Effect of carrier gases on plasmas for oxide etching

Summary form only given. In the study, various plasma diagnostics were carried out in an inductively-coupled-plasma (ICP) oxide etcher at Applied Materials. The inductive power was coupled with two inductive-coils through a semiconducting roof. The plasma density was controlled by the source RF power with linear response over large range of power. The bias power was applied through a ceramic ESC that controls the DC bias therefore the ion energy. In order to achieve high selectivity, C/sub 4/F/sub 8/ gas was used as the main etching gas for it´s high C/F ratio. The C/sub 4/F/sub 8/ molecule can have multi-step dissociation resulting in very rich neutral and ionic spectra. Three carrier gases, He, Ar and Xe, were chosen as a vehicle to vary the plasma characteristics since they have very different ionization thresholds Ei and atomic mass (Ei/spl sim/24, 15 and 11 eV and M=2, 40 and 131 respectively).