Radiant energy – Irradiation of objects or material – Ion or electron beam irradiation
Patent
1988-05-24
1990-07-17
Berman, Jack I.
Radiant energy
Irradiation of objects or material
Ion or electron beam irradiation
250423R, 2504541, 31511181, H01J 37317
Patent
active
049423045
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to apparatus for ion implantation.
THE PRIOR ART
Ion implantation is a process employed in the semiconductor industry for doping integrated circuits and semiconductor substrates. The process has been adapted to implant ions into engineering components since it has been found that for example the hardness and corrosion resistance can be increased and component wear can be reduced by implanting high energy ions into the surface.
Since it is essentially a line of sight process, problems can arise in implanting surfaces of engineering components as they often have projections or recesses so requiring complex manipulation in 3 dimensions so as to produce uniform or sometimes selective treatment under the beam.
The same problem hardly arises with semiconductor wafers since these mainly call for a predictable and uniform dose over each unit of the whole surface, thus requiring a programmed movement about cartesian or polar co-ordinates but essentially on the 2 dimensions of a plane surface.
Thus, with complex surfaces, merely rotating the component may not be sufficient to ensure proper treatment. In addition, heavy or large objects may add a further complication, in that it may not be practicable to manipulate them under the beam because of their sheer size or weight.
It is an object therefore of the present invention to provide an ion implantation apparatus which reduces such problems of treating 3 dimensional surfaces of engineering components.
SUMMARY OF THE INVENTION
The general concept of the invention is to provide ion implantation apparatus comprising a vacuum chamber and an ion source mounted within the chamber or outside the chamber in order to direct a beam of ions at an engineering component disposed within the chamber from various directions.
So as to improve the mobility of the ion source, it is connected to a flexible cable member which supplies electrical power at a high voltage and a flow of gas to be ionized within the ion source to produce the required ions. The single cable is the only item coupled to the ion source, and this makes it a relatively simple procedure to move the ion source.
Where the ion source is mounted against the outside of the chamber, it is preferably secured at a selected one of a plurality of possible positions in order to direct the beam from one of a plurality of alternative directions.
Where the ion source is mounted within the chamber, the ion source is desirably mounted on a mobile arm or boom within the vacuum chamber with the flexible cable extending through the wall of the chamber via a suitable entry point such as a bulkhead. Preferably, movement of the arm is remotely controllable, by a computer or manually (e.g., using a joystick), thus obtaining a robotic arm.
Clearly with such a cable, problems arise as to its connection with the ion source and in particular to ensuring an hermetic seal with the ion source robust enough to withstand the various stresses and strains set up during movement of the ion source and which will provide adequate electrical isolation under normal operating conditions. Further, it is desirable that the cable be easily disconnectable from the source in order, for instance, to permit checking at intervals for vacuum tightness of the various component parts or to facilitate its movement and relocation in another position.
Accordingly, therefore, in a first aspect of the invention there is provided ion implantation apparatus including a vacuum chamber, an ion source which can be selectively disposed at one of various positions on the housing of the chamber, and a flexible cable connected to the ion source, the flexible cable comprising first and second co-axial members, the first member being disposed within the second member, and the first member comprising a first relatively thin insulating tube member and a transmission and a return conductor for conducting electrical power at a high voltage to the source, and the first tube member being coupled to a source of gas so that gas for ioniz
REFERENCES:
patent: 3784858 (1974-01-01), Franks
patent: 4128765 (1978-12-01), Franks
Brochure describing "Tecvac 221 Ion Implanter," published by Tecvac Limited, Cambridge, England.
Berman Jack I.
Tecvac Limited
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