Particle-in-Cell/Monte Carlo simulation of CF4 discharge in capacitively coupled plasma reactor
We present the structures of the CF4 radio-frequency discharge between parallel electrodes using the Particle-in-Cell/ Monte Carlo method. The simulation takes into account four types of charged species, CF3 , CF − 3 , F − ions, and electrons. The cross-sections of electron-CF4 collision processes are based on the paper of Kurihara et al. [1]. Positive–negative ion recombination which plays an important role in the charged particle balance is also considered in the model using method proposed by Nanbu and Denpoh [2]. The structure of the CF4 discharge is typically electronegative discharge and is characterized by the presence of negative ions (F− and CF3 ), which are the dominant negative charged species (see Fig. 1(a)). The electron density profile and electric field at phase in a rf period are shown in Fig. 1. The local maxima of the electron density is significant feature of electronegative discharges, which cannot be observed in electropositive discharges. Moreover, we can observe the double-layer structure (i.e. the local maxima or minima of the electric field) and the field reversal near the bulk-sheath interface. Historically, the double layer phenomena were first described experimentally and theoretically in rf glow SiH4 discharge by T. Makabe et al. [3]. In conclusion, the abundance of negative ions is one of the main features in the discharges and this profoundly influences the sheath dynamics such as electric field reversal, double layer structure and local maxima of electron density.
Influence of negative ions in rf glow discharges in SiH4 at 13.56 MHz.
Etude experimentale menee par spectrometrie d'emission spatiotemporelle et etude theorique menee avec le modele de continuum relaxationnel
Structures of Velocity Distribution Functions and Transport Parameters of the Electron Swarm in Ch4 in a Dc Electric Field
The structure of each term in the density gradient expansion of the velocity distribution function of an isolated electron swarm has been investigated in a DC field by a numerical analysis using a finite element Boltzmann equation method. The electron swarm parameters, including the dissociation rate in CH4, have been calculated over a wide range: 0.1