Plasma immersion implantation using pulsed plasma with DC and pulsed high voltages

New experiments in plasma immersion ion implantation (PIII)
have been performed to explore the extended operation regimes available
with pulsed plasmas. A pulsed extraction voltage and a synchronized pulsed
plasma show a further reduction of thermal load, more stable operation
and improved implantation results. It was even possible to run PIII in
a mode with pulsed plasma and a DC voltage; in this way omitting the costly
high voltage modulating unit. Time resolved measurements of plasma density
and electron temperature have been made to get information about the plasma
buildup and decay process. In all cases a space charge sheath forms around
the sample where the ions are accelerated. The extension of the sheath
has been measured using time resolved Langmuir probe measurements. Iron
and aluminium samples were implanted with nitrogen using a DC plasma and
pulsed extraction voltage, pulsed plasma and pulsed extraction voltage,
and pulsed plasma and a DC extraction voltage. Analysis showed that in
all cases nitrogen could be implanted.