Patent ID: 8617960
Filing Date: 2013-12-31
Classification: H01L,H04R

Abstract:
1. A process of forming an integrated circuit containing a capacitive microphone transducer, comprising the steps: providing a substrate in which said substrate includes a base layer, an etch stop layer formed on said base layer, and a top layer formed on said etch stop layer; forming a first interconnect region on a top surface of said substrate; forming a fixed plate on a top surface of said first interconnect region; forming access trenches through said first interconnect region into said substrate; in which said step of forming said access trenches is performed so that said access trenches extend through said top layer; forming a sacrificial fill region of sacrificial material above said fixed plate; forming a first membrane layer on a top surface of said sacrificial fill region; forming a sacrificial protective layer of sacrificial material over a top surface of said first membrane layer; forming a backside cavity in said substrate, said backside cavity extending from a bottom surface of said substrate to said access trenches; in which said step of forming said backside cavity is performed so that said backside cavity extends through said base layer; removing a portion of said sacrificial material in said access trenches by a process of etching from a back side of said integrated circuit; and removing said sacrificial material from said sacrificial fill region.