Unit pixel for accurately removing reset noise, solid-state image sensing device, and method for summing unit pixel signals

摘要

A unit pixel has a light receiving device containing a photoelectric conversion element for detecting a light to generate photoelectrons. The light receiving device contains a plurality of photoelectron distributors, which each have a first transfer unit for transferring the photoelectrons generated in the photoelectric conversion element, a photoelectron hold unit for temporarily holding the photoelectrons generated in the photoelectric conversion element, a second transfer unit for transferring the photoelectrons held in the photoelectron hold unit, and a floating diffusion layer for storing the transferred photoelectrons and converting the photoelectrons to a voltage. The unit pixel contains a reset transistor for resetting the potential of the floating diffusion layer to a reference potential and a photoelectron discharger for discharging the photoelectrons generated in the photoelectric conversion element.

主权项

1. A unit pixel comprising a light receiving device containing a photoelectric conversion element for detecting a light to generate photoelectrons,
wherein the light receiving device contains at least three photoelectron distributors each having a first transfer unit for transferring the photoelectrons generated in the photoelectric conversion element, a photoelectron hold unit located on one side of the photoelectric conversion element with the first transfer unit interposed therebetween for temporarily holding the photoelectrons generated in the photoelectric conversion element, a second transfer unit located on one side of the first transfer unit with the photoelectron hold unit interposed therebetween for transferring the photoelectrons held in the photoelectron hold unit, and a floating diffusion layer located on one side of the photoelectron hold unit with the second transfer unit interposed therebetween for converting the transferred photoelectrons to a voltage, the unit pixel contains a reset transistor for resetting a potential of the floating diffusion layer to a reference potential and a photoelectron discharger for discharging the photoelectrons generated in the photoelectric conversion element, the photoelectric conversion element has a photogate structure, the photoelectron hold unit has a MOS diode structure, the photoelectrons generated in the photoelectric conversion element are distributed in at least three transfer directions by the at least three photoelectron distributors, and are transferred by each photoelectron distributor from the photoelectric conversion element to the floating diffusion layer, via a two-step transfer including a transfer from photoelectric conversion element to the photoelectron hold unit and a transfer from the photoelectron hold unit to the floating diffusion layer, each photoelectron hold unit of the at least three photoelectron distributors holds the photoelectrons generated in the photoelectric conversion element during three light-receiving periods that are different from each other, the potential of the floating diffusion layer is reset to the referential potential, and a voltage signal at a black level corresponding to a voltage of the floating diffusion layer is read out, and the photoelectron held by the photoelectron hold unit is transferred to the floating diffusion layer, and a voltage signal at a signal level corresponding to a voltage of the floating diffusion layer is read out.