Image Sensor Pixel With Memory Node Having Buried Channel And Diode Portions Formed On N-Type Substrate

A global shutter image sensor including a plurality of pixels disposed on an n-type substrate, wherein each pixel comprises:

• a photodiode disposed in an n-type region of the substrate;
• a memory node disposed in the n-type region of the substrate, the memory node being spaced from the photodiode;
• a floating diffusion disposed in p-type region of the substrate;
• a first transfer gate connected between the memory node and the photodiode;
• and
• a second transfer gate connected between the memory node and the floating diffusion,
• wherein the memory node includes a first buried channel portion disposed under the first transfer gate and having a first doping level, and a first diode portion and having a second doping level that is greater than the first doping level such that a first intrinsic lateral electrical field is generated that drives electrons from the first buried channel portion into the first diode portion, and
• wherein the floating diffusion includes a second buried channel portion disposed under the second transfer gate, said second buried channel portion having a third doping level, said floating diffusion also including a second diode portion having a fourth doping level that is greater than the third doping level such that a second intrinsic lateral electrical field is generated that drives electrons from the second buried channel portion into the second diode portion.