Image sensors including conductive pixel separation structures

Abstract

An image sensor includes a substrate having adjacent pixel regions and respective photodiode regions therein, and a pixel separation portion including a trench extending into the substrate between the adjacent pixel regions. The trench includes a conductive common bias line therein and an insulating device isolation layer between the common bias line and surfaces of the trench. A conductive interconnection is coupled to the common bias line and is configured to provide a negative voltage thereto. Related fabrication methods are also discussed.

What is claimed is: 
     
       1. An image sensor, comprising:
 a substrate comprising a plurality of pixel regions, the substrate having a first surface and a second surface opposite the first surface, wherein the second surface is arranged to receive incident light;   photoelectric conversion parts in the pixel regions of the substrate;   gate electrodes and floating diffusion regions in the pixel regions of the substrate;   a pixel separation structure including a first isolation region and a second isolation region in the substrate that separate the pixel regions from each other, wherein the first isolation region includes an insulating device isolation layer and a metal element, and the second isolation region includes an impurity-doped region; and   doped ground regions disposed between adjacent ones of the floating diffusion regions,   wherein the first isolation region is in contact with the second surface and spaced apart from the first surface, and the second isolation region is disposed between the first isolation region and the first surface.   
     
     
       2. The image sensor of  claim 1 , wherein the second isolation region is doped with an impurity type different from the photoelectric conversion part. 
     
     
       3. The image sensor of  claim 1 , wherein the metal element include a metal-containing layer. 
     
     
       4. The image sensor of  claim 3 , wherein the doped ground regions are doped with an impurity type different from the floating diffusion regions. 
     
     
       5. The image sensor of  claim 1 , further comprising a shallow device isolation layer in contact with the first surface and spaced apart from the first isolation region, the shallow device isolation layer having a depth less than that of the first isolation region. 
     
     
       6. The image sensor of  claim 1 , wherein in plan view, the floating diffusion regions and the doped ground regions are arranged in a straight line. 
     
     
       7. The image sensor of  claim 1 , wherein the gate electrode includes a protruding portion positioned on the substrate and a buried portion inserted into the substrate. 
     
     
       8. The image sensor of  claim 6 , wherein the substrate further comprises an optical black region spaced apart from the pixel region,
 wherein the image sensor further comprises an optical black pattern provided on the optical black region.   
     
     
       9. The image sensor of  claim 6 , wherein the substrate further comprises a pad region spaced apart from the pixel region,
 wherein the image sensor further comprises a through via provided through the pad region.   
     
     
       10. The image sensor of  claim 1 , wherein at least a portion of the photoelectric conversion part overlaps the floating diffusion regions and the doped ground regions. 
     
     
       11. An image sensor, comprising:
 a substrate comprising a plurality of pixel regions, the substrate having a first surface and a second surface opposite the first surface, wherein the second surface is arranged to receive incident light;   photoelectric conversion parts in the pixel regions of the substrate;   gate electrodes and floating diffusion regions in the pixel regions of the substrate;   a pixel separation structure including a first isolation region and a second isolation region in the substrate that separate the pixel regions from each other, wherein the first isolation region includes an insulating device isolation layer, and the second isolation region includes an impurity-doped region; and   doped ground regions disposed between adjacent ones of the floating diffusion regions,   wherein the first isolation region is in contact with the second surface and spaced apart from the first surface, and the second isolation region is disposed between the first isolation region and the first surface, and   wherein in plan view, the floating diffusion regions and the doped ground regions are arranged in a straight line.   
     
     
       12. An image sensor, comprising:
 a substrate comprising a plurality of pixel regions, the substrate having a first surface and a second surface opposite the first surface, wherein the second surface is arranged to receive incident light;   a photoelectric conversion part in each of the plurality of pixel regions of the substrate;   a floating diffusion region on the first surface of the substrate;   a first pixel separation structure including a first isolation region and a first p-type doped region in the substrate that separate the plurality of pixel regions from each other, wherein the first isolation region includes a silicon oxide layer; and   a second p-type doped region disposed on the first surface and adjacent to the floating diffusion region,   wherein the first isolation region is in contact with the second surface and spaced apart from the first surface, and the first p-type doped region is between the first isolation region and the first surface, and   wherein a surface of the first isolation region facing the first surface has an uneven structure.    
     
     
       13. The image sensor of claim 12, wherein the second p-type doped region is a doped ground region.  
     
     
       14. The image sensor of claim 12, wherein the uneven structure is a curved structure.  
     
     
       15. The image sensor of claim 14, wherein the second p-type doped region is electrically connected to a wire disposed on the first surface.  
     
     
       16. The image sensor of claim 14, wherein the first isolation region further includes a metal containing layer.  
     
     
       17. The image senor of claim 16, wherein the metal containing layer has an uneven or a curved surface that faces the first surface.  
     
     
       18. The image sensor of claim 17, further comprising an optical black region adjacent to the plurality of pixel regions and a second pixel separation structure in the optical black region,
 wherein the second pixel separation structure includes a second isolation region, and   wherein the second isolation region is in contact with the second surface and spaced apart from the first surface.    
     
     
       19. The image sensor of claim 18, further comprising an optical black pattern in the optical black region,
 wherein the optical black pattern is disposed on the second surface and includes tungsten.    
     
     
       20. The image senor of claim 19, wherein a surface of the second isolation region facing the first surface has the uneven structure.  
     
     
       21. An image sensor, comprising:
 a substrate comprising a plurality of pixel regions and an optical black pixel region adjacent to the plurality of pixel regions, the substrate having a first surface and a second surface opposite the first surface, wherein the second surface is arranged to receive incident light;   a photoelectric conversion part in each of the plurality of pixel regions of the substrate;   a floating diffusion region on the first surface of the substrate;   a first pixel separation structure including a first isolation region and a first p-type doped region in the substrate disposed between the plurality of pixel regions, wherein the first isolation region includes a silicon oxide layer;   a second p-type doped region disposed on the first surface and adjacent to the floating diffusion region; and   a second pixel separation structure including a second isolation region and a third p-type doped region in the substrate, wherein the second pixel separation structure is disposed in the optical black pixel region,   wherein the first isolation region is in contact with the second surface and spaced apart from the first surface, and the first p-type doped region is disposed between the first isolation region and the first surface,   wherein the second isolation region is in contact with the second surface and spaced apart from the first surface, and   wherein a surface of the first isolation region facing the first surface has an uneven or a curved surface.    
     
     
       22. The image sensor of claim 21, wherein the first p-type doped region vertically extends from the first isolation region toward the first surface.  
     
     
       23. The image sensor of claim 22, wherein the second p-type doped region is electrically connected to a wire disposed on the first surface.  
     
     
       24. The image sensor of claim 23, further comprising a fourth p-type doped region on the first surface,
 wherein a distance from the second surface to the fourth p-type doped region is closer than a distance from the second surface to the second p-type doped region.    
     
     
       25. The image sensor of claim 24, wherein a surface of the second isolation region facing the first surface has an uneven structure.  
     
     
       26. The image sensor of claim 21, wherein the third p-type doped region vertically extends from the second isolation region toward the first surface.  
     
     
       27. The image sensor of claim 26, further comprising a fourth p-type doped region on the first surface,
 wherein a distance from the second surface to the fourth p-type doped region is closer than a distance from the second surface to the second p-type doped region.    
     
     
       28. An image sensor, comprising:
 a substrate comprising a plurality of pixel regions and an optical black pixel region adjacent to the plurality of pixel regions, the substrate having a first surface and a second surface opposite the first surface, wherein the second surface is arranged to receive incident light;   a photoelectric conversion part in each of the plurality of pixel regions of the substrate;   a floating diffusion region on the first surface of the substrate;   a first pixel separation structure disposed between the plurality of pixel regions, wherein the first pixel separation structure vertically extends from the second surface toward the first surface;   a second pixel separation structure in the optical black pixel region, wherein the second pixel separation structure vertically extends from the second surface toward the first surface; and   a first p-type doped region disposed on the first surface and adjacent to the floating diffusion region,   wherein the first pixel separation structure includes a silicon oxide layer and a metal containing layer,   wherein the first p-type doped region is electrically connected to a wire disposed on the first surface, and   wherein a distance from the second surface to a second p-type doped region is closer than a distance from the second surface to the first p-type doped region.    
     
     
       29. The image sensor of claim 28, further comprising an optical black pattern in the optical black pixel region,
 wherein the optical black pattern is disposed on the second surface and includes tungsten.    
     
     
       30. The image sensor of claim 29, wherein in a plan view, the floating diffusion region and the first p-type doped region are arranged in a straight line.