Fabrication of sub-20 nm nanopore arrays in membranes with embedded metal electrodes at wafer scales

Abstract

We introduce a method to fabricate solid-state nanopores with sub-20 nm diameter in membranes with embedded metal electrodes across a 200 mm wafer using CMOS compatible semiconductor processes. Multi-layer (metal-dielectric) structures embedded in membranes were demonstrated to have high uniformity (± 0.5 nm) across the wafer. Arrays of nanopores were fabricated with an average size of 18 ± 2 nm in diameter using a Reactive Ion Etching (RIE) method in lieu of TEM drilling. Shorts between the membrane-embedded metals were occasionally created after pore formation, but the RIE based pores had a much better yield (99%) of unshorted electrodes compared to TEM drilled pores (<10%). A double-stranded DNA of length 1 kbp was translocated through the multi-layer structure RIE-based nanopore demonstrating that the pores were open. The ionic current through the pore can be modulated with a gain of 3 using embedded electrodes functioning as a gate in 0.1 mM KCl aqueous solution. This fabrication approach can potentially pave the way to manufacturable nanopore arrays with the ability to electrically control the movement of single or double-stranded DNA inside the pore with embedded electrodes.

The promises and challenges of solid-state sequencing

“…Large (micron-sized) holes made by selective reactive ion etching (RIE) work very well 15 for identifying individual DNA nucleotides. Careful electron-beam lithography has also allowed nanopores as small as 20 nm diameter to be made by RIE in a scalable way 16 . However, because the geometry of DNA passing through 20 nm apertures is not sufficiently constrained, long DNA molecules produce signals that are reads of the sequence at randomly-selected positions, much like the stochastic sampling described by Di Ventra and Taniguchi 5 .…”

Field-effect control of ions beyond debye-screening limit in nanofluidic transistors

“…This is the first direct experimental proof of strong field-effect control of ions far beyond the Debye-screening limit. The achieved 2.5X current modulation in the 100 nm channel height NFTs is even higher than state-of-the-art 20 nm counterpart devices [5,6,7].…”

“…The state-of-the-art NFTs have required at least one dimension comparable to or smaller than the ionic system's Debye Length, so that sufficient electrostatic control can turn off ion transport in the channel. This requirement imposes fabrication challenges, testing difficulties, and reliability issues [5,6,7].…”

Investigation of field effects in a solid-state nanopore transistor

“…Here we assume that the hydroxyl group is the sole reactive group on the surface and it undergoes the following chemical reactions: [41][42][43][44][45] RÁOH 2 RÁO À + H + (1) Here we assume that the hydroxyl group is the sole reactive group on the surface and it undergoes the following chemical reactions: [41][42][43][44][45] RÁOH 2 RÁO À + H + (1)…”

“…34,45,46 In the previous studies, 47 s chem under zero gate potential was used in explaining the material dependence. This part was motivated by recent experiments showing that the ion current responds differently to the gate voltage depending on the material of the gate oxides.…”