Analog interferometric modulator device with electrostatic actuation and release

Abstract

Examples of methods of manufacturing a microelectromechanical system (MEMS) device can include forming a first reflective layer on a substrate, forming a sacrificial layer over the first reflective layer, removing a portion of the sacrificial layer to form an opening, and filling the opening with a dielectric material to form a post. Some methods further include forming a second reflective layer over the sacrificial layer, removing a portion of the second reflective layer and a portion of the post to form a hole, filling the hole with a conductive material to form an electrode, and removing the sacrificial layer.

1 . A method of manufacturing an electromechanical systems (EMS) device, comprising:
 forming an optical stack over a substrate, wherein the optical stack is partially transparent or translucent and at least partially reflective of light, and includes a first electrode;   forming a sacrificial layer over the optical stack;   forming a reflective element over the sacrificial layer, wherein the reflective element includes a second electrode;   forming a support structure between the first electrode and the second electrode;   forming a third electrode in a portion of the support structure between the first electrode and the second electrode; and   removing the sacrificial layer to form a cavity between the optical stack and the reflective element,   wherein after removing the sacrificial layer, the reflective element is movable between a first position and a second position upon application of a voltage between the first electrode and the second electrode.   
     
     
         2 . The method of  claim 1 , wherein forming the optical stack includes:
 forming a partially reflective layer;   forming an electrically conductive layer, the first electrode including a portion of the electrically conductive layer; and   forming an electrically nonconductive layer over the electrically conductive layer.   
     
     
         3 . The method of  claim 1 , wherein forming the reflective element includes forming an electrically conductive layer over the sacrificial layer, the second electrode including a portion of the electrically conductive layer. 
     
     
         4 . The method of  claim 3 , wherein the reflective element includes a lower surface of the electrically conductive layer. 
     
     
         5 . The method of  claim 1 , wherein forming the support structure includes:
 removing a portion of the sacrificial layer to form an opening; and   filling the opening with an electrically nonconductive material to form a post.   
     
     
         6 . The method of  claim 5 , wherein forming the third electrode includes:
 removing a portion of the post to form a hole in the post; and   filling the hole in the post with an electrically conductive material to form the third electrode.   
     
     
         7 . The method of  claim 1 , wherein forming the reflective element includes:
 forming a first layer; and   forming a second layer over the first layer.   
     
     
         8 . The method of  claim 7 , wherein the first layer is more flexible than the second layer. 
     
     
         9 . The method of  claim 7 , wherein the first layer is thinner than the second layer. 
     
     
         10 . The method of  claim 7 , wherein at least one of the first layer or the second layer is electrically conductive, the second electrode including a portion of the electrically conductive layer. 
     
     
         11 . The method of  claim 1 , wherein forming the reflective element further includes forming one or more extensions above an upper surface of the reflective element. 
     
     
         12 . The method of  claim 1 , wherein at least a portion of the third electrode is lower than the reflective element when the reflective element is in the second position, and wherein at least a portion of the third electrode is higher than the reflective element when the reflective element is in the first position. 
     
     
         13 . The method of  claim 1 , wherein the cavity includes an interferometric optical cavity. 
     
     
         14 . The method of  claim 1 , wherein the reflective element in contact with a portion of the optical stack when in the first position and not in contact with the portion of the optical stack when in the second position. 
     
     
         15 . A method of manufacturing an electromechanical systems (EMS) device, the method comprising:
 forming a first electrode over a substrate;   forming an electrically nonconductive layer over the first electrode;   forming a sacrificial layer over the electrically nonconductive layer;   forming a second electrode over the sacrificial layer;   forming a reflective element over the sacrificial layer;   forming a support structure between the first electrode and the second electrode;   forming a third electrode in a portion of the support structure between the first electrode and the second electrode; and   removing the sacrificial layer,   wherein after removing the sacrificial layer, the reflective element is movable between a first position and a second position,   wherein at least a portion of the third electrode is lower than the reflective element when the reflective element is in the second position, and   wherein at least a portion of the third electrode is higher than the reflective element when the reflective element is in the first position.   
     
     
         16 . The method of  claim 15 , wherein the reflective element includes a lower surface of the second electrode. 
     
     
         17 . The method of  claim 15 , wherein forming the support structure includes:
 removing a portion of the sacrificial layer to form an opening; and   filling the opening with an electrically nonconductive material to form a post.   
     
     
         18 . The method of  claim 17 , wherein forming the third electrode includes:
 removing a portion of the post to form a hole in the post; and   filling the hole in the post with an electrically conductive material to form the third electrode.   
     
     
         19 . The method of  claim 15 , wherein forming the reflective element includes:
 forming a first layer; and   forming a second layer over the first layer.   
     
     
         20 . The method of  claim 19 , wherein the first layer is more flexible than the second layer. 
     
     
         21 . The method of  claim 19 , wherein the first layer is thinner than the second layer. 
     
     
         22 . The method of  claim 19 , wherein at least one of the first layer or the second layer is electrically conductive, the second electrode including a portion of the electrically conductive layer. 
     
     
         23 . The method of  claim 15 , wherein forming the reflective element further includes forming one or more extensions above an upper surface of the reflective element. 
     
     
         24 . The method of  claim 15 , wherein the reflective element is in contact with a portion of the electrically nonconductive layer when in the first position and not in contact with the portion of the electrically nonconductive layer when in the second position. 
     
     
         25 . The method of  claim 15 , wherein removing the sacrificial layer forms an interferometric optical cavity between the reflective element and the electrically nonconductive layer.