LASER-INDUCED DISSOCIATION OF MOLECULES DURING MEASUREMENTS OF HYDROGEN-ATOMS IN PROCESSING PLASMAS USING 2-PHOTON LASER-INDUCED FLUORESCENCE

During measurements of hydrogen atoms in discharge plasmas in silane a nd methane, using a two-photon excitation from the ground state to the n=3 states at 205 nm, the laser-induced dissociation of molecules was found to be the dominant process of hydrogen production, rather than that due to the discharge. Although the laser intensity was kept below the threshold of atomic hydrogen production from parent gases, some r eaction products were at high density which were more easily dissociat ed by the laser irradiation. Quantitative discussions were made of the laser-induced dissociation, and the estimates of reaction product den sities were thus made. (C) 1996 American Vacuum Society.