Synchronous plasma enhancement in RF-driven plasma source for ion implantation

We report an original method to increase periodically the plasma density in RF-driven plasma source for surface treatment of materials by ion implantation. The method consists of supplementary injection of ions, electrons and metastable atoms into the processing RF plasma using very short high voltage pulsed discharges applied on a separate electrode at the same repetition rate as the negative accelerating pulses applied on the target. Thus plasma density is periodically increased by an order of magnitude so that the synchronized negative pulses applied on the target for ion implantation find a background plasma about 10 times denser. The advantages of this new method were revealed by nitrogen implanted tests on copper and brass samples.