Fabrication and characterization of nanoresonating devices for mass detection

We report on a novel fabrication process and preliminary characterization o f a nanomechanical resonating device, which is to be used for mass detectio n. The fabrication of the device is based on laser lithography on Al coated SiO2/p(++)Si/SiO2/Si structures, followed by dry and wet etching. We have fabricated highly doped polysilicon free-hanging cantilevers and anchored d rivers 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 vi brating cantilever structures are approximately 30-50 mu m in length, 1.8 m u m in height, and 500 nm in width. The characterization of the resonators was performed by direct observation of the cantilever through an optical mi croscope. An electrical measuring technique is also presented and discussed . Typical values of resonant frequency and quality factor, at 1 atm, are ap proximately 500 id-It and 50, respectively. Moreover, a dependence of the r esonant frequency on the applied de voltage between the cantilever and driv er has been found. (C) 2000 American Vacuum Society. [S0734-211X(00)08102-6 ].