Ultra-thin, high-lifetime silicon nitride nanopore membranes for biosensing

Thin membranes are highly sought-after for nanopore-based single-molecule sensing and fabrication of such membranes becomes challenging in the <10 nm thickness regime where a plethora of useful molecule information can be acquired by nanopore sensing. In this work, we present a scalable and controllable method to fabricate silicon nitride (Si_xN_y) membranes with effective thickness down to 1.5 nm. Nanopores were fabricated using the controlled breakdown method with estimated pore diameters down to ∼1.8 nm yielding events >500,000 and >1,800,000 from dsDNA and bovine serum albumin (BSA) protein, respectively, demonstrating the high-performance and extended life-time of the pores fabricated in our membranes. We used two different compositions of Si_xN_y for membrane fabrication (near stoichiometric and silicon-rich Si_xN_y) and compared them against commercial membranes. The stoichiometry and the density of the membrane layers were characterized with Rutherford backscattering spectrometry while the nanopores were characterized using pH-conductance, conductivity- conductance and power spectral density (PSD) graphs.