Enhanced Bernas ion source for the Varian EHP-500 medium-current ion implanter

The addition of a 15 A arc power supply and a switch for changing the source magnet field direction has greatly increased the current of multicharged ions and B/sup +/ for the new EHP-500 medium current ion implanter. The increased arc current allows the source to be operated at lower arc voltages to reduce sputter erosion of the filament. Reversing the direction of the source magnetic field improves the fraction of multicharged ions in the plasma; it doubles the current of B/sup ++/. Beam current specifications have increased by 200% for B/sup ++/, 33% for Be, and 150% more for P/sup ++/, P/sup +++/ and As/sup +/, each with similar or improved ion source lifetime compared to the E220/500HP model. The filament lifetime for other species will also be increased by using reduced arc voltages.