By Topic

A Kinetic Model for Plasma Etching Silicon in a SF6/O2 RF Discharge

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)

Time-dependent Boltzmann electron distribution calculations have been made at constant power and pressure in a SF6/O2 plasma with a varying oxygen mole fraction. The results show that as the oxygen fraction increases in a SF6/O2 plasma, the number of high-energy electrons in the tail of the electron distribution and the mean electron energy both increase significantly while the plasma is kept at the same reduced electric field E/N. Rate coefficients have been computed for the electron kinetic processes of these plasmas and merged within a kinetic equilibrium model for the plasma etch process, including neutral gas-phase chemistry, ion chemistry, and surface reactions. Model simulations show good agreement with experimental results for SF6/O2 etching of polysilicon and demonstrate that the anisotropic character of dilute SF6 plasma etching is related to the shift in the electron distribution with increasing oxygen fraction. Competition between F and O species for adsorption to silicon etching sites is also shown to be a factor in determining etch rates, but this competition is not significant until very large (> 80 percent) oxygen concentrations are present. Ionization rates and ion transport to the surface are shown to be much more important. The model simulations provide a rationale for explaining the very high etch rates observed at low-SF6 partial pressures and the increasing anisotropic etch character with greater oxygen dilution of SF6.

Published in:

Plasma Science, IEEE Transactions on  (Volume:14 ,  Issue: 2 )