JPS583578B2 - Ion beam generator - Google Patents

Description

[Detailed description of the invention] The present invention relates to an ion beam generator.

The above-mentioned ion beam generator pumps an inert gas such as argon (Ar) or helium (He) into a sealed high-vacuum (generally about 10-2 to 10-3 Torr) container, and electrodes are placed inside the container. This takes advantage of the fact that the gas turns into ions and electrons when discharged.

At this time, the ions are accelerated by the electric field and collide with the cathode, but at this time, a phenomenon occurs in which material on the surface of the cathode is thrown out (so-called sputtering phenomenon).

Therefore, for example, by placing a substrate on the cathode, the surface of the substrate is cleaned.

This is commonly known as ion bombardment.

Therefore, by melting and evaporating the metal or the like to be coated, the method can be applied to ionizing the metal and depositing it on a substrate to form a thin film pattern or the like.

Conventionally, as the above-mentioned ion beam generator, those using a high frequency discharge type, an electron balance type, a duo plasmatron, etc. are known.

In addition, the above-mentioned argon (Ar), helium (He)
When ionizing an inert gas such as gas, the above-mentioned high frequency discharge type is generally used.

However, this high-frequency discharge type has the disadvantage that the ion extraction system is complicated and large-scale, and the entire device becomes large because a magnetic field is used to focus the ionized material into a beam.

For this reason, the above-mentioned argon (Ar), helium (He)
) and other metal vapors into a beam shape and efficiently ionize them, there is a need for a device that has a simple structure and is miniaturized.

The present invention has been made in view of the above points, and includes an electron beam focusing electrode disposed in the gas inflow passage, and a thermoelectron emitted from a filament (cathode) in the gas inflow passage. It is an object of the present invention to provide an ion beam generator that can be simplified in structure and downsized by configuring the ion beam generator to concentrate the ion beam at one point on a focusing electrode.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The figure is a schematic cross-sectional view of the ion beam generator according to the present invention, and it goes without saying that the ion beam generator is housed in a sealed vacuum container, but the vacuum container is omitted in the figure.

Further, the inside of this vacuum container is maintained at a degree of vacuum of about 10 −5 Torr.

In the figure, reference numeral 1 denotes a pipe serving as a passage for gas flow, and it is disposed approximately in the center of this device.

A gas flow (or metallic gas flow) is fed into the pipe 1 from the inflow side P1, is ionized in the pipe 1 as described later, and is taken out as an ion beam from the discharge side P2.

Further, the vicinity of the discharge side of the pipe 1 is formed like a nozzle portion 2, so that the ions are formed into a beam shape without disturbing their flow.

Furthermore, an electron beam focusing electrode 4 is interposed in the pipe 1 to ionize the gas flow sent from the inlet side, and an electron beam focusing electrode 4 is inserted into the pipe 1 from a filament (cathode) 5 through an electron entrance 3 provided in the pipe 1. The emitted electrons are made to enter the pipe 1.

The filament 5 is arranged in an annular shape surrounding the electron entrance hole 3 provided in the pipe 1.

In addition, the electron beam focusing electrode 4 has a needle-like structure (the shape of an airplane wing) so as not to cause disturbance of the gas flow.
It is supported in the pipe 1 by an insulating stem 6, and the electrode needle 4A of the electron beam focusing electrode 4 is used to connect the pipe 1.
and the nozzle portion 2 of the pipe 1.

As described above, the emitted electrons from the filament 5 are incident into the pipe 1 through the electron entrance 3 of the pipe 1, but the mutual positional relationship between the filament 5 and the electron entrance 3 is The arrangement is such that thermionic electrons emitted from the electron beam go straight to the electron beam focusing electrode 4.

The above electron beam focusing electrode 4 and filament 5
are arranged by electrode plugs 7 and 8, respectively, connected by a socket 9, and fixed by a plug set screw 10.

In addition, 11 in the figure is a filament cover, and 12 is a water cooling pipe.

Therefore, in the device having the above structure, 10-5
Emitting thermionic electrons by heating the grounded filament 5 in a vacuum of Torr, and injecting the thermionic electrons into the pipe 1 through the electron entrance port 3 provided in the pipe 1,
By applying a bias voltage to the electron beam focusing electrode 4, which has a structure that does not cause disturbance of the gas flow, and striking the thermoelectrons from the filament 5, the gas flow is sent through the pipe 1 as a passage. is ionized.

That is, the thermoelectrons emitted from the filament 5 are concentrated on one point of the electron beam focusing electrode 4 disposed in the pipe 1, where the electron beam of the thermoelectrons having high density and high energy is focused. It is also possible that secondary electrons are emitted due to impact on the electron beam focusing electrode 4, but since a bias voltage of about 100 cm is applied to the electron beam focusing electrode 4, these secondary electrons are emitted from the electron beam focusing electrode 4. 4, a denser electron cloud is formed.

In this state (the vicinity of the electron beam focusing electrode 4 in the pipe 1 is in a high-density plasma state).

), ionization is efficiently promoted and the ionized gas is discharged from the nozzle portion 2.

In the above device, in consideration of the influence of heat radiation from the filament 5 on other parts of the vacuum system, the filament force bar 11 is water-cooled by a water cooling pipe 12, and the influence of the heat radiation from the filament 5 is is sufficiently prevented.

In addition, when accelerating ions from the ion source described above, it is possible to easily accelerate the ions by providing several stages of accelerating electrodes at the tip of the nozzle section 2 as necessary, and by arranging a focusing coil on the electrodes. By providing this, the ions can be easily focused.

The present invention is applicable not only to the above-mentioned ion beam generator, but also to an ion source such as an ion probe analyzer, and as an ion evaporation source.

For example, when the ion beam generator of the present invention is applied to the above-mentioned ion evaporation source, it can be used in a high vacuum state of 10-5 Torr or less, the mean free path of the ion beam is long, and the fidelity with the mask is high. Since it is thick, it is possible to form a fine pattern (such as a thin film pattern on a substrate) when performing ion deposition of metal vapor.

In addition, when ion deposition is performed on a substrate as described above, increasing the surface temperature of the substrate increases the adhesion of the ions, so that the light radiation emitted from the filament 5 of the device described above is By concentrating the ions on the surface of the substrate using a moving mirror or the like, the temperature of the surface of the substrate can be increased and good ion deposition can be performed.

Furthermore, when the ion beam generation source of the present invention is applied to high vacuum sputtering, an energy source for colliding high-density ions with a target and maintaining a local plasma state in a high vacuum of about 10-5 Torr is used. The focusing of the optical radiation of the filament 5 (light source) as described above is useful.

As described above, the present invention has a simple structure and small size, and can be used in high vacuum conditions of 10-5 Torr or less, and can be applied to ion evaporation sources, ion probe analyzers, sputtering, etc. It is possible to provide an ion beam generator that can easily generate an ion beam for dry etching.

[Brief explanation of drawings]

The figure is a schematic cross-sectional view showing the ion beam generator of the present invention. 1: Pipe, 2: Nozzle section, 3: Electron entrance, 4: Electron beam focusing electrode, 5: Filament.

Claims (1)

[Claims] 1. In an ion beam generator configured to ionize a gas flow flowing into a pipe into a beam shape, an electron beam focusing device having a needle-like electrode structure disposed in a flow path of the gas flow in the pipe; an electron injection aperture provided radially on the circumferential surface of the pipe at a position approximately in the center of the electron beam focusing electrode; The vicinity of the tip of the pipe where the electron beam focusing electrode having the needle-like electrode structure is disposed is formed into a nozzle shape, and the thermoelectrons emitted from the filament are An ion beam generating device characterized in that the impact is concentrated on one point of the electron beam focusing electrode from an entrance opening.