Simulations of an Ar/HBr/O$_2$ microwave source etch process and the effect of SiBr and SiBr$_2$ cross-sections on computed etch-profiles

Electron--molecule scattering calculations are performed for SiBr and SiBr$_2$ using Quantemol-N.\footnote{J. Tennyson {\it et al}, J. Phys.: Conf. Ser., 86, 012001 (2007)} These cross-sections are then used to construct a set gas phase reactions for the plasma simulation. An etch-profile simulation is then performed using the Monte Carlo Feature Profile Model (MCFPM)\footnote{R. J. Hoekstra {\it et al}, J. Vac. Sci. Technol. A 15, 1913 (1997)} with inputs supplied by simulation of an Ar/HBr/O$_2$ plasma. Computed cross-sections include the total elastic cross-section, dissociative electron impact cross-sections, ionisation cross-sections and an estimate of the dissociative attachment cross-section. The use of Ar/HBr/O$_2$ chemistries have been studied previously\footnote{J. M. Lane {\it et al}, J. Vac. Sci. Technol. A 18, 188 (1999)}$^,$\footnote{S. A. Vitale {\it et al}, J. Vac. Sci. Technol. A, 19, 2197 (2001)} and a reduction in microtrenching was found when HBr was included. An analysis of the contribution of SiBr and SiBr$_2$ to the computed etch profile will be presented at the conference.