Isolation structure having an air gap to reduce pixel crosstalk

Abstract

An isolation structure can be formed between adjacent and/or non-adjacent pixel regions (e.g., between diagonal or cross-road pixel regions), of an image sensor, to reduce and/or prevent optical crosstalk. The isolation structure may include a deep trench isolation (DTI) structure or another type of trench that is partially filled with a material such that an air gap is formed therein. The DTI structure having the air gap formed therein may reduce optical crosstalk between pixel regions. The reduced optical crosstalk may increase spatial resolution of the image sensor, may increase overall sensitivity of the image sensor, may decrease color mixing between pixel regions of the image sensor, and/or may decrease image noise after color correction of images captured using the image sensor.

What is claimed is: 
     
         1 . A pixel array, comprising:
 a first pixel region;   a second pixel region; and   a deep trench isolation (DTI) structure, between the first pixel region and the second pixel region, filled with an oxide material,
 wherein an air gap formed in the oxide material comprises at least 75% of an area in the DTI structure. 
   
     
     
         2 . The pixel array of  claim 1 , wherein a height of the air gap is in a range of 1.5 microns to 10 microns. 
     
     
         3 . The pixel array of  claim 1 , wherein a width of the air gap is in a range of 0.7 microns to 1.3 microns. 
     
     
         4 . The pixel array of  claim 1 , wherein the air gap is formed to reduce optical crosstalk between the first pixel region and the second pixel region. 
     
     
         5 . The pixel array of  claim 1 , further comprising:
 a high absorption region in the first pixel region; and   another air gap formed in the high absorption region.   
     
     
         6 . The pixel array of  claim 5 , wherein a height of the other air gap is in a range of 2000 angstroms to 4000 angstroms. 
     
     
         7 . The pixel array of  claim 5 , wherein a width of the other air gap is in a range of 1500 angstroms to 4000 angstroms. 
     
     
         8 . The pixel array of  claim 1 , wherein the first pixel region and the second pixel region are adjacent pixel regions. 
     
     
         9 . The pixel array of  claim 1 , wherein the first pixel region and the second pixel region are non-adjacent pixel regions in the pixel array. 
     
     
         10 . A pixel array, comprising:
 a first pixel region;   a second pixel region;   a deep trench isolation (DTI) structure, between the first pixel region and the second pixel region, comprising a first air gap;   a first micro-lens formed in the first pixel region;   a second micro-lens formed in the second pixel region,
 wherein a second air gap exists between the first micro-lens and the second micro-lens; 
   a plurality of high absorption regions in the first pixel region; and   a respective third air gap formed in each of the plurality of high absorption regions.   
     
     
         11 . The pixel array of  claim 10 , further comprising:
 a third pixel region; and   another DTI structure, between the first pixel region and the third pixel region, comprising a fourth air gap.   
     
     
         12 . The pixel array of  claim 11 , further comprising:
 a third micro-lens formed in the third pixel region; and   a fifth air gap formed between the first micro-lens and the third micro-lens.   
     
     
         13 . The pixel array of  claim 10 , wherein no more than 25% of an area of the DTI structure is filled with an oxide material, and
 wherein at least 75% of the area of the DTI structure is filled with the first air gap formed by the oxide material in the DTI structure.   
     
     
         14 . The pixel array of  claim 10 , wherein a height of each of the first air gap and the second air gap is in a range of 1.5 microns to 10 microns; and
 wherein a width of each of the first air gap and the second air gap is in a range of 0.7 microns to 1.3 microns.   
     
     
         15 . An image sensor, comprising:
 a pixel array, comprising:
 a first pixel region comprising a photodiode, the photodiode comprising a high absorption region filled with an oxide material and a first air gap; 
 a second pixel region; and 
 a deep trench isolation (DTI) structure, between the first pixel region and the second pixel region, filled with the oxide material and a second air gap. 
   
     
     
         16 . The image sensor of  claim 15 , wherein the oxide material occupies 25% or less of an area in the high absorption region. 
     
     
         17 . The image sensor of  claim 15 , wherein the oxide material occupies 25% or less of an area in the DTI structure. 
     
     
         18 . The image sensor of  claim 15 , wherein a width of the first air gap is in a range of 1500 angstroms to 4000 angstroms. 
     
     
         19 . The image sensor of  claim 15 , wherein a height of the first air gap is in a range of 2000 angstroms to 4000 angstroms. 
     
     
         20 . The image sensor of  claim 15 , wherein the pixel array further comprises:
 a third pixel region; and   another DTI structure, between the first pixel region and the third pixel region, filled with the oxide material and a third air gap.