 6QKw/c- or more at the irradiation position.

Although it is not clear that the present invention has a critical value not in the deposition rate but in the focused diameter of the electron beam,
The material of the perpendicular magnetization film is an alloy containing about 8Q of Co, G
If o, s OKW/c! It is inferred that this is largely related to the fact that the evaporation surface forms a concave portion due to the pressure of the focused electron beam, and the orientation of the evaporated atoms is improved. However, the upper limit is experimentally determined to be 22.5% for Co-based materials to prevent hot water from splashing and creating defects such as pinholes in the membrane. Although it is preferable to make it below OKW/cA, this is not essential and varies depending on the spot diameter of the electron beam.

If the beam spot diameter used in normal vapor deposition is 2 cm or less, the above-mentioned values can be used as a rough guide.

The vapor deposition materials for forming the perpendicular magnetization film used in the present invention include Co-Or, Co-Ni-Or, Co-Cr-
Rh.

Go-Ti, Co-V, Go-Mg, G
o-Mo, Co-W, Co-Ru, etc.

The shape of the evaporation source should be modified as appropriate depending on the width of the substrate, but the above-mentioned power density of the electron beam is the value assuming that the electron beam spot is not moved.
In reality, an operation that moves the spot, usually called scanning, is usually performed.

Further, as the evaporation source container, a material made of ceramic such as ZrO2, MgO, CaO, etc. is used.

In addition, it goes without saying that vapor deposition and material supply are necessary to obtain a long medium, but since the evaporation rates of the above-mentioned materials differ from each other, the supply ratio, temporal operation, etc. must be devised as appropriate. shall be.

Further, the total electric power of the electron beam injection shall be 4 KW or more per weight of the CO-based alloy expressed by 9. This is because if this value is smaller than 4 KW, in order to stably obtain the effects of the present invention, scanning of the electron beam must be devised and becomes complicated.

A more specific embodiment of the present invention will be described below.

The diameter of the cylindrical can is 5.0 Cln, the evaporation source container is a ZRO2 container, and the internal volume is 6 Cm x 6 C.
#IX 23CTn 6go(C,n), the distance between the evaporation surface and the substrate is 38Can, the electron beam has an acceleration voltage of 3 Q KV, and the upper surface of the evaporation source container is placed in the direction perpendicular to the moving direction of the substrate. A magnetic field was applied to deflect and irradiate the electron beam almost perpendicularly, and the beam spot diameter was controlled by changing the focusing magnetic field and the shape of the electron beam generator. As a comparative example, the case where the irradiation was performed from an angle of 40 degrees (the vertical angle from the evaporation surface) is shown.

Polyethylene terephthalate with a thickness of 12 μm was used as the substrate, and Go-C1 containing 20% of cr was selected as the vapor deposition material.

As another example, a thin film of 80%Ni-20%Fe is coated on the substrate in advance by high-frequency magnetron sputtering.
．． The experiment was also carried out using a polyamide film having a thickness of 48 μm and a thickness of 20 μm. Vacuum degree is 3X10-8 Tor
The range was from r to 6×1O-8TOrr (7).

The constituent elements and effects of the present invention are summarized in the following table.

(Left space below) As is clear from the table, according to the present invention, the value of Δθ60 can be reduced to 6 degrees or less using the vacuum evaporation method, and the evaporation rate in the example was 6000 k on average. 100% of the conventional sputtering method. It is 60 times faster than A/513C, and C-axis orientation comparable to that obtained by sputtering can be obtained, which shows how excellent it is in terms of mass production.

In addition to this example, it was confirmed that other materials mentioned above that can be used in the present invention have similar effects.

Effects of the Invention As described above, the present invention uses an electron beam evaporation source and irradiates the electron beam almost perpendicularly to the evaporation surface at a power density of 50 KW/cIA or more to form a perpendicularly magnetized film. A perpendicular magnetization film with good axial orientation can be obtained at a speed one order of magnitude higher than that of the sputtering method, and the practical effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a vapor deposition apparatus used to carry out the present invention, and FIG. 2 is an enlarged sectional view of the evaporation source portion. 1... Board, 2... Cylindrical can, 6
...Evaporation source, 9...Electron beam.

Claims (1)

[Claims] When vacuum evaporating a perpendicularly magnetized film onto a substrate moving along a rotating support, the evaporation source is an electron beam evaporation source, and the electron beam from this evaporation source is focused at 50 KW/cyj or more and A method of manufacturing a magnetic recording medium, characterized in that the irradiation is performed almost perpendicularly to the direction of the irradiation.