A High-Current Oxygen Ion Source

Production of buried oxide layers in silicon by ion implantation requires very high currents of atomic oxygen ions for an acceptable production rate of implanted wafers. A high-current dc ion source developed at Chalk River has been adapted for this application. Total beam current from the source was 230 mA at 52 keV with a 9.5 A arc. Based on the 60% O+ fraction, measured on a source with only three of a possible seven apertures open, up to 138 mA of O+ are available for implantation. Oxygen consumption ranges from 2-3 scc/min (3.4-5.1 Pa·L/s) at typical operating conditions, and filament lifetime from 10 to 15 hours. This paper describes the source and its performance. The source is presently in use on a commercial prototype high current oxygen implanter.