| CPC H04R 17/02 (2013.01) [B81B 3/0072 (2013.01); H04R 1/04 (2013.01); H04R 7/10 (2013.01); H04R 19/04 (2013.01); B81B 2201/0257 (2013.01); B81B 2203/0127 (2013.01); B81B 2203/019 (2013.01); B81B 2203/04 (2013.01); H04R 2201/003 (2013.01); H04R 2420/07 (2013.01); H04R 2499/11 (2013.01)] | 20 Claims |

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1. A piezoelectric microelectromechanical systems diaphragm microphone, comprising:
a substrate defining an opening between a bottom end of the substrate and a top end of the substrate;
two or more piezoelectric film layers disposed over the top end of the substrate and defining a diaphragm structure that is substantially flat and deflect when the diaphragm structure is subjected to sound pressure via the opening in the substrate, the two or more piezoelectric film layers configured to reduce residual stress of the diaphragm structure, the diaphragm structure including a through hole that extends from a top surface of the diaphragm structure to a bottom surface of the diaphragm structure, the through hole configured to define a low frequency roll off for the microphone; and
one or more electrodes disposed over the diaphragm structure.
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