In-situ Monitoring of Residual Strain using Multilayered Microcantilever in Piezoelectric-driven Microactuator

摘要

In the design of MEMS device, the vibrating displacement of actuator is highly dependent on the geometrical design as well as the residual stress of constituent layers. Stress-free multilayers are required for the enhancement of performance and reliability. Residual stress estimation of each constituent layer by conventional curvature measurement method has not been sufficient to describe the displacement behavior of micro actuator. In this study, the multilayered micro-cantilevers have been designed and characterized to monitor the residual strain of each layer and to design them with low residual strain. Thin layers of SiNx, SiOx, Pt and PZT were continuously deposited on oxidized silicon substrate and patterned to cantilever shape. Residual strains of each thin layer of multilayered micro-cantilevers were evaluated from the cantilever deflection by optical interferometer. The residual strains measured from micro-cantilevers were in good agreement with those by finite element method and analytical method. By the finite element analysis of cantilever deflection, the multilayers with low residual strain were applied to piezoelectric-driven microactuator.