Particle filter for partially enclosed microelectromechanical systems

Abstract

A particle filter for a partially enclosed microelectromechanical systems that include a substrate material having at least one micro-device formed thereon. The particle filter includes a first structural layer forming a filter bottom and a second structural layer forming a filter wall. The filter bottom and filter wall are interconnected by at least one support feature to define a particle trap between the filter wall and filter bottom. The particle trap is a gap formed by mating, but non-interconnected portions of the filter wall and filter bottom that operates to trap and prevent particles from passing beyond the filter bottom into the microelectromechanical system.

We claim:  
     
         1 . A method for constructing a particle filter in a microelectromechanical system, the method comprising: 
 depositing and patterning a plurality of alternating layers of filter forming material and sacrificial material on a substrate material to form at least one filter bottom and at least one filter wall; and    removing the sacrificial material to release the at least one filter bottom and the at least one filter wall to define a particle trap between interfacing portions of the filter bottom and filter wall.    
     
     
         2 . The method of  claim 1  wherein the at least one filter bottom and filter wall are interconnected by at least one support feature.  
     
     
         3 . The method of  claim 1  wherein the step of depositing and patterning the plurality of alternating layers of filter forming material and sacrificial material comprises: 
 forming a filter top including at least one etch release aperture.  
 
     
     
         4 . The method of  claim 3  wherein the filter wall encloses an area circumscribing the at least one etch release aperture.  
     
     
         5 . The method of  claim 1  comprising: 
 patterning the filter bottom into a predetermined one of a plurality of geometric configurations.  
 
     
     
         6 . The method of  claim 1  wherein the particle trap comprises: 
 a gap of pre-determined dimension formed between mating but non-interconnected portions of the filter bottom and filter wall.  
 
     
     
         7 . The method of  claim 6  wherein the filter wall at least partially circumscribes a top portion of the filter bottom to define the particle trap.  
     
     
         8 . The method of  claim 7  wherein the filter wall overlaps the top portion of the filter bottom to form the gap between mating but non-interconnected portions of the filter bottom and filter wall.