Spatial variation of plasma parameters and ion acceleration in an inductive plasma system

Plasma parameters of inductively coupled plasma system with an annular plasma source have been studied experimentally. At low pressures (about 1 mTorr), electron temperature inside the plasma source is rather high (8-13 eV) and is much greater than in the diffusion (main) chamber (4-5 eV). The plasma potential inside the source is also much higher than in the main chamber. There is a rapid drop of the electron temperature and plasma potential at the boundary between the plasma source and the main chamber. The drop of the plasma potential at the boundary (about 20 V) means the existence of a strong axial electric field, which retards the electrons inside the plasma source and accelerates the ions from the source into the main chamber. Measurements of ion energy distributions in the main chamber volume reveal the existence of ions with kinetic energies about 15 eV. (c) 2006 American Institute of Physics.