Fabrication, Characterization And Application Of PSZT Piezoelectric Films

Lead zirconate titanate (PZT) has attracted extensive attention because of its excellent electrical performance. Especially because of the characteristics of high sensitivity and output strain, PZT has become one of the most promising materials for MEMS applications. It is required higer and higher of the micro sensor performance with the development of research into the micro field. Therefore, it is necessary to improve the performance of piezoelectric films to satisfy the requirment. Doping is a practical method to improve the comprehensive properties of thin film. In this thesis, the preparation and characteristic of Sr doped PZT thin films (PSZT) as well as the fabrication and sensing performance test of PSZT microcantilever force sensor are investigated.PSZT0, PSZT0.03 and PSZT0.08 thin films are prepared by sol-gel method on Pt/Ti/SiO₂/Si substrates. Surface morphology of the three kinds of PSZT thin films are observed by Atomic Force Microscope (AFM). XRD patterns of PSZT0.08 film with three kinds of pyrolysis temperature are researched and (111) orientation is gained with low temperature while (100) orientation is behaved with higher temperature. Compared to the XRD patterns of the three kinds of thin films, preferred orientation and phase content are changed while lattice constant is decreased after Sr doping. According to the I-V curves of the three films, leakage current is decreased with Sr dopant and it would decrease more with the film thickness increase. After analysing the dielectric constant and dissipation factor frequency spectrogram, dielectric constant increases obviously with Sr dopant and it would increase more with the film thickness increased.Based on the previous work, the fabrication process is optimized and microcantilever force sensors are prepared with the three kinds of PSZT thin films. Elastic coefficient and sensitivity of PSZT microcantilever force sensors are investigated. The performance of microcantilever force sensor with PSZT0.03 thin films was improved most. Subsequently, elastic coefficient and sensitivity of PSZT0.03 microcantilever force sensors with film thicknesses of 1.66um and 2.19um are investigated. The latter has smaller elastic coefficient and higer sensitivity. It is suggested that the sensing performance was improved significantly by the increase of film thickness.