Energy Distribution of Ions in Plasma Etching Reactors

Abstract

AbstractThe energy distributions of the positive ions bombarding the ground electrode in a parallel plate plasma etcher have been measured by means of an electrostatic analyzer after extraction through a 50 μm orifice.Three gases were studied; Ar, CF4 and SF6, with pressures varying from 5 mtorr to 200 mtorr as a function of the discharge frequency.In the low frequency regime (25–125 kHz) the maximum energy of the ions is close to the applied potential (i.e., 500–600 eV).A secondary ion peak is observed and attributed to the secondary electron ionization.SF6 plasma exhibits a behaviour different to that of Ar and CF4 plasmas because of the high electron attachment of the molecule.