Towards multiscale fluidic channel networks via internal oxidation and oxide etching based on self-assembled silicon-on-nothing structures

This paper reports a novel fabrication method for multiscale fluidic channels ranging from sub-100 nm to a few μm in their hydraulic diameters, Dh, corresponding to a factor of ~106 tunability in terms of cross-sectional area and exhibiting comparable height-to-width ratio (h/w or aspect ratio, AR) using conventional thermal oxidation and subsequent oxide etching based on self-assembled Silicon-on-Nothing (SON) structures. Then, oxidation time was controlled to fabricate sub-100 nm nanochannels (~20 nm in D_h and ~1 in AR). For scaling up, oxidized channel was wet chemically etched using hydrofluoric acid (HF) multiple times to make microchannels (~4.5 μm in D_h and ~1 in AR). Through this scheme, nanochannels of which all characteristic dimensions are nanoscale far below 100 nm can be batch-fabricated without employing any nanolithographic schemes.