Patent ID: 9676615
Date: 2017-06-13
CPC Classifications: B81B,B81C,H04R

Claim:
1. A method for fabricating an MEMS microphone, comprising: Step 1, providing a diaphragm silicon substrate, and a multi-cavity silicon backplate with a center area and a boundary area surrounding the center area, a plurality of holes being arranged in the multi-cavity silicon backplate; Step 2, depositing a first dielectric layer on both upper and lower surfaces of the multi-cavity silicon backplate, the first dielectric layer covering bottoms and sidewalls of holes, and depositing a second dielectric layer on both upper and lower surfaces of the diaphragm silicon substrate; Step 3, bonding the lower surface of the diaphragm silicon substrate to the upper surface of the multi-cavity silicon backplate to form capacitor plates of the MEMS microphone; Step 4, thinning the diaphragm silicon substrate to form a monocrystalline silicon diaphragm of the MEMS microphone; Step 5, partially etching the monocrystalline silicon diaphragm and stopping the etch at the second dielectric layer to form a groove and a plurality of spring structure slots in the boundary areas, and to form a plurality of first through holes and second through holes in the center area, the spring structure slots being located between the groove and the center area; Step 6, depositing a silicon rich nitride layer which covers bottoms and sidewalls of the second through holes, and covers parts of upper surface of the diaphragm adjacent to the second through holes, so as to form bumps; Step 7, etching bottom of the groove until the upper surface of the multi-cavity silicon backplate to form the opening; Step 8, etching the lower surface of the multi-cavity silicon backplate to form a back cavity exposing the first dielectric layer at the bottoms of holes; Step 9, partially removing the first dielectric layer and the second dielectric layer to form a remaining portion on the boundary area to support the monocrystalline silicon diaphragm.