Titanium as a micromechanical material

The suitability of titanium for use in microelectromechanical applications is investigated. A range of titanium microdevices, including free-standing fixed-fixed beams and cantilevers, has been successfully fabricated using a fully CMOS compatible, dry-release surface micromachining process. Finite-element simulations have been used to extract a semi-analytical model which describes the pull-in behaviour of fixed-fixed beams, while taking into account the effects of the non-ideal beam anchors. This method has been used to obtain an estimate of the Young's modulus and residual stress in the metal. Capacitance monitoring has shown that the beams remain flat after sacrificial layer release, and interferometry imaging has been used to investigate the stability of beam anchors during device actuation. Furthermore, titanium beams have remained stable under repeated actuation in initial cycle testing and may be suitable for use as a major component of microswitches. One such possible design is outlined.