Optical sensor including stacked photodiodes

Abstract

A complementary metal-oxide-semiconductor (CMOS) image sensor comprises a first photosensitive diode comprising a first semiconductor material is formed in a first semiconductor substrate. A second photosensitive diode comprising a second semiconductor material, which has a different light detection wavelength range than the first semiconductor material, is formed in a second semiconductor substrate. Semiconductor devices for holding and detecting charges comprising a sensing circuit of the CMOS image sensor may also be formed in the second semiconductor substrate. The first semiconductor substrate and the second semiconductor substrate are bonded so that the first photosensitive diode is located underneath the second photosensitive diode. The vertical stack of the first and second photosensitive diodes detects light in the combined detection wavelength range of the first and second semiconductor materials. Sensing devices may be shared between the first and second photosensitive diodes.

1 . A machine readable medium for designing, manufacturing, or testing a design, said machine readable medium embodying a design structure, said design structure comprising a first data representing a first photosensitive diode located in a first semiconductor layer and a second data representing a second photosensitive diode located in a second semiconductor layer and overlying said first photosensitive diode,
 wherein said first data comprises a third data representing a first semiconductor portion which comprises a first semiconductor material and has a doping of a first conductivity type and a fourth data representing a first charge collection well which comprises said first semiconductor material and has a doping of a second conductivity type and abuts a top surface of said first semiconductor portion, and wherein said second conductivity type is the opposite of said first conductivity type; and   wherein said second data comprises a fifth data representing a second semiconductor portion which comprises a second semiconductor material and has a doping of said first conductivity type and a sixth data representing a second charge collection well which comprises said second semiconductor material and has a doping of said second conductivity type and abuts a top surface of said second semiconductor portion, and wherein said second semiconductor material is different from said first semiconductor material.   
     
     
         2 . The machine readable medium of  claim 1 , wherein said first semiconductor material has a first band gap width and said second semiconductor material has a second band gap width, and wherein said second band gap width is different from said first band gap width. 
     
     
         3 . The machine readable medium of  claim 2 , wherein one of said first and second semiconductor materials is silicon and another of said first and second semiconductor materials is germanium. 
     
     
         4 . The machine readable medium of  claim 1 , further comprising:
 another data representing a first semiconductor layer having a doping of said first conductivity type and comprises said first semiconductor material, wherein said first charge collection well and said first semiconductor portion are embedded in said first semiconductor layer; and   yet another data representing a second semiconductor layer having a doping of said first conductivity type and comprises said second semiconductor material, wherein said second charge collection well and said second semiconductor portion are embedded in said second semiconductor layer.   
     
     
         5 . The machine readable medium of  claim 1 , further comprising:
 a seventh data representing a first metal interconnect structure located between said first semiconductor layer and said second semiconductor layer; and   an eighth data representing a second metal interconnect structure located above said second semiconductor layer.   
     
     
         6 . The machine readable medium of  claim 5 , further comprising another data representing at least one conductive structure abutting said first metal interconnect structure and said second metal interconnect structure. 
     
     
         7 . The machine readable medium of  claim 5 , further comprising another data representing an optical lens located over said second photosensitive diode and said first photosensitive diode. 
     
     
         8 . The machine readable medium of  claim 7 , further comprising another data representing a color filter located over said second photosensitive diode and said first photosensitive diode. 
     
     
         9 . The machine readable medium of  claim 1 , further comprising:
 another data representing a first transfer transistor of integral construction with said first photosensitive diode and including a first floating drain and located in said first semiconductor layer; and   yet another data representing a second transfer transistor of integral construction with said second photosensitive diode and including a second floating drain and located in said second semiconductor layer.   
     
     
         10 . The machine readable medium of  claim 1 , further comprising:
 another data representing a transfer transistor of integral construction of integral construction with one of said first photosensitive diode and said second photosensitive diode;   yet another data representing a binning transistor in a semiconductor layer containing said transfer transistor; and   still another data representing a conductive via extending from at least a bottom surface of said second semiconductor layer to at least a top surface of said first semiconductor layer, wherein said conductive via is a portion of an electrically conductive path between said binning transistor and the other of said first photosensitive diode and said second photosensitive diode.