Radiant energy – Irradiation of objects or material – Irradiation of semiconductor devices
Patent
1997-06-20
1999-07-06
Berman, Jack I.
Radiant energy
Irradiation of objects or material
Irradiation of semiconductor devices
250423R, 31511181, H01J 3715, H01J 3708, H01J 2702
Patent
active
059200766
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to an ion beam apparatus for generating a beam of ions and in particular, but not limited to, an ion beam apparatus for use in an ion implanter.
DESCRIPTION OF THE PRIOR ART
A known apparatus used to generate a beam of ions for ion implantation is shown in FIG. 1. The beam generator is intended for use in an ion implanter, for example, as disclosed by Aitken in U.S. Pat. No. 4,847,504. The beam generator comprises an ion source 1 and a pair of electrodes 3 and 5 spaced from the ion source 1 and from each other along the beam line 8. The ion source 1 comprises a chamber 7 in which a plasma is generated. An aperture 9 is formed in the front face of the chamber 7 to allow ions to be extracted, and two sets of opposed apertures 4 and 6 are formed in the electrodes 3 and 5, each for defining the extraction optics for a particular range of extraction conditions. The electrodes 3 and 5 are spaced apart and electrically insulated from each other by a number of electrically insulating spacers 10. The ion source and electrodes are disposed within a vacuum chamber, and the electrode assembly is mounted on the arm 13 of an actuator, which extends through the wall 15 of the vacuum chamber and adjoins the electrode 5 which is furthest from the ion source 1. The arm 13 is coupled to the vacuum chamber wall 15 via bellows 17 so that the arm is free to move in three dimensions.
To generate an ion beam, the ion source is voltage biased relative to the electrodes, and ions are extracted from the ion source, accelerate towards the electrodes and pass through one of the sets of apertures 4 and 6. In the arrangement shown, the forward electrode 5 furthest from the ion source is maintained at ground potential, and the ion source 1 and the other back electrode 3 are voltage biased positively and negatively, respectively, relative to ground. The back electrode 3 closest to the ion source is generally known as the suppression electrode and serves to prevent electrons in the space forward of the electrode assembly, which are required to neutralise the ion beam, from being swept backwards to the ion source. The ion beam is tuned to the required energy and beam current by adjusting the voltage of the suppression electrode 2 and the ion source 1 and/or adjusting the size of the gap between the ion source and the electrodes, by means of the actuator. The position of the electrodes relative to the ion source is also adjusted to optically match the electrodes to the ion source.
One problem with this known arrangement is that the electrically insulating spacers 10 between the suppression and ground electrodes 3 and 5 breaks down in time as the surfaces of the insulating spacers 10 become electrically conductive due to the condensation of conductive particles, such as tungsten fluoride, on the surfaces from the ion source. In order to mitigate this problem, cylindrical shields 12, 14 are placed around each insulating spacer 10 to screen the insulating members from the gas flow and the surface material of the insulating spacers 10 has been carefully selected to reduce the rate of condensation as much as possible.
However, it has been found that when the gap between the electrode assembly and ion source is relatively small, the life of the insulator is dramatically decreased, in spite of the above measures, and in some cases has been found to drop from about 100 hours to only 7 hours.
Thus, it is an object of the present invention to provide an ion beam apparatus in which the duration of electrical insulation between the ion beam extraction electrodes by a given insulating member can be substantially extended as compared to the prior art.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided an ion beam apparatus comprising a source of ions, an evacuatable chamber, first and second electrodes disposed within said chamber for forming an ion beam from ions from said source, the first electrode being electrically insulated from the second electrode and inc
REFERENCES:
patent: 4187124 (1980-02-01), Muller et al.
patent: 4274004 (1981-06-01), Kanai
patent: 4580058 (1986-04-01), Mears et al.
patent: 4806769 (1989-02-01), Mori et al.
patent: 4843563 (1989-06-01), Takahashi et al.
patent: 4849901 (1989-07-01), Shimizu
patent: 4873467 (1989-10-01), Kaufman et al.
patent: 5036252 (1991-07-01), Lob
patent: 5096536 (1992-03-01), Cathey, Jr.
patent: 5164596 (1992-11-01), Noguchi et al.
patent: 5198677 (1993-03-01), Leung et al.
patent: 5229607 (1993-07-01), Matsui et al.
patent: 5317161 (1994-05-01), Chalupka et al.
patent: 5420415 (1995-05-01), Trueira
Nakao et al., "3-dimensional Handling in Nano Manufacturing World", pp. 273-275, 1993.
Pedersen et al., "Three-Stage Acceleration System for High Energy Implanter", Nuclear Instruments and Methods in Physics Research B6, pp. 258-263, 1985.
Burgin David Richard
Loome David
Povall Simon
Applied Materials Inc.
Berman Jack I.
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