Conductive etch stop for etching a sacrificial layer

Abstract

In one embodiment, a micro device is formed by depositing a sacrificial layer over a metallic electrode, forming a moveable structure over the sacrificial layer, and then etching the sacrificial layer with a noble gas fluoride. Because the metallic electrode is comprised of a metallic material that also serves as an etch stop in the sacrificial layer etch, charge does not appreciably build up in the metallic electrode. This helps stabilize the driving characteristic of the moveable structure. In one embodiment, the moveable structure is a ribbon in a light modulator.

1 - 10 . (canceled)  
     
     
         11 . An intermediate micro device structure comprising: 
 a silicon layer over a first metallic electrode, the first metallic electrode serving as an etch stop in a subsequent isotropic etch of the silicon layer to protect an underlying isolation layer; and    a resilient structure over the silicon layer.    
     
     
         12 . The intermediate micro device structure of  claim 11  wherein the resilient structure is part of a ribbon in a light modulator.  
     
     
         13 . The intermediate micro device structure of  claim 11  wherein the first metallic electrode comprises titanium-nitride.  
     
     
         14 . The intermediate micro device structure of  claim 11  further comprising a second metallic electrode over the resilient structure.  
     
     
         15 . The intermediate micro device structure of  claim 11  wherein the resilient structure comprises silicon nitride.  
     
     
         16 . The intermediate micro device structure of  claim 14  wherein the second metallic electrode comprises aluminum.  
     
     
         17 . The intermediate micro device structure of  claim 14  further comprising an oxide layer under the first metallic electrode.  
     
     
         18 - 20 . (canceled)  
     
     
         21 . The intermediate micro device structure of  claim 11  wherein the isolation layer comprises silicon dioxide.  
     
     
         22 . An intermediate micro device structure comprising: 
 a metallic electrode over an isolation layer;    a sacrificial layer over the metallic electrode;    a ribbon structure over the sacrificial layer;    wherein the metallic electrode serves as an etch stop in an etching of the sacrificial layer to form an air gap between the metallic electrode and the ribbon structure.    
     
     
         23 . The intermediate micro device structure of  claim 22  wherein the isolation layer comprises silicon dioxide and the metallic electrode comprises titanium-nitride.  
     
     
         24 . The intermediate micro device structure of  claim 22  wherein the sacrificial layer comprises amorphous silicon.  
     
     
         25 . The intermediate micro device structure of  claim 22  wherein the ribbon structure comprises a metal layer over a resilient material layer.  
     
     
         26 . The intermediate micro device structure of  claim 25  wherein the metal layer comprises aluminum and the resilient material layer comprises silicon nitride.  
     
     
         27 . The intermediate micro device structure of  claim 22  wherein the metallic electrode serves as a bottom electrode and a metal layer of the ribbon structure serves as a top electrode of a light modulator.  
     
     
         28 . An intermediate micro device structure comprising: 
 a ribbon structure having a reflective top electrode;    a bottom electrode being configured to work in conjunction with the top electrode to modulate incident light;    a sacrificial layer between the ribbon structure and a bottom electrode;    wherein the bottom electrode serves as an etch stop in an etching of the sacrificial layer to form an air gap between the ribbon structure and the bottom electrode.    
     
     
         29 . The intermediate micro device structure of  claim 28  wherein the ribbon structure further includes a resilient material layer under the top electrode.  
     
     
         30 . The intermediate micro device structure of  claim 28  further comprising an isolation layer under the bottom electrode.  
     
     
         31 . The intermediate micro device structure of  claim 28  further comprising a substrate under the isolation layer, and wherein the isolation layer comprises silicon dioxide.  
     
     
         32 . The intermediate micro device structure of  claim 29  wherein the top electrode comprises aluminum, the resilient material layer comprises silicon nitride, and the bottom electrode comprises titanium-nitride.