JP2916972B2 - Plasma generation method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for generating plasma by introducing an argon carrier gas from a plasma source into a vacuum vessel and generating plasma from the plasma source in the vacuum vessel.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 59-27499, for example, a plasma beam obtained from a pressure gradient plasma source is flattened by a magnetic field such as a permanent magnet. Some generate sheet plasma. This pressure gradient type plasma source performs glow discharge at the start of discharge (at the time of initial ignition), and shifts to arc discharge at the time of subsequent discharge progress, leading to steady operation.

FIG. 2 is an enlarged sectional view of a cathode portion 1a of a pressure gradient type plasma gun which is a pressure gradient type plasma source. The cathode section 1a is configured by attaching a Mo tube 12 to a housing 11 provided with a gas suction hole and a cooling water storage section. Inside the Mo tube 12, a LaB ₆ disk 14 and a Mo disk 15 are attached, and a Ta pipe 13 is provided. One end of the Ta pipe 13 is attached to the gas suction hole of the housing 11 through an attachment hole provided near the center of the Mo disk 15, and the other end is located near the center of the LaB ₆ disk 14. It is arranged in the provided through hole. A window 16 made of W is provided at the other end of the tube 12 made of Mo so as to emit a beam without contacting the other end of the pipe 13 made of Ta.

[0004] The discharge is ignited first from the glow discharge of the Mo tube 12 and then to the hollow cathode discharge of the Ta pipe 13. In this state, when the discharge current increases and the temperature at the tip of the Ta pipe 13 rises sufficiently, the heat causes the LaB ₆ disc 14 to become hot, and thermionic emission is increased. As a result, the main body of the discharge is LaB ₆
Since the process proceeds to the circular plate 14, stable arc discharge can be obtained.

[0005] As an example of a plasma generator equipped with such a pressure gradient plasma gun, for example, a material vapor vaporized in a vacuum vessel is ionized by plasma, and the film forming material particles are provided in the vacuum vessel. An ion plating apparatus that deposits a metal film or an alloy film on the surface of the substrate provided is used. The pressure gradient plasma gun system used in this ion plating apparatus is basically the same as the hollow cathode (HCD) system, in which arc discharge is performed between a cathode gun and an anode crucible or hearth. In addition, vaporization and ionization of the material are simultaneously performed.

[0006]

In the case of the above-mentioned pressure gradient type plasma gun, when an argon carrier gas is used as a carrier gas to be discharged, a cathode is sputtered during a glow discharge at the beginning of the discharge, and a LaB ₆ gas is produced. There is a problem that the surface of the disk 14 is contaminated by sputtering on the surrounding metal.

More specifically, after ignition by glow discharge, the entire cathode portion continues to be sputtered by the discharged gas ions until the voltage drops due to arc discharge, and thus the cathode portion is cut off. Mo, Ta, and W are partially deposited on the surface of the LaB ₆ disk 14. This allows
If the LaB ₆ disk 14 is contaminated, it may cause discharge unevenness when performing arc discharge.

When the sheet plasma is generated using the LaB ₆ disc 14 thus contaminated, the sheet plasma does not become uniform. For example, in an ion plating apparatus, the formation of a metal film or an alloy film is uniform. Inconveniently cannot be performed.

Generally, the larger the mass of gas ions or the higher the discharge voltage, the greater the etching action by sputtering.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its technical problem is to provide a plasma generation method and a plasma generation method capable of generating uniform plasma without contaminating the cathode surface of a plasma source. It is to provide a device.

[0011]

According to the present invention, an argon carrier gas is supplied from a plasma source into a vacuum vessel,
In the plasma generation method of generating plasma by the plasma source in the vacuum vessel, a glow discharge is performed by supplying a hydrogen carrier gas or a helium carrier gas from the plasma source into the vacuum vessel at the start of discharge by the plasma source. After the transition from the glow discharge to the arc discharge, a plasma generation method for supplying an argon carrier gas instead of a hydrogen carrier gas or a helium carrier gas is obtained.

According to the present invention, there is provided a plasma generating apparatus for supplying an argon carrier gas from a plasma source into a vacuum vessel by a main gas supply means and generating plasma in the vacuum vessel by the plasma source. A plasma generator is provided that includes a sub-gas supply unit that supplies a gas or a helium carrier gas from a plasma source into the vacuum vessel, and a gas supply control unit that controls operations of the main gas supply unit and the sub-gas supply unit.

Further, according to the present invention, in the above-described plasma generator, the plasma source is of a pressure gradient type,
A plasma generator is generated in which plasma is generated as sheet plasma.

[0014]

In the plasma generator of the present invention, separate carrier gases are supplied from the plasma source into the vacuum vessel by two types of needle valves, which are divided into a main gas supply unit and a sub gas supply unit. The two needle valves are independently controlled by a flow rate control mechanism (mass flow controller) as gas supply control means. One flow control mechanism is a hydrogen carrier gas or a helium carrier which is a light mass gas from a gas inlet of a pressure gradient plasma gun as a plasma source via a needle valve as a sub-gas supply means connected thereto at the start of discharge. Glow discharge is performed by supplying gas into the vacuum vessel. Since these hydrogen carrier gas and helium carrier gas have a small sputtering action, the cathode portion is less likely to be contaminated. The other flow control mechanism, after the transition from the glow discharge to the arc discharge during the progress of the discharge, when the discharge voltage drops sufficiently, through the needle valve as the main gas supply means connected to the pressure gradient plasma An argon carrier gas, which is a heavy gas, is supplied into the vacuum vessel from the gas inlet of the gun instead of the hydrogen carrier gas or the helium carrier gas.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below in detail with reference to the drawings.

First, an outline of a plasma generation method will be briefly described. According to the present invention, in an existing plasma generation method in which an argon carrier gas is supplied from a plasma source into a vacuum vessel and plasma is generated by the plasma source in the vacuum vessel, hydrogen is generated at the start of discharge by the plasma source (at the time of initial ignition). A carrier gas or a helium carrier gas is supplied from the plasma source into the vacuum vessel to cause glow discharge. When the discharge voltage is sufficiently reduced after the transition from the glow discharge to the arc discharge, the hydrogen carrier gas or the helium carrier is supplied. An argon carrier gas is supplied from the plasma source into the vacuum vessel instead of the gas. Here, the hydrogen carrier gas or the helium carrier gas supplied at the start of the discharge facilitates the ignition of the discharge.

Therefore, this plasma generating method can be applied to a plasma generating device such as an ion plating device.

Therefore, a more specific description will be given with reference to a side sectional view of an ion plating apparatus which is an embodiment of the plasma generating apparatus of the present invention shown in FIG.

The ion plating apparatus has a gas supply port E for supplying a reaction gas while the inside thereof is maintained in a vacuum atmosphere.
And a crucible 2 provided in the vacuum vessel 10 for dissolving and evaporating the filled material.
And a substrate 4 disposed at a predetermined position in the vacuum vessel 10 and to which film-forming material particles generated by evaporation and ionization of the material are attached.

The vacuum vessel 10 is provided with a mounting port F, and the mounting port F is provided with a cathode portion 1a, a permanent magnet 1b, and a ring-shaped electromagnetic coil 1c which are opposed to each other at a predetermined interval. At the same time, the plasma beam generated by the cathode portion 1a is converged between the permanent magnet 1b and the electromagnetic coil 1c, and the beam is formed into a sheet shape by the pair of magnets 3 and 3 '. Crucible 2 in container 10
Is mounted with a pressure gradient plasma gun 1 for generating a sheet plasma P. Note that an electromagnetic coil 6 for guiding the sheet plasma P is provided near the mounting port F outside the vacuum vessel 10.

Further, the crucible 2 and the pressure gradient plasma gun 1
A discharge circuit 100 for supplying power to the crucible 2 and the pressure gradient type plasma gun 1 is connected to the power supply unit. Note that the vacuum vessel 10 is provided with a gas exhaust port H. Here, the crucible 2 is electrically formed on the anode.

In addition, the pressure gradient plasma gun 1 has a gas inlet D for introducing a helium carrier gas as a light mass gas and an argon carrier gas as a heavy mass gas.
It has. The argon carrier gas and the helium carrier gas are stored in an argon gas tank 7 and a helium gas tank 8, respectively. These gases are supplied from the gas inlet D of the pressure gradient plasma gun 1 via the flow rate control mechanisms 9a and 9b as gas supply control means and the needle valves 5a and 5b as gas supply means, respectively.
0 is supplied.

That is, in the ion plating apparatus which is an example of the plasma generating apparatus of the present invention, two systems of needle valves 5a and 5b are separately provided from the pressure gradient plasma gun 1 as a plasma source into the vacuum vessel 10 by two systems. A carrier gas is supplied, and the two systems of needle valves 5a and 5b are independently controlled by flow control mechanisms 9a and 9b such as a mass flow controller.

The state of transition of discharge in the ion plating apparatus will be specifically described. First, at the start of discharge, one of the flow control mechanisms 9b is connected to a pressure gradient through a needle valve 5b as auxiliary gas supply means connected thereto. A helium carrier gas is supplied into the vacuum vessel 10 from a gas inlet D of the plasma gun 1. Thereby, glow discharge is performed by the pressure gradient type plasma gun 1. However, at this time, the needle valve 5a is closed and stopped without supplying the argon carrier gas.

Next, when the discharge proceeds and the transition from the glow discharge to the arc discharge starts, the other flow control mechanism 9a is connected to the gas inlet D via a needle valve 5a as a main gas supply means connected thereto. An argon carrier gas is gradually supplied into the vacuum vessel 10 instead of the helium carrier gas. Thus, after the transition to the arc discharge completely, only the argon carrier gas is supplied. In this state, the needle valve 5b is closed and the helium carrier gas is stopped without being supplied.

As described above, when the state is changed from the glow discharge to the arc discharge, the flow rate control mechanism 9b gradually stops the supply of the helium carrier gas.
The flow control mechanism 9a gradually starts supplying the argon carrier gas and switches from the helium carrier gas to the argon carrier gas so that the arc discharge is stabilized.

In the ion plating apparatus having such a configuration, when electric power is supplied to the crucible 2 and the pressure gradient plasma gun 1 by the discharge circuit 100, the sheet plasma P is generated in the vacuum vessel 10 and the material is vaporized. The vapor thus formed is ionized in the sheet plasma P to generate film-forming material particles. As a result, the film-forming material particles adhere to the surface of the substrate 4 to form a thin film.

By the way, in the case of this ion plating apparatus, as described above, a helium carrier gas is supplied from the gas inlet D of the pressure gradient plasma gun 1 at the time of discharge ignition to perform a glow discharge, and an argon carrier Since the arc discharge is performed by switching to the gas, the shape of the sheet plasma P is always stably and uniformly adjusted. As a result, the cathode portion 1a is less likely to be sputtered by gas ions in a discharged state, and does not cause discharge unevenness, so that a thin film having a uniform thickness can be formed on the surface of the substrate 4.

Although the ion plating apparatus of the embodiment employs a pressure gradient plasma gun system, an equivalent effect can be obtained by using an HCD system instead.
The same effect can be obtained by using a hydrogen carrier gas instead of a helium carrier gas. Further, a hearth may be used instead of the crucible 2. In addition, in plasma generators other than ion plating equipment,
The configuration of the present invention is applicable. Therefore, the present invention is not limited to the embodiments.

[0030]

As described above, according to the present invention, at the start of discharge (at the time of initial ignition), a light mass helium carrier gas or hydrogen carrier gas is supplied from a plasma source into a vacuum vessel to perform glow discharge. When the discharge progressed from glow discharge to arc discharge, the argon gas was switched to a heavy argon carrier gas, so the glow discharge at the start of discharge by the pressure gradient plasma gun was stably obtained, and the cathode part was contaminated. Will not be done. In addition, since an arc discharge can be stably obtained during the progress of the discharge, a uniform plasma can be obtained in the vacuum vessel. As a result, a plasma generation method and a plasma generation method capable of improving the durability of a plasma source and generating plasma in a stable and uniform state are realized. In particular, when it is difficult for the cathode part to be sputtered by gas ions in a discharged state, plasma is generated without generating discharge unevenness. Therefore, when this plasma generator is used as an ion plating apparatus, a uniform film thickness is formed on the surface of the substrate. This has a special effect that a thin film can be formed.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a basic configuration of an ion plating apparatus which is one embodiment of a plasma generator of the present invention.

FIG. 2 is an enlarged sectional view showing a cathode portion of a pressure gradient plasma gun provided in a conventional plasma generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure gradient type plasma gun 1a Cathode part 1b Permanent magnet 1c, 6 Electromagnetic coil 2 Crucible 3, 3 'magnet 4 Substrate 5a, 5b Needle valve 7 Argon gas tank 8 Helium gas tank 9a, 9b Flow control mechanism 10 Vacuum container 100 Discharge circuit D Gas introduction port E Gas supply port F Mounting port H Gas exhaust port P Sheet plasma

Claims (3)

(57) [Claims] 1. A plasma generating method for supplying an argon carrier gas from a plasma source into a vacuum vessel and generating plasma by the plasma source in the vacuum vessel, wherein a hydrogen carrier gas or a helium carrier is used at the start of discharge by the plasma source. A glow discharge is performed by supplying a gas from the plasma source into the vacuum vessel, and after the glow discharge shifts to an arc discharge, the argon carrier gas is replaced with the hydrogen carrier gas or the helium carrier gas. A plasma generation method, characterized by supplying. 2. A plasma generating apparatus for supplying an argon carrier gas from a plasma source into a vacuum vessel by a main gas supply means and generating plasma from the plasma source in the vacuum vessel, wherein a hydrogen carrier gas or a helium carrier gas is supplied. A plasma generator, comprising: a sub-gas supply unit that supplies the inside of the vacuum vessel from the plasma source; and a gas supply control unit that controls operations of the main gas supply unit and the sub-gas supply unit. 3. The plasma generator according to claim 2, wherein said plasma source is of a pressure gradient type, and said plasma is generated as a sheet plasma.