JP2001236641A - Vapor deposition device for thin film magnetic tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the yield of a product and the utilization efficiency of a vapor deposition material when a metal magnetic thin film is formed on a base film. SOLUTION: A vapor deposition device 1B for thin film magnetic tape wherein the belt-like base film 8 runs along the peripheral surface of a cooling can roll 7 in a vacuum vessel 2 and a metal magnetic material 10 melted in a crucible 9B provided along the direction of the width of the base film 8 below the cooling can roll 7 is vaporized from the opening part of the crucible 9B to form the metal magnetic thin film on one surface of the base film 8 is characterized in that the width of the opening part of the crucible 9B is formed so that a nearly central part in the longitudinal direction, which corresponds to a nearly central part in the direction of the width of the base film 9, is narrow and further formed gradually widely towards both ends from the nearly central part in the longitudinal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor deposition apparatus for a thin film magnetic tape to which an oblique vapor deposition method is applied, and more particularly to a shape of an opening of a crucible.

[0002]

2. Description of the Related Art In recent years, thin-film magnetic tapes, perpendicular magnetic tapes, and the like have attracted attention as magnetic tapes applied to digital video tape recorders and the like in order to achieve high density and thin film.

FIG. 5 is a structural view showing the structure of a general thin film magnetic tape vapor deposition apparatus to which the oblique vapor deposition method is applied, and FIG. 6 shows the vicinity of a cooling can roll in a general thin film magnetic tape vapor deposition apparatus. FIGS. 7A to 7C are a perspective view, a plan view, and a vertical cross-sectional view for explaining the shape of the opening of the crucible installed in a general thin film magnetic tape evaporation apparatus.

As shown in FIG. 5, a vacuum chamber 2 of a general thin film magnetic tape vapor deposition apparatus 1A to which the oblique vapor deposition method is applied is kept in a vacuum state. In this vacuum chamber 2, a supply roll 3, a take-up roll 4, guide rolls 5, 6, and a cooling can roll 7 are rotatably arranged.

[0005] Then, in the vacuum chamber 2, the strip-shaped base film 8 wound around the supply roll 3 is moved along the guide roll 5 on the supply side, the peripheral surface of the cooling can roll 7, and the guide roll 6 on the winding side. It is running in the direction of the arrow toward the winding roll 4.

Here, the base film 8 is made of a polyethylene terephthalate (PET) film or the like. The metal magnetic material 1 which has been set and is evaporated from a crucible 9A, which will be described later, installed below the cooling can roll 7 on one surface of the base film 8
Generally, a method of performing one-roll evaporation in which 0 is continuously performed is adopted.

That is, a crucible 9A formed in a box shape using MgO (magnesia) as a crucible material is installed diagonally below the cooling can roll 7. A ferromagnetic material (hereinafter, referred to as a metal magnetic material) 10 such as Co or CoNi is accommodated in the crucible 9A.

A crucible 9 is provided on the side wall 2a of the vacuum chamber 2.
A pierce-type electron gun 11 for melting the metal magnetic material 10 accommodated in A and evaporating the molten metal magnetic material 10 from the opening of the crucible 9A is attached. The pierce-type electron gun 11 is provided with a metal magnetic material 1 in a crucible 9A.
The electron beam 12 is emitted toward 0, and the metal magnetic material 10 is melted and evaporated on one surface side of the base film 8.

An incident angle regulating mask member 13 is mounted along the lower portion of the cooling can roll 7 so as to face the crucible 9A side.
The metal magnetic material 10 deposited from the crucible 9A when the base film 8 runs along the cooling can roll 7
The maximum incident angle θmax and the minimum incident angle θmin with respect to the base film 8 are regulated.

An oxygen gas introduction pipe 14 is mounted along the lower part of the cooling can roll 7 and inside the incident angle regulating mask member 13 on the side of the minimum incident angle θmin. The oxygen gas introduced into the oxygen gas introduction pipe 14 is blown out toward the evaporated metal magnetic material 10 from the plurality of oxygen gas blowing fine holes formed in the width direction of the base film 8. The mainstream is to oxidize the metal magnetic material 10 evaporated by the gas to ensure the improvement of the magnetostatic property and the reliability (durability and corrosion resistance) of the metal magnetic thin film described later.

The electron beam 12 emitted from the pierce-type electron gun 11 is controlled by a deflection magnet 15 for applying a deflection magnetic field to the orbit and a deflection magnet 16 provided near the crucible 9A. . Accordingly, the electron beam 12 is scanned in the longitudinal direction of the crucible 9A, thereby being scanned in the width direction of the base film 8, and the evaporated metal magnetic material 10 such as Co or CoNi is deposited in the width direction of the base film 8 such as CoO or CoNiO. By repeating this in the length direction of the base film 8, a long thin film magnetic tape is wound up on the take-up roll 4 side.

Here, when the metal magnetic material 10 evaporated from the crucible 9A is formed as a metal magnetic thin film on the base film 8, in consideration of heat resistance to the base film 8, as shown in FIG. A cooler (not shown) is installed inside the cooling can roll 7 rotating in the direction of the arrow, and suppresses deformation and the like of the base film 8 due to a rise in temperature during vapor deposition. In such an oblique deposition method, the edge portion of the base film 8 is provided with an incident angle regulating mask member so that the metal magnetic material 10 from the crucible 9A does not adhere to the peripheral surface of the cooled rotatable cooling can roll 7. The opening dimension of the incident angle regulating mask member 13 in the width direction is set to be smaller than the width dimension of the base film 8.

As shown in FIGS. 6 and 7, the shape of the opening of the crucible 9A is set to a length L slightly longer than the width B of the base film 8 along the width direction of the base film 8. The direction perpendicular to the length direction is set to a constant width W, and the opening of the crucible 9A is L ×
W is formed in a rectangular shape.

[0014]

By using a general thin film magnetic tape evaporation apparatus 1A to which the oblique evaporation method is applied, a metal magnetic material 10 such as Co or CoNi evaporated from a crucible 9A is used as a base film 8. When a metal magnetic thin film is formed thereon, the mask opening of the incident angle restricting mask member 13 is considerably narrow as described above, so that the evaporated metal magnetic material (evaporated metal magnetic material) 1 is used.
The utilization efficiency of No. 0 was about 10 to 15%, and most of the remaining parts were unnecessary deposits. For this reason, it is necessary to further improve the magnetostatic properties in order to widen the mask opening of the incident angle regulating mask member 13 to the minimum incident angle side even slightly and to improve the utilization efficiency of the evaporated metal magnetic material.

Further, in the oblique deposition method, the incident angle of the evaporated flying particles on one surface of the base film 8 largely determines various characteristics. In particular, the dispersion and distribution of the incident angle of the initial growth layer of the metal magnetic thin film. Has had a great influence on the characteristic distribution of the metal magnetic thin film in the width direction of the base film 8. In particular, since the shape of the opening of the crucible 9A is formed so that the width dimension perpendicular to the length direction with respect to the width direction of the base film 8 is a constant width W, the electron beam 12 is supplied to the crucible 9A.
When scanning along the length direction of the crucible 9A, the incident angle of the evaporative flying particles evaporated at this end at the end in the length direction of the crucible 9A is aligned in a substantially constant direction. At the substantially central portion, there are problems such that the evaporative flying particles evaporated from this portion and the evaporative flying particles evaporating from both ends are mixed, and the incident angle of the evaporative flying particles is not aligned in a substantially constant direction. For this reason, after the metal magnetic thin film is formed, the yield of non-defective thin film magnetic tape is poor, and
In order to ensure safety in quality, it is necessary to manufacture thicker films in consideration of the distribution and variation of magnetostatic characteristics, leading to an increase in manufacturing costs due to a further decrease in the use efficiency of the deposited metal magnetic material. Was.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a belt-shaped base film running along the peripheral surface of a cooling can roll in a vacuum chamber;
A metal magnetic material melted in a crucible installed along the width direction of the base film below the cooling can roll is evaporated from an opening of the crucible, and a metal magnetic thin film is formed on one surface of the base film. In the vapor deposition device for a thin film magnetic tape for forming a film, the opening of the crucible is formed such that a substantially central portion in a length direction corresponding to a substantially central portion in a width direction of the base film is formed to be narrow, and the longitudinal direction is reduced. The present invention provides a thin film magnetic tape vapor deposition apparatus characterized in that the width is gradually increased from substantially the center to both ends.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a thin film magnetic tape vapor deposition apparatus according to the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a perspective view showing the vicinity of a cooling can roll in a thin film magnetic tape vapor deposition apparatus according to the present invention.
(A) to (c) are perspective views, plan views, and vertical cross-sectional views for explaining the shape of the opening of the crucible installed in the thin film magnetic tape vapor deposition apparatus according to the present invention, and FIG. FIG. 4 is a view showing the relationship between the width dimension and the magnetostatic property, and FIG. 4 is a view showing the magnetostatic property distribution in the width direction of the film base (base film).

For convenience of explanation, components having the same functions as the components described in the prior art are denoted by the same reference numerals and will be described as appropriate, and new components will be assigned to components different from those in the conventional example. In addition, this embodiment will be described focusing on points different from the conventional example.

As shown in FIG. 1, in the thin film magnetic tape evaporation apparatus 1B according to the present invention, a metal magnetic thin film is formed on one surface of the base film 8 in the vacuum chamber 2 by applying an oblique evaporation method. At this time, a newly developed crucible 9B is replaced with a crucible 9B instead of the crucible 9A installed in the vacuum chamber 2 of the general thin film magnetic tape vapor deposition apparatus 1A described above with reference to FIGS. 7 is characterized by being installed diagonally below.

Here, the shape of the newly developed crucible 9B is shown in an enlarged manner in FIG. 2A, and the opening of the crucible 9B for evaporating the molten metal magnetic material 10 is formed on the base film 8 ( A substantially central portion in the length direction corresponding to a substantially central portion in the width direction of FIG. 1) is formed to be narrow, and is gradually widened from the substantially central portion in the length direction to both end portions. That is, the length L of the opening of the crucible 9B is set slightly longer than the width B (FIG. 1) of the base film 8, and the width Wc of the substantially central portion in the length direction of the opening is narrow. The width W is gradually increased from the substantially central portion to both ends, and the width W of both ends is formed to be the same as the conventional example.

The outline of the vapor deposition device 1B for a thin film magnetic tape will be described. The diameter of the cooling can roll 7 is 1000 mm, the width of the cooling can roll 7 is 600 mm, and
The width of the base film 8 is 560 mm,
The ferromagnetic material (pure Co) in the crucible 9B was melted in a film width of 500 mm, and a 90 ° deflection piercing electron gun 11 (FIG. 5) having an output of 300 kW was used for vapor deposition. The incident angle regulating mask member 13 is made of stainless steel having a thickness of 15 mm and surrounds the outer periphery of the film forming area. In addition, a deflecting magnet 16 (FIG. 5) necessary for proper incidence of the electron beam was provided near the crucible 9B. Further, a feeder (not shown) was provided so that a constant amount of ferromagnetic material (pure Co) was continuously supplied from one end of the crucible 9B. The following experiment was performed using this apparatus 1B.

[Experiment] As shown in FIGS. 2 (b) and 2 (c), the length of the opening of the crucible 9B: L is 700 mm, the width of both ends of the crucible 9B: W is 140 mm, and the crucible 9B
Approximately central portion width: Seven types of crucibles in which Wc is varied in size from 30 mm to 120 mm, which is estimated to be a limit in consideration of the electron beam diameter φ10 mm, and gradually narrows from both ends toward the approximate central portion. 9B was prepared.

On the other hand, as shown in FIGS. 7B and 7C,
For comparison, a conventional crucible 9A was prepared, and the width Wc at the substantially central portion of the crucible 9A was set to 140 mm, which is the same as the width W at both ends of the crucible 9A.

By using the above seven types of crucibles 9B and a conventional crucible 9A, Co was melted in the crucibles 9B and 9A.
(Metallic magnetic material) is evaporated from the opening, and the processing length of 5000 m is controlled by controlling the CoO film to a thickness of 0.2 μm with a transmission type film thickness monitor at an oxygen gas introduction amount of 1800 ccm from the minimum incident angle side. Each film was formed.

Then, the above-mentioned seven types of crucibles 9B and a conventional crucible 9A were used to form films of 5000 m each.
Sampled from the roll, and a part of the CoO film was etched with dilute nitric acid.
It was confirmed that the thickness was 2 μm.

Thereafter, the magnetostatic properties of the remaining unetched portions of each sample were measured by a vibrating magnetometer (VSM). The result is shown in FIG. Hc is the coercive force, M
s indicates the saturation magnetization, and Rs indicates the squareness ratio.

As is clear from FIG. 3, when the width Wc of the central portion of the crucible is 140 mm, the characteristic corresponds to the shape of the crucible 9A of the conventional example, and when the width Wc of the central portion of the crucible is reduced. This is a characteristic according to the invention. Here, when the width Wc of the central portion of the crucible: Wc is 80 mm or less, the coercive force Hc is improved, and the squareness ratio Rs shows a good value, in spite of no change in the saturation magnetization Ms.

This is because, as the width becomes narrower as it approaches the central portion of the crucible, the dispersion of the incident angle of the vaporized flying particles to the base film 8 becomes small, and the incident angle becomes uniform even in the substantially central portion. In particular, it is considered that a remarkable effect is obtained by setting the width of the central portion of the crucible to 80 mm or less, and that a good initial growth layer and grain growth of the CoO film are formed.

FIG. 4 shows a part of the result of measuring the distribution of magnetostatic properties of the same sample in the width direction of the film base material (base film) by VSM. In FIG. 4, in the conventional crucible 9A in which the width Wc at the center of the crucible is set to 140 mm, the coercive force Hc and the squareness ratio Rs drop sharply at the approximate center, whereas the width W at the center of the crucible is W.
It was found that a good magnetostatic property distribution was exhibited when c was narrowed to 80 mm or less.

[0031]

According to the vapor deposition apparatus for a thin-film magnetic tape according to the present invention described in detail above, the opening of the crucible particularly has a substantially central portion in the length direction corresponding to a substantially central portion in the width direction of the base film. Is formed to be narrow and gradually wide from substantially the center to both ends in the longitudinal direction, so that the metal magnetic thin film can be formed well on one surface of the base film, and the metal magnetic thin film can be formed. Can be improved, and the distribution of the magnetostatic property in the width direction of the film substrate (base film) can be greatly improved. As a result, the yield of the thin film magnetic tape and the utilization efficiency of the evaporated magnetic metal material can be improved, and the thin film magnetic tape can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the vicinity of a cooling can roll in a thin film magnetic tape vapor deposition apparatus according to the present invention.

2 (a) to 2 (c) are a perspective view, a plan view, and a longitudinal sectional view for explaining the shape of an opening of a crucible installed in the vapor deposition apparatus for a thin film magnetic tape according to the present invention.

FIG. 3 is a diagram showing a relationship between a width dimension of a crucible center portion and magnetostatic characteristics.

FIG. 4 is a diagram showing a distribution of magnetostatic characteristics in a width direction of a film base (base film).

FIG. 5 is a configuration diagram showing a configuration of a general thin film magnetic tape evaporation apparatus to which an oblique evaporation method is applied.

FIG. 6 is a perspective view showing the vicinity of a cooling can roll in a general thin film magnetic tape evaporation apparatus.

FIGS. 7A to 7C are a perspective view, a plan view, and a vertical sectional view for explaining the shape of an opening of a crucible installed in a general thin-film magnetic tape vapor deposition apparatus.

[Explanation of symbols]

1B: Vapor deposition device for thin-film magnetic tape according to the present invention, 2: vacuum tank, 7: cooling can roll, 8: base film, 9
B: Crucible, 10: Metal magnetic material, 11: Pierce type electron gun, 12: Electron beam, 13: Incident angle regulating mask member.

Claims (1)

[Claims] 1. A belt-shaped base film is run along a peripheral surface of a cooling can roll in a vacuum chamber, and is melted in a crucible provided along the width direction of the base film below the cooling can roll. The metal magnetic material is evaporated from the opening of the crucible, a thin film magnetic tape vapor deposition apparatus for forming a metal magnetic thin film on one surface of the base film, the opening of the crucible, the opening of the base film A thin film magnet, wherein a substantially central portion in the length direction corresponding to the substantially central portion in the width direction is formed to be narrow, and the width is gradually increased from the substantially central portion in the length direction to both end portions. Vapor deposition equipment for tape.