Characterization of piezoelectric PZT beam actuators for driving 2D scanning micromirrors

A silicon micromirror driven by piezoelectric Pb(Zr,Ti)O3 beam actuators has been demonstrated for two-dimensional (2D) scanning mirror applications. Two devices of similar design with different dimensions have been fabricated. The Si mirror is micromachined from the device layer of an SOI wafer, while the piezoelectric beam actuator contains multilayers of Pt/Ti/PZT/Pt/Ti/SiO2/Si which is deposited and released from a SOI wafer. A 1 × 10 PZT arrayed actuator are separately arranged in parallel on a Si beam released from the SOI substrate after the micromachining process. The 10 PZT actuators are electrically connected in series. For the large micromirror device with mirror size of 5 mm × 5 mm, the first resonant frequency for bending mode was measured at 34 Hz, while the second mode, i.e., a twist mode or torsional mode, is measured at a resonant frequency of 198 Hz. For the small micromirror device with mirror size of 3 mm × 3 mm, the bending and torsional modes were observed at 122 Hz and 2.46 kHz respectively. 2D raster scanning patterns were illustrated for both micromirrors. dc superimposed bias effect was also investigated for both mirror sizes. With increased dc bias, larger deflection angles were obtained.