Highly compliant static microcantilevers fabricated in gold nanocomposite materials

Abstract

Static microcantilevers with superior stress sensitivity were produced out of a novel Au–Ta metal nanocomposite, and successfully employed for the detection of chemisorbed dodecanethiol. Au–Ta nanocomposite films of various compositions were first synthesized by co-sputtering in order to assess the chemisorption of alkanethiol molecules on their surfaces. Previous x-ray diffraction analysis showed that from 0–50% at. Ta, the films retain gold's FCC structure and ⟨1 1 1⟩ texture necessary for the formation of an alkanethiol self-assembled monolayer. Attachment of dodecanethiol molecules from vapor phase onto the surface of our Au–Ta films was then quantified using contact angle measurements and x-ray photoelectron spectroscopy. As suggested by the x-ray diffraction results, the incorporation of small amounts of tantalum (5% and 10% at. Ta films) had little adverse effect on the attachment of dodecanethiol. However, this ceased to be the case at 20% at. Ta and above. Static microcantilevers were then fabricated directly out of a 5% Au–Ta nanocomposite alloy by patterning the sputtered Au–Ta layer onto a silicon wafer using contact photolithography and releasing the cantilever with an SF6 reactive ion etch. Cantilevers 140 µm long, 20 µm wide, and 369 nm thick showed a spring constant of 10.5 mN m−1. The detection of chemisorbed dodecanethiol molecules was successfully demonstrated with these structures through the monitoring of static deflections.

Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites

“…Contact metals used as electrodes in piezoelectric devices should thus possess high enough tensile strength to withstand these stresses. To such effect, novel co-sputtered metal nanocomposites optimized for the fabrication of micromechanical devices have been reported [ 47 – 49 ]. These nanocomposites feature grain size as small as a few nanometers and residual stresses substantially lower than those of pure metals.…”

Fabrication and characterization of aluminum-molybdenum nanocomposite membranes

“…Such feature allows the realization of ultrathin released structures. 25,26 Scanning electron microscope (SEM) images of the membranes are shown in Fig. 2, with an individual membrane shown in Fig.…”

“…22 Alternatively, novel cosputtered metal nanocomposites optimized for the fabrication of micromechanical devices have recently been reported. [23][24][25][26] These nanocomposites feature grain size as low as a few nanometers as well as residual stresses substantially lower than pure metals. 1 These materials also offer intrinsic tunability of their affinity to target chemisorbed species through control of their atomic composition.…”

“…1 These materials also offer intrinsic tunability of their affinity to target chemisorbed species through control of their atomic composition. 26 More specifically, a metal nanocomposite composed of 68 atomic percent (at. %) Al and 32 at.…”

Micro-electro-mechanical systems (MEMS): Technology for the 21st century

“…Polimeri mogu da se koriste kao jedan ili dva sloja u bimorfnim strukturama [78]. Uobičajeno je da se kombinuje jedan sloj polimera (na primer poliimida ili epoksidne smole) sa strukturnim slojem zlata [79,80] ili aluminijuma [78], iako je moguće koristiti i dva različita polimerna (na primer poliimidna) sloja [81]. Ključna stvar za dobijanje ovakvih struktura je specifičan izbor svojstava materijala (sa ciljem da se obezbedi dobar početni otklon van ravni s jedne i osetljivost s druge strane).…”