Patent ID: 8962368
Filing Date: 2015-02-24
Classification: H04R

Abstract:
1. A method for manufacturing a CMOS compatible MEMS microphone, comprising: forming a microphone diaphragm by patterning the silicon device layer of an SOI substrate and doping the microphone diaphragm so as to make the microphone diaphragm conductive; forming a CMOS dielectric oxide layer on the silicon device layer and the microphone diaphragm; forming a plurality of deep trenches and a plurality of shallow trenches in the CMOS dielectric oxide layer, wherein the deep trenches are formed vertically from the upper surface of the CMOS dielectric oxide layer to the upper surface of the silicon device layer, the shallow trenches are formed vertically from the upper surface of the CMOS dielectric oxide layer, opposite to the microphone diaphragm, to a certain depth of the CMOS dielectric oxide layer; forming isolation walls and a plurality of dimples by depositing a CMOS passivation layer into the trenches; forming a microphone backplate on the CMOS dielectric oxide layer, by sequentially depositing a CMOS passivation layer, a metal layer and a CMOS passivation layer, with a plurality of through holes formed in the portion of the microphone backplate opposite to the microphone diaphragm; forming a back hole by removing the portion of the SOI substrate underneath the microphone diaphragm; and forming an air gap by removing the CMOS dielectric oxide layer other than the portions of the CMOS dielectric oxide layer confined by the plurality of deep trenches.