JPH0225986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-speed vacuum arc reactive deposition method with highly stabilized discharge and a deposition apparatus therefor.

Tokamak-type fusion reactors use coating materials such as titanium carbide deposited on metal surfaces for parts of the vessel wall that encloses the plasma. These materials suffer catastrophic damage to the surface coating layer due to the large heat flux during plasma abnormalities that occur during fusion reactor operation. As a result, the component metal that has lost its coating layer is directly exposed to plasma and is contaminated by plasma. Therefore, there is an urgent need to develop technology to locally repair damaged areas on the spot. For future fusion reactors, which will be subject to especially strong induced radioactivity, it will be essential to develop technology to repair the inner walls of the reactor without dismantling it. As described above, there is a need for research and development of the technology to coat desired areas with high-quality ceramics on the spot, not only for nuclear fusion reactors but also as inner coating or repair technology for various chemical plant reactors. There is.

Prior Art Conventionally, ceramic coating methods using vacuum arc discharge are known. As shown in FIG. 5, the method is to provide an anode 10 by contacting and interposing an insulating material 11 to the end of the cathode 2, housing the entire body in a vacuum container 12, and installing a base body in the container. A reactive gas was introduced into the container, and a plasma flow of metal vapor and reactive gas was applied to the substrate 13 for vapor deposition. 14
indicates the outlet.

According to this method, (1) it is necessary to increase the area of the discharge surface in order to stabilize arc discharge;

(2) Since the reactive gas is introduced into the vacuum vessel, the reaction pressure must be increased to a certain extent in order to stabilize the arc discharge.

(3) In order to prevent the cathode spot from escaping from the discharge surface, an insulating material is used in contact with the cathode, so the insulating material is evaporated by the arc and mixed into the deposited film as impurities. Additionally, ceramic is deposited on the insulating material, often causing short circuit problems.

(4) This method cannot repair damaged areas on the inner walls of nuclear fusion reactors and chemical plant reactors on the spot. There were drawbacks such as:

Purpose of the Invention This invention was made to eliminate the drawbacks of the conventional vacuum arc reactive vapor deposition method, and it is possible to perform vapor deposition on the spot on damaged inner walls of nuclear fusion reactors and chemical plant reactors. Moreover, it is an object of the present invention to provide a vacuum arc reactive vapor deposition method that has a high ionization rate due to vacuum arc discharge, is stable at high speed, does not contaminate the deposited film, and does not cause any trouble, and a vapor deposition apparatus therefor.

Structure of the Invention (1) A method in which a plasma flow of metal vapor and reactive gas is generated by vacuum arc discharge and is deposited on a substrate by convergent transport, a vacuum arc cathode having pores on the discharge surface is used. The reactive gas is blown out from the pores, and the entire cathode except for the discharge surface of the vacuum arc is covered with a high melting point shield with a narrow gap, and the bright spot of the vacuum arc cathode is directed to the area around the gas outlet on the discharge surface. A vacuum reactive vapor deposition method characterized by generating a concentrated plasma flow and transporting it convergently at the anode.

(2) The vacuum arc cathode consists of a discharge surface with pores for blowing out reactive gas, and the cathode is surrounded by a cooling jacket, and the entire cathode except the discharge surface is surrounded by a high melting point shield with a narrow gap. A vacuum arc reactive vapor deposition apparatus is characterized in that an anode is provided in front of a cathode discharge surface, and a converging coil is provided on the outer periphery of the anode.

To explain the present invention based on the drawings, FIG. 1 is an explanatory diagram of an electrode according to the present invention, in which a cathode 2 is cooled by a water cooling jacket 1, and a discharge surface 3 has a gas outlet 4 having an open end and a gas outlet 4 having an open end. A pore connecting the inlet 5 and the inlet 5 is provided. The reactive gas is ionized in advance by a gas plasma generation system 6 using high frequency waves or the like provided just before the gas inlet 5 of the cathode, and then fed through the gas inlet 5.

On the other hand, in order to prevent the cathode bright spot of vacuum arc discharge from escaping from the discharge surface, the cathode is covered with a ruled 7 made of a material with a high melting point such as titanium, with a gap as narrow as possible, around the area other than the discharge surface. It is being said. A converging coil 9 is provided around the outer periphery of an anode 8 which is cooled by water cooling or the like in front of the cathode 2, and the plasma beam diameter is arbitrarily controlled by a magnetic field.

In the above configuration, the gas plasma generation system 6 does not necessarily need to be provided immediately before the gas inlet 5.

In the present invention, the discharge surface of the cathode 5 is provided with a pore for the outlet of the reactive gas, and the reactive gas is introduced through the pore, so that the cathode bright spot of the vacuum arc can be concentrated around the opening end. The discharge can be highly stabilized. In addition, if the reactive gas is ionized beforehand and introduced, the discharge can be stabilized and the efficiency of the plasma reaction can be increased, so that high-quality ceramic coatings can be deposited at high speed. Furthermore, since the area around the cathode other than the discharge surface is covered with a shield at a small interval, problems such as short circuits between the cathode and the anode due to evaporation of the shield material or adhesion of conductive substances are completely eliminated.

Effects of the Invention In addition to the above-mentioned effects, according to the present invention, (1) discharge is highly stabilized, so that the range of atmospheric gas pressure and discharge current that can sustain discharge is expanded.
(2) At the same discharge current and evaporation rate, the bright spot of the arc is concentrated and stabilized compared to the conventional method, resulting in a significant increase. (3) Since the discharge surface of the cathode can be made small, the vapor deposited material can be discharged at high density from the small area of the cathode surface. Local coverage is therefore possible at desired locations. (4) Since a cylindrical cathode with a small cross-sectional area can be used, it is easy to mechanically and continuously replenish the cathode material, and it is also easy to create an electrode structure suitable for on-site vapor deposition. Excellent effects such as these can be achieved.

Example Using Ti as the cathode material and N ₂ as the reactive gas, TiN was deposited on a molybdenum substrate using the apparatus shown in FIG. The cathode had an outer diameter of 30 mmφ and a length of 50 mm, and a pore with a diameter of 5 mm was provided on the central axis.
The reactive gas was ionized by high-frequency discharge and supplied immediately before the gas inlet of the cathode. As a result of photographing and observing the discharge surface of the cathode surface, it was found that when the reactive gas was introduced from a location away from the cathode in the conventional method, the arc cathode bright spot moved around the entire discharge surface; When the reactive gas is introduced through the pores provided on the discharge surface of the cathode as in the invention, the arc cathode bright spot is only around the reactive gas outlet, and the vapor deposited material is highly concentrated, regardless of whether or not ionization is performed before introducing the reactive gas. It was found that it is released at high density.

The relationship between atmospheric gas pressure and discharge current is shown in FIG. 2. In the figure, A is the conventional method, B,
C is the method of the present invention, B is the case where the reactive gas is introduced without being ionized beforehand, and C is the case where the reactive gas is introduced after being ionized beforehand. As this figure shows, in the case of the present invention, the stable discharge region becomes large. The lattice constant of the TiN film obtained is as follows:
As shown in the figure. The value of the lattice constant of crystallographically sound TiN is 4.24 Å. Considering this point,
The atmospheric gas pressure at which a film with a stoichiometric composition (Ti/N=1.0) is generated is 3×10 ^-3 to 1×10 ^-2 Torr.
It can be seen that the range is within the range of . According to the conventional method, stable discharge cannot be obtained in this pressure range, but according to the method of the present invention, it enters the stable discharge region, and therefore,
A high quality film can be obtained.

Figure 4 shows the deposition rate. In the figure, A is the conventional method,
B and C show the method of the present invention. B is a case in which the reactive gas is introduced without being ionized beforehand, and C is a case in which the reactive gas is introduced after being ionized in advance. As shown in the figure, the evaporation rate is fast according to the method of the present invention.

[Brief explanation of drawings]

Fig. 1 is a diagram showing one embodiment of the electrode according to the present invention, Fig. 2 is a diagram showing the relationship between atmospheric gas pressure and discharge current, and Fig. 3 is a diagram showing the relationship between atmospheric gas pressure and discharge current.
Relationship diagram between lattice constant of film and atmospheric gas pressure, 4th
The figure shows a comparison of vapor deposition rates, and FIG. 5 shows a schematic diagram of electrodes in a conventional method. 1: water cooling jacket, 2: cathode, 3: discharge surface,
4: Reactive gas outlet, 5: Reactive gas inlet, 6:
Gas plasma generation system, 7: Shield, 8: Water-cooled anode, 9: Convergent coil, 10: Anode, 11: Insulating material, 12: Vacuum vessel, 13: Substrate, 14: Exhaust port, A line: In the case of conventional method, B line: When the reactive gas is not ionized in advance in the method of the present invention, C line
Line: When anti-reactive gas is ionized in advance using the method of the present invention.

Claims (1)

[Claims] 1. A vacuum arc cathode having pores on the discharge surface in a method of creating a plasma flow of metal vapor and reactive gas generated by vacuum arc discharge and convergently transporting the plasma flow to deposit it on a substrate. The reactive gas is blown out from the pores, and the entire cathode except for the discharge surface of the vacuum arc is covered with a high melting point shield with a narrow gap, and the bright spot of the vacuum arc cathode is placed around the gas outlet on the discharge surface. A vacuum arc reactive evaporation method that is characterized by generating a plasma stream concentrated at a certain point and transporting it at the anode. 2. The vacuum arc reactive vapor deposition method according to claim 1, wherein the reactive gas is ionized by electric discharge and introduced immediately before the reactive gas is introduced. 3. The vacuum arc cathode consists of a discharge surface with pores for blowing out reactive gas, and the cathode is surrounded by a cooling jacket, and the entire cathode except for the discharge surface is separated by a narrow gap with a high melting point shield. 1. A vacuum arc reactive vapor deposition apparatus characterized in that an anode covered with a convergent coil and a converging coil provided on the outer periphery is provided in front of a cathode discharge surface. 4. The vacuum arc reactive vapor deposition apparatus according to claim 3, wherein a reactive gas plasma generator is provided immediately before the inlet of the reactive gas.