Independent parallel scanning force microscopy using Pb(Zr,Ti)O-3 microcantilever array

We have developed an array of individually controlled piezoelectric Pb(Zr,Ti)O-3 (PZT) microcantilevers for a multiprobe scanning force microscope (SFM). Each cantilever of the array is unimorph beam including a sol-gel derived PZT thin film that has high piezoelectric strain constants in comparison with non-ferroelectric films such as a sputtered ZnO. The cantilever is excited and statically deflected in z direction by applying ac and de voltages to the PZT layer. The variation of vibration amplitude is detected by measuring the change of piezoelectric current through the PZT layer. The 200-mu m-long PZT microcantilevers with the first natural resonance frequency of around 64 kHz have the high actuation sensitivity of 150 nm/V and the maximum range of more than 1.5 mu m. By actuating the self-excited cantilever to keep the current constant, the distances between the tips and sample are independently controlled. We have succeeded in independent dynamic operation using two cantilevers of the array without z feedback actuation of the sample-side scanner and have obtained independent parallel 2 x 1 images.