Aligned horizontal silica nanochannels by oxidative self-sealing of patterned silicon wafers

A simple and reliable procedure for producing horizontal nanochannel arrays with high spatial precision and high throughput at low costs is described. The process is based on the self-sealing of nanogrooves in silicon wafers upon thermal oxidation. Temperature-dependent parameters that determine the overall growth rate of the silicon oxide include the diffusivity and the solid solubility of the oxidants within the oxide, as well as the surface reaction rate at the Si/SiO2 interface. The presence of both convex and concave curvatures on patterned Si substrates results in a pronounced retardation of the oxide growth with respect to planer oxidation. Therefore, the thickness of the generated SiO2 layer is smaller at corners as compared to smooth areas. The retardation effect occurs under both dry and wet oxidation conditions, but it is more effective at concave corners than at convex corners.