In situ method of densification for powder-based piezoelectric thick films for microelectromechanical system applications

Piezoelectric (PZT) (Pb(Zr_0.52Ti_0.48)O₃) thick film-based microtransducers demonstrate excellent piezoelectric performances. PZT thick films on Si-based substrate can be used as piezoelectric actuators and sensors with the introduction of microelectromechanical system technology and the screen printing method. However, the thick films made just by the screen printing method have high porosity compared with bulk product, and the PZT thick films on Si-based substrate have problems regarding degradation of active materials and interface properties owing to inter-diffusion or reaction between Si substrate and PZT materials at high temperature for sintering. Thus, the authors have fabricated screen printed PZT thick films on Si substrate using the screen printing method and sol infiltration for enhancing densification. Ethanol-based photo-cross-linkable sol and conventional diol-based sol were used to compare influence of patterning process. Thick films with relative high densities at low temperature, 800°C and without inter-diffusion and reaction between the layers and thick film were accomplished. Also, it was revealed that the PZT thick film treated by ethanol-based photo-cross-linkable sol showed better electrical properties as well as excellent patternability.