Use of the ultraviolet absorption spectrum of CF₂to determine the spatially resolved absolute CF₂density, rotational temperature, and vibrational distribution in a plasma etching reactor

The CF2densities in a plasma etch reactor used for industrial wafer processing were determined using broadband ultraviolet absorption spectroscopy. The absorption cross sections of CF2at selected wavelengths, used for calculating the number densities from the experimental spectra were determined using Franck Condon factors. The number densities of CF2were also determined in different regions of the plasma, including the center of the plasma and outside the plasma volume. The CF2rotational temperatures and vibrational energy distributions were also estimated.