During the etching process of a silicon nitride layer in CH2F2/H-2/Ar dual-frequency superimposed capacitively coupled plasmas, CHxFy polymer nanodots were formed on the silicon nitride surface and, as a result, silicon nitride nanopillars were fabricated. The H-2 and low frequency power (P-LF) were found to play a critical role in determining the density and diameters of the pillars due to the change in the degree of hydrofluorocarbon polymerization. Silicon nitride nanopillars with a diameter as small as congruent to 25 nm and an aspect ratio as large as congruent to 3.2 were formed, and silicon nanopillars could also be fabricated by the inductively coupled Cl-2/Ar plasma etching of a Si substrate using the silicon nitride nanopillars as a hard mask. (c) 2007 American Vacuum Society.