It has been found that nanoscale etching masks self-form during plasma
etching with SF, when the sample is kept at around -130 degrees C, at
which condensation of the reaction products starts to occur. We have
also found that if nucleation sites are present on the surface, the co
ndensation occurs preferentially on the nucleation sites and the resul
ting condensates act as etching masks, leading to the fabrication of S
i nano-pillars. The above mechanism has been confirmed by fabrication
of Si nanopillars using size-selected Ag clusters as condensation nucl
ei.