JPS5948450B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a ferromagnetic metal thin film type magnetic recording medium having a ferromagnetic metal thin film layer as a recording layer, and its object is to produce a ferromagnetic metal thin film type magnetic recording medium having particularly excellent magnetic properties. An object of the present invention is to provide a method for manufacturing a magnetic recording medium.

A ferromagnetic metal thin film type magnetic recording medium is usually produced by moving a film-like substrate such as a plastic film or a non-magnetic metal film along the circumferential side of a cylindrical can installed in a vacuum evaporation apparatus. When manufacturing a ferromagnetic metal thin film magnetic recording medium that is made by vacuum evaporating materials and has excellent magnetic properties,
Oblique incidence deposition is performed in which a deposition prevention plate or the like is provided in a vacuum chamber and the vapor of the ferromagnetic material is directed obliquely to the substrate.

However, although such oblique incidence evaporation methods improve magnetic properties, the evaporation efficiency is extremely poor, and only a small portion of the vapor flow generated from the ferromagnetic material evaporation source can be used.

Therefore, as a method to improve this, a charged particle source is installed in the vacuum chamber5, and this charged particle source ionizes the gas, etc. in the vacuum chamber into charged particles, and the charged particles are transferred to a ferromagnetic material. Directed to the substrate with a vapor flow of
A method has been proposed in which the direction of incidence of the vapor flow of the ferromagnetic material is controlled during vapor deposition to efficiently deposit the material so that the easy axis of magnetization capacity 20 of the ferromagnetic material is as parallel to the film surface as possible. In this method, the degree of vacuum in the vacuum chamber is 10-3.
Regardless of the degree of ionization, the ionization efficiency is extremely poor because it is performed under a high vacuum atmosphere that allows vacuum evaporation, and because the gas diffused throughout the vacuum chamber is ionized, rather than the gas introduced for charged particle bleaching. Therefore, the energy of the charged particles that control the direction of incidence of the vapor flow of the ferromagnetic material is insufficient, making it impossible to improve the magnetic properties of the resulting magnetic recording medium. 30Also, there is a method of controlling the incident direction of the vapor flow of the ferromagnetic material in the same way as the above method using a non-ionized gas such as argon gas, but since the non-ionized gas has very low energy, The control 35 of the direction of incidence of the vapor flow of the ferromagnetic material is even worse than in the previous method, and therefore this method cannot significantly improve the magnetic properties of the resulting magnetic recording medium.

This invention was made as a result of various studies to improve this drawback, and includes a substrate that moves along the circumferential side of a cylindrical can in a vacuum chamber, and a substrate that faces the substrate sequentially along the direction of movement of the substrate. An ion source that ionizes and introduces gas from outside the vacuum chamber is provided, and an electrode is provided between the ion source and the substrate to converge the ionized gas and guide it to the substrate. , by simultaneously directing a vapor flow of a ferromagnetic material and a high-energy ionized gas from an ion source onto the substrate in a vacuum atmosphere, the deposition efficiency is improved and the magnetic properties of the resulting magnetic recording medium are improved. It has been improved.

According to this invention, an ion source that can ionize gas introduced into the interior in a high vacuum atmosphere by installing an electrode or the like is provided in the vacuum chamber, and the ion source Unlike the conventional method of ionizing gas inside the vacuum chamber, the ion source The high-energy ionized gas obtained by the method is directed toward the substrate, and the direction of incidence of the vapor flow of the ferromagnetic material during deposition is controlled by this high-energy ionized gas.

Further, between the ion source and the substrate moving along the circumferential side of the cylindrical can, an electrode is arranged to converge the ionized gas and guide it to the substrate, so that the vapor flow of the ferromagnetic material is incident. Direction is better controlled. Therefore, the direction of incidence of the vapor flow of the ferromagnetic material can be easily and sufficiently controlled, and not only can the axis of easy magnetization of the ferromagnetic material be made parallel to the film surface as much as possible, but also the deposition efficiency can be improved. The magnetic properties of the resulting magnetic recording medium can be further improved. The present invention will be described below with reference to the drawings.

Figure 1 shows a cross-sectional view of the vacuum evaporation apparatus,
is a vacuum chamber, and the inside of this vacuum chamber 1 is maintained in a vacuum by an exhaust system 2.

Reference numeral 3 denotes six cylindrical cans disposed in the center of the vacuum chamber 1, and a substrate 4 such as a plastic film is moved along the circumferential side of the cylindrical can 3 from an original roll 5 via a guide roller 6. Then, the sheet is wound up by a winding roll 8t via a guide roller 7.

During this time, the substrate 4 moves along the circumferential side of the cylindrical can 3.
The ferromagnetic material 10 is heated and evaporated in the ferromagnetic material evaporation source 9 disposed in the vacuum chamber 1 opposite to the substrate 4, and the vapor flow A is directed to the substrate 4.
At the same time, the gas is ionized from the ion source 11 disposed on the left inner wall of the vacuum chamber 1, facing the substrate 4 moving along the circumferential side of the cylindrical can 3. The ion beam is introduced by the ion source 11 and is focused by the ring-shaped electrode 12 disposed between the ion source 11 and the substrate 4, and is directed toward the substrate 4 as shown by arrow B. Note that 13 is an insulation introduction terminal, and 14 is a power source for the ring-shaped electrode 12. As shown in FIG. 2, the ion source 11 has a gate 17 in which a cathode 15 is housed and a coil 16 disposed on the outer periphery, and a plasma expansion port 18 disposed close to the nozzle-shaped tip of the gate 17. Anode 19 and further anode 19
When gas is introduced from the gas inlet 21 attached to the rear end of the gate 17, the gas is transferred to the filament of the cathode 15 under a high vacuum atmosphere. It is then ionized, drawn out by the anode 19, and introduced into the vacuum chamber 1 via the guide electrode 20 as shown by arrow B. Such an ion source 11
The ionized gas has a high energy of several hundred electron volts, and as described above, it is focused by the ring-shaped electrode 12 and directed to the substrate 4fζ as shown by the arrow B, so that the ionized gas has a high energy of several hundred electron volts. The direction of incidence of the vapor flow A of the ferromagnetic material having a deposition energy on the order of volts is easily and well controlled. Note that the electrode 12 for converging the ionized gas is not limited to a ring-shaped electrode, but may be a net-shaped electrode. When such a focusing electrode 12 is disposed between the ion source 11 and the substrate 4, the ionized gas introduced by the ion source 11 is focused and the ion density increases, so that the vapor flow A This makes it easier to control the direction of incidence. In this way, in this invention, the ion source 11 is used to control the vacuum chamber 1.
Vacuum evaporation is much more efficient than the conventional oblique incidence evaporation method because ionized gas is introduced from the outside and this ionized gas controls the direction of incidence of the vapor flow A of the ferromagnetic material. In addition, the direction of incidence of the vapor flow A is controlled by high-energy ionized gas, and the ionized gas is focused by the focusing electrode to create a gas with high ion density. Since the magnetic flux is directed toward the magnetic field, a ferromagnetic metal thin film magnetic recording medium with excellent magnetic properties can be obtained with sufficient control.

Examples of the gas that is ionized by the ion source 11, introduced into the vacuum chamber 1, and directed toward the substrate 4 include argon gas, helium gas, neon gas, xenon gas, nitrogen gas, as well as argon gas and oxygen gas. A mixed gas and a mixed gas of argon gas and nitrogen gas are preferably used. In particular, a mixed gas of argon gas and oxygen gas makes the ferromagnetic material fine and forms oxides at the grain boundaries. , is used more preferably because it has the function of adjusting the coercive force to a predetermined value.

Furthermore, when the ion source 11 ionizes these gases, the degree of vacuum inside the ion source 11 is set to be lower than 10-3 Torr, so that when the ionized gas is directed to the substrate 4 in this vacuum atmosphere, a good condition is obtained. It is not possible to form a ferromagnetic metal thin film, and if the temperature is higher than 10-6 Torr, it is difficult to ionize the gas, so it is preferable to keep it within the range of 10-3 to 10-6 Torr, and 10-5 to 10-6 Torr. More preferably, it is kept within the range of Note that when using a mixed gas of argon gas and oxygen gas, it is preferable that the partial pressure of the oxygen gas is lower than 1.times.10@-4 Torr. Further, the ionized gas directed from the ion source 11 to the substrate 4 is arranged such that the incident angle α of the ferromagnetic material 10 with respect to the vapor line C with respect to the substrate 4 is in the range of 45° to 90°. If the incident angle α is smaller than 45°, the desired effect will not be obtained, and if it is larger than 90°, the ionized gas will be blocked by the cylindrical can, making it impossible to fully demonstrate the desired effect. There is a fear. As the substrate, plastic films made of commonly used polymer moldings such as polyester, polyimide, polyamide, etc., and metal films made of non-magnetic metals such as copper are used, and ferromagnetic materials forming the ferromagnetic metal thin film layer are used. In addition to single metals such as cobalt, nickel, and iron, alloys or oxides of these and CO
-P, CO-Ni-P, and other ferromagnetic materials commonly used in vacuum deposition are used.

Next, embodiments of the invention will be described.

Example 1 After surface treatment (argon gas, Honpart treatment) was performed on a polyester base film approximately 9μ thick, it was loaded into the vacuum evaporation apparatus shown in Fig. 1, and the inside of the vacuum evaporation apparatus was heated for approximately 10-J. It was evacuated to 100 g.

Next, at the same time as starting the vapor deposition of cobalt metal, ionized argon gas was ionized in a vacuum atmosphere of 1×10-5 Torr by an ion source installed in the vacuum evaporation equipment at an incident angle of 80° with respect to the cobalt vapor line. A ferromagnetic metal thin film layer was formed by depositing cobalt metal on a polyester base film to a thickness of 0.3 μm, and this was cut to a predetermined width to produce a magnetic tape. Example 2 Same as Example 1 except that the gas to be ionized in the ion source in Example 1 was changed from argon gas to a mixed gas of argon gas and oxygen gas (partial pressure of oxygen gas 3 x 10-5 Torr). He used it to make magnetic tape.

Example 3 Same as Example 1 except that the gas to be ionized in the ion source in Example 1 was changed from argon gas to a mixed gas of argon gas and nitrogen gas (partial pressure of nitrogen gas 3 x 10-5 Torr). He used it to make magnetic tape.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1 except that argon gas was introduced from the ion source into the vacuum evaporation apparatus without being ionized.

Comparative Example 2 In Example 1, argon gas was introduced into the vacuum evaporation apparatus in advance, a charged particle source was provided in the vacuum evaporation apparatus in place of the ion source, and the argon gas inside the vacuum evaporation apparatus was removed by this charged particle source. A magnetic tape was made as in Example 1 except that the gas was ionized and directed onto the polyester base film.

The coercive force (Hc) and squareness (Br/Bm) of the magnetic tapes obtained in each Example and each Comparative Example were measured.
The following table shows the results.

As is clear from the above table, the magnetic tapes obtained by the manufacturing method of the present invention (Examples 1 to 3) are higher than the magnetic tapes obtained by the conventional manufacturing method (Comparative Examples 1 and 2).
Compared to the above, all of the magnetic tapes have a larger coercive strength and a larger square shape, which indicates that the magnetic tape obtained by the manufacturing method of the present invention has excellent magnetic properties.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a vapor deposition apparatus used to carry out the manufacturing method of the present invention, and FIG. 2 is an enlarged cross-sectional view of an ion source disposed within the vapor deposition apparatus. 1... Vacuum chamber, 3... Cylindrical can,
4...Substrate, 9...Ferromagnetic material evaporation source, 10...Ferromagnetic material, 11...Ion source, 12... Electrode, A... Vapor flow of ferromagnetic material.

Claims (1)

[Claims] 1 Into a vacuum chamber, a substrate moves along the circumferential side of a cylindrical can, a ferromagnetic material evaporation source faces the substrate sequentially along the direction of movement of the substrate, and ionized gas is introduced from outside the vacuum chamber. An ion source is disposed between the ion source and the substrate, and an electrode is disposed between the ion source and the substrate to converge the ionized gas and guide it to the substrate. A method for manufacturing a magnetic recording medium, comprising the step of simultaneously directing the gas to the substrate to form a ferromagnetic metal thin film layer on the substrate.