Kinetics of hydrogen atoms in high-density CF4/H2 plasmas studied by (2+1)-photon laser-induced fluorescence spectroscopy

We measured the distribution of absolute H atom density in high-density, low-pressure CF4 plasmas with the addition of H-2 by (2+1)-photon laser-induced fluorescence spectroscopy. The H atom density had hollow-shaped distributions, i.e., the H atom density adjacent to the chamber wall was higher than that in the plasma column. In addition, when the chamber wall was covered with hydrogenated fluorocarbon film, we detected H atoms without the addition of feedstock H-2. These experimental results indicate surface production of H atoms from hydrogenated fluorocarbon film. The surface production rate was sensitive to the property of fluorocarbon film. When the property of fluorocarbon film was unified, the surface production rate increased linearly with the pressure of feedstock H-2, suggesting a recycling process of H atoms between gas phase and fluorocarbon film as a mechanism of plasma-surface interaction in CF4/H-2 plasmas. (C) 2003 American Institute of Physics.