Cantilever type PZT Microsensor using resonance frequency for BioMEMS Application

摘要

Among various materials for microelectromechanical system [MEMS] devices, piezoelectric thin films have attracted considerable attention since they are one of the essential materials in microfabricated devices such as microsensors and microactuators. In this study, we propose a new and simple cantilever type Pb(Zr,Ti)O_3 [PZT] microsensor using RuO_2 which could detect the resonance frequency variation. Since RuO_2 has good electrical conductivity and stiffness, it can replace the double layer of electrode and supporting layer to a single layer in a cantilever beam. Also, Si substrate was isotropically etched from the surface using SF_6 plasma. These unique technique simplifies the structure and process of a cantilever. The cantilever consists of Al, PZT and RuO_2 layers. To find relationships between resonance frequency and shape of cantilever, microsensors with various widths and lengths were fabricated and their resonance frequencies were measured by laser doppler vabrometer(LDV) system. In addition, detection sensitivity of microsensor was investigated The resonance frequency decreased as the length of cantilever increased.