Buried Nanopore Membranes with Enhanced Mechanical Robustness for High-Resolution Single-Molecule Sensing

The mechanical fragility of ultrathin membranes limits the broader deployment of solid-state nanopores for high-resolution single-molecule sensing. Here, we introduce a buried nanopore architecture in which silicon nitride (SiN_x) membranes are recessed within the silicon substrate using a time-controlled double-sided, anisotropic, wet etching process. This buried geometry enables sub-micrometer lateral membrane dimensions and achieves more than an order-of-magnitude improvement in impact resistance relative to conventional membranes formed at the wafer surface. Electrical conductance measurements reveal a reduced effective membrane thickness, suggesting enhanced ionic confinement and spatial resolution. We demonstrate the sensing capability of these buried nanopores through translocation measurement of double-stranded DNA, as short as 22 base pairs, confirming the high signal resolution of the buried membrane nanopores for label-free molecular analysis. The proposed fabrication method enhances mechanical durability, measurement resolution, and device yield, offering a scalable route for robust high-resolution nanopore biosensors.