ION ENERGY-DISTRIBUTIONS IN SICL4 AND AR/O2 DRY ETCHING DISCHARGES

Mass-resolved energy distributions (IEDs) are reported for a variety of ions striking the grounded electrodes of two dissimilar dry etching reactors operating at 13.56 MHz. All IEDs are recorded using the same electrostatic sector field energy analyser/quadrupole mass analyser combination. The chemistries studied are the etching of III-V multilayer structures in SiCl4 plasmas and photoresist removal in Ar/O2 Plasmas. Values for plasma potential are determined and contrasted with theoretical predictions. The predominantly collisionless IEDs show peak splittings in good agreement with an analytical model, from which the dependence on ion mass and sheath width are determined. A marked decrease in sheath width in O2 and SiCl4 plasmas compared with argon is inferred and attributed to the effect of negative ions.