JPH01275747A - Manufacture of thin metallic film - Google Patents

Abstract

PURPOSE:To manufacture a thin metallic film having high ratio of low vapor pressure components with a uniform compsn. over a long length by supplying a vapor-depositing material contg. low high vapor pressure components and a vapor-depositing material contg. high vapor pressure components higher than that while they are selectively heated to melt. CONSTITUTION:In a vacuum cell, molten metal 15 in a crucible 14 is heated to evaporate by the primary source 16 of an electron beam and is vapor-deposited onto a polymeric film substrate 11 running on the circumference of a can 12 to manufacture a thin metallic film. In the above manufacture, a primary vapor-depositing material 18 having the lower ratio of high vapor pressure components such as Cr than that in the compsn. of the desired film and a secondary vapor-depositing material 19 having the higher ratio of the high vapor pressure components than the above are supplied into the crucible 14 while they are heated to melt by the secondary source 22 of an electron beam. At this time, by the regulation of a monitor 23 for evaporating composition, an electron beam from the above secondary source 22 of an electron beam is deflected to selectively heat the vapor depositing materials 18 and 19. By this method, the compsn. of the molten metal 15 is regulated to stably form the thin film contg. the uniform compsn. having high ratio of low vapor pressure components such as Co and having low ratio of high vapor pressure components such as Cr over a long length.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a manufacturing method for stably forming a metal thin film by vacuum evaporation. The present invention relates to a method for manufacturing perpendicular magnetic recording media, which have an important effect on functions, such as perpendicular magnetic recording media with excellent high-density recording characteristics.

2. Description of the Related Art Vacuum deposition is generally used as a method for forming thin films over large areas and for mass production because of its high deposition rate, and is also suitable as a method for manufacturing, for example, metal thin film magnetic recording media. As metal thin film media, it has been found that Co-based magnetic thin film media, particularly Co--Cr media, are most suitable as perpendicular magnetization media with excellent short wavelength recording characteristics. Co-Cr media has excellent magnetic properties when the wt% of Co and Cr in the media film is about 80:20. It is necessary to control the composition in the evaporation crucible so as to maintain the concentration ratio in the evaporation crucible. Co and Cr metals are generally high melting point materials;
In the case of vapor deposition, electron beam heating is generally used as the melting and evaporation means, examples of which are shown in FIGS. 2 and 3. Figure 3 shows a method using a single crucible evaporation source, in which a Co-Cr alloy, in this case an alloy with a high Co content, is loaded in advance into a crucible 1 and heated and melted with an electron beam 2. . At this time, the alloy in crucible 1 is
Because the vapor pressure difference is large, the Cr component with high vapor pressure evaporates first, and the Cr concentration in the film becomes as shown in Figure 4.
For example, even if the initial alloy ratio is Co93:Cr7, the Cr concentration is high at the initial stage of deposition, and as the deposition time progresses, the Cr concentration in the film increases.
The r concentration gradually decreases. Therefore, in FIG. 3, the composition is controlled while replenishing the Cr grains 3.

Fig. 3 is a diagram showing a conventional method using a binary evaporation source of Co and Cr, in which Co and α are evaporated in separate crucibles 4. It is deposited on a polymer film substrate 7. At this time, 8 is an adhesion prevention plate, 9 is an unwinding roller, and 1o is a winding roller 2. In FIG. 2, as in FIG. 3, the adhesion prevention plate 8. A can 6° unwinding row 291 and a winding roller 1o are provided to continuously form a thin film.

When forming a film using such a vacuum evaporation method, the magnetic recording medium is constructed on a polymer film, and recording and reproduction are performed by contacting the magnetic head, so the smoothness of the medium, especially the spacing between it and the head is important. It is necessary that there are no foreign substances that could cause loss, or that the magnetic properties are maintained over a long length, and the length must be commensurate with the production scale. be done. However, the method shown in FIG. 2 has the following problems. That is, in this method, Or, which has a high vapor pressure, is in a metallic state when the Cr concentration is high and it is difficult to make it into a wire, and therefore it is replenished as metal particles.

At this time, since the Cr metal is sublimable, it cannot be supplied to the crucible 1 by heating and melting it, and therefore it is supplied in the form of granules as shown in the original country. However, in this case, since the Cr grains are granular, they tend to adsorb various non-condensable gases, and if they are supplied into the molten metal in that state, a so-called bumping phenomenon occurs, causing molten metal with a relatively large diameter to form in the deposited film. Foreign matter with the same composition occurs,
Contact with the magnetic head has caused serious problems such as recording loss. In addition, in the conventional example shown in FIG. 2, there is a method to cope with long lengths without supplying Co material, but this method basically has the above-mentioned problems.

On the other hand, the method shown in FIG. 3 basically does not have the problem of foreign matter generation as shown in FIG. 2, but it does have the following problems. That is, the advantage of manufacturing such a magnetic recording medium by the vacuum deposition method is that it can be mass-produced at high speed, and the deposition rate is about several thousand people/sec.

In the case of such a high evaporation rate, the composition control is not successful in the binary evaporation method, which means that the evaporated particles of both types become unevenly mixed, and the evaporated particles become uneven on the upstream and downstream sides of the film substrate, that is, in the film thickness direction. There was a problem in that concentration non-uniformity occurred and characteristics could not be ensured.

Problems to be Solved by the Invention When forming an alloy thin film with such a large vapor pressure difference, it is necessary to control the composition on the evaporation source side, for example by replenishing a metal component with a high vapor pressure, or by binary evaporation. There are methods to control the composition at each source, but there are problems such as bumping phenomenon occurring during replenishment, nonuniform film composition over a long length, and composition unevenness in the film thickness direction. .

Means for Solving the Problem When forming an alloy thin film in which the proportion of metals with low vapor pressure is large and the proportion of metals with high vapor pressure is small, the evaporation crucible is heated by a first electron beam. , a first vapor-deposited material whose proportion is lower than the proportion of high vapor pressure components in the desired film composition by the second electron beam, and a second vapor-deposited material in which the proportion of components whose vapor pressure is higher than that of the first vapor-deposited material is increased. The evaporation materials No. 2 and 2 are selectively heated and melted and fed together to the evaporation furnace.

Action: Depending on the evaporation composition from the evaporation crucible, a evaporation material with a lower proportion of high vapor pressure components than the proportion of high vapor pressure components in the desired film composition and a evaporation material with a higher proportion of components with higher vapor pressure than that of the desired film composition are selectively selected. By heating and melting it and feeding it into the crucible,
The film composition of the alloy thin film is made uniform over a long length, and the bumping phenomenon is prevented by supplying the melt to the crucible in a molten state.

Embodiment FIG. 1 shows the internal structure of a vacuum evaporation apparatus embodying a manufacturing method according to an embodiment of the present invention.

In the figure, 11 is a long and wide polymer film substrate, which forms an alloy thin film under the rotating cylindrical can 12 while traveling along the periphery of the cylindrical can. Reference numeral 13 denotes an adhesion prevention plate and mask, which limits the area to which the alloy thin film is adhered to the polymer film substrate 11. A crucible 14 made of heat-resistant material is installed at the bottom of this, and at this time, crucible 1
4 has an elongated shape in the width direction of the polymer film substrate 11. Inside the crucible 14, a metal with a low vapor pressure and a metal with a higher vapor pressure exist in a molten state, and this molten metal 16 is heated and evaporated by the first electron beam 16 above, and the metal with a higher vapor pressure It is deposited on the molecular film 11. At this time the first
The electron beam source 16 is scanned at a certain frequency in the longitudinal direction of the crucible 14, as shown by the arrow. Further, the power applied to the first electron beam source 16 and the scanning frequency are controlled by an evaporation rate monitor 17 provided in the evaporation particle space.

On the other hand, at the end of the crucible 14, a desired alloy thin film is obtained.
In order to achieve this, first, the first vapor deposition material 18 has a lower proportion than the high vapor pressure component in the desired film composition, and the second vapor deposition material 1 has a higher proportion of high vapor pressure components than the first vapor deposition material.
9 are installed in the form of rods, each of which is configured to enter the upper part of the crucible 14 via a feeding device 20, 21. Further, this vapor deposition material is placed on top of the vapor deposition materials 18 and 19.

Second electron beam source 2 for heating and melting the materials 18 and 19
2 is located, and the electron beam from this electron beam source 22 is deflected by an internal magnetic field so that it can selectively irradiate the vapor deposition materials 18 and 19, respectively.

Further, the selection of electron beam irradiation, input power, and feeding speed of the vapor deposition material 18, 19 are controlled by signals from an evaporation composition monitor 23 provided in the evaporation particle space.

The mode of operation of the embodiment configured in this manner is as follows. That is, to start vapor deposition, first, a vertical medium of a desired film composition, for example Co-0r, is used, and its composition is C.
When attempting to obtain a film of o80% - Cr20, the second electron beam is supplied while supplying the first vapor deposition material 18 in which the proportion of Cr as the second component is lower than the proportion of Cr in the desired film composition. The material is selectively heated and melted by an electron beam from a source 22, supplied into a crucible 14, and heated and evaporated by a first electron beam source 16. At this time, the composition of the evaporated particles is as shown in Figure 4, even when the Cr content of the feed material is low (93% Co-7% Cr), the Cr composition is approximately 30% at the beginning, and then the Cr concentration gradually decreases to a certain level. After a predetermined period of time, the desired film composition becomes 80% Co-20% Co. When this state is reached, the shutter 24 is opened and the polymer film substrate 11 is evaporated. Further, after a while in this state, the Cr concentration decreases. Therefore, the second evaporation material 19 having a high Cr content is irradiated with an electron beam from the second electron beam source 22, heated and melted, and then supplied to the crucible 14, thereby changing the composition of the evaporated particles to 80% Co - 20% Cr. It is possible to maintain it. At this time, the second
If only the vapor deposition material 19 is heated and melted, the Cr ratio will increase again, so the irradiation from the second electron beam source 22 is controlled by re-irradiating the first vapor deposition material. At this time, in order to maintain the amount of molten metal in the crucible 14 to some extent and perform continuous vapor deposition for a long time, it is desirable to control the amount of the heating bath of the first vapor deposition material. It is better to have a material composition that keeps the proportion of high-pressure components as low as possible (for example,
By doing so, the loss time from the start of vapor deposition to the start of vapor deposition can be reduced.

The layer material and the vapor deposition material with a higher vapor pressure component ratio are selectively supplied to a crucible that is heated and melted with an electron beam, and the crucible is further heated with another electron beam to melt the vapor deposition material. There is no bumping phenomenon that occurs when directly feeding the material into the crucible, and even if there is impurity in the evaporation material, it will only be generated in the supply section, and it is easy to configure the material so that it does not adhere to the substrate. As a result, a medium with excellent film surface properties can be produced. Furthermore, composition control during evaporation is possible simply by selectively irradiating the evaporation material with an electron beam.
In addition, the composition can be controlled even over a long length of kana during mass production.

Furthermore, in this embodiment, the supply section for vapor deposition material is provided at one end of the crucible, but if the substrate becomes wider, it may be provided at the other end as well, thereby making the composition uniform in the width direction of the substrate.

Effects of the Invention According to the present invention, a vapor deposition material having a lower proportion of high vapor pressure components than the proportion of high vapor pressure components in a desired film composition and a vapor deposition material having a higher proportion of high vapor pressure components than this vapor deposition material can be selectively used. By vapor-depositing it while melting it and supplying it to a crucible,
A smooth film without bumping phenomena can be produced, and furthermore, a perpendicular magnetic medium with a uniform film composition over a long length can be produced stably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a vapor deposition apparatus embodying a metal thin film production method according to an embodiment of the present invention, FIGS. 2 and 3 are block diagrams of a metal thin film production apparatus according to a conventional method, and FIG. 4 is a Co- It is a figure showing the relationship between Cr concentration and time in Cr alloy evaporation. 11... Polymer film substrate, 14...
- Crucible, 16...First electron beam source, 18...
...First vapor deposition material, 19... Second vapor deposition material, 22. Old... Second electron beam source. Name of agent: Patent attorney Toshio Nakao and 1 other person11
-11 at most electron film 3tk[lΔ-4)lco'/6---;l-7 electron beam source 18---1st evaporation material 19---1st evaporation 2nd observation point Figure 2? Figure 3

Claims (2)

[Claims] (1) The inside of the crucible is heated by a first electron beam, and a first vapor deposition material whose proportion is lower than the proportion of high vapor pressure components in the desired film composition and a proportion of vapor pressure components higher than the first vapor pressure component A second evaporation material with a high vapor pressure is supplied into the crucible while being selectively heated and melted by a second electron beam, and a metal thin film having a large proportion of low vapor pressure components and a small proportion of high vapor pressure components is evaporated under vacuum. A method for producing a metal thin film, characterized in that it is formed by a vapor deposition method. (2) The method for producing a metal thin film according to claim 1, wherein the high vapor pressure component is Cr and the low vapor pressure component is Co.