Large-scale ferromagnetic enhanced Ar/Cl₂ ICP

A low frequency (100 kHz) ferromagnetic enhanced inductively coupled plasma (FMICP) source has been developed to obtain a large volume of dense Cl₂/Ar plasma. The influence of chlorine addition on the FMICP parameters was investigated both experimentally and numerically using a global (volume averaged) model of Ar/Cl₂ discharge. Radial distributions of the positive ions flux as well as the values of FMICP voltage were measured at a fixed FMICP current of 10 A for molecular chlorine concentrations of 0–4 vol%. Plasma species densities were calculated for various values of chlorine content of 0–4 vol% and absorbed power of 500–2000 W. The calculations showed that chlorine ion density exceeds argon ion density even at low chlorine content of about 0.5 vol%. While experimentally measured discharge voltage and power increased almost linearly up to 3 times with chlorine addition, the experimental and numerical data on plasma density demonstrated only a weak dependence on the discharge power. Thereby, at a fixed FMICP current the discharge power adjusts itself to keep plasma density at the same level even despite a significant change in plasma composition. (paper)