Elevated mems device in a microphone with ingress protection

Abstract

A micro electro mechanical system (MEMS) microphone includes a base including a port extending through the base, a shim assembly, an ingress protection element, and a MEMS device. The shim assembly is disposed on the base and over the port. The shim assembly has a plurality of walls that form a hollow interior cavity. The shim assembly also has a top surface and a bottom surface coupled to the base. The ingress protection element extends over and is coupled to the top of the shim assembly to enclose the cavity of the shim assembly. The shim assembly elevates the ingress protection element above the base and is effective to prevent the passage of contaminants there through. The MEMS device includes a diaphragm and a back plate and is disposed over the ingress protection element.

What is claimed is: 
     
         1 . A micro electro mechanical system (MEMS) microphone comprising:
 a base including a port extending through the base;   a shim assembly disposed on the base and over the port;   an ingress protection element coupled to the shim assembly such that the shim assembly elevates the ingress protection element above the base, wherein the ingress protection element prevents passage of contaminants therethrough; and   a MEMS transducer disposed over the ingress protection element, wherein an exposed length of the ingress protection element underneath the MEMS transducer is greater than a diameter of the port.   
     
     
         2 . The MEMS microphone of  claim 1 , wherein the shim assembly, the ingress protection element, and the MEMS transducer cooperatively form an acoustic seal. 
     
     
         3 . The MEMS microphone of  claim 1 , wherein:
 the shim assembly is formed using an epoxy material; and   the shim assembly comprises walls that cooperatively form an interior cavity.   
     
     
         4 . The MEMS microphone of  claim 1 , wherein the ingress protection element comprises a metal screen with a plurality of openings. 
     
     
         6 . The MEMS microphone of  claim 1 , wherein the shim assembly comprises a top surface and a bottom surface, the bottom surface coupled to the base and the top surface coupled to ingress protection element. 
     
     
         7 . The MEMS microphone of  claim 1 , further comprising an application specific integrated circuit (ASIC) disposed on the base. 
     
     
         8 . The MEMS microphone of  claim 1 , wherein the MEMS transducer comprises a first diaphragm, a first backplate, a second diaphragm, and a second backplate. 
     
     
         9 . The MEMS microphone of  claim 8 , wherein the port comprises a first port, the MEMS microphone further comprising a second port extending through the base. 
     
     
         10 . A micro electro mechanical system (MEMS) device assembly comprising:
 a base;   a port extending through the base;   a shim assembly coupled to the base;   an ingress protection element disposed over the port and comprising a top surface and a bottom surface, the bottom surface coupled to the shim assembly such that the shim assembly elevates the ingress protection element above the base, wherein the ingress protection element prevents passage of contaminants therethrough; and   a MEMS transducer coupled to the top surface of the ingress protection element.   
     
     
         11 . The MEMS device assembly of  claim 10 , wherein:
 the shim assembly is formed using an epoxy material; and   the shim assembly comprises walls that cooperatively form an interior cavity.   
     
     
         12 . The MEMS device assembly of  claim 10 , wherein the ingress protection element comprises a metal screen with a plurality of openings. 
     
     
         13 . The MEMS device assembly of  claim 10 , wherein an exposed length of the ingress protection element underneath the MEMS transducer is greater than a diameter of the port. 
     
     
         14 . The MEMS device assembly of  claim 10 , wherein the MEMS device further comprises a second diaphragm and a second back plate. 
     
     
         15 . A method of manufacturing a micro electro mechanical system (MEMS) microphone comprising:
 forming a shim assembly on a base of the MEMS microphone;   forming an ingress protection element over a port extending through the base such that a bottom surface of the ingress protection element is coupled to the shim assembly and the shim assembly elevates the ingress protection element above the base; and   forming a MEMS transducer coupled to a top surface of the ingress protection element.   
     
     
         16 . The method of  claim 15 , further comprising coupling an integrated circuit to the base. 
     
     
         17 . The method of  claim 15 , further comprising forming a lid coupled to the base. 
     
     
         18 . The method of  claim 15 , wherein forming the shim assembly comprises using an epoxy material to form a plurality of walls that cooperatively define an interior cavity. 
     
     
         19 . The method of  claim 15 , wherein forming the ingress protection element comprises forming the ingress protection element such that an exposed length of the ingress protection element underneath the MEMS transducer is greater than a diameter of the port. 
     
     
         20 . The method of  claim 15 , wherein forming the ingress protection element comprises using a metal material to form a mesh screen with a plurality of openings.