| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | Sebastian Mohr, Quantemol Ltd, UK |
| Authors: | S. Mohr, Quantemol Ltd, UK J.R. Hamilton, University College London, UK A. Asokan, University College London, UK J.C. Tennyson, University College London, UK |
| Correspondent: | Click to Email |
Discharges in reactive gases such as SF6 and C4F8 are commonly used for industrial etching and deposition processes. The necessary surface reactions are induced by the free radicals in these discharges which are created by electron impact and heavy particle collisions. The process speed is thus usually determined by the densities of the free radicals, a prior knowledge of these densities and their dependence on parameters such as the pressure, input power or the gas composition is desired.
Numerical simulations of reactive gas discharges are employed to systematically study the chemical reaction rates and particle densities as functions of the aforementioned parameters. Furthermore, a reliable set of rate coefficients or cross sections for the included reactions are needed.
Quantemol-N, which provides full accessibility to the well-known UK molecular R-matrix codes [1], is used to model electron polyatomic molecule interactions including those with radicals. A wide range of cross-sections, otherwise not available experimentally are calculated for the required plasma chemistries. An expert system, Quantemol-VT, based on the Hybrid Plasma Equipment Model (HPEM) [2] is then used to model plasma tool on a reactor scale.
We provide results of a systematic study of an C4F8 discharge which is commonly used for deposition during the Bosch process. This study further compares the effect of including cross sections calculated with Quantemol-N against use of datasets comprising only known and commonly used cross sections taken from experimental studies. A plasma model of the discharge in a GEC cell is provided for a plasma chemistry containing CxFy radical reactions (calculated with Q-N) and without. The two models are compared and the role of CxF y radicals in plasma processing is highlighted.
[1] Tennyson, J., Brown, D., Munro, J., Rozum, I., Varambhia, H. and Vinci, N. (2007). Quantemol-N: an expert system for performing electron molecule collision calculations using the R-matrix method. 86(1), p.012001.
[2] Kushner, M. (2009). Hybrid modelling of low temperature plasmas for fundamental investigations and equipment design. Journal of Physics D: Applied Physics, 42(19), p.194013.