JPS58158028A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain residual magnetization which is large in a vertical direction, by using a thin ''Permalloy '' film formed by vacuum deposition in the presence of oxygen as an underlying layer for a magnetic layer for recording by vertical magnetization consisting of Co-Cr. CONSTITUTION:A ''Permally film of which the (111) facets are oriented in parallel with the plane of the film is vapor deposited on a substrate under the conditions under which the ratio X between an average rate of deposition and partial pressure of oxygen attains X>2X10<7>/sec.Torr, as an underlying layer, and a Co-Cr film is vapor deposited thereon, whereby a magnetic recording medium suited for a recording system by vertical magnetization is obtained.

Description

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

A perpendicular recording method is a magnetic 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. Perpendicular recording media have a magnetic layer (hereinafter referred to as ■-Or perpendicular magnetization) on a substrate made of a non-magnetic material such as a polymeric material or a non-magnetic metal. ) is formed by sputtering or vacuum evaporation. However, perpendicular recording media (hereinafter referred to as single-layer media) in which four directly magnetized films are formed directly on a non-magnetic substrate have low efficiency when recording and reproducing signals. A two-layer film medium has been developed for this purpose.

This is a device in which a magnetic layer made of a permalloy thin film having an axis of easy magnetization in the plane of the film is provided between a substrate made of a non-magnetic material such as a polymer material or a non-magnetic metal and a Co-0r perpendicularly magnetized film. . A structure like this.

By using a dual-layer film medium, recording efficiency and reproduction efficiency are improved compared to a single-layer film medium, and the efficiency improvement is particularly remarkable when recording and reproducing signals using a known auxiliary pole-excited vertical head.

■In order to obtain a -Or perpendicularly magnetized film, it is necessary to orient the C axis of the dense bulk structure in the direction perpendicular to the film surface.
In the case of a layered film medium, the C-axis orientation of -CrllE is influenced by the orientation of the permalloy film. The reason for this is [
The effect of epitaxy during formation of -Or film is considered,
In order to obtain a [with]-α film with good C-axis orientation on a permalloy film, a crystal must be grown so that the (111) plane of permalloy is parallel to the film surface. Experiments have revealed that when forming permalloy films by vacuum evaporation, it is necessary to limit the ratio X between the film deposition rate and the oxygen partial pressure inside the vacuum evaporation apparatus in order to meet the above requirements. became.

The present invention provides a method of manufacturing a magnetic recording medium with excellent recording and reproducing efficiency by forming a permalloy film with good orientation by a vacuum evaporation method by limiting the above-mentioned X.

The present invention will be specifically explained below.

When a permalloy film is formed by vacuum evaporation, the deposition rate of the film and the type and amount of residual gas greatly affect the properties of the film. The experimental results show the average deposition rate of the permalloy film and the internal GEE of the vacuum evaporation equipment. Oeya 28,
. It was revealed that a permalloy film in which the (111) plane is oriented parallel to the film surface can be obtained by increasing the temperature to more than , Z seconds Torr, and as a result, a two-layer film medium with excellent properties can be obtained. . This will be explained below.

In a two-layer film medium, unless the half-width Δθ5° of the rocking curve with respect to the (002) plane of the Co-0r film is set to 18 degrees or less, the characteristics when recording and reproducing signals will be poor.

An example is shown in FIG. Note that Δθ5o is considered to express the dispersion of the orientation of the (002) plane, and the smaller this value is, the better the orientation is. The vertical axis in Figure 1 is the wavelength of 0.5 for the two-layer film medium.
The relative value of the output when recording and reproducing a μm signal is shown, and the horizontal axis shows Δθ5o of the Co-0r film. In addition, an auxiliary magnetic pole excitation type vertical head is used as the recording and reproducing head.
The thicknesses of the permalloy film and the ■-Or film in the two-layer film medium were both 0.2 μm.

When the Δθ group exceeds 18 degrees, the output deteriorates rapidly.

The reason for this seems to be that when Δθ5o is less than 18 degrees, the residual magnetization of the ■-Or film is oriented perpendicular to the film plane, but when it is 18 degrees or more, it is oriented in the film plane.

As a result of experiments, it has become clear that in order to obtain a Go-Or perpendicular magnetization film with Δθ5o of 18 degrees or less in a two-layer film medium, it is sufficient to form the film with a vacuum lid or higher.

The inside of the evaporation device was heated to 5 x 10'T using a cryopump.
Argon, nitrogen, and oxygen were introduced into the evaporation apparatus after the vacuum level was set to hrr, and permalloy was evaporated and its characteristics were investigated. It became clear that the deposition rate of the film and oxygen had an effect. Argon and nitrogen 2X10'T
Although the introduction of up to orr was investigated, no effect on the membrane was observed.

The deposition rate and oxygen partial pressure of the film both affect the properties of the permalloy film, but each does not affect them independently, but in the form of their ratio X. FIG. 2 shows the relationship between Δθ5o regarding the (OO2) plane of the Co--Or film in a two-layer film medium and X at the time of permalloy film deposition. Curves 1, 2, 3, and 4 are for substrate temperatures of 20, 150, and 25, respectively, during deposition.
The relationship for the cases of 0 and 30°C is shown. The film thickness of both the permalloy film and the Co-0r film is 0.2 μm, and the Co-
The 0r film was formed by a vacuum evaporation method at a deposition rate of 100 mm/sec. The smallest value of Δθ5o was obtained when the substrate temperature during permalloy film deposition was 250°C. From Figure 2, when the substrate temperature during permalloy film deposition is 250°C,
By making 2 X 1 cJ-L- or more, 18
It can be seen that a Co-Or film having a value of Δθ5o of less than degrees seconds·Torr can be obtained. In cases other than 250'C, the value of X that makes Δθ5o 18 degrees or less is larger than that in the case of 250°C. Therefore, in a two-layer film medium, Δθ.

In order to obtain a Co-0r perpendicular magnetization film in which the angle is 18 degrees or less,
The value of X during permalloy film deposition was set to 2×107−1− seconds・
It is necessary to set it to Torr or higher.

As described above, according to the present invention, a two-layer film medium with excellent characteristics such as recording and reproducing efficiency can be easily obtained.

[Brief explanation of the drawing]

Figure 1 shows the dependence of the output on Δθ when a signal is recorded and reproduced on a two-layer film medium, and Figure 2 shows the Δθ5o of the ■-Or film in the two-layer film medium and the X when permalloy film is deposited. FIG. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 5o (1) Fig. 2 7-(f)

Claims (1)

[Claims] A permalloy thin film is formed on the substrate by vacuum evaporation,
In a method for manufacturing a magnetic recording medium, in which a magnetic layer having an axis of easy magnetization perpendicular to the film surface and containing C and Or as main components is further formed thereon, the permalloy thin film is formed by a vacuum evaporation method. A method of manufacturing a magnetic recording medium characterized by: