Silicon microphone with enhanced impact proof structure using bonding wires

A backplateless silicon microphone, comprising:

• (a) a substrate having a front side and a back side with a backside hole formed through said substrate;
• (b) a dielectric spacer layer formed on the front side of the substrate;
• (c) a diaphragm that is aligned above said backside hole and is made of a membrane layer formed on the dielectric spacer layer, said diaphragm has a center and an outer edge;
• (d) a spring surrounding and connecting to the diaphragm, said spring is made of said membrane layer and has a plurality of perforations formed therein, and is connected to a plurality of “m” pads where m≧3;
• (e) a plurality of “m” pads made of said membrane layer and formed on the dielectric spacer layer wherein a pad and an underlying portion of the dielectric spacer layer form a rigid anchor;
• and
• (f) an air gap formed within said dielectric spacer layer and below said diaphragm and spring.

A method of forming a backplateless silicon microphone with wire bonding protection, comprising:

• (a) providing a substrate having a front side and a back side wherein a stack comprised of a lower dielectric spacer layer and upper membrane layer is formed on said front side, and a hardmask is disposed on said back side;
• (b) forming one or more via openings in said membrane layer and dielectric spacer layer to expose certain portions of said substrate;
• (c) forming a plurality of first electrodes and a plurality of “n” bonding pads at certain locations on said membrane layer, and one or more second electrodes in said one or more via openings on said substrate;
• (d) etching said membrane film to form a plurality of perforated holes and a plurality of slot shaped openings therein to define a diaphragm having a center and an outer edge, a spring surrounding and connected to said diaphragm wherein said spring has perforations formed therein and is connected to a plurality of “m” pads where m≧3;
• (e) etching an opening in said hard mask and forming a backside hole through the substrate that is aligned below said diaphragm;
• (f) removing a portion of said dielectric spacer layer in a release step to form an air gap between the diaphragm and back side hole and between the spring and substrate;
• and
• (g) connecting said plurality of “n” bonding pads with a plurality of “n/2” bonding wires such that each bonding wire connects two bonding pads and crosses at least a portion of the spring or the diaphragm and thereby serves as a restraint to limit a vibration of the spring or the diaphragm in a direction away from the substrate.