Mechanistic Study of the Nanoscale Negative-Tone Pattern Transfer from DNA Nanostructures to SiO₂

We report a mechanistic study of a DNA-mediated vapor phase HF etching of SiO 2 . The kinetics of SiO 2 etching was studied as a function of the reaction temperature, time, and partial pressures of H 2 O, HF, and 2-propanol. Our results show that DNA locally increases the etching rate of SiO 2 by promoting the adsorption of water and that the enhancement effect mostly originates from the organic components of DNA. On the basis of the mechanistic studies, we identified conditions for high-contrast (>10 nm deep), high-resolution (∼10 nm) pattern transfers to SiO 2 from DNA nanostructures as well as individual double-stranded DNA. These SiO 2 patterns were used as a hard mask for plasma etching of Si to produce even higher-contrast patterns that are comparable to those obtained by electron-beam lithography.