Residual strain measurement of piezoelectric multilayers by spiral structure

A new structure is described to measure the residual strain of thin film of piezoelectric multi-layers. The spiral shaped structure consists of the four fixed-guided beams. Piezoelectric multilayers consisting of SiOx/Pt/PZT/Pt on SiNx substrate are used to evaluate the suggested structure. Finite element analysis predicts that the out-of-plane displacement of the spiral structure by residual stress depends linearly on the beam length, but there is little difference depending on the beam width. PZT is prepared by sol-gel method and multilayered spiral structures are released by microfabrication technique. Sensitivity analysis of the spiral structure with various layer stack shows that the high displacement of piezoelectric multilayers can be decreased by the application of SiOx layer with compressive stress over the piezoelectric multilayers.