JPH01274347A - Ion beam device - Google Patents

Abstract

PURPOSE:To reduce the pollution of a drawing electrode by disposing a movable shutter in a required position. CONSTITUTION:A movable shutter 7 is provided between the slit 1a of a metal vessel 1 containing a filament 2 and a drawing electrode 4. This shutter 7 is closed during drawing no ion but forming a plasma, so that it is polluted by the chemical reaction with a neutron emitted from the slit 1a, while the electrode 4 is not polluted. Thus, the electrode 4 is less polluted but at the time of ion drawing, and the maintenance interval for disassembly, cleaning and exchange of the electrode can be extended, resulting in an increase in availability of the ion beam device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion beam device equipped with a hot cathode type ion source used for ion implantation into bovine conductors.

[Conventional technology]

FIG. 3 shows the r4 configuration of a conventional hot cathode type ion source in an ion beam apparatus. FIG. 3(a) is a cross-sectional view, and FIG. 3(b) is a longitudinal sectional view. This ion source is widely used in ion implantation devices and is called a hot cathode PIG type or Freeman type. Reference numeral 1 denotes a hermetically sealed metal container which is formed into a rectangular tube shape and has a slot 7) la on its side wall surface, and is usually called an arc chamber. This metal container 1 has a filament 2 which is a hot cathode and is electrically insulated from the metal container 1 by penetrating in the axial direction through insulating bushings 3 attached to the center of each of the upper and lower wall surfaces.
It is equipped with The metal container 1 is housed in a vacuum container (not shown), and the inside thereof is maintained in a vacuum state via a pickpocket 7) la.

A current is applied to the filament 2 from a filament heating power source (not shown), and the filament 2 is heated to around 2000° C. to emit thermoelectrons. On the other hand, a DC power supply 11 is connected between the filament 2 and the metal container 1 to connect several wires with the polarity shown. A voltage of several hundred volts is applied. Then, thermionic electrons emitted from the filament 2 head toward the metal container 1 with an acceleration corresponding to this applied voltage. When plasma source gas is supplied into the metal container 1 by a gas supply means (not shown), thermionic electrons collide with the molecules of the source gas and ionize the gas molecules in an avalanche-like manner, causing an arc discharge to flow inside the metal container. A high-density plasma is generated. At this time, in order to increase the range of the accelerated thermoelectrons until they reach the metal container 1 and increase the ionization efficiency of the source gas molecules, the filament 2 is placed in the axial direction of the filament 2 in the metal container 1, that is, in the direction of the arrow 6. A magnetic field generating means is provided outside the vacuum container so that a magnetic field with a magnetic flux density of several tens to hundreds of Gauss in the direction is applied.

Ions in the plasma generated in this manner are applied from the slit la so that the metal container l5I11 becomes positive between the metal container 1 and the extraction electrode 4 arranged opposite to the slit la. The ion beam is extracted by a high-voltage electric field from a high-voltage DC power supply, becomes an ion beam 5, passes through the slit 4a of the extraction electrode 4, and heads toward the workpiece.

[Problem to be solved by the invention]

Problems with conventional ion beam apparatuses equipped with this type of hot cathode type ion source are as follows. That is, ions in the plasma are accelerated toward the filament, collide with the filament, and sputter the filament, so that neutral particles of the filament material (for example, tungsten W) are generated, and these neutral particles flow out from the slit. However, it adheres to and stains the extraction electrodes and nearby components. In addition, chemically active radicals in the plasma (for example, PH if the raw material gas is phosphine PH) also flow out from the slit and cause a chemical reaction and adhere to the extraction electrode and components in its vicinity. and deface it.

Hot cathode ion sources cannot prevent such phenomena from occurring during plasma generation. Therefore, when the ion beam device is operated for a long time, the extraction electrodes and the like become contaminated and a thin film is formed on their surfaces. This WI film peels off from time to time (with slight vibrations, etc.) When the thin film peels off, sharp parts such as steps are created, and the electric field is concentrated there. As a result, abnormal discharge occurs between the extraction electrode and the metal container. This occurs and interferes with the operation of the device.In order to prevent this abnormal discharge, it is necessary to periodically disassemble, clean, or replace the ion source and extraction electrode over a long period of time. Therefore, there was a problem that the operating rate of the ion beam device was low and the running cost was high.

It is an object of the present invention to provide an ion beam device equipped with a hot cathode type ion source that eliminates the above-mentioned conventional problems, has less contamination of the drawer Xa, etc., has a high operating rate, and has low running costs. .

[Means to solve the problem]

In order to achieve the above object, according to the present invention, plasma generated in a semi-hermetically sealed metal container having a slit on the wall and a filament inside the metal container is connected to the slit on the outside of the metal container. In an ion beam apparatus equipped with a hot cathode type ion source that draws ions out of the metal container to form an ion beam by applying a voltage between extraction electrodes arranged facing each other and the metal container. , a movable shutter is provided between the slit and the extraction electrode.

[For production]

In this way, in an ion beam device equipped with a hot cathode type ion source, a movable shutter is provided between the metal container and the extraction electrode, and the shutter is closed when plasma is being generated and ions are not being extracted. . When the ion beam device is operated with this configuration, plasma is generated and ions are generated! When it is not extracted, the shutter is only contaminated, but the extraction electrode etc. are not contaminated. Therefore, the extraction electrode etc. are contaminated only when ions are extracted. Therefore, the interval between maintenance such as disassembly and cleaning of the extraction electrode etc. can be extended, and it is possible to increase the operating rate of the ion beam device and reduce running costs.

〔Example〕

FIG. 1 shows the configuration of a hot cathode type ion source section of an ion beam apparatus according to an embodiment of the present invention. FIG. 1(a) is a cross-sectional view, and FIG. 1(b) is a longitudinal sectional view, and the same members as in FIG. 3 are given the same reference numerals and explanations are omitted. In this embodiment, the movable shutter 7 disposed between the lead electrode 4 and the lead electrode 4 of the metal container 1 is a rod 8 which is introduced from the outside of the vacuum container 9 into the vacuum container 9 in a sealed manner.
The vacuum chamber 9 can be driven in the direction of the arrow 10 from the outside of the vacuum container 9. The driving method is not limited to this embodiment. A cross-sectional view of the arrangement of the movable shutter 7 is shown in FIG. Here too, the same members as in FIG. 3 are given the same reference numerals and their explanations will be omitted. FIG. 2(a) shows the shutter position when plasma is generated and ions are not extracted. Such a case occurs, for example, in an OFF state when an ion implanter controls implantation into a workpiece by turning on and off a high voltage applied to the extraction electrode 4. By arranging the movable shutter 7 at this position, sputtered particles and radicals will not adhere to the extraction electrode 4 and the like. FIG. 2(b) shows the shutter position when plasma is being generated and ions are extracted. If the movable shutter 7 is moved to this position, the movable shutter 7 will not adversely affect the extraction of ions.

〔Effect of the invention〕

As described above, according to the present invention, since a movable shutter is disposed between the slit of the metal container and the extraction electrode, when plasma is generated and ions are not extracted, neutrals from the slit are removed. It is possible to prevent particles and radicals from flowing out, and it is possible to reliably reduce the formation of a thin film on the surface of the extraction electrode and components in its vicinity. Therefore, if the thin film peels off, the electric field will concentrate in that area, causing abnormal discharge and causing trouble in the operation of the ion beam device. Since maintenance intervals such as replacement of parts can be lengthened, the operating rate of the ion beam device can be increased and running costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a hot cathode type ion source section of an ion beam apparatus according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a cross-sectional view.
) is a longitudinal cross-sectional view, and Figure 2 is a cross-sectional view of a typical shutter arrangement; (a) is a case in which ions are not extracted; (b)
When extracting ions, FIG. 3 is a block diagram of a conventional hot cathode type ion source section of an ion beam apparatus, in which (a) is a cross-sectional view and (b) is a vertical cross-sectional view. 1: Metal container, 1a Nislit, 2: Filament, 4
: Extraction electrode, 7: Movable shutter. ta slit i2 section

Claims (1)

[Claims] 1) In an ion beam device comprising a metal container having a filament inside and a slit on the wall, and an extraction electrode provided on the outside of the metal container facing the slit, the slit and the extraction electrode An ion beam device characterized by having a movable shutter between.