Absolute densities and kinetics of H atoms and CFx radicals in low-pressure, high-density CHF3 plasmas

Absolute densities of CF, CF2, and H in helicon-wave CHF3 plasmas were measured by laser-induced fluorescence spectroscopy. It was found that the H atom density was higher than the CF and CF2 radical densities. The radial distributions of the CF, CF2, and H densities had hollow shapes, namely, the densities in the plasma column were lower than those in the outside area. This result indicates that H and CFx are produced from hydrogenated fluorocarbon film deposited on the chamber wall. It was observed that the CF2 density increased significantly in the afterglow, which was a direct evidence for surface production of CF2. In addition, the temporal variation of the H density also suggests surface production of H atoms in the afterglow. (c) 2005 Elsevier B.V. All rights reserved.