Method for Fabricating a Micromirror

Abstract

A method for fabricating a micromirror is disclosed. A set of coarse features is formed in a low-temperature oxide (LTO) layer deposited on a front side of a wafer. A set of fine features is then formed in a photosensitive material layer deposited on top of the LTO layer. After removing a portion of the LTO layer to align the width of the coarse features with the width of the fine features, the first silicon dioxide layer and the first and second silicon device layers are etched to form stator comb fingers and rotor comb fingers accordingly. Finally, a portion of the substrate on a back side of the wafer is removed, and the silicon dioxide layers are removed from the front and back sides of the wafer to form a rotatable mirror.

1 . A method of fabricating a micromirror, said method comprising:
 forming a set of coarse features in a low-temperature oxide (LTO) layer deposited on a front side of a wafer having a substrate, a first and second silicon device layers separated from each other by a first and second silicon dioxide layers;   forming a set of fine features in a photosensitive material layer deposited on top of said LTO layer, wherein said fine features are constrained laterally within said coarse features;   removing a portion of said LTO layer to align the width of said coarse features with the width of said fine features;   etching said first silicon dioxide layer and said first and second silicon device layers to form stator comb fingers and rotor comb fingers; and   removing a portion of said substrate on a back side of said wafer, and said silicon dioxide layers from said front and back sides of said wafer to form a rotatable minor.   
     
     
         2 . The method of  claim 1 , wherein said wafer is a double silicon-on-insulator (DSOI) wafer. 
     
     
         3 . The method of  claim 1 , wherein said etching further includes
 etching said first silicon device layer by using said LTO layer and said photosensitive material layer as a mask;   etching said first silicon dioxide layer by using said LTO layer and said photosensitive material layer as a mask; and   removing said photosensitive material layer.   
     
     
         4 . The method of  claim 1 , wherein said etchings are performed by a Deep Reactive Ion Etching (DRIP process. 
     
     
         5 . The method of  claim 1 , wherein said method further includes coating a thin metal film on a surface of said micromirror.