Improvement of stresses in multilayer structures with SiO/sub 2//Pt/Pb(Zr,Ti)O/sub 3//Pt thin-film stacks for micro-scanner actuators

Stresses in MEMS multilayer structures with SiO/sub 2//Pt/Pb(Zr,Ti)O/sub 3//Pt thin-film stacks on Si substrates for micro-scanner actuators were investigated by measuring radius of wafer curvature for each film. The stresses in each film after the last coating were in tension except the Pt top electrode. The Pt bottom electrode shows an especially large tensile stress of approximately 1.3 GPa. The beam-scanners were then fabricated to,investigate the curving state of multilayer structure released from Si substrate. The curving states of beams are related to not only the stresses in each film but also the balance of flexural rigidity of each film. A beam without any curvature was obtained successfully by changing the thickness of each film. A large optical scanning angle of 40-degree was obtained at the first resonance frequency of 2.78 kHz for the fabricated straight beam-scanner.