Plasma processing diagnostics play two different roles-characterizatio
n and control. The goal of plasma characterization is to establish con
nections of data with external parameters and to verify models. The go
al of control diagnostics is to make noninvasive in situ measurements
of relevant processing parameters. Diagnostics used in semiconductor e
tching are considered. These include Langmuir probes, laser induced fl
uorescence, optical emission spectroscopy, infrared and Fourier transf
orm infrared absorption spectroscopy, mass spectrometry, microwave int
erferometry, and radio frequency diagnostics. An example is given of t
he use of many diagnostics in characterizing SiO2 and Si etching by fl
uorocarbons. (C) 1997 American Institute of Physics.