Patent ID: 8467559

Claim:
A microphone sensing element without a dedicated backplate, comprising: (a) a substrate having front and back sides with one or more back holes formed therein; (b) a dielectric spacer layer formed on the front side of the substrate; (c) a diaphragm that is aligned above said one or more back holes; (d) a plurality of rigid pads formed on said dielectric spacer layer; (e) a plurality of perforated springs wherein each perforated spring has a side that is separated from a nearest diaphragm side by a gap; and has a first end attached to a substantial portion of the nearest side of said diaphragm and a second end that is connected to one of said rigid pads, each perforated spring has a lengthwise dimension formed parallel to the nearest diaphragm side, said perforated springs and diaphragm are suspended above an air gap overlying the substrate, and said diaphragm, plurality of rigid pads, plurality of perforated springs are patterned in a same membrane layer with a plurality of holes and slot openings whereby holes in the perforated springs allow air ventilation through the perforated springs and thereby reduce air damping in the air gap during vibrations of the perforated springs and diaphragm; and (f) a first electrode formed on one or more of said rigid pads and one or more second electrodes formed on the substrate wherein a first electrode and a second electrode establish a variable capacitor circuit when said diaphragm and said perforated springs vibrate up and down in a direction perpendicular to said substrate in response to a sound signal.