Sense node capacitive structure for time of flight sensor

摘要

An increased sense node capacitance, mainly for 3D time-of-flight (TOF) applications, includes a storage structure that combines the advantages of gate and diffusion capacitance in order to improve the overall capacitance. The storage structure provides higher capacitance per unit area and accordingly a better fill-factor/sensitivity of the pixel; improved noise behaviour because of the use of gate capacitances, better protection against interacting signals and thus better signal quality.

主权项

1. A pixel comprising:
a substrate; a photosensitive area in the substrate that converts light into photogenerated charges; a storage structure, comprising an integration gate and a diffusion capacitance, that stores the photogenerated charges, wherein the diffusion capacitance functions as a sense node, and wherein the diffusion capacitance is embedded in the integration gate; an amplifier for reading out photogenerated charges via the sense node; and a barrier gate which separates the photogenerated charges in the integration gate and the diffusion capacitance from the photosensitive area, wherein photogenerated charges are transferred to the storage structure by flowing over the barrier gate and into the integration gate and the diffusion capacitance.