Method for Encapsulating a Device in a Microcavity

Abstract

Manufacturing a semiconductor device involves forming ( 200 ) a sacrificial layer where a micro cavity is to be located, forming ( 210 ) a metal layer of thickness greater than 1 micron over the sacrificial layer, forming ( 220 ) a porous layer from the metal layer, the porous layer having pores of length greater than ten times their breadth, and having a breadth in the range 10 nm-500 nanometers. The pores can be created by anodising, electrodeposition or dealloying. Then the sacrificial layer can be removed ( 230 ) through the porous layer, to form the micro cavity, and pores can be sealed ( 240 ). Encapsulating MEMS devices with a porous layer can reduce costs by avoiding using photolithography for shaping the access holes since the sacrificial layer is removed through the porous membrane.

1 . A method of manufacturing a semiconductor device comprising the steps of:
 forming a sacrificial layer where a micro cavity is to be located;   forming a metal layer of thickness greater than 1 micron over the sacrificial layer;   forming a porous layer by anodization of the metal layer, the porous layer having pores of length greater than ten times their breadth, and having a breadth in the range of 10-500 nanometers;   removing at least some of the sacrificial layer through the porous layer, to form the micro cavity; and   sealing the pores.   
   
   
       2 - 5 . (canceled) 
   
   
       6 . The method of  claim 1 , the metal layer comprising aluminum of a thickness less than 4 μm. 
   
   
       7 - 16 . (canceled)