Synthesis of 10-mu m-thick lead zirconate titanate films on 2-in. Si substrates for piezoelectric film devices

To achieve micro-machined piezoelectric film devices, crack-free and dense 10-mu m-thick lead zirconate titanate (PZT) films were successfully deposited onto 2-in. Pt/Ti/SiO2/Si substrates using an automatic coating system, and disk-shaped structures with a diameter from 20 to 100 mu m were fabricated by an RIE process. The prepared PZT thick film disks showed well-saturated P-E hysteresis curves and butterfly-shaped longitudinal displacement curves. The AFM-measured piezoelectric constant of the 30-mu m-diameter PZT thick film disk after poling at 100 V for 10 min was AFM d(33)=290 pm/V. The resonant and anti-resonant frequencies of the thickness oscillation mode were observed at 180 MHz. The calculated thickness mode effective coupling factor was (k(eff))(2)=0.1 for the poled 30-mu m-diameter PZT thick film disks. These results suggest that the prepared PZT thick film disks are applicable for piezoelectric micro devices such as micro-machined ultrasonic transducers.