AVS 50th International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuM

Paper PS-TuM9
Loss Kinetics of CF@sub x@ Radicals and F Atoms in the Afterglow of Inductively Coupled Pulsed Plasmas

Tuesday, November 4, 2003, 11:00 am, Room 314

Session: Plasma Diagnostics: Processing
Presenter: X. Wu, University of New Mexico
Authors: X. Wu, University of New Mexico
J.L. Cecchi, University of New Mexico
Correspondent: Click to Email
We have studied the time evolution of the concentrations of CF, CF@sub 2@, and F in inductively coupled pulsed (ICP) plasmas after the termination of the discharge. The feed gases included CHF@sub 3@ and C@sub 2@F@sub 6@, with additions of H@sub 2@and O@sub 2@, to vary the amount of radicals and F produced in the discharge. Our observations were made over the pressure range from 10 to 60 mTorr and for inductively coupled powers of 300 to 900 W. Concentrations were determined by time-resolved wavelength modulated diode laser absorption spectroscopy for the radicals and by time-resolved actinometry for F. The latter measurements were facilitated by maintaining a small amount of power on the wafer chuck after the termination of the ICP power pulse. CF and F both exhibited first order exponential decays. The decay rates of CF increased with increasing pressure, suggesting the presence of gas phase loss processes in addition to losses at surfaces. The decay rates of CF varied linearly with F concentration, indicating that the gas phase reaction is likely due to the recombination with F atoms. CF@sub 2@ exhibited second-order decay. Possible mechanisms for this will be discussed.