Technological process for the fabrication of a MEMS microswitch actuated by a PZT thin film

The research in the field of microrelay is now oriented to MEMS devices. They offer the possibility of high integration and low cost, exploiting semiconductor technologies. About MEMS microrelay, piezoelectric actuation offers the advantages of low power consumption, low actuation voltage, low actuation time and long life time. Actuators and microrelays based on piezoelectric thin films are usually made of silicon, exploiting SOI wafers. The aim of this thesis is the fabrication of a silicon nitride microrelay, exploiting the low residual stress of a 2 μm thick silicon nitride film, actuated by a PZT thin film. Silicon wafers finished with a silicon nitride film bring to a fabrication process simpler and faster than a process that employs SOI wafers. A big problem to face is the growth of PZT films with good piezoelectric properties with bottom electrodes deposited over silicon nitride. In particular the aim is to design and fabricate a microrelay with geometries in order to carry high currents, of the order of 1 A.