Back-illuminated image sensors having both frontside and backside photodetectors

An image capture device, comprising:

• a back-illuminated image sensor, comprising:
• a sensor layer of a first conductivity type having a frontside and a backside opposite the frontside;
• an insulating layer disposed on the backside of the sensor layer;
• a circuit layer electrically connected to the sensor layer and adjacent to the frontside of the sensor layer;
• one or more frontside regions of a second conductivity type formed in at least a portion of the frontside of the sensor layer;
• a backside region of the second conductivity type formed in the backside of the sensor layer, wherein a portion of the sensor layer is disposed between the backside region and the one or more frontside regions;
• a plurality of frontside photodetectors of the first conductivity type for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of frontside photodetectors is disposed in the sensor layer adjacent to the frontside and the one or more frontside regions are disposed over or adjacent to the frontside photodetectors;
• a discrete plurality of backside photodetectors of the first conductivity type separate from the plurality of frontside photodetectors for converting light incident on the backside of the sensor layer into photo-generated charges, wherein the plurality of backside photodetectors is disposed in the sensor layer and contiguous to portions of the backside region of the second conductivity type, and wherein each frontside photodetector is paired with a respective backside photodetector to form photodetector pairs and a portion of the sensor layer is contiguously disposed between the frontside and backside photodetectors in each photodetector pair;
• a first voltage terminal disposed on the frontside of the sensor layer;
• and
• one or more connecting regions of the second conductivity type disposed in respective portions of the sensor layer between the first voltage terminal and the backside region for electrically connecting the first voltage terminal to the backside region.