REACTIONS OF LASER-GENERATED FREE-RADICALS IN SILICON DEPOSITION PROCESSES

The production of molecular free radicals by selective laser photolysis affords a convenient method for studying the reactions of such free radicals with surfaces. The photodeposition of silicon thin films presents an excellent example of the interplay of laser-initiated chemistry and laser-spectroscopic diagnostics in elucidating dissociation and deposition mechanisms. Infrared multiple-photon dissociation of alkyl- or arylsilanes leads to formation of silylene radical (SiH2); a number of other dissociation products are found with phenylsilane. The electronic excited states of SiH2 may dissociate to Si(1D) and Si(3p) atoms, in the latter case by coupling through the a3B1 state. Observation of the atom production threshold allows a determination of the heat of formation of SiH2. © 1990.