New Interpretation of the Mechanism for Etching Ti in a SF6 Plasma

Recent data and a mechanism for the etching of titanium in an SF ~ plasma by Reeves et al. are re-examined. Slight modifications to their mechanism are introduced, which yield an improved description of the pressure d pendence of the etch rate and the Ti atom concentration. Possibilities for further refinements are proposed, including the effects of RF power and ion bombardment. In spite of the widespread use of dry etching for the pat-terning of thin films in microelectronics fabrication, the etch mechanisms for many important processes are only incompletely understood. 1'2This is due to two kinds of difficulties in characterizing such processes. First, an etch-ing plasma is an extremely complex medium, consisting of numerous reactants and products, so that it is often difficult to obtain reliable diagnostics on all the relevant species. And second, it is difficult to set up a tractable model for the potentially arge number of important reac