Mems cavity-coating layers and methods

Abstract

Devices, methods, and systems comprising a MEMS device, for example, an interferometric modulator, that comprises a cavity in which a layer coats multiple surfaces. The layer is conformal or non-conformal. In some embodiments, the layer is formed by atomic layer deposition (ALD). Preferably, the layer comprises a dielectric material. In some embodiments, the MEMS device also exhibits improved characteristics, such as improved electrical insulation between moving electrodes, reduced stiction, and/or improved mechanical properties.

1 . An optical interferometric modulator comprising:
 an optical stack comprising a partial reflector and a first dielectric layer;   a movable structure including a reflective layer that is movable relative to the optical stack;   a cavity defined by the optical stack and the movable structure; and   a conformal oxide dielectric layer formed over the first dielectric layer and the movable structure with a thickness of at least about 10 Å over each of the first dielectric layer and the movable structure within the cavity.   
     
     
         2 . The optical interferometric modulator of  claim 1 , further including a deformable layer coupled to the movable structure. 
     
     
         3 . The optical interferometric modulator of  claim 1 , wherein the conformal oxide dielectric layer is a metal oxide. 
     
     
         4 . The optical interferometric modulator of  claim 1 , wherein the conformal oxide dielectric layer includes Al 2 O 3 . 
     
     
         5 . The optical interferometric modulator of  claim 1 , wherein the conformal oxide dielectric layer includes SiO 2 . 
     
     
         6 . The optical interferometric modulator of  claim 1 , wherein the conformal oxide dielectric layer includes a nitride. 
     
     
         7 . The optical interferometric modulator of  claim 1 , wherein the conformal oxide dielectric layer is exposed to the cavity. 
     
     
         8 . The device of  claim 1 , wherein the conformal oxide dielectric layer formed over the first dielectric layer has a thickness that is approximately the same as a thickness of the conformal oxide dielectric layer formed over the movable structure. 
     
     
         9 . The device of  claim 1 , wherein the movable structure has a first side and a second side within the cavity that are substantially parallel to each other, wherein the first side faces the optical stack and the second side faces an opposing side of the cavity, wherein the conformal oxide dielectric layer is formed over the first and second sides of the movable structure. 
     
     
         10 . The device of  claim 9 , wherein the conformal oxide dielectric layer formed over the first side of the movable structure has a thickness that is approximately the same as a thickness of the conformal oxide dielectric layer formed over the second side of the movable structure. 
     
     
         11 . The device of  claim 1 , wherein the reflective layer has a surface that is substantially parallel to a surface of the optical stack when the interferometric modulator is in a relaxed state and in an actuated state. 
     
     
         12 . The optical interferometric modulator of  claim 1 , wherein the thickness of the conformal oxide dielectric layer is from about 50 Å to about 400 Å. 
     
     
         13 . The optical interferometric modulator of  claim 1 , wherein the thickness of the first dielectric layer and conformal oxide dielectric layer is less than about 100 nm. 
     
     
         14 . The optical interferometric modulator of  claim 1 , wherein the thickness of the conformal oxide dielectric layer is from about 100 Å to about 250 Å. 
     
     
         15 . The optical interferometric modulator of  claim 1 , wherein the reflective layer has a surface that is substantially parallel to a surface of the optical stack when the optical interferometric modulator is in a relaxed state. 
     
     
         16 . A display comprising an array of optical interferometric modulators each like the optical interferometric modulator of  claim 1 , further including:
 a seal circumscribing the optical interferometric modulator; and   a backplate secured to the seal.   
     
     
         17 . An apparatus comprising:
 the display of  claim 16 ;   a processor that is configured to communicate with said display, said processor being configured to process image data; and   a memory device that is configured to communicate with said processor.   
     
     
         18 . The apparatus of  claim 17 , further including a driver circuit configured to send at least one signal to the display. 
     
     
         19 . The apparatus of  claim 18 , further including a controller configured to send at least a portion of the image data to the driver circuit. 
     
     
         20 . The apparatus of  claim 17 , further including an image source module configured to send said image data to said processor. 
     
     
         21 . The apparatus of  claim 20 , wherein the image source module includes at least one of a receiver, transceiver, and transmitter. 
     
     
         22 . The apparatus of  claim 17 , further including an input device configured to receive input data and to communicate said input data to said processor. 
     
     
         23 . A method for manufacturing an interferometric modulator comprising:
 forming a sacrificial layer over a first electrode;   forming a deformable layer over the sacrificial layer;   removing the sacrificial layer, thereby forming a cavity between the first electrode and the deformable layer; and   depositing a conformal oxide layer having a thickness of greater than 10 Å in the cavity by atomic layer deposition after removing the sacrificial layer.   
     
     
         24 . The method of  claim 23 , wherein depositing a layer in the cavity by atomic layer deposition includes depositing a layer including at least one of Al 2 O 3  and SiO 2 . 
     
     
         25 . The method of  claim 23 , further including completing fabrication of the interferometric modulator, wherein the conformal oxide layer is exposed to the cavity in the completed interferometric modulator.