Wafer-Scale Maskless Process to Fabricate Sub-20nm Silicon Nitride Nanopores for Ultrafiltration

Abstract

We report a wafer-scale process developed at imec for fabricating solid-state ultrafiltration membranes on 300 mm wafers. Maskless nanopatterning was achieved using block copolymers (BCP), enabling precise pattern transfer and dimensional control across a 2 cm² area. The process utilizes 30 nm LPCVD SiN membranes, and an optimized frontside protection protocol combined with deep reactive ion etching of the backside silicon. Subsequent controlled release protocols produce freestanding, defect-free membranes with uniform 20 nm wide nanopores at a 40 nm pitch. This scalable approach provides a robust foundation for advanced ultrafiltration and biomedical applications.