JPH02137126A - Method for manufacturing magnetic recording media - Google Patents

Abstract

PURPOSE:To prevent lack of signals by etching the surface of a rod-shaped or wiry Co-Cr or Co-Ni-Cr alloy, supplying the etched alloy into a molten material to be vaporized, and depositing the vapor on a substrate. CONSTITUTION:The surface of a rod-shaped or wiry Co-Cr or Co-Ni-Cr alloy 8 is etched, the etched alloy is supplied into a molten material 7 to be vaporized, and the vapor is deposited on a substrate. Since the alloy 8 is etched and then supplied into the molten material 7, the oxide film on the surface is previously removed, and hence splashing is not caused. Although the surface of granular Cr is difficult to etch, the rod-shaped or wiry Cr alloy is easily etched. By this method, lack of signals if prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a manufacturing method for producing a long magnetic recording medium having excellent high-density recording characteristics and having a constant composition over a long length.

2. Description of the Related Art A perpendicular magnetic recording system is known as a magnetic recording system with excellent short wavelength recording characteristics. The magnetic layer of the magnetic recording medium used in this method needs to have perpendicular magnetic anisotropy. When a signal is recorded on a perpendicular magnetic recording medium, residual magnetization tends to be oriented perpendicular to the film surface of the medium, and the demagnetizing field within the medium decreases as the wavelength becomes shorter. As a result, high reproduction output can be obtained in the short wavelength region.

Many Co-based alloy thin films have been studied as magnetic layers for perpendicular magnetic recording media. Among these, alloy thin films mainly composed of Co and Cr or Co, Ni, and Cr are attracting the most attention because of their excellent recording and reproducing characteristics and corrosion resistance.

Co--Cr or Co--Ni--Crf alloy thin films are generally produced by vacuum evaporation or sputtering. Comparing the vacuum evaporation method and the sputtering method, the former can form a film at a film deposition rate that is 100 times or more higher than the latter, so the former is extremely advantageous in mass production.

In the vacuum evaporation method, since Co, Ni, and CI are high melting point metals, it is necessary to use an electron beam evaporation source as the evaporation source.

However, since the vapor pressures of Co and CI are significantly different, the vacuum evaporation method is used to deposit Co-Cr or Co-Cr with a constant composition over a long length.
It is difficult to produce an alloy thin film containing Ni-Cr as a main component. Note that the vapor pressure of Ni is C.

Since it is almost equal to , it is easy to control the composition of Ni.

When Co and Cr are evaporated from the same evaporation source and a Co-Cr film is continuously deposited on a moving long substrate, the film contains a large amount of Cr in the initial stage of deposition, as shown in Figure 2. A Co--Cr film is formed, and at the end of the deposition, a Co--Cr film that does not contain much Cr is formed. In a Co-Cr film, the magnetic properties change if the film composition changes, so
This makes mass production difficult.

The above problem can be solved by performing vapor deposition while supplying granular Cr into the molten metal of the vaporized substance. This method will be explained below using FIGS. 3 and 4.

FIG. 3 shows a schematic diagram of an example of the inside of a vacuum evaporation apparatus that performs evaporation while moving a substrate. 1 is a polymer substrate and runs along the circumferential surface of the cylindrical can 2.

A molten metal 7 of evaporated material is contained in a crucible 6 of an electron beam evaporation source. The evaporated substance is C0-Cr or Co
-Ni-Cr alloy. Evaporated Co.

Cr and Ni atoms adhere to the polymer substrate 1 that is moving on the circumferential surface of the cylindrical can 2, forming a Co-Cr film or a Co-
A Ni-Cr film is formed. 3 and 4 are bobbins around which the polymer substrate 1 is wound. 6 is a shielding plate for preventing unnecessary atoms from adhering to the polymer substrate 1. 12 is granular C
This is a device that supplies r14. In addition to granular Cr, granular Co-Cr or granular Co-Ni-Cr
It is okay to use. The Cr granules 14 enter the molten metal 7 of the vaporized substance along with the Cr feed 13. When a film is produced while supplying Cr grains into the molten metal 7 of the evaporated substance in a controlled amount using the CI supply device 12 in this manner, a long Co-Or film having a constant composition can be obtained. FIG. 4 shows the dependence of the film composition on the deposition time when deposition was performed while supplying CI grains. As shown in FIG. 4, there is no change in the composition as shown in FIG. 2 even with the passage of time, and it can be seen that the composition remains almost constant.

Problems to be Solved by the Invention As described above, while supplying CI grains into the molten metal, Co -Cr
When a film or a Co-Ni-Cr film is vapor-deposited, a film having a constant composition can be produced over a long length, but it has become clear that a problem arises in that splashes occur during supply. Here, the splash refers to alloy grains with a diameter of several tens of micrometers or less that fly out from the hot molten metal. In an electron beam evaporation source, the temperature of the part of the molten metal that is irradiated with the electron beam is very high, and splash is generally likely to occur from the molten metal that is in a boiling state. In particular, when solids such as CI particles are added to the molten metal in a boiling state, the supplied Cr
Oxygen in the oxide film on the grain surface dissociates and is extremely likely to be generated. When a splash occurs, it is deposited on the substrate. When a signal is recorded on a magnetic recording medium with splashes attached, the contact between the medium and the magnetic head becomes insufficient at the splash portion, resulting in signal loss. Therefore,
It is undesirable for splash to occur when Cr grains are supplied into the molten metal.

Means for Solving the Problems The present invention solves the above problems by transferring Co and Cr or an alloy mainly composed of Co, Ni, and Cr as a magnetic layer by a vacuum evaporation method using an electron beam evaporation source. In the manufacturing method of magnetic recording media that is continuously formed on a substrate, rod-shaped or linear Co-Cr or Co
- characterized by performing vapor deposition while supplying the Ni-Cr alloy into the molten metal of the evaporated substance after etching the surface thereof,
Preferably, the etching is performed using an ion gun during film formation.

Function According to the present invention, the Co-
Cl or Co-Ni-Cr alloy is etched smoothly and the oxide film on its surface is removed.
No splash occurs. Although it is difficult to etch the surface of granular Cr, as in the present invention,
A rod-shaped or linear Cr alloy can be easily etched. Since no splash occurs during vapor deposition, a high-density magnetic recording medium with almost no signal loss can be obtained.

EXAMPLES Hereinafter, the manufacturing method of the present invention will be explained based on specific examples.

A perpendicular magnetic recording medium was manufactured using a vacuum evaporation apparatus having the configuration shown in FIG. The polymer substrate 1 has a film thickness of 8 μm.
m polyimide film was used. The diameter of the cylindrical can 2 was 6oα, and the temperature of the circumferential surface was 260°C. The electron gun (not shown) of the electron beam evaporation source has an accelerating voltage of 30
A KV pierce-type straight gun was used. A magnetic screw crucible was used as the crucible e, and the Co--Cr alloy was filled in the crucible.

The distance between the polymer substrate 1 and the surface of the molten metal 7 of the evaporated substance was set to 26α. With a film deposition rate of 1 μm/sec and a polymer substrate traveling speed of 24 m/min, C! An o-Cr film was formed. 8 is a rod-shaped Cr alloy supplied to the molten metal 7 of the evaporated substance.

The composition of this rod-shaped Cr alloy 8 is determined by the amount and rate of supply.

Adjust according to the amount of evaporated substances, film deposition rate, etc.

In this experiment, a rod-shaped Cr alloy 8 was used with a diameter of 2゜n.
A Co-Cr alloy with an r content of 27% by weight was used. In addition, when the evaporated substance is Co-Ni-Cx alloy, rod-shaped C
An o-Ni-Cr alloy may be used.

Reference numeral 9 denotes a feeding device for feeding the rod-shaped Cr alloy 8 into the molten metal of the evaporated substance. This feeding device feeds the rod-shaped Cr alloy 8 in the direction of arrow A while rotating it in the direction of arrow B. 11
is generated from the ion gun 1o, and irradiates the rod-shaped Cr alloy 8 to coat its surface with ions other than elatin (Xe and other ions may also be used. In addition, the neutralizer equipped in the ion gun 10 is not used There is no difference even if it is not used.In this experiment, a Kaufmann type ion gun with a grid diameter of 3c11 was used, and the ion acceleration voltage was set to 1.sKV.
.

The ion current density was 2 mA/d. Further, the feed rate of the rod-shaped Cr alloy 8 was set to 3α/min. In addition, on the surface of the molten metal 7 of the evaporated substance, the irradiation position of the electron beam and the rod-shaped C
The shortest distance of the r-alloy supply position was set to 61.

A Co-Or film was deposited on the polymer substrate 1 under the above conditions, and the number of splashes on the surface of the formed film was examined.

The results are shown in the table. The same table also shows the results for the membranes produced under the same conditions as above except that no ion gun was used, and the membranes produced by the conventional method shown in FIG. Note that the splash was observed using an optical microscope and a scanning electron microscope.

As is clear from the table, in the conventional method, an extremely large number of splashes adhere to the polymer substrate, resulting in too many signal deletions, making it impossible to use it as a magnetic recording medium. or,
Even if a rod-shaped Cr alloy is supplied instead of the 01 grains, there will still be a lot of splash, and it cannot be used as a magnetic recording medium unless an ion gun is used. In contrast to these methods, according to the method of the present invention, no splash is observed and it can be used as a magnetic recording medium.

As described above, the reason why there is almost no splash according to the method of the present invention is thought to be that the oxide film on the surface of the rod-shaped Cr alloy, which is the supplied material, is etched and removed by the ion beam.

That is, if there is an oxide film on the surface of the rod-shaped Cr alloy that is the feed substance, when the feed substance is fed into the molten metal, the oxide film does not dissolve immediately and floats to the part irradiated with the electron beam. When the electron beam hits this oxide, the oxygen dissociates, creating a splash. On the other hand, if the oxide film is etched and removed by an ion beam and then the material to be supplied is supplied into the molten metal of the evaporation source, no splash will occur because there is no cause for splash.

In the above, an example has been described in which the rod-shaped Cr alloy surface is etched using an ion gun during vapor deposition, but etching may be performed using an ion gun or plasma before vapor deposition, and then vapor deposition may be started. Alternatively, the surface oxide film of the rod-shaped Cr alloy, which is the supplied material, may be removed by wet etching using aqua regia or the like. However, the method of supplying the rod-shaped CI alloy while etching it with an ion gun during vapor deposition as in the above embodiments can completely remove the oxide film and thus provide the best effect. Note that the shape of the supplied substance may be linear instead of rod-shaped. However, since it is difficult to remove the surface oxide film in the form of particles, no reduction in splash can be expected.

Effects of the Invention As explained above, according to the method for manufacturing a magnetic recording medium of the present invention, since the occurrence of splash during vapor deposition is extremely small, high-density magnetic recording media with almost no signal loss can be produced with high productivity. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the inside of a vacuum evaporation apparatus for explaining an example of the manufacturing method of the present invention, and Fig. 2 shows evaporation when a long Co-Cr film is produced without supplying Cr or CI alloy. A diagram showing an example of the relationship between time and film composition, FIG. 3 is a schematic diagram of the inside of a vacuum evaporation apparatus equipped with a device for continuously supplying Cr grains, and FIG. 4 is a diagram showing an example of the relationship between time and film composition. -Cr
FIG. 3 is a diagram showing an example of the relationship between the deposition time and the film composition when a film is deposited. DESCRIPTION OF SYMBOLS 1... Polymer substrate, 7... Molten metal of evaporated substance, 8... Rod-shaped Cτ alloy, 9... Rod-shaped Cr alloy supply device, 10... ...Ion gun,
11...Ion. Name of agent: Patent attorney Shigetaka Awano and one other person
4 -m- 5-°゛6-・- 7・・- 1% molecular toad until the cylindrical campopiso 1i Molten metal of gourd seed 2 Figure 10-4 On gun 11-・-ion No. Figure 3

Claims (2)

[Claims] (1) Co by vacuum evaporation method using an electron beam evaporation source
In a method for manufacturing a magnetic recording medium, in which a magnetic layer is continuously formed on a moving substrate, a magnetic layer is formed of a magnetic layer containing Co-Cr or an alloy containing Co, Ni, and Cr as main components. - A method for producing a magnetic recording medium, which comprises etching the surface of a -Cr alloy and then supplying it into a molten metal of an evaporated substance while performing vacuum deposition on the substrate. (2) The method for manufacturing a magnetic recording medium according to claim 1, wherein the etching is performed using an ion gun during film formation.