A Piezoelectric MEMS Cantilever Actuated By Nb-doped Lead Zirconate Titanate Film

Piezoelectric micro cantilever is based on Micro-Electro-Mechanical System (MEMS) technology. On silicon wafer, one end of the structure is fixed and the other end can move perpendicular to the substrate. In this research, we made the piezoelectric cantilever by using Nbo.o2-Pb(Zro.6Tio.4)03(PNZT) as the piezoelectric thin film and LaNiO3(LNO) as lower electrode. Compared to the traditional PZT thin film and Pt lower electrode, this film has better piezoelectric and electromechanical properties.The dynamic analysis of piezoelectric cantilever is done by using the piezoelectric theory. Through the computer finite element analysis method, we get the relationships between the structure parameters and the performance of piezoelectric cantilever. Then, get the LNO electrode and PNZT piezoelectric thin film by using magnetron sputtering and sol-gel method. Electrical test results shows that, the resistivity of LNO film is about2mΩ·cm. It is suitable to be used as electrode material because of its good electrical conductivity. PNZT film is well crystallized with perovskite structure. Scanning electron microscope (SEM) observation shows that the surface of PNZT thin film is compact and the thickness of PNZT film is about1.3μm. The test results of ferroelectric properties shows that, the largest remnant polarization of PNZT/LNO film is about16.55uC·cm-2, average coercive voltage is4.7V. The fatigue test shows that the film has good fatigue strength. Therefore, the prepared PNZT/LNO film meets the requirements of making piezoelectric MEMS cantilever. Then, this research designed the process of piezoelectric cantilever by using sputtering, lithography, etching and the combining of the PNZT sol-gel process and MEMS micro processing technology. Release the cantilever structure by using the deep silicon etching and finish the process of making MEMS piezoelectric cantilever. Finally, the modal analysis is done by using a laser Doppler vibrometer and obtained the vibration frequency spectrum curves, mechanical quality factors and mode shapes.