Vertically arranged semiconductor pixel sensor

A pixel array, comprising:

• a plurality of pixel sensors, each comprising:
• a photodiode region;
• a floating diffusion region over the photodiode region,
• wherein the floating diffusion region comprises:
• a drain region,
• a p-type region, and
• one or more extension regions, and
• wherein the drain region, the p-type region, and the one or more extension regions are surrounded by an undoped substrate;
• and
• a poly gate region surrounding the floating diffusion region;
• a reset transistor adjacent to at least one pair of the plurality of pixel sensors;
• and
• a source-follower transistor adjacent to the at least one pair of the plurality of pixel sensors.

A pixel sensor, comprising:

• an undoped substrate;
• a photodiode region;
• a floating diffusion region over the photodiode region and physically separated from the photodiode region by the undoped substrate,
• wherein the floating diffusion region comprises:
• a drain region,
• a p-type region, and
• one or more extension regions, and
• wherein the drain region, the p-type region, and the one or more extension regions are surrounded by a portion of the undoped substrate;
• and
• a poly gate region surrounding the floating diffusion region.