JPH02217465A - Plasma beam generator - Google Patents

Abstract

PURPOSE:To form a homogeneous film in the width direction on a wide base plate by generating annular plasma beams by a hollow cathode gun and flattening the annular plasma beams by a magnetic field generator and irradiating an evaporating source with the flattened plasma beams. CONSTITUTION:The hollow cathode 1 of a hollow cathode gun is constituted of a cylinder 1A and a column 1B and plasma beams 2 are generated which are annular and low in plasma density of the center part. Then the plasma beams 2 are flattened by a magnetic field generator 3 which consists of the oppositely arranged magnets 3A, 3B while holding the prescribed interval. An evaporating source 6 which is introduced into a crucible 5 lengthened in the width direction of a base plate is irradiated by the flattened plasma beams 4 and a vaporating flow analogous to the beam shape is formed. Further the hollow cathode is preferably formed of one or more kinds selected among from Ta, W and LaB6. Thereby a film can be vapor-deposited which has uniform thickness in the width direction of the base plate. The plasma beam generator is favorable to continuous vapor depositing treatment for a wide long-sized material.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a plasma beam generation device used in dry rating processing, and in particular a device that generates a flat plasma beam that is advantageously suited for forming a film on a wide board. Regarding.

(Prior Art) In recent years, a process of improving the mechanical properties of various materials by forming a thin film of a different substance on the surface of the material has been actively carried out using the dry brating method. For example, corrosion resistance can be improved by depositing zinc on a steel plate (steel strip), and wear resistance can be improved by depositing T1Ni on a cutting tool such as a drill blade or a cutting tool.

In the dry brating process, it is essential to evaporate the film-forming substance. Specifically, a high-melting point metal lump is processed to create a depression, and the film-forming substance (evaporation source) is placed in this depression.
The evaporation source is heated by directly applying electricity to the high melting point metal mass,
There are two methods: evaporating the evaporation source, and placing the evaporation source in a crucible and applying resistance heating to the crucible to heat and evaporate the evaporation source, but it is difficult to evaporate high melting point metals such as Ti, making this method less versatile. Inferior. Although it is possible to evaporate the high melting point metal by using the sputtering method, it cannot overcome the drawback that the film formation rate is slow. Therefore, in order to heat and evaporate the evaporation source, it is advantageous to directly irradiate the evaporation source with a plasma beam or an electron beam with a large amount of current, that is, a large output.

On the other hand, a technology has been developed to continuously apply dry rating treatment to long objects such as steel strips. The thickness in the direction becomes non-uniform, leading to defects in film quality and shape, and the properties of the resulting product deteriorate.

A method to solve this problem is to wrap a long object around a roll and guide the steam from the melting point through a duct to form a film uniformly in the width direction of the long object, as reported in Tetsu to Hagane, vol.
72 (1986), P. 1070.

This method is suitable for evaporating low melting point metals such as zinc, but is disadvantageous when evaporating high melting point metals such as Ti.

(Problems to be Solved by the Invention) Therefore, the present invention is advantageously suited for uniformly forming a film of a high-melting point metal on a wide, large-area substrate.
The purpose is to propose a flat plasma beam generator.

(Means for Solving the Problems) The present invention includes a hollow cathode gun and a magnetic field generator that expands the width and flattens the plasma beam irradiated from the hollow cathode gun. is a plasma beam generating device characterized by having solid columnar bodies arranged concentrically inside.

In addition, in implementation, the hollow cathodes are Ta, ..., W, and L.
It is advantageously suitable to consist of one or more types selected from aBh.

By the way, it is possible to linearly scan the electron beam generated by an electron gun by controlling the magnetic field, and it is generally possible to scan the electron beam generated by an electron gun in a linear manner.
Although the amount of evaporation can be increased due to the low current characteristics, the probability of collision between evaporated particles and electrons becomes low, resulting in insufficient ionization of evaporated particles. This is not a particular problem when zinc is used as the evaporation source, but when evaporated Ti is reacted with NZ to form TiN, the reactivity decreases if the ionization rate is low. However, coating defects are more likely to occur.

Therefore, it is preferable to use a beam with a large amount of current, that is, a hollow cathode plasma beam, as the heat source for evaporation.

Now, the plasma beam generator according to the present invention has a solid columnar body concentrically arranged inside the hollow cathode of a hollow cathode gun. For example, a hollow cathode having the structure shown in FIGS. 1(a) to (c) is advantageous. Compatible with The hollow cathodes l in the same figure (a) to (c) are cylinders IA whose cross sections are circular, oval, and rectangular, respectively.
A columnar body IB having a similar cross section is arranged concentrically inside the plasma generating part, and both are characterized in that the cross-sectional shape of the plasma generating part is annular.

Further, as the magnetic field generating device, a device that forms the magnetic lines of force horizontally can be used, such as by arranging flat plate magnets horizontally at regular intervals with the same poles facing each other.

By passing the beam between the two magnets, the beam can be flattened.

(Function) The end face of the plasma beam generated by the cylindrical hollow cathode of a conventional hollow cathode gun is circular as shown in Fig. 2 (a), and when this beam is flattened by a magnetic field generator, it becomes the same. As shown in Figure (b), the end face of the beam changes from circular to oval. A plasma beam whose end face shape, that is, the beam irradiation trace is an elongated oval, has a plasma density lower at both ends than at the center, and the plasma density distribution is shaped like a convex lens.

Therefore, the evaporation source is irradiated with this plasma beam.
The amount of evaporation is smaller at both ends than in the center, resulting in uneven product film thickness.

On the other hand, the end face of the plasma beam generated by the hollow cathode gun according to the present invention has an annular shape as shown in FIG. When this happens, the end face of the beam becomes rectangular, as shown in FIG. 5(b), and the plasma density distribution can be made uniform.

(Example) FIG. 4 shows a preferred example of a plasma beam generator according to the present invention.

In the figure, 1 is a hollow cathode of a hollow cathode gun, which is composed of a cylinder IA and a cylinder IB, 2 is a plasma beam generated by this hollow cathode 1, and 3 is a magnetic field generator, which are arranged facing each other with a predetermined gap. 4 is a plasma beam flattened by a magnetic field generator 3, 5 is a crucible, and 6 is an evaporation source.

A plasma beam 2 generated by a hollow cathode 1 is flattened into a plate-shaped plasma beam 4 by passing a magnetic field generated by a magnetic field generator 3 as shown in the figure, and then this plasma beam 4 is By irradiating the crucible 5 extending in the width direction of the substrate to form an evaporation flow similar to the beam shape, a film having a uniform thickness can be deposited in the width direction of the substrate.

Next, using the plasma beam generator shown in the figure, a TiN film was deposited on a stainless steel strip substrate with a width of 500 mm and a thickness of 0.3 mm under the following conditions to a thickness of 0.0 mm in the center.
TiN in the width direction of the resulting product was formed with a target of 5 μm.
The film thickness distribution was investigated. For comparison, processing was also carried out under similar conditions using a conventional plasma beam generator with a cylindrical hollow cathode.

The results of each survey are shown in Table 1.

Table 1 In Table 1, the copper strip passing speed is 3 m/min, the beam current is 1000 A, and the beam width after flattening is 300 A.
It is mm.

As described above, in the invention examples, a good film thickness distribution is obtained in the range from the ends to the center of the plate width.

(Effects of the Invention) This invention is particularly suitable for continuous vapor deposition processing on wide and elongated objects, that is, by using this invention, a uniform coating can be formed in the width direction even on a wide substrate. be able to.

[Brief explanation of the drawing]

Figures 1 (a) to (c) are end views showing the structure of the hollow cathode;
Figure 2 (a), (b) and Figure 3 (a), (
b) is a schematic diagram showing irradiation marks of a plasma beam, and FIG. 4 is a schematic diagram showing a plasma beam generator according to the present invention. 1-Hollow cathode 2.4・-Plasma beam 3
Magnetic field generator 5- Crucible 6- Evaporation source Figure 1 Figure 2 (a) (b)

Claims (1)

[Claims] 1. It is equipped with a hollow cathode gun and a magnetic field generator that expands the width and flattens the plasma beam irradiated from the hollow cathode gun, and the hollow cathode of the hollow cathode gun is solid inside. A plasma beam generator characterized by having columnar bodies arranged concentrically. 2. Claim 1, wherein the hollow cathode is made of one or more selected from Ta, W, and LaB_6.
The plasma beam generator described in .