A new and simple approach of nanometer-scale sidewall formation has been explored and developed for dry-etching-based pattern transfer techniques. The sidewalls are formed by applying a solvent-based silylation process to the optically exposed and developed resist pattern, followed by an anisotropic oxygen reactive ion etching (RIE) step. The new technique is capable of forming sidewall masks with dimensions ranging from 50 to 500 nm, depending on the silylation conditions. The sidewall masks have been used for successful pattern transfer into SiO2 and Si3N4 by CF4–RIE. This new and simple nanometer sidewall formation technique is easily reproducible and very uniform and, in certain application areas, might be an alternative to more complex and expensive lithography techniques.