Highly c-axis-oriented monocrystalline Pb(Zr, Ti)O3 thin films on si wafer prepared by fast cooling immediately after sputter deposition

We successfully developed sputter deposition technology to obtain a highly c-axis-oriented monocrystalline Pb(Zr, Ti)O₃ (PZT) thin film on a Si wafer by fast cooling (~-180°C/min) of the substrate after deposition. The c-axis orientation ratio of a fast-cooled film was about 90%, whereas that of a slow-cooled (~-40°C/min) film was only 10%. The c-axis-oriented monocrystalline Pb(Zr_0.5, Ti_0.5)O₃ films showed reasonably large piezoelectric coefficients, e_31,f = ~-11 C/m², with remarkably small dielectric constants, ε_r = ~220. As a result, an excellent figure of merit (FOM) was obtained for piezoelectric microelectromechanical systems (MEMS) such as a piezoelectric gyroscope. This c-axis orientation technology on Si will extend industrial applications of PZT-based thin films and contribute further to the development of piezoelectric MEMS.