Measurement of d15 shear-mode displacement in ferroelectric PZT film

d₁₅ shear-mode displacements in a ferroelectric PZT(52/48) film could be observed by using a FIB processing and SPM probe measurement for the first time ever. The PZT sample with a beam shape was fabricated by a combination of a sputtering deposition, a FIB machining, and a Cu damascene process. In order to compensate for the effect of constraints arisen from the beam sample structure, FEM simulation analyses were employed. The obtained d₁₅ piezoelectric constant of the sputter PZT film was 590 pm/V. The d₃₁ piezoelectric constant of the same PZT film was also measured by a conventional tip displacement of cantilever method. The obtained d₃₁ value was -120 pm/V. Though the d₁₅ value is as large as that of bulk shape, the d₃₁ value was slightly smaller than that of bulk. The difference may be explained that an intrinsic stress existed in the lower portion of the PZT film.