Fabrication and characterization of nanoresonating devices for mass detection

Abstract

Fabrication of a nanosize metal aperture for a near field scanning optical microscopy sensor using photoresist removal and sputtering techniques Fabrication of submicron suspended structures by laser and atomic force microscopy lithography on aluminum combined with reactive ion etching We report on a novel fabrication process and preliminary characterization of a nanomechanical resonating device, which is to be used for mass detection. The fabrication of the device is based on laser lithography on Al coated SiO 2 /p ϩϩ Si/SiO 2 /Si structures, followed by dry and wet etching. We have fabricated highly doped polysilicon free-hanging cantilevers and anchored drivers for lateral cantilever vibration, where the motion of the cantilever is parallel to the substrate. The cantilevers are actuated electrically by applying an ac voltage between the cantilever and driver. The laterally vibrating cantilever structures are approximately 30-50 m in length, 1.8 m in height, and 500 nm in width. The characterization of the resonators was performed by direct observation of the cantilever through an optical microscope. An electrical measuring technique is also presented and discussed. Typical values of resonant frequency and quality factor, at 1 atm, are approximately 500 kHz and 50, respectively. Moreover, a dependence of the resonant frequency on the applied dc voltage between the cantilever and driver has been found.

Modified atomic force microscopy cantilever design to facilitate access of higher modes of oscillation

“…10 Here, either the mass uptake or the surface stress modifies the resonance frequency. Due to the higher quality factor of higher resonance modes these are more sensitive and their application should increase the experimental resolution.…”

Peer Reviewed: Microcantilever Transducers: A new Approach in Sensor Technology

“…For nanoscale cantilevers with fundamental frequencies similar to those of SAW devices (i.e., 10 5 -10 6 Hz), calculations predict mass sensitivity down to the single-molecule level (10 -21 g). Although a challenging technological task, implementation of such cantilevers is currently being pursued (23). When the damping effect of the medium is rather strong, the resonance frequency shifts can be related to changes in the viscosity of the medium.…”

Ultrasensitive mass sensor fully integrated with complementary metal-oxide-semiconductor circuitry

“…The resonance frequency is reduced when the V dc is increased, due to electrostatic spring softening. 15 The unperturbed resonance frequency of the system is determined to be f 0 = 1.487 MHz from the intersection of the linear fit with the y axis at zero-applied voltage, Fig. 2͑b͒.…”