CMOS image sensor with pump gate and extremely high conversion gain

A CMOS active pixel image sensor comprising an array of pixels, each pixel configured for selective intra-pixel charge transfer from a respective storage node that is primarily located under a transfer gate of the pixel, wherein the transfer gate is operable to transfer charge from the storage node to a floating diffusion according to a pump gate architecture that is configured to selectively transfer at least a portion of charge accumulated in the storage node to the floating diffusion in response to an individual pulse being applied to the transfer gate, by pumping charge (i) from the storage node to a first potential well in response to the individual pulse pulsing the transfer gate from an OFF state to a given ON state, and (ii) to the floating diffusion from the first potential well over a first potential barrier that is between the transfer gate and the floating diffusion, in response to the individual pulse pulsing the transfer gate being from said given ON state to an OFF state, wherein the first potential well is primarily located under the transfer gate.

A CMOS active pixel image sensor comprising an array of pixels formed in a semiconductor substrate, each pixel configured for selective intra-pixel charge transfer from a respective storage node, wherein each pixel comprises:

• a transfer gate that is formed on a first surface of the semiconductor substrate and is operable to transfer charge from the storage node to a floating diffusion formed in the semiconductor substrate, wherein the floating diffusion has a dopant concentration of a first conductivity type and is decoupled from the transfer gate by an intervening virtual barrier region comprising a gateless semiconductor region that has a second conductivity type opposite to the first conductivity type and that provides a potential barrier to charge flow from beneath the transfer gate to the floating diffusion;
• and
• a pinned photodiode having a pinning region of the second conductivity type that extends in the substrate along a vertical direction substantially perpendicular to the first surface, wherein the pinning region is configured to form a pinned photodiode with a laterally disposed semiconductor region of a first conductivity type, a p-n junction interface of the pinned photodiode thereby extending along the vertical direction.