NEGATIVE-ION SOURCE FOR IMPLANTATION AND SURFACE INTERACTION OF NEGATIVE-ION BEAMS

An rf-plasma-sputter type heavy negative-ion source can deliver a few mA to 12 mA of dc negative-ion currents such as boron, carbon, silicon, and copper negative-ion beams. These negative-ion currents are comparable with the positive-ion currents for conventional high current positive-ion implantation, and thus could be newly used in place of positive ions. Surface interaction of negative-ion beams is extremely distinctive when negative ions are implanted into insulated materials or insulators. The surface charge-up voltage of insulated materials by negative-ion implantation saturates at only several volts, so that no breakdown of insulators takes place. As a whole system, a negative-ion implanter without charge neutralizer would be simpler and more economical than a positive-ion implanter.