Silicon micromachining processes combined with thick-film printed lead zirconate titanate actuators for microelectromechanical systems

Thick-film printed lead zirconate titanate (PZT) structures can be combined with micromachined silicon structures and offer relatively large actuation forces as compared to alternative techniques. This letter describes the initial investigation into the compatibility issues of micromachining silicon wafers with PZT layers printed on the surface. Many standard micromachining etching processes have been carried out on a range of silicon substrates incorporating platinum electrode/thick-film PZT structures. Wet etches were found to be unsuitable since they attacked the adhesion of the bottom electrode to the substrate, Plasma etching processes do not appear to attack the PZT, although in the case of the CHF3 + ArSiO2 etch, there is drop in the measured dielectric which could reduce the d(33) coefficient of the film. Other than this, plasma process can be used for the micromachining of the silicon substrate after thick-film processing, greatly expanding the range of applications suited to this combination of technologies. (C) 1999 Elsevier Science B.V. All rights reserved.