ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
The Calutron-Bernas ion source has been modified for high-dose ion implantation (〉1016 ions/cm2). The modified ion source has stable arc, uniformly bright illumination, and dense plasma. It consists of a hairpin-shaped tungsten (W) filament as a hot cathode at one end, and a disk-type graphite anode at the other end about 8 cm away; both the electrodes are fitted in an arc discharge chamber made of graphite only. The anode potential of 150–200 V and filament current of about 60 A initiates a stable bright arc. A magnetic field (0.1–0.5 kG) along the cathode-anode axis enhances the electron ionizing efficiency, helps in collimating the electrons, and contributes also in the plasma confinement near the aperture. The operational life of W filament (1.2 mm diam) in an ambient of oxygen or nitrogen at pressure 10−3–10−4 Torr varies from 25 to 35 h. Further, a needle valve or an in-built minioven is used, respectively, when the feed material is a gas/liquid or a solid charge. The gas/vapors is/are admitted at a proper location into the arc chamber so as to be conducive for the generation of high-density plasma. One rectangular face of the arc chamber (graphite box) is provided with an aperture (8 cm×0.2 cm) for lateral extraction of ions. For most elements, the extracted ion beam that is subsequently accelerated through a mass analyzing 60° magnetic sector is quite intense at the target; the nitrogen ion-beam current has been achieved up to 60 μA/cm2. Consequently, high-dose implantation ((approximately-greater-than)1017 ions/cm2) of singly charged 30-keV ions has been carried out for surface modification of materials.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1141228
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