Abstract

Surface studies have established that radicals frequently react with surfaces which are inert to the parent molecule. Dissociation of the parent molecule provides a reaction channel which avoids the often large activation barrier inherent in parent molecule-surface interactions. The interaction of gaseous NF₃ with amorphous silicon is an excellent example of this type of behavior. While NF₃ does not measurably chemically react with silicon at ambient temperatures, the fluorine containing radicals produced from laser dissociated NF₃ readily do so. Some fraction of the fluorosilyl reaction products spontaneously desorb, resulting in silicon removal (etching). In this study parallel incident dissociating radiation did not contact the silicon surface, indicating that the observed etching reactions result from purely chemical effects. Effects due to transient surface heating or physical ablation can be discounted.

© 1987 Optical Society of America