Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Olivier Marcelot (1) , Vincent Goiffon (1) , Serena Rizzolo (1) , Federico Pace (1) , Pierre Magnan (1)

1 DEOS - Département Electronique, Optronique et Signal

TCAD simulations are conducted on a 4T PPD pixel, on a conventional gated photodiode, and finally on a radiation hardened pixel. Simulations consist in demonstrating that it is possible to reduce the dark current due to interface states brought by the adjacent gate, by means of a sharing mechanism between the photodiode and the drain. The sharing mechanism is activated and controlled by polarizing the adjacent gate at a positive \itshape off \upshape voltage, and consequently the dark current is reduced and not compensated. The drawback of the dark current reduction is a reduction of the full well capacity of the photodiode, which is not a problem when the pixel saturation is limited by the readout chain. Some measurement performed on pixel arrays confirm the TCAD results.

Mots clés: CMOS Image Sensors; CIS; Simulation; Deep Submicron Process; CMOS; Pinned photodiode; PPD; Dark current; Solid-state image sensor; STI

Domaines: Optique / photonique

Olivier Marcelot, Vincent Goiffon, Serena Rizzolo, Federico Pace, Pierre Magnan. Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations. IEEE Transactions on Electron Devices, 2017, 64 (12), pp.4985-4991. ⟨10.1109/TED.2017.2762433⟩. ⟨hal-01997956⟩