Development of a 200 kV high current accelerator with post acceleration mass analysis for O + implantation into silicon

Abstract

The formation of a buried insulating layer by oxygen ion implantation into silicon is a main contender for the bulk production of silicon on insulator material and has led to the development of dedicated implanters for the industry. To be economic, high currents of O + are required with good uniformity and impurity control. The beam system described here, which comprises the plasma source, ion accelerator and mass analyser, has been developed at Culham Laboratory for the OXIS 100 ion implanter in a collaborative programme with VG Semicon and Harwell Laboratory and with financial support from the Department of Trade & Industry. The key areas of development have been the large volume radio frequency plasma source with its inherent low impurity yield and long lifetime, the triode single stage accelerator providing multiple beamlets at energies up to 200 kV, and finally the double sector analysing magnet with short focal length to disperse the beamlets of the separated atomic oxygen ions over the wafer target.