Charge Exchange Ion Energy Distribution at the RF Electrode in a Plasma Etching Chamber

Ar ion energy distribution affected by the charge exchange collision in a sheath was measured by an ion energy analyzer in the rf mode at the rf electrode in a plasma etching chamber. Dependence of the energy distribution on Ar gas pressure ranging from 1.4 to 19.3 mTorr was measured. Under high pressure, an extra peak in addition to the saddle-shaped peaks was observed, and the energy distribution of the ions in the low-energy region increased. These experimental features were adequately explained by a simple calculation model. We also calculated energy distributions of neutrals that were generated by the charge exchange collision, and suggested the connection of the high-energy neutrals with the plasma etching process.