JPS6018912A - Thin film formation by vacuum evaporation - Google Patents

Abstract

PURPOSE:To make the width of a slot of a mask to be made large some extent and improve vertical magnetic characteristics by fixing an incident angle of an evaporation stream against a supporting material surface within a predetermined narrow range. CONSTITUTION:A high polymer film as a supporting material 1 is paid off from one roller 3 and laid along a cooling drum 2 and taken up by another roller 4. A mask 5 is provided between the drum 2 and a crucible 6 and a slit 7 is opened in the mask 5 on a center line Z connecting the center of the drum 2 and the center of the crucible 6. A deposition material S is contained in the crucible 6 and the material S is irradiated by an electron beam EB. The material S is heated and evaporated by the irradiation and incides against the surface of the supporting material 1 through the slit 7. The irradiation point of the electron beam EB is scanned along the width direction of the supporting material 1 only and at the same time the crucible 6 is moved along the running direction of the supporting material 12 while the deposition is carried out and the vertical magnetic characteristics of the supporting material 1 is improved.

Description

Detailed Description of the Invention The present invention relates to a method of forming a thin film on the surface of a base material by vacuum evaporation. The present invention relates to a method of forming a perpendicularly magnetized film, its base film, etc. by vertically injecting a magnetic metal or other vapor deposition material onto the surface of a substrate such as a molecular film and performing vacuum vapor deposition.

2. Description of the Related Art As magnetic recording bodies such as magnetic tapes are increasingly used as recording media in fields such as image processing and information processing, various magnetic recording methods are being developed and put into practical use. Under these circumstances, in recent years, perpendicular magnetic recording has attracted attention as a high-density magnetic recording method.
Technological improvements are being made from various directions.

Currently used perpendicular magnetic recording media are produced by sputtering or vacuum deposition directly onto the surface of a base material made of non-magnetic material such as a polymer film, or by forming a thin film (base film) of high magnetic permeability material such as permalloy. The main type is a thin film (magnetized film) of a magnetic metal whose main components are CO and Cr adhered to each other through a film. Among these, the sputtering method has low productivity and has some problems in industrial mass production, but the other vacuum evaporation method has excellent productivity and is promising as a method suitable for industrial production. being watched.

When producing a perpendicular magnetic recording medium using the vacuum evaporation method, C
In order to improve the axial orientation, it is necessary to make the evaporation airflow of the evaporation material perpendicular to the surface of the base material. However, when regulating the incident angle of the evaporation air flow in the vacuum evaporation method, it is necessary to use a slit (irradiation window) with a certain width opened in the mask.
Therefore, the angle of incidence of the evaporation air flow has a width that can actually be achieved with the component that is incident perpendicularly to the surface of the base material as the center.

In addition, the vapor-deposited material is heated and evaporated by irradiating it with an electron beam. In this case, a uniform magnetized film or base film is formed on the surface of the base material, and at the same time, the vapor-deposited material in the crucible is uniformly evaporated. The electron beam is irradiated while sweeping the surface of the evaporation material so as to evaporate the material without any evaporation. However, if the irradiation point of the electron beam is moved relative to the slit along with this sweep, the emission point of the evaporated air stream also moves, and the range of the angle of incidence on the surface of the metal base material also changes. .

As is well known, there is a close relationship between the C-axis orientation and the incident angle of the vapor-deposited material onto the surface of the substrate, and the perpendicular magnetic properties of the magnetic recording medium are greatly influenced by the C-axis orientation. Therefore, in order to improve the perpendicular magnetic properties, the width of the incident angle of the evaporative air flow must be kept within an allowable range.

To explain this problem in more detail with reference to FIG. 1, an example is shown in which a magnetic tape is manufactured as a magnetic recording medium.

A tape-shaped polymer film serving as the base material 1 is applied to the cooling drum 2 from one roller 3 and then wound onto the other roller 4. Between the cooling drum 2 and the crucible 6,
There is a mask 5 in which a slit 7 is formed on a center line Z connecting the centers of the cooling drum 2 and the crucible 6. An electron beam E is applied to the vapor deposition material S stored in the crucible 6.
B is irradiated, and an evaporation airflow of the same material S, which is heated and evaporated thereby, passes through the slit 7 and enters the surface of the base material 1.

At this point, the distance from the center of the cooling drum 2 to the surface of the vapor deposition material S is set to 2. The radius of drum 2 is R.

Assuming that the width of the slit 7 is d on the left and right sides of the figure from the center line Z, the maximum incident angle θm of the evaporation air flow that enters the surface of the base material 1 can be approximately determined by the following equation.

θm #(d/R), XZ/(zR)
That is, in this case, it is shown that the incident angle exists in a width of ±θm with O as the center.

However, due to the sweep of the electron beam EB, its irradiation point moves left and right in the figure around the center line Z, and due to the accompanying movement of the emission point of the evaporation air flow, the maximum incident angle actually changes by Δθ. As a result, the evaporation air flow includes an incident angle component in the range of ±(θ4.+Δθ) with respect to the surface of the base material 1.

Now, if the maximum movement distance of the irradiation point from the center line Z due to the movement of the irradiation point is X to the left and right in the figure, then the maximum incident angle θ17 when the irradiation point is farthest from the center line Z is
The increment Δθ of 1 becomes Δθ#x/ (z−R); as is clear from this formula, the above increment Δθ is
It becomes larger as X becomes larger and (z-R) becomes smaller. In other words, the movement width 2x of the irradiation point of the electron beam EB is small,
Distance from vapor deposition material S to cooling drum 2 (z-R'),
That is, as the distance from the vapor deposition material S to the base material 1 increases, the above Δθ
can be made smaller.

However, reducing the moving width 2x of the irradiation point means reducing the volume of the crucible 6, and increasing the distance from the evaporation material S to the base material 1 means that the magnetic recording body manufacturing apparatus Both of these include disadvantageous conditions in terms of manufacturing. In particular, in a range where the maximum incident angle θm is small, the vapor deposition efficiency η is inversely proportional to the distance (z-R), so increasing the distance between the cooling drum 2 and the ejection point of the evaporative air flow increases the vapor deposition efficiency η. This causes a decrease in the amount of water.

These problems exist not only in the formation of a perpendicularly magnetized film as described above, but also in all cases where it is necessary to make the vapor deposition material perpendicular to the surface of the base material 1. For example, when manufacturing a perpendicular magnetic recording material, when forming a magnetized film on the surface of the base material 1 via a base film such as permalonite Ti, when forming the base film, the evaporation air flow of the above material is directed to the surface of the base material. It is necessary to make the deposition perpendicular to the incident light, and therefore this case also involves the same problems as above.

This invention was made to solve the above-mentioned problems when forming a perpendicularly magnetized film, its base film, etc. by vacuum evaporation, and fixes the irradiation point of the electron beam EB in the running direction of the base material 1. As a result, the maximum incident angle θTll is fixed, suppressed within an allowable range for the performance of the magnetic recording medium, and the deposition efficiency η is improved. Hereinafter, the configuration of the present invention will be explained in detail together with its embodiments.

In the method according to the present invention, the irradiation point of the electron beam EB is
The crucible 6 is swept only in the width direction of the electron beam EB.
Vapor deposition is performed while moving in the running direction of the base material 1 with respect to the irradiation point. That is, while moving the irradiation point of the electron beam EB in the width direction of the base material 1, the position is absolutely fixed in the running direction of the device 1, whereas the crucible 6, that is, the vapor deposition material S side This is to move the relative. For this reason,
The emission point of the evaporation air flow emitted from the vapor deposition material S by irradiation with the electron beam EB (the same position as the irradiation point of the electron beam EB) is located in the traveling direction of the base material 1 with respect to the base material 1 and the mask 5. It does not move, and the maximum incident angle θm of the evaporation air flow is always fixed at a constant angle.

From this, compared to the conventional case, the increase Δ in the maximum incident angle θm caused by the sweeping irradiation of the electron beam EB
The maximum incident angle θm can be reduced by θ. In other words, as long as the maximum incident angle θ is kept to the same angle as in the conventional case, the width of the slit 7 can be made wider. Now, suppose that the width of the slit 7 can be increased by Δd, and the width of the slit 7 is d'=d+Δ
If d, then Δd=x(R/Z), so d'-d+x(R/z).

Here, since the vapor deposition efficiency η is proportional to the width d of the slit 7, if the vapor deposition efficiency when the width of the slit 7 is d and d' are respectively η and η', the ratio is as follows. It is determined by the formula.

η'/η-1+ (x/d) (R/z) In this case, (
Since x/d) is the shield 1 and (R/z) is about 1/2, the vapor deposition efficiency can be improved by about 50% by setting the width of the slit 7 to d'.

Next, the results of tests conducted to confirm the above theoretical effects will be described below as Examples 1 and 2.

(Example 1) An alloy consisting of 75wt% Co and 25wt% Cr is vacuum-deposited onto a polyethylene terephthalate tape with a thickness of 10μ5 and a width of 150m+a through a mask that regulates the incident angle in the vertical direction. . In this case, the crucible containing the vapor deposition material is placed 40 m in the running direction of the tape.
Vapor deposition was performed while moving between ±40 widths at a speed of m/sec. In addition, other conditions are as follows.

Cooling drum radius = 250 Tape running speed: 2 to 10 m/min Distance from vapor deposition material to cooling drum: 500 mm Vapor deposition atmosphere: 5
X 10' Torr Electron beam irradiation point diameter: 3 For comparison, as Comparative Example 1, the crucible side was fixed under the same vapor deposition conditions as above, and the electron beam was oriented ± in the tape running direction.
Vapor deposition was performed while sweeping irradiation with a width of 40 mm at a speed of 49 wm/sec.

For each of these cases, the horizontal axis is the maximum incident angle θm of the evaporated air flow with respect to the tape surface regulated by the mask, and the C-axis orientation is shown when the thickness of the evaporated film is 3,000 mm ( FIG. 2 is a chart showing these relationships, with the vertical axis representing the half-width Δθ5o of the rocking curve for the 002) surface. Further, in this chart, the relationship between the maximum incident angle θm and the vapor deposition efficiency η is shown by a dotted line.

As is clear from this result, in Example 1, when the half-value width Δθ5o of the rocking curve of the deposited film is 10°, the deposition efficiency η is 26%, whereas in Comparative Example 1, this is 19.5%. It can be seen that the former is superior to the latter.

(Example 2) An alloy consisting of 70wt% Co and 30wt% Ni was placed on a tape made of polyethylene telecrate with a thickness of 10 μm and a width of 150 mm, and the incident angle was regulated in the vertical direction while introducing oxygen gas. When performing vacuum deposition through a mask, the deposition was performed while moving the crucible in the running direction of the tape at the same width and speed as in the above example. The vapor deposition conditions in this case are the same as in Example 1 above.

On the other hand, for comparison, vapor deposition was carried out under the same conditions as in Comparative Example 1, with the crucible side fixed and the electron beam being swept in the running direction of the tape, and this was designated as Comparative Example 2.

As in the case of Example 1, FIG. 3 shows the relationship between the maximum incident angle θm and the half-width Δθ5o of the rocking curve of the deposited film as a graph together with Comparative Example 2. In this case as well, it can be understood that the same thing as in 1. Example 1 can be understood.

As described above, according to the present invention, when a thin film such as a magnetized film is formed on the surface of a substrate such as a polymer film by vacuum evaporation, the incident angle of the evaporation air flow with respect to the surface of the substrate is determined. Since it can be fixed within a narrow range, it is possible to manufacture a magnetic recording medium with generally excellent perpendicular magnetic properties. Further, when the incident angle of the evaporation air flow is suppressed within a certain range, the width of the slit in the mask can be widened to a certain degree, so that the vapor deposition efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the method according to the present invention, and FIGS. 2 and 3 show the relationship between the maximum incident angle of the evaporation air flow and the half-width of the rocking curve of the deposited film in the example, respectively, together with a comparative example. This is the diagram shown. 1 - Base material 5 - Mask 6 - Crucible EB - Electron beam S... Vapor deposition material Patent applicant Taiyo Yuden Co., Ltd. Same as above Eiko Engineering Co., Ltd. Representative patent attorney Kazuyoshi Hojo $ 1 Figure 82 Figure Δeso') 3rd Continuing from Figure 1st page ■Applicant Eiko Engineering Co., Ltd. 4254 Senzoku, Sakamon-cho, Mito City

Claims (1)

[Claims] 1. By irradiating an electron beam, a deposition material such as a magnetic metal is heated and evaporated in a vacuum state, and the evaporation air flow is passed in a fixed direction through a mask for regulating the incident angle onto the surface of a base material such as a polymer film. In a thin film formation method using vacuum evaporation, in which the electron beam is incident perpendicularly on the same surface and is adhered to the same surface to form a thin film such as a perpendicularly magnetized film or its base film, the irradiation point of the electron beam is set to the width of the substrate. A method for forming a thin film by vacuum evaporation, characterized in that the evaporation is performed while the crucible containing the evaporation material is moved in the traveling direction of the substrate.