Corrugated diaphragm for piezoelectric microphone

This paper describes design and fabrication issues of a micromachined piezoelectric microphone with a corrugated diaphragm on a silicon chip. The microphone is built on a corrugated silicon-nitride diaphragm with piezoelectric ZnO film and electrodes. The diaphragm is corrugated in order to reduce the residual stress which has been a predominant factor limiting the diaphragm deflection for a given acoustic pressure in case of a micromachined diaphragm. A theoretical calculation is presented to show the effectiveness of the corrugation in reducing the residual stress and thus improving the performance of the piezoelectric microphone. Also presented are some initial experimental results confirming the effectiveness of the corrugation in reducing the residual stress