JP3208218B2 - Apparatus and method for manufacturing magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium manufacturing apparatus and method for manufacturing a magnetic recording medium having excellent high-density recording / reproducing characteristics.

[0002]

2. Description of the Related Art At present, magnetic recording / reproducing apparatuses tend to be miniaturized and densified, and metal thin-film type media have been attracting attention as exceeding the limit of high density of conventional coating type media.
In this regard, a metal thin film type medium made of Co—Ni—O has been put to practical use as a magnetic tape for a VTR. As a method for manufacturing a thin film type magnetic layer, an oblique deposition method is known.

Hereinafter, an example of a conventional vapor deposition method will be described with reference to the drawings. FIG. 2 schematically shows a conventional continuous vacuum evaporation apparatus for performing oblique evaporation. In FIG. 2, 1 is a polymer film substrate, 2 is a cylindrical can, 3 is a shielding plate that defines an initial angle of incidence, 4 is a shielding plate that defines a final angle of incidence,
5 is a nozzle for introducing oxygen, and 6 is an evaporation source. Polymer film substrate 1 running along cylindrical can 2
On top, evaporated atoms from the evaporation source 6 that have passed through the opening between the shielding plates 3 and 4 are deposited. The incident angle is defined by the angle formed between the evaporated atoms and the normal to the substrate 1. The shield plate 3 changes the initial incident angle φi, and the shield plate 4 changes the final incident angle φf.
Can be regulated. The magnetic properties of the magnetic layer are controlled by the range of the incident angle and the introduction of oxygen. The inside of the continuous vacuum deposition apparatus is separated into two chambers A and B, and each chamber is provided with exhaust ports 8 and 7 for evacuation, and each is connected to an exhaust pump (not shown). .

[0004]

In the continuous oblique vapor deposition method, the initial incident side is farther from the evaporation source than the final incident side, and the density of flying evaporative atoms is low. Further, in the conventional apparatus shown in FIG. 2, even if oxygen is introduced from the oxygen introduction nozzle 5 arranged on the final incident side,
All the introduced oxygen does not react on the final incident side and is taken into the film.

[0005] Excess oxygen diffuses into the vapor deposition apparatus and reaches the initial incidence side. Therefore, on the initial incidence side,
Since the vapor atom density is low, the ratio of introduced oxygen to vapor atoms becomes higher than that at the final incidence side. In such a case, when an optimal amount of oxygen is introduced into the final portion of the film formation, that is, into the surface layer portion of the film, oxygen becomes excessive in the initial portion of the film formation, and the saturation magnetization decreases. In order to obtain an excellent magnetic recording medium, it is desired to increase the saturation magnetization of the portion formed on the initial incidence side where the incident angle is high.

[0006]

SUMMARY OF THE INVENTION The present invention provides an apparatus and a method for manufacturing a magnetic recording medium having excellent high-density recording / reproducing characteristics from the above-mentioned viewpoints. In a continuous vacuum vapor deposition apparatus for manufacturing a thin-film magnetic recording medium by oblique vapor deposition on a polymer film substrate running along the peripheral surface, an initial incident angle of evaporated atoms with respect to the polymer film substrate is defined. A space surrounding the shielding plate is substantially surrounded by a pair of partitioning plates disposed on the upstream and downstream sides of the shielding plate on which the polymer film substrate travels to form a room, and the chamber is evacuated. Wherein the exhaust port and the exhaust pump are provided independently of the exhaust port and the exhaust pump for evacuating other portions inside the continuous vacuum evaporation apparatus.
The invention uses Co and O or Co or Co on a polymer film substrate by using the magnetic recording medium manufacturing apparatus of the first invention.
When forming a magnetic layer containing Ni, O and Ni as main components, the residual gas pressure in one chamber substantially surrounded by a pair of partition plates is made lower than the residual gas pressure in other parts inside the manufacturing apparatus. It is characterized by the following.

[0007]

According to the present invention, the residual gas pressure in a chamber substantially enclosed by a pair of partition plates can be reduced, so that the ratio of oxygen to evaporated atoms on the initial incidence side can be reduced. The saturation magnetization of the high incident component of the film formed on the incident side increases. As a result, the anisotropy of the film becomes stronger,
The obtained film becomes a magnetic layer having excellent recording / reproducing characteristics.

[0008]

FIG. 1 shows an embodiment of an apparatus for manufacturing a magnetic recording medium according to the present invention. In FIG. 1, 1 is a polymer film substrate,
2 is a cylindrical can, 9 is a substantially plate-shaped shielding plate for defining an initial incident angle, 4 is a shielding plate for defining a final incident angle, 5 is a nozzle for introducing oxygen, and 6 is an evaporation source. On the polymer film substrate 1 running along the cylindrical can 2, evaporated atoms from the evaporation source 6 passing between the shielding plates 9 and 4 are deposited. The incident angle is defined by the angle formed between the evaporated atoms and the normal to the substrate.
The final incident angle φf can be regulated by the shielding plate 4. The magnetic properties of the magnetic layer are controlled by the range of the incident angle and the introduction of oxygen. The inside of the vacuum evaporation apparatus is divided into approximately three chambers A, B, and C. The two chambers A and B are almost the same as the conventional apparatus of FIG. 2, and each chamber is provided with exhaust ports 8 and 7 for evacuation, and each is connected to an exhaust pump (not shown). ing.

The difference between the vacuum deposition apparatus of the present invention and the conventional apparatus is that a substantially plate-shaped shielding plate 9 and its vicinity are provided with partition plates 10 and 1.
A third room C separated from the other rooms A and B by 0 ′,
It has an independent exhaust port 11 and an exhaust pump (not shown). Hereinafter, the third chamber C will be described.

The third chamber C is provided independently of the other chambers A and B for the purpose of controlling the residual gas pressure on the initial incidence side. For that purpose, partition plates 10 and 10 'are provided so that a differential pressure can be obtained for the other chambers A and B. It is necessary to install the downstream partition plate 10 so as not to define the incident angle, and it is necessary to appropriately adjust the interval with the shielding plate 9 that determines the incident angle. If this interval is too wide,
It becomes difficult to provide a differential pressure. If it is too narrow, the conductance of the exhaust gas becomes small, and it becomes difficult to control the residual gas pressure. Therefore, it is necessary to optimize the distance between the partition plate 10 and the shielding plate 9 in consideration of the capacity of the exhaust pump and the conductance of the exhaust system. On the other hand, it is preferable that the upstream partition plate 10 ′ is as close to the cylindrical can 2 as possible. Although FIG. 1 shows a cross-sectional view and no display of a side partition, it is needless to say that it is important to follow the peripheral surface of the cylindrical can 2 as much as possible.

Next, a method for manufacturing the magnetic recording medium of the present invention will be described. Using the manufacturing apparatus of the present invention described above,
When forming a magnetic layer containing Co and O, or Co, Ni and O as main components, it is important to keep the ratio of oxygen to evaporated atoms at the initial incidence portion low. For that purpose, the residual gas pressure in the third chamber C is made lower than in the other chambers. If the residual gas pressure can be kept low and the ratio of oxygen to evaporated atoms can be kept low, the saturation magnetization of the high incidence component of the film formed on the initial incidence side will increase. When the saturation magnetization of the high incident component of the film increases, the anisotropy increases, and the obtained film becomes a magnetic layer having excellent recording and reproducing characteristics.

An embodiment of the present invention will be described more specifically.

Using the apparatus for manufacturing a magnetic recording medium according to one embodiment of the present invention shown in FIG.
Then, a Co—O film was formed as a magnetic layer. The diameter of the cylindrical can 2 is 1 m.
Melted by an electron beam of 0 kW. 1.2 liters of oxygen per minute was introduced from the gas introduction nozzle 5. The running speed of the polymer film substrate 1 is 60 m / min. The partition plate 10 on the downstream side was placed with its tip being 5 cm below the shielding plate 9. In addition, an upstream partition plate 10 ′ is installed 15 cm above the shielding plate 9, and the tip thereof is a cylindrical can 2.
2 mm away from the peripheral surface of The third chamber C was exhausted from the exhaust port 11. The residual gas pressure during vapor deposition was 1 × 10 ⁻³ Torr in the first chamber A above the apparatus and 1 × 1 in the second chamber B below.
0 ^-4 Torr, and the third chamber C was 5 × 10 ^-5 Torr. The saturation magnetization of the Co—O magnetic layer manufactured in this state was 470 emu / cc. The anisotropic energy Ku of this magnetic layer was 2.6 × 10 ⁶ erg / cc.

As Comparative Example 1, a magnetic layer was formed in the same manner as described above. However, the exhaust port 11 of the third chamber was closed. The residual gas pressure in the third chamber during vapor deposition is 5 × 10 ^-4 T
orr, and the other rooms were almost the same as above. The saturation magnetization of the manufactured magnetic layer was 450 emu / cc, and the difference from the above magnetic layer was slight. However, the anisotropic energy was 1.5 × 10 ⁶ erg / cc, which was considerably small.

As Comparative Example 2, a magnetic layer was formed in the conventional apparatus shown in FIG. 2 without the third chamber under substantially the same conditions as described above. The saturation magnetization of the manufactured magnetic layer is 460 em
u / cc, which is an intermediate value between the two magnetic layers. The anisotropic energy was 1.8 × 10 ⁶ erg / cc, which was close to that of the magnetic layer of Comparative Example 1.

As described above, it was found that the saturation magnetization of the magnetic layer was improved by providing the third chamber and evacuating, but it was found that the magnetic anisotropy energy was further increased. This is thought to be due to the fact that, by providing the third chamber and evacuating, the saturation magnetization in the initial part of the film formation was increased, and the crystallinity of the magnetic layer in which the initial part of the film formation continued to grow increased. Can be That is, it is considered that the crystal magnetic anisotropy was increased and the anisotropic energy of the magnetic layer was increased.

Next, the recording and reproducing characteristics of the three magnetic layers were evaluated. For the evaluation, a commercially available 8 mm VTR was used, and the C / N at a recording frequency of 7 MHz was evaluated and compared. Looking at the results with the magnetic layer of Comparative Example 2 as a reference, the value was +2 dB for the magnetic layer manufactured in the example of the present invention and -1 dB for the magnetic layer of Comparative Example 1. As described above, by using the manufacturing apparatus and the manufacturing method of the present invention, a magnetic recording medium having excellent recording and reproducing characteristics can be manufactured.

However, it was found that when the third chamber was not provided and the gas was not exhausted, the characteristics deteriorated more than before, and it became clear that the control of the residual gas pressure on the initial incidence side was important.

In the above, the Co-O film has been described, but the present invention is also effective for a Co-Ni-O film.
Further, the present invention works effectively even when the incident angle is an angle other than the above embodiment.

[0020]

According to the present invention, a magnetic recording medium having excellent recording / reproducing characteristics can be produced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a magnetic recording medium manufacturing apparatus of the present invention.

FIG. 2 is a diagram illustrating an example of a conventional magnetic recording medium manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymer film substrate 2 Cylindrical can 7 Exhaust port 8 Exhaust port 9 Shielding plate 10 Partition plate 10 'Partition plate 11 Exhaust port A Separated chamber B Separated chamber C Separated chamber

────────────────────────────────────────────────── (5) References JP-A-4-283422 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/85 C23C 14/00-14 / 58 G11B 5/64 H01F 41/20

Claims (2)

(57) [Claims] 1. A continuous vacuum vapor deposition apparatus for producing a thin-film magnetic recording medium by oblique vapor deposition on a polymer film substrate running along the peripheral surface of a cylindrical can. A space surrounding the shielding plate that defines the initial incident angle of the evaporated atoms is substantially surrounded by a pair of partitioning plates disposed on the upstream side and the downstream side of the polymer film substrate running on the shielding plate to form a room, An exhaust port and an exhaust pump for evacuating the chamber are provided independently of an exhaust port and an exhaust pump for evacuating other portions inside the continuous vacuum evaporation apparatus. For manufacturing magnetic recording media. 2. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein Co and O or C is formed on a polymer film substrate.
When forming a magnetic layer containing o, Ni, and O as main components, the residual gas pressure in one chamber substantially surrounded by a pair of partition plates is lower than the residual gas pressure in other parts inside the manufacturing apparatus. A method for manufacturing a magnetic recording medium.