Sol-gel deposition of PZT thick film on Pt/Ti/SOI substrate and application to 2D micro scanning mirror

The present study reports the sol-gel deposition of PZT thick films on Pt/Ti/SOI substrate and its application to the micro cantilevers and 2D micro optical scanning mirrors. Crack-free PZT thick films (2.7 μm) have fabricated on Pt/Ti/SOI substrate. Thin SiO₂ layer on the top of the SOI substrate was found to play important role as a burner layer to avoid breaking the Pt/Ti bottom electrode layer. The micro cantilevers and 2D micro scanning mirrors fabricated by MEMS technologies are flat suggesting the advantage of using SOI substrate instead of Si substrate. The deflection of the tip of the 800 μm-long × 250 μm-width micro cantilever was measured to be 5.9 μm at 5 V. The absolute value of the transverse piezoelectric constant |d₃₁| of the PZT thick film calculated from the deflection is as high as 84 pC/N. The scan angle of the cantilever via resonant actuation at 2387 Hz is as high as 40 degree with only 6 V (peak-to-peak). The response time of micro cantilevers were measured to be within 0.3-1 ms. These data indicate the potential application of the present 2D micro scanning mirrors to wavelength division multiplexing (WDM) systems driven at several voltage.