Fabrication and application of a microfluidic-embedded silicon nanowire biosensor chip

We report the fabrication of a silicon nanowire (SiNW) transistor array realized in a top-down process on 4″ silicon-on-insulator (SOI) wafers. This process is a second, optimized version combining thermal nanoimprint lithography and wet chemical etching to define planar nanowires and contact lines out of the top silicon layer in one etching step. We used ion implantation to reduce series resistance of source and drain contact lines. In total 56 individually addressable SiNWs were aligned in two lines. Wires dimensions were down to 60nm in width and40nminheight having lengthsupto40 μm.Duetoan improved processing we obtained almost identical wire structures and electronic properties throughout the 4″ wafer enabling direct comparison of signals from one chip. The wires were capped by a microfuidic structure, which was used to administer different analyte solutions. First pH characterization measurements and molecular detection experiments using charged polyelectrolytes (PEs) and poly(D)lysine were successful. In future these devices could be used to observe diffusion of analytes in a time-dependent, spatially- and quantitatively-resolved readout.