Recently there have been tremendous interests about the fabrication of the solid state nanopore due to its capability of the nanosize biosensor. In this report, the dynamics of the Au nanopore formation on the pyramidal membrane will be reported. The nanopores on the microfabricated Au coated SiO2 pyramid were fabricated using focused ion beam (FIB) and high energy electron beam techniques such as transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). For high scanning electron beam irradiation using FESEM, shrinking of the Au nanopore was always observed. The nanopore formation dependent upon the primary electron voltage, and the scan rate of the FESEM electron beam was carefully examined. The higher closing rates for the faster scan rate and the lower electron accelerating voltage are observed. For the TEM electron beam exposure, the closing or the opening of the pore was observed depending upon the electron beam current. We do believe that this phenomenon can be attributed to the capillary force and the vaporization of the materials on the viscous liquid membrane due to TEM electron beam irradiation.
Recently there has been tremendous interest about the dynamical sequence of fabrication of the solid state nanopore due to its capability of the nanosize solid state biosensor as a single molecule sensor. Depending upon the instruments such as transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM), the dynamics of nanopore formation present different physical mechanisms. In this report, formation of the nanopores was examined. Metallic nanopores with ~ 50 nm diameter on top of the oxide pyramid were fabricated using conventional Si microfabrication techniques followed by wet isotropic etching of the oxide; sputter metal deposition followed by the focused ion beam (FIB) techniques. No shrinking phenomena were observed for the nanopore diameter greater than 50 nm under electron beam irradiation using TEM. However, for high scanning electron beam irradiation using FESEM, shrinking of the Au nanopore was always observed. We do believe that these phenomena can be attributed to the liquid phase surface modification for TEM electron beam and adiabatic solid state phase surface modification for high scanning FESEM. For a huge amount of energy input from high scan rate and the poor thermal conduction to its surrounding area, the energy spike inside the electron penetration area would occur. However, a TEM electron beam irradiation without repetitive scan can provide the liquid phase surface modification.
Recently there have been tremendous interests about the fabrication of the solid state nanopore due to the capability of
the solid state nanopore as a single molecule sensor. The SiN nanopore and the SiO2 nanopore have been fabricated with
high energy electron beam exposure such as transmission electron microscopy, field emission electron microscopy, and
focused ion beam sculpting. However, the plasmonic Au nano-pore can be utilized as a nanobio optical sensor due to the
106 fold increase of the Raman signal intensity. Hence, in this report, the fabrication of the plasmonic nanopore with less
than ~ 10 nm on the apex of the micronsize pyramidal structure using various high energy electron beam exposure.
Under the electron beam exposure of FESEM followed by EPMA, the widening and the shrinking of the Au nanopore
were observed depending upon the EPMA probe current. The diameters of the Au nanopore was also reduced
successively from ~ 5 nm down to zero using 200 keV TEM. From these experimental results, the dynamics of the
nanopore formation are found to depend on the viscosity of the membrane, radiation damage, and evaporation of the
materials under high vacuum condition. This fabricated plasmonic nano-pore device can be utilized as geneome
sequencing device or a single-molecule sensor.
Recently there have been tremendous interests about the single molecule translocation through the SiN nanopore array.
For DNA translocation and characterization, SiN nanopore array is easy to fabricate with high energy electron beam
exposure. It is well known that the metallic nanopore can provide the huge enhancement, 106 fold increase of the
electromagnetic field at the metallic nanopore due to "hot spot" effect. In addition, the fabricated plasmonic micro device
provides huge photon transmission through the fabricated nanochannel. In this report, we microfabricated the plasmonic
nanopore with ~ 101 nm on top of the micronsize pyramidal structure for translocation and optical characterization using
conventional microfabrication process and electron beam heating. The reduced Au nanopore due to electron beam
heating is found to provide the huge optical transmission resulted in the huge photonic pressure gradient between the free
space and nanopore inside. The huge pressure gradient can be attributed to the resonance transmission between the
fabricated V groove cavity and the nanosize waveguide formed during the metal deposition. This fabricated plasmonic
nano-aperture device can be utilized as bio-molecule translocation and optical characterization.