Novel patterning of thick film PZT

A vast amount of research has been carried out on PZT films with thicknesses ranging from 100 nm to 3-4 µm for implementation in micro-electromechanical systems (MEMS). There are several fabrication methods for such films; e.g. sputtering, chemical solution deposition (CSD), chemical vapour deposition (CVD) and pulsed laser deposition (PLD).   Some applications, like high frequency transducers operating in the thickness mode, require lower frequencies and thus thicker films. There is a clear need for patterned films in the thickness range 10-50 µm. PZT films in this thickness range and of high quality can be fabricated using a composite method. The use of normal thin film patterning techniques is, however, difficult for thick films due to the amount of material that has to be removed. Wet etching by HCl/HF mixes is applicable, even though significant undercutting will take place due to its isotropic nature. A new patterning technique suitable for composite thick films using an epoxy mould will be presented.