JPS59141210A - Vacuum deposition device - Google Patents

Abstract

PURPOSE:To enhance metal deposition efficiency to the surface of a supporter, and to reduce cost of the whole of a magnetic recording medium by a method wherein a member to obstruct the inflow of a molten metal to the beam irradiating part of a metal evaporation source is provided directly under the irradiating position thereof by shallowing depth of the molten metal at the part thereof. CONSTITUTION:An irradating part according to an electron beam 7 is heated up to the boiling point to generate a vapor current 8 extending in the width direction A of a film base 1. Therefore, an evaporating material 6 at the irradiating part is reduced to form a recessed part on the surface of the molten metal of the evaporating material 6. While, because the molten metal at the adjoining part to the irradiating part has higher viscosity as compared with the molten metal at the irradiating part, and moreover resistance at time when the molten metal flows to the irradiating part thereof from the adjoining part is enhanced because depth of the irradiating part is shallowed according to a projection 10, replenishment of the molten metal to the recessed part of the irradiating part thereof is delayed. Accordingly, in the steady state that the evaporating quantity of the evaporating material and the replenishing quantity thereof are equalized, the molten metal surface of the irradiating part of the electron beam 7 becomes to form a recessed surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a vapor deposition apparatus used for vacuum vapor deposition, and particularly in a vapor deposition apparatus that heats and evaporates an evaporation source using an energy beam such as an electron beam.

In recent years, as the amount of information to be recorded has increased, the demand for high-density magnetic recording has become even stronger, and vacuum evaporation has replaced the conventional coating-type production method in which a binder-type magnetic liquid is coated on a flexible support and dried. Various studies have been conducted on so-called non-coating type manufacturing equipment that deposits a ferromagnetic metal thin film on the support without using a binder using methods such as sputtering, ion blating, etc., and various proposals for practical use have been made. It is being done.

Among these non-coating type manufacturing equipment, oblique incidence vacuum evaporation equipment, in which the evaporation beam of magnetic metal is incident obliquely on the support surface, has a relatively compact processing process and has good magnetic properties. It is practical because a thin film with specific characteristics can be obtained.

This oblique incidence vacuum evaporation apparatus generally moves the support above the evaporation source in a straight line or in a curved manner along the outer circumferential surface of a cylindrical can. The method is characterized in that a ferromagnetic metal thin film is deposited on the support surface to a specified thickness at one time by an evaporated metal flow, but since the support surface and the evaporated metal flow are located obliquely relative to each other, , compared to the case where the incident angle is zero (incidence perpendicular to the surface of the support), the thickness of the deposited film is a cosine (Co51ne) times larger, and the vapor deposition efficiency decreases significantly as the incident angle increases. This is unavoidable, and if the angle of incidence between the support and the evaporation source becomes a dog, the distance between the support and the evaporation source becomes a dog, which further reduces the evaporation efficiency. It was something. In addition, the magnetic properties of the deposited film, especially the coercive force, depend on the angle of incidence (Reference: 5chued
e: J, A, p, 35 2558 (1964))
Therefore, it was necessary to keep the angle of incidence constant within as narrow a range as possible. For this reason, a shield plate or the like is usually provided between the support and the evaporation source to exclude vapor flows at angles of incidence other than the desired one, but the provision of this shield plate further reduces the evaporation efficiency.

This decrease in vapor deposition efficiency is caused by relatively expensive non-ferrous metals such as C.
When using O, Co-Ni, Co-Ni-Cr, etc., it is difficult to achieve significant cost reduction, and this is an important problem to be solved for practical use.

In order to improve the low evaporation efficiency of conventional equipment, a device has been proposed in which the side walls of the crucible, which is the container for the evaporation source, are made high (to regulate the distribution of vapor flow). Cooled metal is deposited on the top of the wall,
It becomes difficult to continue vapor deposition.

Additionally, a device has been proposed in which a reflecting wall heated to a temperature higher than the melting point of the vapor deposition material is provided above the crucible, and unnecessary vapor flow is reflected by the reflecting wall to a desired angle of incidence, thereby increasing vapor deposition efficiency. (Japanese Unexamined Patent Publication No. 57-155368), however, since a high-temperature portion is formed over a wide area in this device, there is a problem that radiant heat from this high-temperature portion heats other members in the device and has an adverse effect.

The present invention has been made in view of the above circumstances, and aims to improve the efficiency of vapor deposition of a magnetic material onto a support in an oblique incidence vacuum evaporation apparatus.

In the vacuum evaporation apparatus of the present invention, the molten metal of the evaporation source is placed directly below the beam irradiation position of the metal evaporation source that deposits a metal vapor flow onto a support such as a film base by heating by irradiation with an energy beam such as an electron beam. This is characterized by the provision of a member that partially reduces the depth and prevents the molten metal from flowing into the irradiation position.

When energy beam irradiation to the evaporation source is started by the vacuum evaporation apparatus of the present invention, only this beam irradiation position is intensely heated (heated), the evaporation source in this part evaporates, and the molten metal level in this part lowers.

On the other hand, the molten metal in the area adjacent to the beam irradiated area has a lower temperature than the molten metal in the beam irradiated area, and therefore has a relatively high viscosity. In addition, according to the apparatus of the present invention, the depth of the beam irradiated area is made shallow to increase the resistance when the molten metal flows into the beam irradiated area from the adjacent area. The molten metal does not easily flow into the beam irradiated area where the molten metal level has been lowered, and therefore the molten metal level in the irradiated area is lowered. Further, the energy beam scans the evaporation source in the width direction of the support, and the molten metal surface eventually becomes a concave surface having an axis in the width direction of the support. Thereby, the distribution of the vapor flow is concentrated toward the center of the curvature of the curved surface, and the efficiency of vapor deposition onto the support can be increased.

Note that when manufacturing a magnetic recording medium using the apparatus of the present invention, F is used as the ferromagnetic metal for forming the magnetic thin film.
Metals such as e, Co, Ni or Fe-Co, Fe-
Ni, Co-Ni, Fe-Co-Ni Fe
-R,h Fe-CIJ Co-Cu C
.

-Au Co -Y Co-La Co-Pr
Co-GdCo-8m, Co-PtNi
-Cu Mn-B1 Mn-8b, Mn-Al
, Fe-Cr, Co-Cr, Ni-Cr
, Fe-Co-Cr, Fe-Co-N
A ferromagnetic alloy such as i-Cr is used. The thickness of the magnetic film is generally about 0.02 μm to 5.0% m, preferably about 0.02 μm to 5.0% m, because it needs to be thick enough to provide sufficient output as a magnetic recording medium and thin enough to be sufficient for high-density recording. It is 0.05 μm to 2.0 pm.

Further, as the support, a plastic base such as polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate, or polyethylene naphthalate can be used.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side sectional view showing one embodiment of the present invention. For example, a long film base 1 for a magnetic tape is sent out and continuously sent from a roll 2 to a winding whirl 4 via a cooling can 3. For example, there is Co-Ni in the crucible 5.
An evaporation material 6 such as an alloy is stored, and this evaporation material 6 is heated by an electron beam 7 from above and becomes a vapor flow 8 which reaches the film base 1 on the cooling can 3 and is deposited on the film base 1. Forms a film. Additionally, a shield plate 9 is provided between the evaporation material 6 and the film base 1.
is provided to eliminate unnecessary steam flow 8'.

In this embodiment, a protrusion 10 extending from the bottom of the crucible 5 is disposed below the surface of the molten material 6 and directly below the irradiation position of the electron beam 7. FIG. 2 is a schematic diagram showing a crucible 5 in which the protrusion 10 is disposed at the bottom. The crucible 5 is made of ceramic and has a long shape in the width direction of the film base 1 (in the direction of arrow A). Further, the protrusion 10 is provided at the bottom of the crucible 5, and has a height such that the upper surface is located directly below the molten metal surface.
It has a square jft shape with a length approximately equal to the distance between both wall surfaces of the crucible 5 facing in the direction of arrow A.

The electron beam 7 scans the evaporation material 6 in the width direction of the film base 1 (in the direction of the arrow), thereby turning the evaporation material 6 into a molten state, and the beam irradiated area in particular is heated to the boiling point and spreads across the width of the film base 1. A steam flow 8 is generated extending in the direction (direction of arrow A). As a result, the evaporated material 6 in the portion irradiated with the electron beam 7 decreases, and the molten surface of the evaporated material 6 forms a recess. On the other hand, the molten metal in the area adjacent to the beam irradiated area has a higher viscosity than the molten metal in the beam irradiated area, and the protrusion 10 makes the depth of the beam irradiated area shallow (so that the molten metal flows from the adjacent area to this beam irradiated area). Since the resistance at the time of inflow is high, replenishment of the molten metal to the four parts of the beam irradiation area is delayed. Therefore, in a steady state where the amount of evaporation material is equal to the amount of replenishment, the electron beam 7 The molten metal surface in the irradiated area forms a concave surface.

The distribution of the vapor flow released from the molten metal surface into the vacuum is c
It is known that it is proportional to osθ·cosψ (θ is the angle between the vapor flow and the normal to the molten metal surface, and ψ is the angle between the vapor flow and the normal to the support).

For this reason, the vapor flow emitted from the concave surface has a distribution that is concentrated toward the center of the curvature of the concave surface.

By the way, in oblique incidence vacuum evaporation equipment, there is a close relationship between the angle of incidence on the support and the magnetic properties, especially the coercive force, and the coercive force of the magnetic film will be lowered if a component with a small angle of incidence is mixed in. A shield plate 9 blocks vapor flows 8' at angles of incidence other than the desired one. For this reason, the proportion of the metal evaporated stream evaporated from the crucible 5 that is effectively deposited on the support, that is, the deposition efficiency, is extremely reduced. By the way, according to the experiments of the present inventors, 80% cobalt,
A Co-Ni alloy containing 20% nickel was used as the evaporation material, a 15 μm thick polyester base film was used as the support, and the incident angle of the evaporation flow was controlled to 30° for evaporation, resulting in a magnetic layer thickness of 1500A. , coercive force 10500
e, B) The deposition efficiency when obtaining a magnetic thin film with an l curve squareness ratio of 0.93 was 5%.

However, in this example, the molten metal surface in the beam irradiation area is formed into a concave surface as described above, and the film base 1 is placed near the center of the curvature of this concave surface, so that the evaporation rate is significantly greater than in the past. Efficiency can be improved. According to an experiment conducted using this example under the same conditions as the experiment described above, it was possible to improve the vapor deposition efficiency to 9%. By the way, alloys mainly composed of cobalt (Co, Co-Ni, Co-Ni-C) suitable as magnetic recording materials
(r, etc.) are very expensive, the cost of the cobalt alloy accounts for a large proportion of the total cost of a magnetic recording medium, such as a vapor-deposited video tape.

However, according to this embodiment, the deposition efficiency can be greatly improved as described above, and therefore the cost of the entire magnetic recording medium can be significantly reduced.

FIG. 3 is a schematic diagram of a crucible showing another embodiment. The crucible 5a of this embodiment has a rectangular parallelepiped shape that is long in the width direction (direction of arrow B) of the film base 1, and is supported by both walls facing in the width direction (direction of arrow B) of the film base 1, and is directly below the beam irradiation position. The columnar member 10a is positioned within the surface of the molten metal. This embodiment also provides substantially the same effects as the embodiment shown in FIG. 2.

FIG. 4 is a schematic diagram showing a crucible used when the support is a disk. Protrusion 1 provided on the bottom of crucible 5b
0b has a cylindrical shape, and is arranged so that the circular upper surface of the protrusion 10b is located directly below the surface of the molten metal at the electron beam irradiation position. When electron beam irradiation is started using this embodiment, the molten metal surface of the irradiated portion becomes a bowl-shaped concave surface, and the metal vapor flow from here forms a distribution concentrated in the direction of the center of the curvature of this concave surface. This makes it possible to improve the efficiency of vapor deposition onto a disk centered near the center of this curvature. In addition,
In this case, since the disk is arranged at an angle with respect to the vapor flow, it is desirable to rotate the disk itself during the vapor deposition period to make the thickness of the vapor deposited film on the surface of the disk uniform.

The chamber (vacuum chamber) of this device is roughly pumped using a rotary pump, and once pumped using a booster pump, etc.
It is necessary to maintain the pressure at about 0-4 to 10-5 Torr.

As explained in detail above, the vacuum evaporation apparatus of the present invention is provided with a member directly below the beam irradiation position of the metal evaporation source to reduce the depth of the molten metal and prevent the molten metal from flowing into this irradiation area. As a result, the molten metal surface in the beam irradiation portion is made concave so that the metal vapor flow is concentrated in the direction of the support, so that the efficiency of metal vapor deposition onto the support surface can be improved. Furthermore, by improving the deposition efficiency, the cost of the entire magnetic recording medium can be significantly reduced, and the practical value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG. 2 is a schematic diagram showing one embodiment of the present invention.
FIGS. 3 and 4 are enlarged views showing the crucible in the figure, and schematic views showing other embodiments of the crucible. ■...Support (film base) 3...Cooling can 5 5a...Rutsu boro...Evaporation source 7...Electron beam 8...Metal vapor flow 10...Protrusion 10a. ...Column member 15 = ! 43-

Claims (4)

[Claims] (1) In a vacuum evaporation apparatus that forms a magnetic metal thin film by depositing a metal vapor flow obtained by heating an evaporation source with an energy beam under reduced pressure on the surface of a non-magnetic support, the beam of the metal evaporation source A vacuum evaporation apparatus characterized in that a member is provided directly below the irradiation position of the evaporation source to partially reduce the depth of the molten metal. (2) the member is provided at the bottom of the evaporation source container;
2. The vacuum evaporation apparatus according to claim 1, wherein the protrusion has an upper surface and extends uniformly in the width direction of the support. (3) The vacuum evaporation apparatus according to claim 1, wherein the member is a columnar member supported by both widthwise opposite walls of the support body of the evaporation source container. (4) The vacuum evaporation apparatus according to claim 1, wherein the member is a projection provided at the bottom of the evaporation source container and having a substantially circular upper surface.