Europhys. Lett.
Volume 75, Number 1, July 2006
Page(s) 63 - 69
Section Physics of gases, plasmas and electric discharges
Published online 24 May 2006
Europhys. Lett., 75 (1), pp. 63-69 (2006)
DOI: 10.1209/epl/i2006-10068-x

Numerical study of dual-frequency capacitively-coupled discharges in electronegative $\chem{SF_{6}}$

L. Z. Tong and K. Nanbu

Institute of Fluid Science, Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

received 14 March 2006; accepted in final form 3 May 2006
published online 24 May 2006

Discharge structures and properties of dual-frequency capacitively-coupled plasma (CCP) discharges in SF6 are studied by using a one-dimensional Particle-in-Cell/Monte Carlo (PIC/MC) method. The simulations are carried out at a gas pressure of 25 $\un{mTorr}$ for a fixed low-frequency (LF) source of 3.2$\un{MHz}$ and a high-frequency (HF) source of 27-50$\un{MHz}$. Results show that in dual-frequency discharges both sources nonlinearly interact even if the source frequencies are significantly different from each other (e.g., 3.2 and 50$\un{MHz}$). In the presence of the LF source, the electron density in the bulk plasma reduces in comparison with the density for the case without LF source. The non-equilibrium behavior between the electron-SF6 collisional ionization or attachment and density diffusion is found for a HF source frequency higher than 49$\un{MHz}$. The electron temperature in the bulk plasma is higher than 5$\un{eV}$, which sustains the discharge by compensating the loss of electrons due to strong attachment.

52.80.Pi - High-frequency and RF discharges.
52.35.-g - Waves, oscillations, and instabilities in plasmas and intense beams.

© EDP Sciences 2006