Patent ID: 7362873

Claim:
An acoustic transducer comprising: a supporting substrate; an electrically conductive, fixed counter electrode formed on the substrate; an electrically conductive diaphragm positioned over the fixed counter electrode, said diaphragm including an annular indentation to maintain a selected distance between said diaphragm and said counter electrode when a bias voltage is applied between the counter electrode and the diaphragm; a plurality of suspension structures formed on the substrate and attached to the diaphragm to support the diaphragm whereby intrinsic mechanical stress in said diaphragm and imposed stress from said supporting substrate are eliminated, said suspension structures having a restoring force equal to or greater than stiction forces between the diaphragm and supporting substrate; and a plurality of metal pads formed on said supporting substrate to provide an electrical connection to said diaphragm and said counter electrode; whereby an electrostatic force associated with the bias voltage overcomes the restoring force of the suspension structures, causing the diaphragm to be pulled towards the supporting substrate; and whereby said counter electrode includes a plurality of holes to allow air in a gap between the counter electrode and the diaphragm to escape, thereby reducing acoustical damping in the transducer.