Patent ID: 7536769

Claim:
A method of fabricating an acoustic transducer comprising the steps of: forming a bulk layer on a supporting substrate; forming a plurality of cavities in said bulk layer; covering the bulk layer and supporting substrate with a first sacrificial material, whereby said plurality of cavities are filled with said first sacrificial material; planarizing said first sacrificial layer until the bulk layer is exposed; depositing and patterning an electrically insulating layer on said first sacrificial layer and bulk layer and on an opposite side of said substrate; depositing and patterning an electrically conductive layer on said patterned electrically insulating layer to form a fixed electrode; depositing a second sacrificial layer and patterning the second sacrificial layer in first selected areas; depositing a third sacrificial layer and patterning the third sacrificial layer in second selected areas; depositing and patterning an electrically conductive layer to form a diaphragm with an annular indentation and a suspension structure; depositing and patterning a metal to form contact pads for interconnection; removing in bulk the substrate under the diaphragm; and removing all sacrificial layers to complete formation of the acoustic transducer.