Mems device and process

Abstract

The application describes MEMS transducers and associated methods of fabrication. The MEMS transducer has a flexible membrane with a vent structure comprising a moveable portion which opens in response to a differential pressure across the membrane to provide a flow path through the membrane. At least one edge of the moveable portion comprises one or more protrusions and/or recesses in the plane of the moveable portion.

1 .- 46 . (canceled) 
     
     
         47 . A MEMS transducer comprising: a flexible membrane, the flexible membrane having a vent structure comprising a moveable portion which is at least partly separated from the rest of the membrane by a channel which extends through the membrane and defines a first edge of the moveable portion, the channel defining a meandering path. 
     
     
         48 . The MEMS transducer as claimed in  claim 47 , wherein the channel further defines a second edge adjacent to the first edge of the moveable portion. 
     
     
         49 . The MEMS transducer as claimed in  claim 48 , wherein the second edge is an internal edge of the membrane and/or an edge of a second, adjacent moveable portion of the vent structure. 
     
     
         50 . The MEMS transducer as claimed in  claim 47 , wherein the vent structure has an equilibrium position at which the moveable portion is substantially in plane with the rest of the membrane. 
     
     
         51 . The MEMS transducer as claimed in  claim 50 , wherein the first edge has a shape that substantially compliments the shape of the second edge when the vent structure is at the equilibrium position. 
     
     
         52 . The MEMS transducer as claimed in  claim 50 , wherein the first and second edges are interdigitated when the vent structure is at the equilibrium position. 
     
     
         53 . The MEMS transducer as claimed in  claim 48 , wherein the channel provides a volume between the first edge of the moveable portion and the second edge, and wherein the first and second edges are interdigitated 
     
     
         54 . The MEMS transducer as claimed in  claim 50 , wherein at least a portion of the channel exhibits a sinusoidal, a square-wave, a triangle-wave, or a saw-tooth shape when the vent structure is at the equilibrium position. 
     
     
         55 . The MEMS transducer as claimed in  claim 47 , wherein said transducer comprises a capacitive sensor. 
     
     
         56 . The MEMS transducer as claimed in  claim 47 , wherein said transducer comprises a microphone. 
     
     
         57 . The MEMS transducer as claimed in  claim 56 , further comprising readout circuitry. 
     
     
         58 . An integrated circuit comprising a MEMS transducer as claimed in  claim 47  and readout circuitry. 
     
     
         59 . The MEMS transducer as claimed in  claim 47 , wherein the transducer is located within a package having a sound port. 
     
     
         60 . An electronic device comprising a MEMS transducer as claimed in  claim 47 . 
     
     
         61 . The electronic device as claimed in  claim 60 , wherein said device is at least one of: a portable device; a battery powered device; an audio device; a computing device; a communications device; a personal media player; a mobile telephone; a games device; and a voice controlled device.