A global model of microwave induced hexametyhldisiloxane/oxygen coaxial surface wave discharge*

A volume-averaged global model is developed for a microwave induced coaxial hexamethyldisiloxane/oxygen surface wave discharge. Positive ion and neutral flux at the coaxial walls are analytically estimated [Efe Kemaneci et al 2017 J. Phys. D: Appl. Phys. 50 245203]. A total number of 1200 homogeneous and heterogeneous gas phase reactions are identified for a set of 100 different plasma species and implemented in the model. The simulation results are benchmarked against a variety of measurements for a variation of input power, pressure and oxygen to hexamethyldisiloxane flow ratios. An agreement is obtained between the simulation results and the measurements of electron temperature, electron density as well as of hexamethyldisiloxane, carbonmonoxide, carbondioxide and various hydrocarbon concentrations. Hexamethyldisiloxane, pentamethyldisiloxanyl, methane, carbonmonoxide, water, hydrogen and oxygen molecules are the most dominant species in the discharge. A significant amount of positive charge is formed by pentamethyldisiloxanyl ion (Si$_2$OC$_5$H$_{15}^+$) via electron impact dissociative ionization of the hexamethyldisiloxane molecule. Underlying reaction mechanisms in the plasma are identified and their relative contributions are quantified.