Negative Hydrogen Ions Produced by Electron Temperature Control in an RF Plasma

Abstract

The formation of negative hydrogen ions is investigated in a pure hydrogen RF plasma using a grid-method for electron temperature control. Using the grid method we produce both high and low electron temperature plasmas in the separated regions in the chamber, in which the electron temperature in the downstream region is controlled by the grid potential. The production rate of negative ions depends strongly on the grid potential. We observe efficient negative hydrogen ion production in the downstream region when the grid is negatively biased in the hydrogen pressure range of 2–5 mTorr.