Influence of chamber scaling on different level polymerizing processing gases

We have previously examined influence of chamber scaling (both diameter and source to chuck gap) on fluorocarbon film deposition/etch for CF$_{4}$ plasmas$^{1, 2}$. In this paper, we extend those studies to more polymerizing fluorocarbon chemistry, C$_{4}$F$_{8}$. In CF$_{4} $ discharges, film growth on unbiased substrates go from deposition to etch as the source to chuck gap increases. In C$_{4}$F$_{8}$ discharges film growth occurs for all gaps and chamber diameters examined. It is found that ions play an important role in deposition with CF$_{4}$ but not with C$_{4} $F$_{8}$. This difference may be attributed to the structures of the parent gases. Dissociation of a C-C bond in C$_{4}$F$_{8}$ may result in an `unwrapping' of the cyclic structure. When this radical fills an open bond site on a surface, a new site is created. On the other hand, CF$_{3}$ will cap bond sites in CF$_{4}$ plasmas. Thus ion impact is required for site formation in CF$_{4}$ plasmas but not in C$_{4}$F$_{8}$ plasmas. \newline \newline $^{1)}$ EA Joseph, \textit{et al}., J. Vac. Sci. Technol. A 22 (3), May/Jun 2004 \newline $^{2) }$BS Zhou, et al., J. Vac. Sci. Technol. (submitted)