Novel patterning of composite thick film PZT

There is a clear need for thick PZT films (10–100 μm) in micro-electromechanical systems (MEMS). Some applications, like high frequency transducers operating in the thickness mode, require frequencies in the MHz region and thus thicker films, which in addition will provide more power. Thicker films are also important in actuator systems and sensors as it will generate more force and voltage, respectively. Integration of complex structures of thick films in thick films in MEMS is challenging. The use of normal thin film patterning techniques is difficult for thick films due to the amount of material that has to be removed and the isotropic nature of wet etching. A new patterning technique suitable for composite thick films using an epoxy mould is presented. By filling a micro mould of SU-8 photoresist with PZT paste details down to 20 μm with vertical feature walls could be patterned in a 15 μm thick film.