Diagnostics of an inductively coupled CF4/Ar plasma

Experimental data for radiative and metastable state densities in pure argo n and in mixture of 5% CF4 in argon are obtained to study the effect of CF, on kinetics of inductively coupled plasma (ICP). The measurements were mad e by a combination of optical emission spectroscopy and computer tomography for radiative levels and by laser absorption for metastable state profiles , The data were obtained in an inductively coupled rf (13.56 MHz) plasma wi th a single coil and full cylindrical symmetry. At low pressures of 5 and 1 5 mTorr the data in pure argon and in the mixture do not differ much, both in the magnitude and in the radial and axial profiles. However, at 50, 100, and 300 mTorr there is a dramatic change when CF4 is introduced. The metas table density increases due to the smaller electron induced quenching while axial and radial profiles are quite different. Unfortunately introduction of CFS spoils the degree of azimuthal isotropy. The observed results and ex planations based on the important role of metastables and stepwise processe s in kinetics of high electron density ICP are supported by measurements of plasma density by using a double probe. (C) 2000 American Vacuum Society. [S0734-2101(00)01303-8].