Two-dimensional hybrid simulation of dual-frequency capacitively coupled CF₄ plasma

A two-dimensional hybrid model is used to study the two-dimensional characters of the plasma parameter such as the ion flux, the ion energy and angular distributions in radial and axial directions. It shows that the electric field and the sheath character at the center of the electrode are different from those at the area between the electrode and the side wall. At the area between the electrode and the side wall, the influence of the electrode is relatively small, and the sheath structure is determined by the ambipolar diffusion. Therefore, the axial electric field is small, the radial electric field is relatively stronger, and the sheath near the side wall is much thinner than that in the center of the RF electrode. The ion flux and the ion energy distributions on the electrode remain the same at the center area of the discharge chamber, however, the electric field in axial direction decreases between the side wall and the edge of electrode, which leads to a decrease of the ion flux in this region. The ion angular distributions also have little change at the center area of the discharge chamber. However, the radial electric field becomes stronger than the axial field between the side wall of the chamber and the edge of the electrode. This makes the ions in that area strike the lower electrode with a much larger angle.