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, wherein the gate electrodes are disposed directly on the first surface; 
 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 directly on the first surface and 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 , 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; and 
 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, 
 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. 
 
     
     
       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, wherein the gate electrodes are disposed directly on the first surface; 
 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 directly on the first surface and 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 including a plurality of pixel regions, and including a first surface and a second surface that is disposed opposite to the first surface and receives incident light;   a plurality of photoelectric conversion parts, each of the plurality of photoelectric conversion parts being disposed in a corresponding one of the plurality of pixel regions;   a plurality of gates disposed on the first surface of the substrate;   a plurality of floating diffusion regions disposed in the substrate;   a pixel separation structure disposed in the substrate, and including a first isolation region and a second isolation region, the first isolation region including an insulating device isolation layer and a metal-containing layer, the second isolation region including an impurity-doped region; and   a plurality of impurity regions disposed in the substrate and disposed directly on the first surface of the substrate,   wherein the first isolation region contacts the second surface of the substrate and is spaced apart from the first surface, and   the second isolation region is disposed between the first isolation region and the first surface.   
     
     
       13. The image sensor of claim 12, wherein each of the plurality of floating diffusion regions contacts the first surface of the substrate. 
     
     
       14. The image sensor of claim 12, wherein each of the plurality of floating diffusion regions contacts a corresponding one of the plurality of gates. 
     
     
       15. The image sensor of claim 12, wherein at least one of the plurality of impurity regions is doped with p-type impurities. 
     
     
       16. The image sensor of claim 12, wherein each of the plurality of impurity regions is doped with p-type impurities. 
     
     
       17. The image sensor of claim 12, wherein each of the plurality of floating diffusion regions is doped with n-type impurities. 
     
     
       18. The image sensor of claim 12, wherein the insulating device isolation layer includes a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer. 
     
     
       19. The image sensor of claim 12, wherein the impurity-doped region of the second isolation region is doped with p-type impurities. 
     
     
       20. The image sensor of claim 12, wherein the second isolation region partially covers the first isolation region. 
     
     
       21. The image sensor of claim 12, further comprising a shallow device isolation layer in contact with the first surface and spaced apart from the first isolation region.