Processing of PZT piezoelectric thin films for microelectromechanical systems

Piezoelectric Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films for microelectromechanical systems (MEMS) were deposited on platinum coated silicon substrates by sol-gel processing using lead acetate trihydrate as the lead source. A thickness uniformity of better than 1% variation over 4" wafers was achieved. Auger depth profiling showed good compositional homogeneity through the film thickness, with some lead loss at the film surface. A PbO top layer on the top of PZT thin films gave improved properties. Grazing angle scanning XRD confirmed that the PbO top layer helped prevent the formation of a pyrochlore surface layer during crystallization. Work on reactive ion etching of the PZT thin films was also initiated. It was found that Cl₂/CCl₄ mixtures could be used to etch PZT with an etching rate of 100~150 Å/min, and HCFC-124 with a rate of 320 Å/min