Ion Energy Distribution in a Radiofrequency C4F8

The dependence of ion energy distribution (IED) of a planar radiofrequency driven inductively coupled plasma source on pressure and power is analyzed by using a plasma monitor. The transition from capacitive coupling (E mode) to inductive coupling (H mode) is observed between 100 and 200 W for a C 4 F 8 gas pressure in the range from 0.8 to 8 Pa. In the H mode, the concentration of light ions is higher due to an increase in dissociation and ionization rate of C 4 F 8 . In the E mode, the IED consists of a large peak (around 20 eV) with an appearing saddle structure (0.8 Pa), whereas at higher pressure (8 Pa), the IED exhibits an important contribution near zero energy, indicating a collisional sheath. In the H mode, in most cases, the IED consists of one peak which is narrower for higher mass.