Characterization of silicon nitride films for a silicon nanowire-based biosensor

We report the exploration of silicon nitride thin films prepared by low-pressure chemical vapor deposition (LPCVD) and by radio frequency (RF) sputter deposition utilized in the top down fabrication of sub-70nm silicon nanowires for biochemical sensing with functionalization. A series of experiments were performed to characterize the suitability of the films in the overall fabrication of the nanowires. It was observed that the sputtered silicon nitride had to be thicker than the LPCVD silicon nitride to serve as a sufficient masking layer, as expected. However, the higher density LPCVD film required a longer etch duration. Through a series of chemical etching, oxidation, and ellipsometric measurements, the investigators conclude that the sputtered nitride film serves as a more effective barrier film for top down nanowire fabrication.