A method of adjusting plasma processing of a substrate in a plasma reactor
having an electrode assembly. The method includes the steps of
positioning the substrate in the plasma reactor, creating a plasma in the
plasma reactor, monitoring optical emissions emanating from a plurality
of different regions of the plasma in a direction substantially parallel
to the surface of the substrate during plasma processing of the
substrate, and determining an integrated power spectrum for each of the
different plasma regions and comparing each of the integrated power
spectra to a predetermined value. One aspect of the method includes
utilizing an electrode assembly having a plurality of electrode segments
and adjusting RF power delivered to the one or more electrode segments
based on differences in the integrated power spectra from the
predetermined value. Another aspect of the invention includes altering
the flow of gas to different regions of the plasma in response to
differences in the integrated power spectra detected by the fiber optic
sensors. Several types of novel electrode assemblies suitable for
carrying out the method of the invention are also disclosed.