JPH0222462A - Crucible and production of metallic thin film using said crucible - Google Patents

Abstract

PURPOSE:To form a metallic thin film having a uniform composition distribution in the cross direction by using a crucible provided with an opening having a longitudinal axis in the cross direction of a substrate and plural high-vapor- pressure component supply port in the longitudinal direction of the opening at the time of vacuum-depositing a thin film of an alloy of the metals having different vapor pressures on the long-sized and wide substrate. CONSTITUTION:The long-sized and wide polymeric film substrate 11 is traveled along the periphery of a rotating cylindrical can 12, and a Co-Cr alloy 15 in a crucible 14 is melted and vaporized by an electron beam 16 to form an alloy thin film on the substrate 11. At this time, the crucible 14 has a slender opening in the cross direction of the substrate 11, plural high-vapor-pressure component supply ports 18 are provided in the longitudinal direction, high-vapor-pressure Cr grains 20 are supplied from a feeder 17, the crucible is widened by the width W in the vicinity of the supply port 18, and a shield plate 19 is provided. By this method, the composition distribution of the Co-Cr alloy thin film to be formed on the substrate 11 is uniformized, and bumping is controlled.

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 a metal thin film type medium, it has been found that a CO-based magnetic thin film medium, particularly a Co--Cr medium, is most suitable as a perpendicular magnetization type medium 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 approximately 80:2o. It is necessary to control the composition in the evaporation crucible so as to maintain the concentration ratio in the evaporation crucible.

In general, Co and Cr metals are high melting point materials, and in the case of vapor deposition, electron beam heating is generally used as the means for melting and evaporating them, examples of which are shown in FIGS. 5 and 6.

Conventional Example 1 shown in FIG. 5 is 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 with an electron beam 2. It is something that melts.

At this time, since the alloy in the crucible 1 has a large vapor pressure difference, the Cr component with a high vapor pressure evaporates first, and the Cr concentration in the film decreases with the evaporation time, for example, the initial alloy proportion is changed to Co
Even in the case of 93:Cr7, the Cr concentration is as high as 40% at the initial stage of vapor deposition, and the Cr concentration in the film gradually decreases as the vapor deposition time progresses. For this purpose, in FIG. 5, the composition is controlled while replenishing the Cr grains 3.

Conventional Example 2 shown in FIG. 6 is a method using a binary vapor deposition source of Co and Cr, and Co and Cr are deposited in separate crucibles 4.
5 and deposited on a polymer film substrate running on a can 6.

8 is an adhesion prevention plate υ, 9 is an unwinding roller, and 1o is a winding υ roller. In addition, in Conventional Example 1, as in Conventional Example 2, a thin film is continuously formed using an anti-adhesive plate, a can, an unwinding roller, and a winding roller.

When forming a film using such a vacuum evaporation method, a magnetic recording medium is constructed on a polymer film, and recording and reproduction is performed by contacting a magnetic head, so the smoothness of the medium, especially the relationship between the magnetic head and the head, is It is necessary that there are no foreign substances that cause spacing loss, or that the magnetic properties are maintained over a long length, and the length needs to be commensurate with the production scale. be done.

However, the conventional example 1 shown in FIG. 6 has the following problems. That is, in this method,
Cr, which has a high vapor pressure, is in a metallic state in a state where the Cr concentration is high and it is difficult to make it into a wire, so it is supplied as metal particles. At this time, since the Cr metal is sublimable, it cannot be heated and melted to be supplied to the crucible, and the Cr metal is supplied in the form of particles as shown in the explanation below. 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 of the same composition is generated, which causes major problems such as recording failure when it comes into contact with a magnetic head.

In addition, in the conventional example 1, as shown in FIGS. 7 and 8, there is a method that can handle long substrates without supplying CO material, but this method basically has the above problems. It is. When actually forming a film on a wide substrate film, it is required that the composition ratio be uniform in the width direction of the substrate. The composition distribution shown in the figure can be obtained. Therefore, it is necessary to suppress the bumping phenomenon without supplying Cr metal and to make the composition distribution uniform over a wide area.

- Force cylinder 6 In the conventional example 2 shown in FIG. 6, there is basically no problem with the generation of foreign matter as in the conventional example 1, but it has the following problems. That is, the advantage of producing such a magnetic recording medium by the vacuum evaporation method is its high-speed mass production, and the evaporation rate is on the order of several thousand micrometers. 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 using binary evaporation. Although there is a method of controlling the composition at each source, there are problems such as bumping phenomenon occurring during replenishment, non-uniform film composition over a long length or wide width, and compositional unevenness.

Means to Solve the Problem A plurality of high vapor pressure component replenishment boats are provided in the longitudinal direction of a crucible that has an opening with a longitudinal axis in the width direction of the substrate, and in the vicinity of the replenishment port, the crucible 11] is expanded and the upper part of the crucible is expanded. When heating and melting the metal in the crucible while scanning the electron beam in the longitudinal direction of the crucible, the scan speed near the supply port is made slower than the scan speed around the crucible.

By providing a plurality of high vapor pressure component supply ports in the longitudinal direction of the crucible, the composition of the alloy thin film can be made uniform in the longitudinal direction of the crucible, that is, in the width direction of the wide substrate. Furthermore, by widening the width of the crucible near the high vapor pressure component replenishment boat and closing off its upper part, it is possible to suppress the bumping phenomenon inside the crucible during replenishment of the high vapor pressure component. In addition, by making the electron beam scan speed near the supply port slower than the scan speed in the surrounding area, the convection effect is promoted, making the composition uniform within the crucible and allowing high vapor pressure components to flow into the high power density area. It is possible to prevent the occurrence of bumping.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows the internal groove structure of the vacuum evaporation apparatus used in the example. In the figure, reference numeral 11 denotes a long and wide polymer film substrate, which runs along the periphery of a rotating cylindrical can 12 and forms an alloy thin film under it. 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 a heat-resistant material is installed below this, and this crucible 14 has an elongated shape in the width direction of the polymer film substrate 11. In 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 15 is heated by an electron beam 16 from above and evaporated, forming the polymer film. 11. At this time, an alloy metal 15 to be vapor-deposited is loaded into a crucible 14 made of a heat-resistant material, and is heated and melted by an electron beam 16. Further, at this time, the evaporation material is an alloy of CO and Or, and Cr, which is a high vapor pressure component, evaporates first. Therefore, as shown in the figure, Cr is supplied into the crucible 14 from a Cr supply device 17 via a plurality of high vapor pressure component replenishment ports 18. Also, this supply port 1
The upper part of the part 8 is closed with a shielding plate 19 made of the same material as the crucible 14, so that the deposited substance does not evaporate upward from that region.

FIG. 2 shows a top view of the crucible 14 portion. The crucible 14 body has a long shape in the width direction of the substrate,
A plurality of high vapor pressure component replenishment ports 18 are provided in the direction of the pitcher force, and furthermore, near the replenishment port 18, the crucible width is W.
As shown in FIG. 1, a shielding plate 19 is provided.

3 is a cross-sectional view of the crucible 14 shown in FIG. 2 taken along the longitudinal centerline, and the supply port 18 is surrounded by a shielding plate 19.

Furthermore, in FIG. 4, the vertical axis shows the scanning speed of the electron beam 16 scanning in the crucible longitudinal direction, and the horizontal axis shows the crucible longitudinal position. In the area corresponding to the supply port 18, the scanning speed is plotted against the surrounding This is to make it slower than the scan speed.

The mode of operation of the embodiment configured in this way is as follows. That is, by the electron beam 16 scanned in the longitudinal direction of the crucible 14, the Co-Cr molten alloy 15 flies toward the substrate 11 at a predetermined evaporation rate depending on the intensity of the electron beam 16, passes through the adhesion prevention plate 13, and It is deposited on the continuously running polymer film 11. At this time, the high vapor pressure component O
r evaporates first, and the Or composition decreases. Therefore, 901 grains 20 are supplied through a plurality of supply ports 18 provided in the longitudinal direction of the crucible 14, that is, in the width direction of the substrate.

At this time, the scanning speed of the electron beam 16 is slower in the vicinity of the replenishment port 18 than in the surrounding area, and as a result, the temperature of the molten metal in the vicinity of the replenishment port 18 increases as compared to the temperature of the surrounding molten metal, and due to the difference in surface tension, This causes a convection phenomenon as shown by the arrows in FIGS. 2 and 3. This convection is caused by crucible 1
4. Promote uniformity of Cr concentration in the longitudinal direction, and direct molten Cr from the supply port 18 to the crucible surface side where it actually evaporates.
It can promote the diffusion of r.

In addition, the width of the crucible is expanded near the supply port 18,
Moreover, because the upper part is closed, supply port 1
No. 8 can prevent the generation of droplets caused by bumping of the sublimable Cr particles supplied to the crucible.

Effects of the Invention According to the present invention, when forming alloy thin films with different vapor pressures on a wide substrate, the composition distribution in the width direction can be made thinner.
In addition, it is possible to suppress the bumping phenomenon that replenishes high vapor pressure components,
As a result, an alloy thin film with excellent surface properties can be obtained on a wide substrate.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a vacuum evaporation apparatus used in an embodiment of the present invention, Fig. 2 is a top view of the crucible portion in Fig. 1, Fig. 3 is a central cross-sectional view of Fig. 2, and Fig. 4 is a top view of the crucible portion in Fig. 1. A scanning velocity distribution diagram of the electron beam in the longitudinal direction of the crucible, FIG. 6 is a configuration diagram of the metal thin film manufacturing apparatus according to conventional example 1, FIG. 6 is a configuration diagram of the metal thin film manufacturing apparatus according to conventional example 2, and FIG. 7 is the conventional example. A configuration diagram of a metal thin film manufacturing apparatus corresponding to a long substrate in Example 1. FIG. 8 shows the composition distribution of high vapor pressure components (Cr) in the width direction of the substrate when the high vapor pressure components are supplied by the method shown in FIG. 7. It is a diagram. 11... Polymer film substrate, 14...
- Crucible, 16... Electron beam, 18... High vapor pressure component supply port, 19... Shielding plate. Name of agent: Patent attorney Shigetaka Awano and 1 other person//
--Takago 7 Film

Claims (4)

[Claims] (1) A crucible used when continuously forming alloy thin films of metals with different vapor pressures on a long and wide substrate by vacuum evaporation, and having an opening having a longitudinal axis in the width direction of the substrate; A crucible comprising a plurality of high vapor pressure component replenishment ports provided along the longitudinal direction of the opening. (2) The crucible according to claim 1, characterized in that the opening width is widened near the supply port and the upper part thereof is closed. (3) The crucible according to claim 1, characterized in that the metal in the crucible is heated and melted while scanning the electron beam in the longitudinal direction of the crucible, and the scanning speed near the supply port is made slower than the scanning speed of the surrounding area. Method for manufacturing thin metal films. (4) The method for producing a metal thin film according to claim 3, wherein the high vapor pressure component is Cr and the low vapor pressure component is Co.