Fabrication and Electro-Mechanical Characteristics of Piezoelectric Micro Bending Actuators on Silicon Substrates

Abstract

Fabrication and the electro-mechanical characteristics of fourteen types of piezoelectric micro bending actuators (PMBA) on silicon substrates using sol-gel multi-coated, thick PZT (Pb(Zr_0.52, Ti_0.48)O₃) films and MEMS processes were investigated. A PMBA was a piezoelectric body adhered to an elastic body. If an electrical field is applied to the z-axis, the piezoelectric body expands along the z-axis while contracting along the x- and y-axes. The elastic body was therefore deflected due to the generated bending moment. It was thought that PMBA might be used for designs of micro-fluidic devices and micro transducers. PMBA were fabricated using 2 μm-thick PZT films on Pt (350 nm)/SiO₂ (500 nm)/Si (300 μm) substrates with a MEMS process. Fourteen types of PMBA were fabricated with different sizes of silicon diaphragms, PZT films and top electrodes. When sizes of silicon diaphragms, PZT films, and Pt top electrodes with 3000 μm by 1389 μm, 4000 μm by 1000 μm, and 4000 μm by 980 μm were reduced down to 3000 μm by 194 μm, 4000 μm by 140 μm, and 4000 μm by 120 μm, respectively, the center displacements of PMBA were decreased from 0.70 μm to 0.13 μm at 5 Hz and 12 V_pp. At 5 V_pp and 10 kHz, in case of Sample 1 of Group 4, the center displacements were maintained in the range of 0.50 μm-0.56 μm up to 1.25 G cycles without remarkable degradation.