New line of high voltage high current pulse generators for plasma-based ion implantation

The two general specifications required for plasma-based ion implantation a re low pressure, large size plasmas and high voltage high current pulse gen erators. In addition, pulses with rise and fall times of the order of the i nverse ion plasma frequency and with much longer durations than those of th e inverse ion plasma frequency are most often required, To fulfill these re quirements, a new type of high voltage generator using a pulse transformer has been developed. A "mettglass"(R) magnetic core is used as step-up pulse transformer. Voltage at the primary is provided by transistor switches whi ch can achieve rise and fall times of less than 1 mu s and maximum pulse cu rrents of 100 A. The primary of the transformer consists of 96 turns wired in parallel and the secondary of 96 turns wired in series. The performances reported with this pulse generator were obtained on a test resistor and th en on a substrate immersed in a plasma. (C) 1999 American Vacuum Society. [ S0734-211X(99)02402-6].