Experimental and Simulation study on discharge characteristics of low-pressure dual-frequency capacitively coupled Ar/O2 Plasma with High and low Frequency Power

Liang-Chao Wu, Gui-Qin Yin

The argon and oxygen mixed gases plasma were produced by using dual-frequency  capacitively coupled plasma((DF-CCP). The high frequency (HF) was 94.92 MHz and the radio frequency (LF) was 13.56 MHz. In experiments, the mixed Ar/O2  plasma with different discharged power of HF and RF were analyzed by optical emission spectroscopy (OES). The excited particle species were analyzed by optical emission spectroscopy, and the electron temperature was calculated by using the double line intensity ratio method. In simulation, the electron density, the potential and electric field distribution were obtained by a one-dimensional particle-in-cell with Monte Carlo collisions (PIC-MCC) method according to the experimental conditions. These results showed that under low pressure conditions (50 mTorr), the electron density increased with the HF power increase and decreased with the LF power increase. The electron temperature decreased with the HF power increase and increased with the LF power increase. As the LF power increases, the thickness of the sheath was widened, which would led the plasma discharge area to be reduced, electron density decreased, and electron temperature increased. The HF power had no big effect on thickness of the sheath. The numerical results were well agreed with the experimental phenomenon.