PLASMA IMMERSION ION-IMPLANTATION USING PULSED PLASMA WITH DC AND PULSED HIGH VOLTAGES

New experiments in plasma immersion ion implantation (PIII) were perfo rmed to explore the extended operation regimes available with pulsed p lasmas. A pulsed extraction voltage and a synchronized pulsed plasma s how a further reduction of thermal load, more stable operation and imp roved implantation results. It was even possible to run PIII in a mode with pulsed plasma and a d.c. voltage, omitting the costly high volta ge modulating unit. Time resolved measurements of plasma density and e lectron temperature were performed to get information about the plasma build-up and decay process. In all cases a space charge sheath forms around the sample across which the ions are accelerated. The extension of the sheath was measured using time resolved Langmuir probe measure ments. Iron and aluminium samples were implanted with nitrogen using a d.c. plasma/pulsed extraction voltage; pulsed plasma/pulsed extractio n voltage; and pulsed plasma/d.c. extraction voltage. Analysis of the treated samples showed that in all cases nitrogen was implanted. (C) 1 997 Elsevier Science S.A.