In this article we report the structure and the microfabrication method of a novel micro-scanning force microscopy (SFM) device. It is a lead zirconate titanite (PZT) bimorph structure in the shape of a cantilever supported by bridges. Electric fields applied to the separated sections of the electrodes on the levers can induce lever deflection and actuate the tip in x, y, and z directions. The cantilever can vibrate and sense its own vibration amplitude to detect the surface topography in the cyclic contact SFM mode. In the fabrication process, the sol–gel method is modified for constructing high quality PZT films 3 μm thick. The single bridge device has shown microscopy sensitivity of 0.32 nA/nm in a vertical direction, with actuation sensitivities of 70–80 nm/V in a lateral direction. The multibridged structure has been proven to be effective in elevating the eigenfrequency, which is very important for improving the SPM data rate.

This paper describes the design, fabrication and characterization of a bulk-PZT-actuated MEMS deformable mirror (DM). An analytical model was employed to optimize the DM's structure. The fabrication techniques for PZT thick film actuators were also experimentally explored, including the bonding of bulk PZT ceramics and a silicon wafer by epoxy resin, and the thinning of the bulk PZT ceramics using a wet-etching method. A 10 × 10 array of 1.75 mm × 1.75 mm PZT thick film actuators was successfully fabricated. The PZT actuators showed a stroke of about 4.5 µm at 100 V. When a 36 µm thick silicon membrane mirror was assembled, the measured mirror deflection at 100 V was approximately 3.8 µm. The assembled DM showed an operating frequency bandwidth of 21 kHz and an influence function of approximately 30%. The displacement hysteresis was greatly eliminated by using the method of staying on the same segment.

High-quality lead zirconate titanate (PZT) thick films have been prepared on silicon substrates by combining PZT-Si bonding and wet-etching technology. The bulk PZT wafer was first bonded to the silicon substrate using a 2 µm thick intermediate layer of epoxy resin with a bonding strength higher than 10 MPa. Then the bulk PZT was thinned by a wet-etching method. The thickness of the final PZT films depends on the etching time. The PZT thick films after being polished showed a surface roughness of about 20 nm (RMS), which can satisfy most of the requirements in MEMS. The prepared PZT thick films show a dielectric constant as high as 2400 below 100 kHz, remnant polarization of 13 µC cm −2 , piezoelectric constant d 31 of about −280 pm V −1 and Young's modulus of about 63 GPa. The measured electromechanical properties of the PZT thick films were comparable to those of the corresponding bulk ceramics. This approach makes it possible to obtain high-quality PZT films because it separates the PZT wafer fabrication from the target substrate and consequently allows integration of the PZT thick films onto many kinds of substrates. Finally, a self-sensing bulk PZT thick film actuator was fabricated as an example of a basic PZT-Si diaphragm structure that can be used in piezoelectric micropumps, and its sensing and actuating performances were also demonstrated.

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The deposition technology for thin PZT (Pb(Zr0.52,Ti0.48)O3) layers has reached an advanced state in the application area of memory fabrication. On the other hand, the application of PZT layers for actuation of micro electromechanical system (MEMS) is not well established. A relatively thicker film is necessary for this application. Conventional preparation techniques provide poor deposition rates and the accumulated residual stress during deposition results in the deposited layer peeling off. Another difficulty lies in the low etching rate of the multilayered structure of SiO2/Ti/Pt/PZT. These are the reasons why we have studied thick PZT film preparation technology and efficient pattering processes. Thick film deposition processes include repeated multilayer coating by the sol-gel method, the excimer laser ablation deposition (ELAD), and the jet molding system (JMS). Pattering processes include RIE, ECR and deposition methods on a non-planar surface. The electrical properties of PZT layers were determined for microfabricated actuators.