Image sensor and method of fabricating the same

Abstract

The image sensor includes a substrate; a wiring structure formed on a front side of the substrate and including a plurality of wiring layers and a plurality of insulating films; a first well formed within the substrate and having a first conductivity type; and a first metal wiring layer directly contacting a backside of the substrate and configured to apply a first well bias to the first well.

1 . A method of fabricating an image sensor, the method comprising:
 forming a first well within a substrate, the first well having a first conductivity type;   forming a wiring structure on a front side of the substrate, the wiring structure including a plurality of wiring layers and a plurality of insulating films; and   forming a first metal wiring layer directly contacting a backside of the substrate and configured to apply a first well bias to the first well.   
     
     
         2 . The method of  claim 1 , wherein the substrate comprises a sensing region including a plurality of unit pixels, a peripheral region including a circuit for controlling the unit pixels, and a pad region, wherein the first metal wiring layer directly contacts the backside of the substrate in the peripheral region. 
     
     
         3 . The method of  claim 2 , further comprising:
 forming a backside insulating film, which comprises a trench exposing at least part of the backside of the substrate in the peripheral region, on the backside of the substrate, wherein the forming of the first metal wiring layer comprises conformally forming the first metal wiring layer along a top surface and sidewalls of the backside insulating film and a portion of the backside of the substrate which is exposed by the trench.   
     
     
         4 . The method of  claim 2 , further comprising:
 forming a backside insulating film on the backside of the substrate by exposing the backside of the substrate in the peripheral region via a plurality of through-holes, wherein the forming a first metal wiring layer step includes filling the through-holes with the first metal wiring layer.   
     
     
         5 . The method of  claim 1 , further comprising:
 forming a second well within the substrate, the second well having a second conductivity type different from the first conductivity type; and   forming a second metal wiring layer directly contacting the backside of the substrate, the second metal wiring layer being separated from the first metal wiring layer, and configured to apply a second well bias different from the first well bias to the second well.   
     
     
         6 . The method of  claim 1 , further comprising:
 forming a third well within the substrate, the third well having the second conductivity type different from the first conductivity type,   wherein the forming of a wiring structure step includes forming a third metal wiring layer that applies a third well bias different from the first well bias to the third well.   
     
     
         7 . A method of fabricating an image sensor, the method comprising:
 providing a sensing region, a peripheral region, and a pad region defined within a substrate;   forming a first well within the substrate in the peripheral region, the first well having a first conductivity type;   forming a wiring structure on a front side of the substrate, the wiring structure including a plurality of wiring layers, a plurality of insulating films, and an auxiliary pad;   forming a backside insulating film on a backside of the substrate;   exposing the auxiliary pad in the pad region by forming a contact hole, the contact hole configured to penetrate the backside insulating film and the substrate;   exposing at least part of the backside of the substrate in the peripheral region by patterning the backside insulating film in the peripheral region;   forming a contact in the contact hole, the contact being electrically connected to the auxiliary pad; and   forming a pad in the pad region and the first metal wiring layer in the peripheral region, the pad being electrically connected to the contact on the substrate in the pad region.