A pulsed ion source by non metal shunting arc discharge

Abstract

The shunting arc is a pulsed arc discharge self-ignited in a low pressure gas without external trigger source. The majority ion species in the plasma produced by the shunting arc are determined by the material attached between the electrodes across which a voltage pulse is applied. Possible applications of the shunting arc to a pulsed ion source for plasma based ion implantation (PBII) will be discussed. It has been found that shunting arc discharges can be ignited with nonmetallic materials, such as carbon and silicon, over a wide range of parameters such as charging voltage of a capacitor for the arc discharge as well as environmental argon gas pressure. It appears to be the requirement for the arc to be ignited that the material is heated enough to attain the vapor pressure necessary for ignition. Visible light spectroscopy of the arc-produced plasma has shown that it contains an abundance of nonmetallic ions and neutrals from the material, depending upon the gas pressure. Ions are extracted from the plasma by applying a 7 kV, 10 /spl mu/s negative high voltage pulse to a target. It has thus been demonstrated that the shunting arc may be applied to a pulsed nonmetallic ion source for PBII.