A COMPACT ELECTRON-CYCLOTRON-RESONANCE PROTON ION-SOURCE

The demand has increased for a high-current, long lifetime ion source in various fields of application. The present work concerning the prod uction of atomic hydrogen ions H+ in competition with molecular ions H -2(+) has been essentially motivated by recent trends in the field of passivation of silicon [V. ie Thanh, M. Eddrief, and C. A. Sebenne, Ap pl. Phys. Lett. 64, 3308 (1994)]. For a given low neutral energy, pass ivation with a neutral atomic beam H instead of H, is preferred. The m ost straightforward method to produce the neutral beams is by the extr action of low energy atomic ions, and neutralization by electron captu re. We have thus developed an electron cyclotron resonance coaxial hyd rogen ion source that produces a 30-mm-diam ion beam, is operated with a microwave power in the range of 50-130 W, and has a pressure of neu trals in the range of 6X10(-4)-4X10(-3) mbar. We have compared the pro portion of extracted H+ and H-2(+), ions with the two principal parame ters of the plasma: the pressure of neutrals and microwave injected po wer. These parameters have been optimized for the production of an 83% atomic ion beam. (C) 1996 American Institute of Physics.