Acoustic transducers with a perforated damping backplate based on PZT/silicon wafer bonding technique

This paper reports on a membrane-type acoustic transducer fabricated by bonding a piezoelectric ceramic Pb(Zr,Ti)O3 (PZT) plate to a silicon on insulator (SOI) wafer. A special Si backplate with perforated acoustic holes is also bonded to the membrane to broaden the acoustic frequency spectrum. Key techniques in the fabrication include a low-temperature bonding technique using a spin-on polymer, design of electrode interconnect, chemical mechanical polishing (CMP) for thinning down the bulk PZT, and deep reactive ion etching bulk micromachining of silicon. High quality integrated transducers on SOI wafer have been successfully demonstrated and the fabrication and measurement results are presented.