Method of making piezoelectric microphone with deflection control

A method of making a piezoelectric microphone, comprising:

• forming a membrane over a silicon (Si) substrate having a first and second sacrificial layer disposed on opposite surfaces thereof, the membrane being formed on the first sacrificial layer;
• forming a first hardmask (HM) over the membrane;
• forming first and second vias through the first HM and partially through the membrane
• exposing a portion of a top thin film surrounding each via,
• forming a first pad layer in the first and second vias and over the exposed top thin film;
• forming a trench to the first sacrificial layer between the first and second vias and a gap between the trench and second via;
• patterning a second HM over the membrane, in the first and second vias, the trench and the gap and to expose areas of the first pad layer around the first and second vias, and
• forming a second pad layer over the second HM and in the exposed areas around the first and second vias to form pad structures.