JPH02249133A - Production of perpendicular magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain not only high productivity but also the excellent perpendicular magnetic anisotropic performance of Co-Cr in terms of performance by a vacuum deposition method by forming a film while irradiating the surface of a high-polymer substrate with the electrons accelerated by >=3kV acceleration voltage in the direction approximately parallel with the substrate surface. CONSTITUTION:The film is formed on the high-polymer substrate 2 while the surface thereof is irradiated with the electrons 7 accelerated by >=3kV acceleration voltage in the direction approximately parallel with the substrate surface. The momentum of the vapor deposited atoms 5 on the substrate 2 is increased by the accelerated electrons 7 from an electron gun 6 and, therefore, the crystal orientability is improved and the intercrystalline segregation of Cr is accelerated. The perpendicular magnetic recording medium having the perpendicular magnetic anisotropic film which is high in the perpendicular anisotropic magnetic field Hk and the coercive force Hc in the direction perpendicular to the film plane is obtd. in this way with the high productivity by the vacuum deposition method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a perpendicular magnetic recording medium with excellent high-density recording characteristics.

2. Description of the Related Art A perpendicular magnetic recording system is known as a magnetic recording system with excellent short wavelength recording characteristics. This method requires a perpendicular magnetic recording medium having perpendicular magnetic anisotropy. When a signal is recorded on such a medium, the magnetization is directed perpendicular to the film surface of the medium. Therefore, as the wavelength of the signal becomes shorter, the demagnetizing field within the medium decreases, and a higher reproduction output can be obtained.

Perpendicular magnetic recording media that are currently commonly used are directly on a non-magnetic substrate such as a polymer film, or on a TI,
A Co-based alloy magnetic layer having perpendicular magnetic anisotropy is formed by sputtering via a base layer of Ge1S1, Cod, AQ20a, etc. Especially C.

In the sputtered film containing Cr, the amount of Cr is 30% by weight.
In the following range, the crystal system has a close-packed hexagonal structure, and its C
Since the axis can be oriented in a direction perpendicular to the film surface, a perpendicular magnetic anisotropic film can be easily realized.

However, since the sputtering method has a slow rate of forming magnetic thin films,
It is difficult to produce perpendicular magnetic recording media at low cost. In contrast to the sputtering method, the vacuum evaporation method
A CO-based alloy perpendicular magnetic anisotropy film can be obtained at a fast film deposition rate of A/sec.

Problems to be Solved by the Invention In order for a perpendicular magnetic anisotropic film to have excellent short wavelength recording and reproducing characteristics, it is preferable that the perpendicular anisotropic magnetic field Hk and the coercive force He in the direction perpendicular to the film surface be large. However, when a Co-Cr perpendicular magnetic anisotropic film, which is conventionally considered to have the best properties among the Go-based alloy perpendicular magnetic anisotropic films, is produced by vacuum evaporation, the Hk of the film is 2. ~3KOe1He
was about 7000e at most, which was lower than that of a Co--Cr perpendicular magnetic anisotropy film fabricated by sputtering. As described above, the performance of the Co--Cr perpendicular magnetic anisotropic film obtained by the vacuum evaporation method was inferior to that obtained by the sputtering method. Therefore, there is a need for the development of a method for producing a perpendicular magnetic recording medium having Co-Orr perpendicular magnetic anisotropy, which has not only high productivity but also excellent performance in terms of performance, using a vacuum evaporation method.

Means for Solving the Problems The present invention realizes the above-mentioned needs, and provides perpendicular magnetic recording in which a perpendicular magnetic anisotropic film made of an alloy containing Co and Cr is formed on a polymer substrate by a vacuum evaporation method. The method for manufacturing a medium is characterized in that film formation is performed while irradiating electrons accelerated at an acceleration voltage of 3 KV or more in a direction substantially parallel to the surface of the polymer substrate.

Effect According to the configuration of the present invention, when electrons accelerated with an acceleration voltage of 3 kV or more are irradiated in a direction substantially parallel to the substrate surface,
Since the momentum of the vapor-deposited atoms on the substrate increases, the crystal orientation of the perpendicular magnetic anisotropic film formed on the substrate is improved. As a result, a perpendicular magnetic recording medium having a perpendicular magnetic anisotropic film having a high Hk can be obtained. Furthermore, since it is a perpendicular magnetic anisotropic film containing Co and Cr, He also increases. This is because the main cause of Hc in a perpendicular magnetic anisotropic film containing CO and Cr is the segregation of Cr to the grain boundaries, and the increase in the momentum of the deposited atoms on the substrate causes the segregation of Cr to increase. This is because it promotes

Example Next, one embodiment of the present invention will be described based on FIG.

FIG. 1 shows an example of the internal configuration of the vacuum evaporation apparatus in this embodiment. Reference numeral 1 denotes a substrate holder made of stainless steel, which can be heated. In the experiment, the temperature of substrate holder 1 was set to 2.
The temperature was kept constant at 50'C. As the polymer substrate 2, a polyimide film was used. 3 is an electron beam evaporation source, into which a C'o=Cr alloy as an evaporation substance 4 is filled. Note that the reason why the electron beam evaporation source 3 is used as the evaporation source is to evaporate high melting point metal such as co at a high evaporation rate.

5 is an evaporated atom such as evaporated Co10r. 6 is an electron gun with an accelerating voltage of 3 kV or more. 3kV from electron gun 6
The electrons 7 accelerated as described above are emitted toward the polymer substrate 2 in a direction substantially parallel to the substrate surface. For comparison, an experiment was also conducted in which the electron gun was placed at the 6' position indicated by the broken line and a film was formed while emitting electrons toward the polymer substrate.

The film thickness was 0.25 μm using the vacuum evaporation equipment shown in Figure 1.
The experimental results when a Co-0r perpendicular magnetic anisotropic film was formed are shown in the table. The acceleration voltage of the electron gun is 10kV,
The current was 0.5 A1 and the film deposition rate was 0.4 μm/sec.

From the table, in the case of the conventional method that does not irradiate electrons, ll
k 2.5 kOe, Hc 13000e, but according to the method of this example, Hk 4.5 kOe1
It can be seen that the magnetic properties are significantly improved compared to Hc 8000e. This improvement is thought to be because accelerated electrons from the electron gun increase the momentum of the deposited atoms on the substrate, improving crystal orientation and promoting grain boundary segregation of Cr.

However, even if you irradiate accelerated electrons from an electron gun, the method is not appropriate (the position of the electron gun is 6 in Figure 1).
’), it can be seen from the table that there is no effect. In other words, when the electron irradiation direction is not approximately parallel to the substrate surface, but has an irradiation direction that also has a component perpendicular to the substrate surface, as in the case of electrons from an electron gun placed at position 6' in Figure 1. In this case, Hk decreases slightly and Hc decreases significantly. A high S/N ratio cannot be obtained with such a film. When electrons are irradiated from a direction with a component perpendicular to the film surface, Hk
The reason for the lack of improvement in lHc is thought to be as follows.

In the case of such electron irradiation, the polymer substrate is directly bombarded with electrons and gas is generated. It is thought that this gas has an adverse effect and the characteristics of the Go-Cr film are not improved.

Therefore, the direction of electron irradiation must be approximately horizontal to the film surface. In the above example, the acceleration voltage of the electron gun is set to 10 kV.
I mentioned the example where the current was 0.5A, but 3k
When the acceleration voltage was V or more, the effect of improving characteristics was observed. 3
There was almost no effect below kV. Furthermore, results similar to those described above were obtained even when a polymer substrate such as a polyamide film, polyetherimide film, polyethylene terephthalate film, or polyethylene naphthalate film was used instead of a polyimide film as the substrate. In addition,
The magnetic layer of the present invention is not limited to a Co-0r film.

Co-Cr-N1, Co-Cr-W, Co-0r-
Nb1Co-Cr-Ta1Co-Cr-Nl-CutC
Even with alloy films such as o-Cr-Ni-AI, the effects of the present invention appear in exactly the same way as above.

Next, another embodiment of the present invention will be described based on FIG.

In the vacuum evaporation method, a tape-shaped perpendicular magnetic recording medium can be obtained with high productivity by forming a thin film while running a polymer substrate along the circumferential surface of a cylindrical can. FIG. 2 is a schematic diagram of the internal structure of such a vacuum evaporation apparatus. The polymer substrate 8 runs along the circumferential surface of the cylindrical can 9 in the direction of the arrow 13. A shielding plate 12 is arranged between the evaporation source 3 and the cylindrical can 9, and the evaporated atoms 5 adhere to the substrate 8 through the opening of this shielding plate.

10 and 11 are a supply roll and a take-up roll for the substrate 8, respectively. When producing a perpendicular magnetic anisotropic film containing CO and Cr using such a vacuum evaporation apparatus, an electron gun 6 is installed as shown in FIG. Improvements in I(k and Hc) can be seen by irradiating with .

Effects of the Invention According to the present invention, a perpendicular magnetic recording medium having a perpendicular magnetic anisotropic film having a high perpendicular anisotropic magnetic field Hk and a high coercive force He perpendicular to the film surface can be produced using a vacuum evaporation method with excellent performance. Obtained through sex.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the inside of a vacuum evaporation apparatus in one embodiment of the present invention, and FIG. 2 is a schematic diagram of the interior of a vacuum evaporation apparatus in another embodiment of the invention. 2.8...polymer substrate, 3...evaporation source, 4...
...Evaporation substance, 5..Evaporation atom, 6..Electron gun, 7..Electron.

Claims (1)

[Claims] In a method of manufacturing a perpendicular magnetic recording medium in which a perpendicular magnetic anisotropic film made of an alloy containing Co and Cr is formed on a polymer substrate by a vacuum evaporation method, a voltage of 3 kV or more in a direction substantially parallel to the surface of the polymer substrate is applied. 1. A method for manufacturing a perpendicular magnetic recording medium, comprising forming a film while irradiating electrons accelerated at an accelerating voltage.