Thermal strain development in sol-gel derived PZT thin films using DIC

The piezoelectric performance of electroceramic thin films is highly influenced by the level of residual stresses that develop during the heating stages of film fabrication. To determine critical stages of stress/strain development during thermal treatment, the mechanical response of PZT sol-gel thin films (c.a. 40 nm thickness) is measured via a fluorescence-based digital image correlation method (DIC). For the DIC method, a suspension of silica nanoparticles (c.a. 140 nm diameter) in ethanol is spincast onto the sample surface to provide the random speckle pattern necessary for performing DIC strain measurements. During thermal processing, the in-plane strains are monitored for blanket PZT sol-gel films deposited on Pt/Ti/SiO2/Si substrates. Additionally, results of the strain development within thin film features patterned via a mediated octadecyltrichlorosilane (ODS) monolayer are also presented. Within the patterned features, principal strains were found to vary significantly from the constrained blanket film case at the same temperature.