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

The detection of higher modes of oscillation in atomic force microscopy can provide additional information on sample properties. However, the limited bandwidth of the photodiode in the beam deflection detection technique often limits the detectable frequency range. We present a novel cantilever design, which allows lowering the frequency of higher modes of oscillation, maintaining the frequency of the fundamental resonance. Simulations by finite element methods show that the ratio between the second mode and the fundamental resonance frequency can be adjusted between 2 and 10, compared to 6.3 for the regular rectangular cantilever design. Even stronger changes are observed for the third oscillation mode, corresponding to a torsional cantilever oscillation. Cantilevers with modified geometry were fabricated using silicon micromachining processes and subsequently tested, confirming the results from the simulation. (c) 2006 American Institute of Physics.