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Plasma Etching of Si in SF6/O2 and NF3/O2 Mixtures: Computer Simulations And Experimental Results.

Published online by Cambridge University Press:  28 February 2011

Harold M. Anderson ,
Bradley K. Smith  and
Ron W. Light
Harold M. Anderson
Affiliation:
University of New Mexico, Department of Chemical and Nuclear Engineering, Albuquerque, New Mexico 87131
Bradley K. Smith
Affiliation:
University of New Mexico, Department of Chemical and Nuclear Engineering, Albuquerque, New Mexico 87131
Ron W. Light
Affiliation:
Sandia National Laboratory, Albuquerque, New Mexico 87185
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Abstract

Profile control in polysilicon etching with SF6/O2 and NF3/O2 gas mixtures has been explored as a function of feed gas composition, power, pressure and total flow.Polysilicon appears to etch anisotropically under certain anomalous combinations of these parameters, such as high power/dilute etchant gas composition, low power/high etchant gas composition and high power/high etchant gas composition.Very rapid etch rates (3.5 μm/min) and anisotropic etching were obtained simultaneously in SF6/O2 mixtures at 250 mtorr.In order to provide a rational for explaining these anomalies, a kinetic model for these plasmas has been developed which couples electron impact events in the plasma to gas-phase chemistry and surface reactions of the etching process.Peculiarities in the electron energy distribution function (EEDF) of these gas mixtures, determined by Boltzmann calculations, appear related to the anisotropy under dilute conditions.However, anisotropic etching observed at 250 mtorr and rich SF6 gas mixtures appears more related to anomalies in power deposition to the discharge, possibly including wave interactions or resonant processes.Comparisons between computer simulations and experimental results are presented.

Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 68: Symposium C – Plasma Processing , 1986 , 273
Copyright
Copyright © Materials Research Society 1986

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