Silicon light trap devices, systems and methods

Abstract

Embodiments relate to buried structures for silicon devices which can alter light paths and thereby form light traps. Embodiments of the lights traps can couple more light to a photosensitive surface of the device, rather than reflecting the light or absorbing it more deeply within the device, which can increase efficiency, improve device timing and provide other advantages appreciated by those skilled in the art.

1 . A device comprising:
 a silicon structure having a surface to be exposed to light rays; and   a light trap structure formed within the silicon structure spaced apart from the surface and comprising a plurality of light trap elements adjacent one another and each having a surface proximate to and unparallel with the surface to be exposed to light rays.   
     
     
         2 . The device of  claim 1 , wherein the surface proximate to and unparallel with the surface to be exposed to light rays has a radius. 
     
     
         3 . The device of  claim 1 , wherein the surface proximate to and unparallel with the surface to be exposed to light rays comprises a peak. 
     
     
         4 . The device of  claim 3 , wherein am angle of the peak is between about 50 degrees and about 60 degrees. 
     
     
         5 . The device of  claim 4 , wherein the angle of the peak is about 54.7 degrees. 
     
     
         6 . The device of  claim 1 , wherein the plurality of light trap elements each comprise a cavity within the silicon structure. 
     
     
         7 . The device of  claim 6 , wherein each cavity is formed from a trench etched in the silicon structure. 
     
     
         8 . The device of  claim 1 , wherein each surface proximate to and unparallel with the surface to be exposed to light rays is configured to reflect light toward the surface to be exposed to light rays at an angle greater than about 16 degrees. 
     
     
         9 . The device of  claim 1 , wherein the device comprises a photodetector device. 
     
     
         10 . The device of  claim 1 , wherein each light trap element is about 0.5 micrometers (μm) to about 3 μm wide and about 1 μm to about 5 μm high. 
     
     
         11 . The device of  claim 1 , wherein each light trap element is spaced apart from the surface to be exposed to light rays by at least about 0.7 μm and not more than about 50 μm. 
     
     
         12 . The device of  claim 1 , further comprising a structure formed on the surface to be exposed to light and comprising a plurality of light-focusing structures. 
     
     
         13 . A light trap structure buried within a silicon structure and comprising:
 a plurality of light trap elements adjacent one another and each having a surface proximate to and unparallel with a surface of the silicon structure to be exposed to light rays.   
     
     
         14 . The light trap structure of  claim 13 , wherein the plurality of light trap elements comprise a plurality of cavities. 
     
     
         15 . The light trap structure of  claim 13 , wherein the surface proximate to and unparallel with the surface to be exposed to light rays has a radius. 
     
     
         16 . The device of  claim 13 , wherein the surface proximate to and unparallel With the surface to be exposed to light rays comprises a peak. 
     
     
         17 . The device of  claim 16 , wherein an angle of the peak is between about 53 degrees and about 56 degrees. 
     
     
         18 . The device of  claim 13 , wherein the plurality of light trap elements each comprise a cavity within the silicon structure. 
     
     
         19 . The device of  claim 18 , wherein each cavity is formed from a trench etched in the silicon structure. 
     
     
         20 . The device of  claim 13 , wherein each surface proximate to and unparallel with the surface to be exposed to light rays is configured to reflect light toward the surface to be exposed to light rays at an angle greater than about 16 degrees. 
     
     
         21 . The device of  claim 13 , wherein each light trap element is about 0.5 micrometers (μm) to about 3 μm wide and about 1 μm to about 5 μm deep. 
     
     
         22 . The device of  claim 13 , wherein each light trap element is spaced apart from the surface to be exposed to light rays by at least about 0.7 μm and not more than about 50 μm. 
     
     
         23 . A method comprising:
 providing a silicon structure; and   forming a plurality of light trap elements adjacent one another in the silicon structure and each having a surface proximate to and unparallel with a surface of the silicon structure to be exposed to light rays.   
     
     
         24 . The method of  claim 23 , wherein forming a plurality of light trap elements further comprises:
 forming a plurality of trenches in the silicon structure; and   producing a cavity from each of the plurality of trenches.   
     
     
         25 . The method of  claim 24 , further comprising forming a light-focusing structure on the silicon structure.