title: Fabrication of 3-nm-thick Si3N4 membranes for solid-state nanopores using the poly-Si sacrificial layer process.
abstract: To improve the spatial resolution of solid-state nanopores, thinning the membrane is a very important issue. The most commonly used membrane material for solid-state nanopores is silicon nitride (Si3N4). However, until now, stable wafer-scale fabrication of Si3N4 membranes with a thickness of less than 5 nm has not been reported, although a further reduction in thickness is desired to improve spatial resolution. In the present study, to fabricate thinner Si3N4 membranes with a thickness of less than 5 nm in a wafer, a new fabrication process that employs a polycrystalline-Si (poly-Si) sacrificial layer was developed. This process enables the stable fabrication of Si3N4 membranes with thicknesses of 3 nm. Nanopores were fabricated in the membrane using a transmission electron microscope (TEM) beam. Based on the relationship between the ionic current through the nanopores and their diameter, the effective thickness of the nanopores was estimated to range from 0.6 to 2.2 nm. Moreover, DNA translocation through the nanopores was observed.
authors.affiliation: Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-koigakubo, Kokubunji, Tokyo, 185-8603.
authors.forename: Itaru
authors.initials: I
authors.lastname: Yanagi
authors.affiliation: Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-koigakubo, Kokubunji, Tokyo, 185-8603.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-koigakubo, Kokubunji, Tokyo, 185-8603.
authors.forename: Koji
authors.initials: K
authors.lastname: Fujisaki
authors.affiliation: Hitachi Ltd., Central Research Laboratory, 1-280 Higashi-koigakubo, Kokubunji, Tokyo, 185-8603.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Takeda
mesh_terms: D004553:Electric Conductivity; D008567:Membranes, Artificial; D058608:Nanopores / Q000648:ultrastructure*; D009994:Osmolar Concentration; D016062:Porosity; D017655:Silicon Compounds / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D017655:Silicon Compounds; C032734:silicon nitride