Mechanical characteristics and applications of diamondlike-carbon cantilevers fabricated by focused-ion-beam chemical vapor deposition

Diamondlike-carbon (DLC) cantilevers were fabricated with a commercially available focused-ion-beam chemical-vapor-deposition (FIB-CVD) system using a beam of 30keV Ga+ ions, and the mechanical characteristics of the cantilevers were measured. Vibration frequency of the cantilevers was passively measured using scanning electron microscopy. Resonant frequency of DLC cantilevers fabricated at 0.1–0.5pA beam current was found to be constant. The equivalent spring constant of the cantilevers was identified by squeezing the tip of a Si3N4 cantilever and a DLC cantilever together. Using the measured displacement, the spring constant of the DLC cantilever was calculated as (1.1±0.2)×10−2N∕m. Furthermore, Young’s modulus and the density of the DLC cantilevers were measured to be 187±32GPa and (3.8±0.7)×103kg∕m3, respectively. The DLC cantilevers were used as mass sensors in an ultrasensitive sensing application. A small amount of DLC was deposited on the tip of a DLC cantilever as a mass adhesion by FIB-CVD at 0.5pA beam current. As a result, the authors were able to measure a small amount of mass shift in the femtogram range using a DLC cantilever.