Patent ID: 7329933

Claim:
A silicon microphone sensing element with a softly constrained diaphragm, comprising: (a) a diaphragm comprised of a semiconductor layer, said diaphragm has an edge, bottom surface, and a plurality of holes formed an equal distance from said edge and from a first trench that defines said edge wherein said diaphragm is formed over a backplate region with acoustic holes in a front side of a substrate and above a back hole with an opening in a back side of the substrate, said backplate region and diaphragm are separated by an air gap; (b) an electrical lead-out arm that extends from the edge of said diaphragm and is comprised of the same semiconductor material as in the diaphragm and has a shape defined by a set of second trenches in the semiconductor layer; (c) a rigid semiconductor layer having a plurality of horizontal sections disposed on a dielectric stack on said front side of the substrate, a plurality of holes formed an equal distance from the trench surrounding the diaphragm edge, and vertical sections that connect said horizontal sections and said front side of the substrate; (d) a dielectric spacer stack disposed on a portion of said horizontal sections and having openings formed therein on said diaphragm and said electrical lead-out arm; (e) a first electrode formed on said dielectric spacer stack and within an opening that contacts said electrical lead-out arm; and a second electrode formed on said dielectric spacer stack and within an opening that contacts a horizontal section of said rigid semiconductor layer; (f) a soft constraint layer having an upper section formed above the edge of said diaphragm, above and within the first trench and plurality of holes, and above a portion of the rigid semiconductor layer, and having a lower section attached to the bottom surface of the diaphragm and rigid semiconductor layer adjacent to the first trench and plurality of holes; and (g) a substrate with front and back sides, a back hole formed in the substrate with an opening in said back side, and a backplate region with acoustic holes formed between the back hole and front side of the substrate.