IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Plasma Science Tuesday Sessions
       Session PS1-TuM

Paper PS1-TuM9
Measurements and Models of Ion Energy Distributions in High-Density, Radio-Frequency-Biased CF@sub 4@/Ar Discharges

Tuesday, October 30, 2001, 11:00 am, Room 103

Session: Diagnostics II
Presenter: M.A. Sobolewski, National Institute of Standards and Technology
Authors: M.A. Sobolewski, National Institute of Standards and Technology
Y. Wang, National Institute of Standards and Technology
A.N. Goyette, National Institute of Standards and Technology
Correspondent: Click to Email
Ion dynamics in the narrow sheaths of high-density plasmas, especially in sheaths biased by radio-frequency (rf) voltages, are complicated and nonlinear. Models of such high-density, rf sheaths are needed to predict ion bombardment energies in simulations of high-density plasma etching. To provide data to test these models, we have measured ion energy distributions (IEDs) in CF@sub 4@/argon discharges in a high-density, inductively coupled plasma reactor, using a mass spectrometer equipped with an ion energy analyzer. Energy distributions of CF@super +@, CF@sub 2@@super +@, CF@sub 3@@super +@, and Ar@super +@ ions were measured as a function of pressure, mixture, inductive source power, rf bias frequency and rf bias amplitude. Simultaneous measurements by a capacitive probe and a Faraday cup provide enough information to completely determine the input parameters of sheath models and allow direct comparison of calculated and measured IEDs. For conditions where the rf bias period is much smaller than, or much larger than, the time it takes ions to cross the sheath, very simple models are able to predict the features of the measured IEDs. When the rf bias period approaches the ion transit time, however, more complicated models are required. One recently developed model@footnote 1@ which include a complete treatment of the time-dependent ion dynamics in the sheath, was found to accurately predict the behavior of measured IEDs over the entire range of rf bias frequency. @FootnoteText@ @footnote 1@M. A. Sobolewski, Phys. Rev. E 62, 8540 (2000).