Uniform-bridge-gradient time-of-flight photodiode for image sensor pixel

A complementary metal-oxide semiconductor (CMOS) image sensor (CIS) comprising:

• a semiconductor substrate of a first doping type;
• an array of uniform-bridge-gradient (UBG) time-of-flight (ToF) pixels integrated with the semiconductor substrate, each UBG ToF pixel having a respective one of a plurality of UBG ToF photodiode blocks, each UBG ToF photodiode block comprising:
• a plurality of taps disposed onto the semiconductor substrate and comprising at least a first readout tap and a second readout tap, each of the plurality of taps having a respective one of a plurality of transfer gates configured for selective activation by an activation network and a respective one of a plurality of collection nodes;
• a photodiode region implanted into the semiconductor substrate and comprising:
• a photodiode-defining implant of a second doping type complementary to the first doping type implanted to a first implant depth over the photodiode region;
• a first bridging implant of the second doping type implanted to a second implant depth over a first portion of the photodiode region that forms a first lateral bridge region across the plurality of taps along an edge of the photodiode region nearest to the plurality of taps;
• and
• a second bridging implant of the second doping type implanted to a third implant depth over a second portion of the photodiode region that forms a second lateral bridge region across the plurality of taps and at least partially overlaps with both the photodiode-defining implant and the first bridging implant, the third implant depth being deeper than both the first implant depth and the second implant depth.