Use of the ultraviolet absorption spectrum of CF ₂ to determine the spatially resolved absolute CF ₂ density, rotational temperature, and vibrational distribution in a plasma etching reactor

The CF ₂ densities in a plasma etch reactor used for industrial wafer processing were determined using broadband ultraviolet absorption spectroscopy. The absorption cross sections of CF ₂ at selected wavelengths, used for calculating the number densities from the experimental spectra were determined using Franck Condon factors. The number densities of CF ₂ were also determined in different regions of the plasma, including the center of the plasma and outside the plasma volume. The CF ₂ rotational temperatures and vibrational energy distributions were also estimated.