JPS6124214A - Manufacture of co-o thin film type vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic film of excellent and stabilized quality while a chamber is maintained in an oxygen atmosphere of high degree of vacuum by a method wherein oxygen gas is inoized in the space partitioned from the chamber containing a source of evaporation and an electron gun with which the source of evaporation is heated up and eveporated, and said inoized oxygen gas is made to irradiate on a substrate. CONSTITUTION:The cobalt vapor emitted from a source of evaporation is made incident on a substrate 2 almost vertically. At this time, the interior of a chamber 6 containing the source of evaporation 1 and an electronic gun 3 is not brought into a low vacuum state, but it is maintained in a high vacuum state of 10<-4>Torr or above which is suitable for emission of an electron beam from the electron gun 5. Oxygen gas is introduced into a cell 7, it is ionized by the impact of the thermion emitted from a filament 8, and the ion is made to irradiate on a substrate 2 by the accelerating voltage impressed between the filament 8 and the substrate 2. Through these procedures, the vapor of cobalt emittef from the source of evaporation 1 is reacted with the oxygen ions emitted from the ion gas 3 and deposited to the subsrate 2, thereby enabling to form a Co-O vertical magnetic film.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a perpendicular magnetic recording medium having magnetic properties in the direction perpendicular to the surface of a base material. The present invention relates to a method of manufacturing a Co-0 optical thin film magnetic recording medium in which a film is manufactured.

[Conventional technology]

The use of perpendicular magnetic recording is being considered as a high-density recording method with excellent short wavelength recording characteristics.

In this method, a thin-film perpendicular magnetic recording medium is used in which a magnetic film is produced by vertically injecting vapor of a ferromagnetic material onto a base material.

This type of magnetic recording medium replaces Co-Cr magnetic recording media, which have been mainly studied up to now.

A Co-0 optical thin film magnetic recording medium has been proposed (for example, p. 419 of the proceedings of the 30th Japan Society of Applied Physics).

This recording medium satisfies many conditions required for perpendicular magnetic recording media, and is expected to be put into practical use in the future.

Conventionally, the Co-0 based magnetic film is produced by vertically injecting cobalt vapor onto a substrate and reacting it with oxygen in a chamber. It has been proposed to use a so-called reactive vapor deposition method. In this method, it is necessary to maintain the inside of the chamber in an oxygen atmosphere with a relatively low degree of vacuum9.
A low vacuum of 10' Torr or less and an oxygen atmosphere are required.

Generally, when vacuum evaporating high melting point materials such as cobalt,
An electron impact method is used in which the evaporation source is heated and evaporated by irradiating it with an electron beam. However, when emitting an electron beam, from the viewpoint of stability etc., +10-'
A degree of vacuum of Torr or higher is required, preferably 10'
A degree of vacuum of Torr or higher is required. Therefore C
There is a large difference between the degree of vacuum of the oxygen atmosphere and the degree of vacuum required to fabricate an o-0 magnetic film. It was necessary to adopt a so-called differential pumping method, in which the chamber containing the evaporation source and substrate is depressurized to the required degree of vacuum separately from the chamber containing the evaporation source and substrate.

[Problem that the invention seeks to solve]

However, if this differential exhaust system is adopted.

In addition to complicating the device and its operation, this also imposes restrictions on the electron beam irradiation path, which poses a major obstacle to constructing a highly productive device.

Furthermore, if the chamber is maintained in an oxygen atmosphere with a low degree of vacuum, the so-called getter effect, in which the cobalt vapor evaporated from the evaporation source condenses on the inner walls of the chamber, adsorbs surrounding oxygen, becomes noticeable, especially when the evaporation occurs. Fluctuations in the degree of vacuum inside the vacuum chamber at the start become large. This variation in the degree of vacuum brings about a major change in the state of the magnetic film that is produced.

This causes loss of uniformity in the quality of the magnetic recording medium.

This invention was made to solve the above-mentioned problems in the conventional method for manufacturing a Co-0 based thin film perpendicular magnetic recording medium. The purpose of this invention is to provide a method for manufacturing a special magnetic recording medium that can obtain a magnetic film of stable quality, thereby improving productivity and stabilizing the quality of the recording medium.

〔Effect of the invention〕

Hereinafter, the configuration of the present invention will be explained together with the configuration of the apparatus shown in FIG.

The base material 2 is installed horizontally in the chamber 6.

An evaporation source 1 made of cobalt is arranged below this. An electron gun 5 is disposed on the side of the evaporation source 1, and electron beams emitted from the gun are irradiated onto the evaporation source 1 by electromagnetic deflection means (not shown).

On the other hand, the ion gun 3 is arranged within the chamber 6. The ion gun 3 has a space partitioned off from the chamber 6 for ionizing oxygen gas, that is, a self in the illustrated case, and oxygen gas is supplied to the self through a valve 4. It has become so. In addition.

In the illustrated apparatus, the ion gun 3 is a so-called Kaufmann type ion gun.

Other ionization means, such as a high frequency discharge type ion gun, can also be used as long as they have the same function as the above-mentioned self. - In this invention, a device as described above is used.

Cobalt vapor emitted from an evaporation source 1 is made to enter a base material 2 approximately perpendicularly. At this time, the chamber 6 containing the evaporation source 1 and the electron gun 5 is not brought into a low vacuum state, but is maintained at a high vacuum state of 10' Torr or higher, which is suitable for emitting an electron beam from the electron gun 5. Then, introduce oxygen gas into the self,
This is ionized by the impact of thermionic electrons emitted from the filament 8, and the base material 2 is irradiated with the ions by an accelerating voltage applied between the filament 8 and the base material 2.

[For production]

The cobalt vapor emitted from evaporation source 1 is.

Since it reacts with the oxygen ions emitted from the ion gun 3 and adheres to the base material 2, a Co-0 based perpendicular magnetic film is produced.

At this time, the value of the ratio j/r between the cobalt deposition rate r (person/S) and the oxygen ion current density j (μA /Cd) has a great influence on the magnetic properties of the magnetic recording medium. That is,
As the value of j/r becomes smaller, the residual magnetization M in the perpendicular direction
There is a tendency for r□ to be smaller than the residual magnetization M r4 in the in-plane direction. In addition, the vertical holding force I (cl is j/
r becomes maximum around 25 μA/87 people/d. Furthermore, the saturation magnetization Ms tends to decrease as j/r becomes smaller. Considering these points, j/r is 20~
A range of 30 μA-s/person is most appropriate.

〔Example〕

Next, embodiments of the present invention will be described.

Cobalt with a purity of 99.9% was used as an evaporation source 1, and an electron beam was irradiated onto the evaporation source 1, so that the cobalt vapor was made to almost perpendicularly enter a 35-inch square glass substrate 2 placed horizontally. At the same time, oxygen gas was introduced into the self of the ion gun 3 at a rate of 1 scc or less to ionize it, and the ionized gas was made to enter the base material 2 to produce a Co-0 magnetic film with a thickness of approximately 3000 mm.

In this case, the evaporation rate r from the evaporation source 1 is set to 10 to 5.
0 person/s, oxygen gas ion current density from 0.1 to 0
．． By changing each within the range of 4mA/cJ, j
/r was varied in the range of 10 to 35 μA-3/person・c+ (.In addition, the pressure in chamber 6 was initially set to 10' To
Vapor deposition was started as rr, but the pressure during vapor deposition was 3
X 10-5 Torr.

Next, the M-H characteristics of the thus produced magnetic film in the in-plane direction and the perpendicular direction were measured using a sample vibrating magnetometer, and the saturation magnetization, residual magnetization, and coercive force were determined. Furthermore, the thickness of the magnetic film was measured using an optical interference film thickness meter. From this result, the graph in Figure 2 shows some of the magnetic properties in terms of the relationship between the cobalt evaporation rate r (person/S) and the oxygen ion current density j (μA/e11 ratio j/r). be.

Note that the residual magnetization Mr in the perpendicular direction is the residual magnetization Ml-,? in the in-plane direction. It is larger than the .

j/r was approximately 20 μA-s/person・0 m1 or more. [Effects of the Invention] As explained above, according to the present invention, the chamber 6 is heated to a high vacuum of 10'Torr or more without CO 0 system magnetic film can be produced, and therefore stable electron beam irradiation can be performed without employing special means such as differential pumping. Moreover, this makes it difficult for pressure fluctuations in the chamber 6 to occur due to the getter action, making it possible to manufacture magnetic recording media of stable quality with high productivity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the invention. FIG. 2 is a graph showing the magnetic properties of the magnetic recording medium obtained in the same example. 1- Evaporation source 2- Base material 3--Ion gun 5- Electron gun 6- Chamber

Claims (1)

[Claims] 1. Cobalt vapor is vertically incident on a non-magnetic base material and oxygen is reacted with the cobalt to form
In a method for manufacturing a 0-based thin film perpendicular magnetic recording medium,
Co-0 thin film perpendicular magnetic recording characterized by ionizing oxygen gas in a space partitioned off from a chamber containing an evaporation source and an electron gun for heating and evaporating the evaporation source, and irradiating the ionized oxygen gas onto a substrate. Method of manufacturing media. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the means for ionizing oxygen gas is a Kauffman type ion gun. 3. The magnetic recording according to claim 1 or 2, wherein the ratio j/r of the cobalt deposition rate r and the oxygen gas ion current density j is in the range of 20 to 30 μA·s/Åcm^2. Method of manufacturing media.