Thermal control is provided for an extraction
electrode of an
ion-beam producing
system that prevents formation of deposits and unstable operation and enables use with ions produced from condensable vapors and with
ion sources capable of cold and hot operation. Electrical heating of the extraction
electrode is employed for extracting
decaborane or octadecaborane ions.
Active cooling during use with a hot
ion source prevents
electrode destruction, permitting the extraction electrode to be of heat-conductive and
fluorine-resistant aluminum composition. The service lifetime of the
system is enhanced by provisions for in-situ etch cleaning of the
ion source and extraction electrode, using reactive
halogen gases, and by having features that extend the service duration between cleanings, including accurate vapor flow control and accurate focusing of the
ion beam optics. A
remote plasma source delivers F or Cl ions to the de-energized
ion source for the purpose of cleaning deposits in the
ion source and the extraction electrode. These techniques enable long equipment uptime when running condensable feed gases such as sublimated vapors, and are particularly applicable for use with so-called cold ion sources and universal ion sources. Methods and apparatus are described which enable long equipment uptime when
decaborane and octadecaborane are used as feed materials, as well as when vaporized elemental
arsenic and
phosphorus are used, and which serve to enhance beam stability during
ion implantation.