Piezoelectric characterization of ain thin films on silicon substrates

Abstract

The electric field induced deformations of thin piezoelectric, aluminium nitride (AlN) layers, on top ofa silicon substrate, were studied by numerical calculations and interferometric measurements. Our calculationby finite element method demonstrates that substrate deformation under the top electrode may be comparableto the deformation in the thin AlN layer, for a given applied voltage. Simulations also show the effect of aclamped or free substrate condition and the relative contributions of d33 and d31 piezoelectric constants. ALaser scanning vibrometry technique was used to measure deformations in the top surface with sub-picometervertical resolution. By comparing calculations and experimental data, quantitative information about both d31and d33 constants can be obtained.