MPI/MS detection of SiF and SiF₂ radicals produced from the reaction of F₂ and NF₃ with silicon

SiF and SiF₂ radicals, produced in the thermal reaction of F₂ and NF₃ with solid silicon, have been detected by multiphoton ionization mass spectrometry in the 438 and 321 nm wavelength regions, respectively. The reaction pathway to the production of SiF radicals is of minor significance compared with SiF₂ production over a wide range of temperatures and pressures. In both cases it was found that little or no fragmentation of the parent ion occurs upon ionization. MPI/MS is thus shown to be a useful diagnostic tool for studies of fluorine-silicon etching reactions.