Special modulator for high frequency, low-voltage plasma immersion ion implantation

Plasma immersion ion implantation is a burgeoning surface modification tech nique and not limited by the line-of-sight restriction plaguing conventiona l beam-line ion implantation. It is therefore an excellent technique to tre at interior surfaces as well as components of a complex shape. To enhance t he implant uniformity and increase the thickness of the modified layer, we are using a high frequency, low-voltage process to achieve high temperature and dose rate to increase the thickness of the modified layer. The low vol tage conditions also lead to a thinner sheath more favorable to conformal i mplantation. In this article, we will describe our special modulator consis ting of a single ended forward converter with a step-up transformer. The mo dulator is designed to operate from 5 to 35 kHz and the output voltage is a djustable to an upper ceiling of 5000 V that is deliberately chosen to be o ur voltage limit for the present experiments. We will also present experime ntal data on SS304 stainless steel materials elucidating the advantages of our modulator and high frequency, low-voltage experimental protocols. (C) 1 999 American Institute of Physics. [S0034-6748(99)00803-5].