JPH05290749A - Ion source - Google Patents

Abstract

PURPOSE:To suppress electrifying conductive dust so that the dust may be prevented from being transferred between every two ion beam drawer electrodes to lessen any opportunity of causing electric discharge by laying insulating films respectively on both or either of the mutually opposed faces of the ion beam drawer electrodes that draw out ion beams. CONSTITUTION:Insulating films 8 made of silicon nitride are laid respectively on both or either of the mutually opposed faces of every two of accelerating electrodes 2, decelerating electrodes 3 and earthing electrodes 4 respectively juxtaposed with one another. As a result of that, each of the insulating films 8 can suppress electrifying conductive dust so that any possibility of shuttling the conductive dust between every two electrodes may be lessened to lessen any opportunity of causing electric discharge even if a conductive target-material attached to each of the electrodes is peeled from the electrode to form the conductive dust by film stress. This can eliminate a problem of abnormal heating caused by applying ion beams to an object other than a target and the cause of contamination so that any possibility of striking ions against the decelerating electrodes and the earthing electrodes may be lessened to lengthen the life of each electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion source for reducing the discharge between ion beam extraction electrodes for extracting an ion beam.

[0002]

2. Description of the Related Art A conventional ion source will be described with reference to FIGS. In these figures, 1 is an ion beam extraction electrode group for extracting an ion beam from an ion emission source,
2, 3, 4 are acceleration electrodes, deceleration electrodes, which constitute the electrode group 1,
It is a ground electrode and is composed of a porous electrode or a single-hole electrode, and conductive molybdenum, carbon, or the like is used. An ion beam 5 of the inert gas extracted by the electrode group 1 sputters a conductive metal target.

[0003]

As described above, when the ion beam 5 sputters a conductive metal target, the sputtered target material often bounces and adheres to the extraction electrode group 1, as shown in FIGS. 4 and 5. As described above, the attached conductive target material 6 is peeled from the electrode 2 due to the film stress, and becomes the conductive dust 7. The conductive dust 7 reciprocates between the electrodes 2 and 3 under a high DC voltage, and triggers discharge to generate discharge.

This discharge has the following adverse effects. 1. The instantaneous ion beam 5 of the discharge cannot be extracted from the ion emission source, and the ion beam 5 that has passed through the electrode group 1 after the discharge is diffused and is irradiated to a place other than the required place, and abnormal heating of the irradiated place occurs. It causes contamination. 2. The discharge triggered the deceleration electrode 3 and the ground electrode 4 where current does not flow because ions do not hit much during normal operation.
The ions hit the electrodes and shorten the life of the electrodes 3 and 4.

3. There is a possibility that current control may be changed from voltage control to current control due to an excessive current flowing into the deceleration power supply through the deceleration electrode 3 due to discharge, and therefore the current rating of the deceleration power supply is changed to the current of the acceleration power supply. It is necessary to make it the same as the rating, and the deceleration power supply becomes expensive. The present invention has been made in consideration of the above points, and an object of the present invention is to provide an ion source that reduces the discharge in the ion beam extraction electrode group.

[0006]

In order to solve the above-mentioned problems, the ion source of the present invention is one in which both or one of the facing surfaces of the ion beam extraction electrodes arranged in parallel to extract an ion beam is covered with an insulating film. Is.

[0007]

The ion source of the present invention constructed as described above is
Since both or one of the facing surfaces of the ion beam extraction electrode is covered with the insulating film, it becomes difficult for conductive dust, which is a trigger for discharge, to reciprocate between the electrodes, and the trigger for discharge is reduced.

[0008]

EXAMPLES Examples will be described with reference to FIGS. 1 and 2. In these drawings, the same reference numerals as those in FIGS. 3 to 5 indicate the same or corresponding ones, and the difference from the conventional example is that the electrodes are covered with an insulating film 8 such as silicon nitride Si ₃ N ₄ . FIG. 1 shows an insulating film 8 covering both of the opposing surfaces of the acceleration electrode 2, the deceleration power supply 3 and the ground electrode 4 which are arranged in parallel, and FIG. 2 shows only the surface of the deceleration electrode 3 facing the acceleration electrode 2. The insulating film 8 is covered.

Therefore, even if the conductive target material 6 attached to the electrode is peeled off from the electrode due to the film stress and becomes the conductive dust 7, at least one of the opposing surfaces is covered with the insulating film, and thus the dust is removed. The inflow of charge to 7 is suppressed, the charging of the dust 7 does not proceed, the dust 7 rarely reciprocates between the electrodes, and the trigger of discharge is extremely reduced.

Since the trigger of discharge is reduced, the following effects are produced. 1. It operates normally, and the ion beam irradiates the part other than the target to eliminate the cause of abnormal heating and contamination. 2. The deceleration electrode 3 and the ground electrode 4 are less likely to be hit by ions, and the service life of the electrodes 3 and 4 is not shortened.

3. Even if discharge occurs between the electrodes, the deceleration electrode 3
The insulating film 8 reduces the amount of current flowing into the deceleration power supply, reduces the current rating of the deceleration power supply, and makes the deceleration power supply inexpensive.

Next, the experimental results will be described. When the ion beam is argon, the target is aluminum, and the acceleration current is 300 mA, in the case of the conventional non-insulating film, the maximum current of the deceleration electrode during discharge is 340 mA and the life of the electrode is 1
Although it was 000 hours, when one of the facing surfaces was covered with an insulating film, the maximum current was 120 mA and the life of the electrode was 5
When it is extended to 000 hours and both opposite surfaces are covered with an insulating film, the maximum current is 60 mA and the life of the electrode is 7
It grew to 000 hours.

[0013]

Since the present invention is configured as described above, it has the following effects. Ion source of the present invention, the conductive target material attached to the electrode coated with an insulating film on both or one of the facing surfaces of the ion beam extraction electrodes arranged in parallel to extract the ion beam, is peeled from the electrode due to the film stress, When it becomes conductive garbage 7,
Since at least one of the facing surfaces is covered with an insulating film, the inflow of charge into the dust, that is, the charge of dust can be suppressed, the dust does not reciprocate between the electrodes, and the discharge trigger is extremely high. Can be reduced.

[Brief description of drawings]

FIG. 1 is a cut front view of an embodiment of the present invention.

FIG. 2 is a cutaway front view of another embodiment.

FIG. 3 is a cut front view of a conventional example.

FIG. 4 is an enlarged view of a part of FIG.

5 is an enlarged view of a part of FIG. 4. FIG.

[Explanation of symbols]

 2 acceleration electrode 3 deceleration electrode 4 ground electrode 8 insulating film

Claims (1)

[Claims] 1. An ion source in which an insulating film is coated on either or both of opposing surfaces of ion beam extraction electrodes arranged in parallel to extract an ion beam.