Capillary filling of sub- 10 nm nanochannels

We have developed a procedure for accurate fabrication of silicon-based nanochannels down to a few nanometer channel height, based on the use of a thin thermal silicon oxide spacer layer. Nanochannels with a predictable and carefully measured height between 5 and 50 nm were successfully fabricated and filled with de-ionized water. For all channel heights the filling kinetics behaves according to the classical Washburn law for capillary filling, with a small correction for a loss of liquid at the moving front at a constant rate and a smaller than expected Washburn coefficient (up to a factor of 1.6 smaller for water in 5 nm channels