JPH02185966A - Method for generating sheet plasma current uniform in its crosswise direction - Google Patents

Abstract

PURPOSE:To form a wide coating film uniform in its crosswise direction by providing the through holes of the hollow cathode of an HCD gun in parallel and specifying the flow rate of a plasma source gas to be led to the hole and/or the magnetic field for widening a sheet plasma current. CONSTITUTION:The hollow cathode 1 of the hollow cathode gun (HCD gun) is a rectangular plate, and plural through holes 2-1 to 2-7 extending in the short-side direction are formed in parallel in the long-side direction. A plasma source gas passes through each through hole, a current is energized, and the flow rate of the gas is independently controlled with respect to the holes 2-1 and 2-2, the holes 2-3, 2-4 and 2-5, and the holes 2-6 and 2-7 to generate the sheet plasma uniform in its crosswise direction. Alternatively, the sheet plasma is led to the gap between the magnets 6A and 6B opposed at a specified interval, the intensity of the magnetic field between the magnets 6A(B)-1 at the center and the magnets 6A(B)-2,3 at both ends is adjusted, and a sheet plasma 7 having a uniform electron density in its cross direction is obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is directed to HCD (Hollow Cathode)
The present invention relates to a method of generating a wide plasma flow, a so-called sheet plasma flow, in a hollow cathode gun (hereinafter referred to as an HCD gun) used when performing ion blating using the Discharge method.

Ion blating method using plasma is TiN
, TiC, Tt(CN), and other ceramic coatings. As for the ion brating method,
HCD method, EB (Electron Beam)
+ Techniques such as the RF (Radio Frequency) method, the Marutei arc method, and the arc discharge method have been implemented.

Among these methods, the HCD method has an ionization rate of 20 to 60
%, and the film formation rate is 0.05 to 0.5 tt m
/win is relatively fast, so TiN 5Tic 5Ti
It is widely used for ceramic coatings such as (CN) or CrN. In particular, in the HCD method, the N2 gas flow rate,
It has the advantage that ceramic coating can be easily and smoothly performed even if the requirements such as degree of vacuum, bias voltage, substrate temperature, and substrate pretreatment change slightly.

Regarding HCD method ion blating, for example, Metal Surface Technology, 35 (1) P, 16-24 (1984
), Powder and Powder Metallurgy 32 (1985) P, 55
There is a disclosure in ~60.

(Prior art) By the way, current HCD guns use a hollow cathode made of Ta cylinder, and the deposition area on the substrate is circular, so it is difficult to coat a wide surface to be deposited, such as a wide steel plate. In this case, the HCD gun must be moved in the width direction of the board, making it difficult to obtain a uniform coating in the width direction of the board.

JP-A-63-57767 and JP-A-63-50 regarding coating treatment on wide and large-area substrates.
Publications No. 463 and No. 63-50473 disclose a method for vapor deposition by applying a magnetic field to multiple crucibles and branching and converging plasma generated by a pressure gradient type plasma gun to multiple crucibles. There is.

However, in both methods, multiple guns and crucibles exist independently, so it is difficult to create the same atmosphere for the vapor flow from each crucible, and the equipment required is expensive due to the multiple guns, so it is difficult to achieve this in practice. Many problems remain before its application.

(Problems to be Solved by the Invention) Therefore, the purpose of this invention is to propose an advantageous method for generating a sheet plasma flow that is optimal for achieving uniform coating treatment on a wide, large-area substrate. shall be.

(Means for Solving the Problems) That is, the present invention provides a hollow cathode gun having a hollow cathode in which a rectangular plate-like body is provided with through holes for plasma generation extending in the direction of the short side and parallel to each other in the direction of the long side. When generating a sheet plasma flow by applying electricity while flowing a plasma source gas through the through-holes, plasma source gases having different flow rates at the center and both ends of the through-hole row are introduced into each through-hole. A method for generating a sheet plasma flow uniform in the width direction (first invention) characterized by In order to widen the width of the sheet plasma flow generated by a hollow cathode gun equipped with a hollow cathode using a magnetic field, the magnetic field divided into the central part of the width of the sheet plasma flow on the exit side of the hollow cathode gun and its opposite ends is divided into different strengths. Method for generating a sheet plasma flow uniform in the width direction (Second method)
invention).

Now, FIG. 1 shows a hollow cathode of an HCD gun suitable for use in the present invention. The hollow cathode 1 is a rectangular plate-like body in which a plurality of through holes 2-1 to 2-7 extending in the short side direction are formed in parallel in the long side direction. The material of the hollow cathode 1 may be Ta, which is commonly used, but W or LaB6, which have a high melting point, are advantageously suitable. In particular, LaB is characterized by easy initial heating, good discharge characteristics, and 150
It has advantages such as being able to withstand high temperatures of 0°C or higher and being able to form complex shapes through sintering. Furthermore, a composite material may be used in which the low temperature part of the hollow cathode is made of Ta and the high temperature part is made of W or LaB6.

In order to generate a plasma flow in the HCD gun equipped with the above-mentioned hollow cathode, a plasma source gas,
For example, electricity is applied while flowing Ar, He, or a mixed gas thereof. The plasma flow generated in each through-hole becomes a sheet-like plasma flow as a whole on the exit side of the through-hole, but depending on the position on the hollow cathode, for example, there is a difference in temperature between the central part in the long side direction and the both ends thereof. If this happens, there will be a difference in electron density between the center of the sheet plasma flow and both ends thereof, so it is necessary to make the plasma flow uniform.

Therefore, by independently controlling the flow rate of the plasma source gas introduced into the through holes in the through holes 2-1.2, 2-3, 4.5, and 2-6.7, uniform sheet plasma can be generated across the width. Flow.

Note that the above-described flow rate control of the plasma source gas is performed using, for example, a mass flow controller.

Unlike conventional flowmeters, mass flow controllers are based on electrically controlling the flow rate in pipes, so they can accurately control even small amounts of gas.

Next, FIG. 2 shows an ion brating device equipped with an HCD gun used in the second invention.

In the figure, 3 is an HCD gun equipped with the hollow cathode shown in Figure 1, 4 is a first electrode, 5 is a second electrode, 6 is a magnet, and 7 is an HCD gun.
Sheet plasma flow from the gun, 8 is an evaporation source such as Ti, 9 is a crucible, 10 is a magnet, 11 is a focusing coil that serves as a path for the evaporated substance, 12 is a reaction gas introduction tube such as a meter,
13 is a copper strip serving as a substrate, 14 is a rewinding reel, 15 is a take-up reel, 16 is an exhaust port, and 17
is a vacuum chamber.

In this ion brating device, the plasma beam 7 generated from the HCD gun 3 under the conditions of low voltage and large current is generated by the magnetic field (hereinafter referred to as the blade bus magnetic field) generated by the magnet 6, as shown in FIG. A wider sheet plasma flow is created. This sheet plasma flow is then guided by a magnet 10 to a crucible 9 in a vacuum chamber 17 to melt and ionize the evaporation source 8. The ionized evaporated material passes through the high plasma atmosphere within the focusing coil 11, reacts with the reactant gas, and is deposited on the steel strip 13.

Here, the magnet 6 that further widens the width of the sheet plasma flow is composed of magnets 6A and 6B that are arranged facing each other at a predetermined interval, and guides the sheet plasma flow into this gap to make the sheet plasma flow wider. Further, the magnets 68 and 6B are divided into three parts in the width direction, that is, the magnets 6A-1 and 6B are placed in the center.
-1, and magnets 6A-2, 3 and 6B-2 at both ends.
, 3 respectively, and magnets 6A-1 and 6B-
1, 6A-2 and 6B = 2, 6A-3 and 6B
-3 by adjusting the magnetic field strength to produce a sheet plasma flow with uniform electron density in the width direction. Specifically, this can be achieved by combining a magnet and an electromagnet.

By the above operation, it is possible to irradiate the crucible 9 with a sheet plasma flow that is uniform in the width direction, and therefore it is possible to form a uniform vapor deposition film in the width direction even on a substrate that is wide in the width direction.

Although permanent magnets are normally used for the magnets 6A and 6B, when controlling the strength of the magnetic field across the width direction as in the present invention, it is desirable to use electromagnets for high precision control.

(Function) This invention uses an HCD gun in which a plurality of through holes, which serve as plasma generation areas, are arranged in parallel to spread a bundle of plasma beams emitted from the through holes in the width direction and By adjusting the amount of gases such as Ar and He, it is possible to generate a sheet plasma flow with uniform electron density across the width.

In addition, the sheet plasma flow generated by the above HCD gun can be made wider by the Cubs magnetic field.
In this case, it is advantageous to simultaneously adjust the amount of gas introduced into each through hole.

By applying the sheet plasma flow generated as described above to the ion blating process, a beam spot corresponding to the evaporation source that is long in the width direction can be obtained. Uniform vapor deposition becomes possible.

If this widening of the plasma flow shape by the magnetic field is applied to a conventional plasma beam from a cylindrical hollow cathode, the beam intensity will be reduced and the deposition speed will be slow. Therefore, optimization of the plasma beam shape by a magnetic field can be realized for the first time by applying the HCD gun according to the present invention.

(Example) C: 0.031 wt%, Cr: 18.7 wt%,
Mn: 0.01 wt%, P: 0.013 wt%
and S: 0.011 wt% on the surface of a stainless steel copper plate (thickness: 0.25 mm, width: 500 mm+) using the ion blating apparatus shown in Figure 2. When depositing the film with a thickness of mm, the flow rate of the gas introduced into each through hole of the hollow cathode was adjusted as shown in the table below, and the Cubs magnetic field shown in FIG. 3 was also adjusted as shown in the table below.

Furthermore, as a comparison, ion blating processing was also performed without adjusting the Ar gas flow rate or the Caps magnetic field.

The results of examining the color tone, uniformity, and adhesion of the film of the thus obtained product are also listed in the table below.

As is clear from the above table, the coating obtained by the ion blating treatment using the sheet plasma flow obtained according to the present invention was uniform in both color tone and film thickness, and had good adhesion.

(Effects of the Invention) If the sheet plasma flow obtained according to the present invention is used for ion blating treatment, it is possible to form a uniform coating in the width direction, especially when the substrate is wide. It is possible to realize coating treatment that is not affected by the width of the film.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the HCD gun used in this invention, Fig. 2 is a schematic diagram showing an ion brating device suitable for carrying out this invention, and Fig. 3 explains how the width of a sheet plasma flow is widened by a caps magnetic field. FIG. 1... Hollow cathode 2-1 to 2-7... Through hole 3... HCD gun 4... First electrode 5...
・Second electrode 6.6A-1 to 6A-3, 6B-1 to 6B-3...Magnet 7...Sheet plasma flow 8...Evaporation source 9...
・Crucible 10...Magnet 11...Focusing coil 12...Introduction tube 13...Steel strip
14... Rewinding reel 15... Take-up reel 16 Exhaust port 17... Vacuum chamber

Claims (1)

[Claims] 1. Using a hollow cathode gun, which is equipped with a hollow cathode in which through holes for plasma generation extending in the short side direction are provided in parallel in the long side direction in a rectangular plate-like body, the through holes are When generating a sheet plasma flow by applying electricity while flowing a plasma source gas through the through holes, plasma source gas having different flow rates at the center and both ends of the through hole array is guided to each through hole in the width direction. How to generate a uniform sheet plasma flow. 2. The width of the sheet plasma flow generated by a hollow cathode gun, which has a rectangular plate with a hollow cathode in which through-holes for plasma generation extending in the short side direction are provided in parallel in the long side direction, is determined by a magnetic field. A method for generating a sheet plasma flow that is uniform in the width direction, which is characterized by applying magnetic fields with different strengths to the central part of the width of the sheet plasma flow on the outlet side of a hollow cathode gun and the opposite ends of the sheet plasma flow when expanding. .