JPS61126633A - Production of vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent reproduction output by forming a thin film consisting essentially of Co, Ni and Fe by specifying the ratio between the average deposition rate thereof and the oxygen partial pressure in a vacuum deposition device to form the back layer of a vertical magnetic anisotropic film of a vertical magnetic recording medium. CONSTITUTION:The soft magnetic layer consisting of Co, Ni and Fe is formed as the back layer of the vertical magnetic anisotropic film consisting of Co-Cr, etc. on the substrate consisting of polyimide film, etc. by a vacuum deposition method at the ratio (x) between the average deposition rate and oxygen partial pressure maintained under 2X10<7>Angstrom /sec. The always stable formation of the back layer having <=20 Oe coercive force is thus made possible. the coercive force is too large and is unsuitable if x is specified to <=2X10<7>Angstrom /sec. The verti cal magnetic recording medium which is suitable for high-density recording, has excellent recording and reproducing efficiency and decreases noise is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention has excellent high-density recording and reproduction characteristics. The present invention relates to a method of manufacturing a perpendicular magnetic recording medium.

(Conventional structure and its problems) Conventionally, as a magnetic recording method with excellent high-density recording characteristics,
There is a perpendicular magnetic recording method, which uses a perpendicular magnetic recording medium with a perpendicular anisotropic film as a magnetic layer.

When a signal is recorded on such a medium, the residual magnetization is oriented in a direction perpendicular to the film surface of the medium, and the shorter the wavelength of the signal, the smaller the demagnetizing field within the medium, resulting in excellent reproduction output.

There is a perpendicular magnetic recording medium called a single layer medium.

This is a perpendicular magnetic anisotropic film formed on a substrate made of a non-magnetic material such as a polymer material or a non-magnetic metal.
The films include Co-Cr film, Go-0 film, Co-
Ni-0 films, Ba-ferrite films, etc. have been developed.

In contrast to the above-mentioned single-layer media, there is something called a two-layer media. This is a device in which a soft magnetic backing layer such as a permalloy film is formed between a nonmagnetic substrate and a perpendicular magnetic anisotropic film, and a significant improvement in recording and reproducing efficiency can be seen.

In particular, when a known auxiliary pole-excited perpendicular magnetic head, which is considered to be the most suitable perpendicular magnetic recording head, is used, the improvement in recording and reproducing efficiency is extremely remarkable.

As the soft magnetic underlayer in the above two-layer film medium, 2
A magnetic film having a coercive force of 00e or less is suitable. 20
If it exceeds 0e, the function of the soft magnetic underlayer as a part of the magnetic head decreases, resulting in deterioration of recording and reproducing efficiency.

Methods for forming the soft magnetic underlayer include vacuum evaporation, sputtering, and plating, but the vacuum evaporation method is the most superior in terms of productivity. -Mo-Ni-Fe film or C
O-based amorphous films and the like are mainly being studied using sputtering methods. When using the vacuum evaporation method, Co-N
The inventors have found that the i-Fe film is the best.

As a result of further experiments and research, the present inventors found that when producing a Co-Ni-Fe film using a vacuum evaporation method, in order to obtain a two-layer film medium that exhibits satisfactory recording and reproducing efficiency, the film It has been clarified that it is necessary to limit the ratio X between the deposition rate and the oxygen partial pressure inside the vacuum evaporation apparatus.

(Object of the invention) The present invention provides the following by limiting the above-mentioned X using a vacuum evaporation method.
To stably form a Go-Ni-Fe film of 200e or less,
Therefore, it is an object of the present invention to provide a method for manufacturing a perpendicular magnetic recording medium with excellent recording and reproducing efficiency. In a method for manufacturing a perpendicular magnetic recording medium of a two-layer film medium, in which a thin film is formed, and a perpendicular magnetic anisotropic film is further formed on the thin film, the thin film containing Co, Ni and Fe as main components. The ratio between the average deposition rate and the oxygen partial pressure inside the vacuum evaporation apparatus is 2×107 Å/sec・To
The above object is achieved by setting the value to be rr or more.

(Explanation of Examples) The present invention will be described in detail below using Examples.

When forming a Co-Ni-Fe film by vacuum evaporation method,
The deposition rate of the film and the type and amount of residual gas have a large effect on the magnetic properties of the film. According to experiments, Co-Ni-Fe
If the ratio X between the average deposition rate of the film and the oxygen partial pressure in the vacuum evaporation apparatus is set to 2×10 7 Å/sec・Torr or more, 20
It has been revealed that a Co--Ni--Fe film having a coercive force of 0.08 or less can be stably obtained, and can therefore be obtained from a perpendicular magnetic recording medium of a two-layer film medium with excellent characteristics. To explain this in a little more detail, argon, nitrogen, and oxygen are introduced into a vacuum evaporation equipment set to 5XlO-'' Torr, and Co-N
An i-Fe film was deposited. The results revealed that the film deposition rate and oxygen affected the film's magnetic properties. In addition, argon and nitrogen are 8 x 10-'Torr
However, no effect was seen on the magnetic properties of the formed Co-N1-Fe film, and as mentioned above, the deposition rate or oxygen partial pressure of the film independently affects the magnetic properties of the film. Rather, their ratio, that is, the ratio X between the deposition rate of the Go-Ni-Fe film and the oxygen partial pressure, is
It has been found that when depositing a -Ni-Fe film, it affects its magnetic properties.

The figure shows the relationship between the above-mentioned X and the coercive force of the film when a Co--N1--Fe film is deposited by vacuum evaporation.

Curves 1, 2 and 3 are Co, Ni, sFem, respectively.
s 1CO2 (INis□Fets and C0BNis7
It shows the relationship between films with a composition called FETs. The film thickness was 8,000 yen, a heat-resistant polymer film was used as the substrate, the substrate temperature during vapor deposition was 230°C, and the film deposition rate was 8,000 yen.
00 to 12,000 people/second.

Although the ratio X was changed by changing the film deposition rate or the amount of oxygen introduced, Co--Ni--Fe films having the same coercive force were obtained as long as the value of X was the same.

From the figure, a Co-Ni-Fe film with a coercive force of 200e or less can be obtained by making X more than 2X10'8/sec.Torr, but when it becomes less than about 1X10'8/sec.Torr, the coercive force becomes It can be seen that the size suddenly increases, making it unsuitable as a soft magnetic underlayer for a two-layer film medium.

l×107Å/sec・Torr to 2XIO' people/sec 4o
In the range of X of rr, the dependence of coercive force on X is too large, so this region is unsuitable for film formation.

That is, in order to stably create a Co-Ni-Fe film used as a soft magnetic underlayer for a two-layer film medium,
It is necessary to set it to 7 Å/sec.Torr or more.

The composition of the Go-Ni-Fe film is Co:
32% and Ni in the range of 50 to 75%, as in each curve 1 and 2.3 shown in the figure, if However, in the case of a composition other than the above, a film with a coercive force of 200e or less could not be formed no matter how X was changed.

Further, even when the substrate temperature during vapor deposition was changed from room temperature to 300° C., the results shown in the figure hardly changed.

Although it is not clear why the results shown in the figure are obtained,
It is considered that when X becomes smaller, the film has perpendicular anisotropy due to the fine structure.

A specific example is given below.

A polyimide film with a thickness of 50 μm is used as a substrate, and a film thickness of 60 μm is used as a substrate.
00 Go. A Go-Cr perpendicular magnetic anisotropy film with a film thickness of 2000 was used as a two-layer film medium via a film of Ni and 5Fe1=.

It was formed by a vacuum evaporation method. The above Co. Ni, ,Fe
1. In the film formation, X is set to 4×107 Å/sec・Torr
and 4×10r″ person/second・Torr,
I made two types. The former satisfies the conditions of the present invention, but the corporation does not. If the perpendicular magnetic anisotropic films as two-layer film media formed by the former and latter are A and B, respectively, then Co2°NiG in A.

The coercive force of Fe film and film is 50e, and B is 310e.
Met. The following table shows the results of recording and reproducing on these two-layer film media A and B using a known auxiliary pole excitation type perpendicular magnetic head.

The film thickness of the main pole of the auxiliary pole excitation type perpendicular magnetic head was 0.2 μm. In the table above, 7 KF
RPI is a recording state in which magnetization is reversed 7000 times per inch (pressure 2.5 am), and D. is the recording density at which the reproduction output is half of the value of 7 KFRPI.

In addition, the output value of 7KFRPI is based on the value of the two-layer film medium B, that is, the output value of the two-layer film medium A as OdB.
From the table 0, which shows the values of the two-layer film medium A that satisfies the conditions of the present invention, the output value at 7 KFRPI is 1. It can be seen that it is excellent in both respects.

(Effects of the Invention) In the production of a perpendicular magnetic recording medium as a two-layer film medium, the present invention clarifies the deposition conditions for a Co-Ni-Fe film as the backing layer, and provides a perpendicular magnetic recording medium with excellent recording and reproducing characteristics. It is a method of manufacturing recording media, and its use can be of great benefit.

[Brief explanation of the drawing]

The figure is a diagram showing the relationship between coercive force and manufacturing conditions of a Co--Ni--Fe film as a backing layer of a two-layer film medium. X: Ratio between the deposition rate of the Co-Ni-Fe film and the oxygen partial pressure.

Claims (1)

[Claims] A method for manufacturing a two-layer perpendicular magnetic recording medium, in which a thin film mainly composed of Co, Ni, and Fe is formed on a substrate using a vacuum evaporation device, and a perpendicular magnetic anisotropic film is further formed on the top surface of the thin film, The thin film mainly composed of Co, Ni, and Fe is formed at a ratio of the average deposition rate to the oxygen partial pressure inside the vacuum evaporation apparatus of 2×10^7 Å/sec・Torr or more. A method for manufacturing a perpendicular magnetic recording medium.