FABRICATION OF HIGH QUALITY PZT THICK FILM USING LIFT-OFF TECHNIQUE

H.J. Zhao, T.L. Ren, J.S. Liu, L.T. Liu, Z.J. Li
Institute of Microelectronics, Tsinghua University, CN

Keywords: PZT, thick film, lift-off, SU-8

Abstract:
Lead-zirconate-titanate (PZT) is a typical ferroelectrical material with outstanding properties. The demand for the thickness of PZT films used in MEMS is usually over 1μm due to the advantages of the thick thin films, so the integration processes of silicon-based PZT films are the points. In recent years, various methods of fabrication of PZT thick films have been proposed. However, these methods have low compatibility with conventional IC/MEMS processes or can not obtain enough large actuator forces. The present paper proposes a simple fabrication technique of high quality PZT thick films with a single coat and using a thick photoresist SU-8 which call for lift-off technique. The PZT films obtained using single spin-coating with the thickness of 100μm or higher, which is proportional to the thickness of the photoresist SU-8, are crack-free and have good morphology. The PZT films with perfect perovskite structure have excellent piezoelectric property and the d33 is about 170pC/N. Ferroelectric hysteresis loops are measured, and the remnant polarization (Pr) of the PZT ceramics pellet is about 25mC/cm2 and the coercive field (EC) is about 27kV/cm. In the radio-frequency (RF) region, the dielectric constant is about 350 and the dielectric loss is less than 0.01.

NSTI Nanotech 2003 Conference Technical Program Abstract