Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-02-11
2001-06-26
Kiliman, Leszek (Department: 1773)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192200, C204S192320, C204S298010, C204S298070, C204S298330, C427S131000, C427S132000, C427S250000, C428S690000, C428S690000, C428S900000
Reexamination Certificate
active
06251230
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and a device for manufacturing a thin film, and further relates to a magnetic: recording medium. More specifically, this invention relates to a device and a method of manufacturing a thin film and a magnetic recording medium useful for magnetic tapes.
BACKGROUND OF THE INVENTION
In modern society, thin films are widely used in our daily life. Particularly, thin films used for wrapping paper, magnetic tapes, capacitors, etc. are manufactured by a continuous winding vacuum deposition method which allows for high speed mass production. Research and development of thin film magnetic recording media is widely practiced so as to increase recording density. Among highly dense magnetic recording thin film media, Co oxide-based thin films are popular, being commercialized for video tapes.
As a method of manufacturing tape-type Co oxide-based thin film magnetic recording media, the continuous winding vacuum deposition method (Journal of the Magnetic Society of Japan. Vol. 18, Supplement, No. S1 (1994), Proceedings of the Third Perpendicular Magnetic Recording Conference '94, page 439-442) is generally applied. The method is excellent in its productivity. A conventional continuous winding vacuum deposition method is explained by FIG.
2
. Referring to the figure, an electron beam
6
is irradiated so as to deposit magnetic layer on a film on a long macromolecular substrate
4
while the substrate is running along the surface of a cylinder can
5
. As a result, magnetic recording media are mass produced. In other words, long macromolecular substrate
4
is unwound from a unwinding roller
3
in a rotating direction
12
in a vacuum container
2
, which is vacuum exhausted by an exhaust system
1
. The substrate is irradiated by means of electron beam
6
while the substrate is running along the surface of cylinder can
5
. After the substrate is deposited by an electron beam deposition source
7
at the aperture of a shielding plate
9
, it is wound by a winding roller
10
. Reaction gas is introduced from a gas-introducing nozzle
8
so as to carry out reactive deposition. In the figure,
10
is the winding roller,
11
is a guide roller,
12
indicates the rotating direction, and
21
is an electron gun. Co or Co—Ni is used as a magnetic material. Since the reactive deposition are carried out in an oxygen atmosphere by introducing oxygen from gas-introducing nozzle
8
, a long Co—O or Co—Ni—O magnetic tape is manufactured. Due to the reactive deposition in an oxygen atmosphere, crystal particles constituting the thin film separate magnetically, thus increasing coercive force. In addition, oxidized sections formed on the surface of the film and between crystal grain boundaries prevent rust, thereby improving the hardness of the film and its mechanical durability.
As mentioned above, the continuous winding deposition method is suitable for mass-producing thin films and can improve the properties of a thin film by the above-mentioned reactive deposition. However, gas introduced to the deposition atmosphere scatters vaporized atoms even though it improves the properties of the film. The properties depend on the incidence angle of vaporized atoms into the substrate and the scattering conditions of the atoms, so that the properties decline when the flow of vaporized atoms is disturbed by introduced gas. Thus, gas should be introduced so as not to disturb the flow of vaporized atoms. In addition, the recording density of magnetic recording media should be improved since the amount of information for recording is further increasing with the development of the information age. Besides high recording density, mass productivity as well as the excellent recording and reproducing properties of the media are required in manufacturing the media. In order to reduce media noise and provide high C/N, conventional magnetic recording media should have a two-layered magnetic layer, so that the deposition of a magnetic layer has to be carried out twice. In order to make the orientation of magnetic particles the same, the second magnetic layer has to be formed after forming the first magnetic layer and then winding the first layer, so that the productivity of the media declines. Therefore, an improvement in recording density of the media is expected by introducing gas without disturbing the flow of vaporized atoms, while the mass productivity and the recording and reproducing properties of media are maintained.
SUMMARY OF THE INVENTION
It is an object of this invention to solve the above-mentioned conventional problems by providing a method and a device for manufacturing a thin film and a magnetic recording medium, thus improving the properties of a thin film by introducing gas without disturbing the flow of vaporized atoms and mass-producing magnetic recording thin films of high quality.
In order to accomplish this object, the first method of manufacturing a thin film of the invention is to form a thin film on a substrate by a vacuum deposition method. The thin film is formed while introducing reaction gas. The aggregate of gas flux is applied to a thin film forming section by a nozzle having minute tubes. A metal, an alloy metal or the like is used for the thin film. An example of the thin film is one made of a magnetic material such as Co—O, Co—Ni—O, or the like. As the reaction gas, any gas except inert gas can be applied. For instance, oxidizing gas such as oxygen gas, ozone gas or the like is used. In addition, nitrogen monoxide, nitrogen dioxide, carbon monoxide, carbon dioxide, chlorine gas or the like can also be applied. As, in a sputtering method, nitrogen gas functions as reaction gas in an activating atmosphere such as a high-frequency excitation atmosphere, so that nitrogen gas can also be applied in an activating atmosphere. A preferable degree of vacuum for vacuum deposition depends on the evaporating source. However, the degree of vacuum applied for a conventional vacuum deposition method is applied to this invention. More specifically, 1×10
−2
torr or less degree of pressure can be applied to form a thin film.
It is preferable that the ratio of the inside diameter (D) of the minute tube to its length (L) is 1:10, or the value of L is greater than 10.
It is also preferable that the ratio of the inside diameter (D) of the minute tube to a center distance between the minute tube and a neighboring minute tube (X) is 1:4, or the value of X is smaller than 4.
It is further preferable that a reaction gas flux from the minute tube is excited by high-frequency excitation and is then targeted to a film forming section.
The second method of manufacturing a thin film of the invention is to form a magnetic layer directly or via a bottom layer by an electron beam deposition method on a long macromolecular substrate which runs along a supporting body in vacuum. Metals used for forming the magnetic layer are deposited on the substrate from a main aperture of a shielding plate which is applied to regulate the direction of the metals. At the same time, gas including oxygen is directed to the substrate at the deposition end side of the main aperture, and oxygen gas flux is directed to the film-forming area by the sub-aperture from a sub-aperture of the shielding plate on the deposition starting side of the main aperture.
It is preferable that a 6 nm thick or thicker non-magnetic layer is formed by a reaction deposition method with the flux of oxygen gas from the sub-aperture to a film forming section.
It is preferable that a gap between the edge of the main aperture on the deposition starting side and the supporting body is 5 mm or less.
It is also preferable that the minute tubes having the ratio (D/L), between the length (L) and the inside diameter (D). of 0.1 or less are applied so as to blow the flux of oxygen gas.
A seamless belt can also be used as the supporting body, though a cylindrical can is generally applied.
The third method of manufacturing a thin film of the invention is to form a magnetic layer directly or via a bottom
Honda Kazuyoshi
Maezawa Yoshiharu
Odagiri Masaru
Okazaki Sadayuki
Kiliman Leszek
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
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