A dc-pulsed capacitively coupled planar Langmuir probe for plasma process diagnostics and monitoring

Abstract

An improvement to the RF-biased planar Langmuir probe technique proposed by Braithwaite et al (1996 Plasma Sources Sci. Technol. 5 67) is demonstrated, and applied to the case of an industrial CCP reactor. Compared with the RF-biased probe, the new technique uses dc pulses instead of RF bursts, which provides similar results but with simpler electronics. The ion fluxes determined by both techniques are compared under the same O2/Ar plasma conditions using available literature data for the RF-biased case. The data show not only the same trends but very close absolute values of ion fluxes for all studied plasma conditions after correcting for the chamber-area difference. Furthermore, the new technique has the additional benefit of providing information on the ‘electron transition region’ of the I–V curve, as well as allowing the resistance and capacitance of films deposited on the probe to be determined. Finally, both experimental data and numerical simulations of the I–V characteristics and the film parameters are presented for different oxidizing plasmas.