Patent ID: 7346178
Filing Date: 2008-03-18
Classification: H04R

Abstract:
1. A method of forming a microphone sensing element without a dedicated backplate component, comprising: (a) providing a substrate having a front side and a back side wherein a stack comprised of a lower dielectric spacer layer and an upper membrane film is formed on said front side and a hardmask is disposed on said back side; (b) forming a plurality of vias in said upper membrane film that extend through the lower dielectric spacer layer to contact said front side of the substrate; (c) forming a plurality of first electrodes at certain locations on said upper membrane film and a second electrode in one or more of said vias; (d) etching said upper membrane film to form openings that define a diaphragm and a perforated plate that adjoins each side or corner of the diaphragm, a mechanical spring having two ends that is connected on one end to the diaphragm and on the other end to a pad, and a pad that anchors each mechanical spring to the lower dielectric spacer layer; (e) etching an opening in said hardmask and a back hole in the substrate that are aligned below said diaphragm; and (f) removing a portion of said lower dielectric spacer layer in a release step to form an air gap between the diaphragm and the back hole.