nn8b06805_si_003.avi (3.34 MB)
Photothermally Assisted Thinning of Silicon Nitride Membranes for Ultrathin Asymmetric Nanopores
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posted on 2018-11-20, 00:00 authored by Hirohito Yamazaki, Rui Hu, Qing Zhao, Meni WanunuSculpting
solid-state materials at the nanoscale is an important
step in the manufacturing of numerous types of sensor devices, in
particular solid-state nanopore sensors. Here we present mechanistic
insight into laser-induced thinning of low-stress silicon nitride
(SiNx) membranes and films. In a recent
study, we observed that focusing a visible wavelength laser beam on
a SiNx membrane results in efficient localized
heating, and we used this effect to control temperature at a solid-state
nanopore sensor. A side-effect of the observed heating was that the
pores expand/degrade under prolonged high-power illumination, prompting
us to study the mechanism of this etching process. We find that SiNx can be etched under exposure to light of
∼107 W/cm2 average intensity, with etch
rates that are influenced by the supporting electrolyte. Combining
this controlled etching with dielectric breakdown, an electrokinetic
process for making pores, nanopores of arbitrary dimensions as small
as 1–2 nm in diameter and thickness can easily be fabricated.
Evidence gathered from biomolecule-pore interactions suggests that
the pore geometries obtained using this method are more funnel-like,
rather than hourglass-shaped. Refined control over pore dimensions
can expand the range of applications of solid-state nanopores, for
example, biopolymer sequencing and detection of specific biomarkers.