Photodetector of an image sensor
AssigneeSTMicroelectronics S.r.l.
InventorFrançois Roy
Life of this patent
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Abstract
A photodetector formed in monolithic form including a first active area of doped single-crystal silicon corresponding to first and second photodiodes having the same surface area as two charge transfer MOS transistors, and as one storage diode; a second active area of doped single-crystal silicon arranged next to the portion of the first active area associated with the second photodiode and corresponding to a precharge switch; and a third active doped single-crystal silicon area arranged next to the portion of the first active area associated with the first photodiode and corresponding to two read MOS transistors in series, in which the surfaces of the second and third active areas exposed to light are substantially identical.
Claims12
A monolithic photodetector comprising:
- a pixel of a pixel matrix, said pixel further comprising:
- a first active area of doped single-crystal silicon including first and second photodiodes having a same surface area, as two charge transfer MOS transistors, and as one storage diode, a cathode of each photodiode being connected to a cathode of the storage diode via one of the charge transfer MOS transistors;
- a second active area of doped single-crystal silicon arranged next to a portion of the first active area associated with the second photodiode and including a precharge switch having a first terminal connected to the cathode of the storage diode and a second terminal connected to a reference voltage;
- and
- a third active doped single-crystal silicon area arranged next to the portion of the first active area associated with the first photodiode and including two read MOS transistors in series, the gate of one of the read transistors being connected to the cathode of the storage diode and the drain or the source of one of the read transistors being connected to a processing system,
- wherein the surfaces of the second and third active areas exposed to a lighting are substantially identical;
- wherein the precharge switch is a MOS transistor with two parallel gates;
- and
- wherein the gates of the two read transistors correspond to portions of first and second polysilicon strips and wherein the two gates of the MOS transistor with two gates correspond to portions of third and fourth parallel polysilicon strips, the sum of the surface areas exposed to light of the third and fourth parallel polysilicon strips being substantially equal to the sum of the surface areas exposed to light of the first and second polysilicon strips.
A monolithic photodetector comprising:
- a pixel of a pixel matrix, said pixel further comprising:
- a first active area of doped single-crystal silicon including first and second photodiodes having a same surface area as two charge transfer MOS transistors, and as one storage diode;
- a second active area of doped single-crystal silicon arranged next to a portion of the first active area associated with the second photodiode and including a precharge switch;
- and
- a third active doped single crystal silicon area arranged next to the portion of the first active area associated with the first photodiode and including two read MOS transistors in series;
- wherein the surfaces of the second and third active areas exposed to light are substantially identical;
- wherein the precharge switch is a MOS transistor with two parallel gates;
- and
- wherein the gates of the two read transistors correspond to portions of first and second polysilicon strips and wherein the two gates of the MOS transistor with two gates correspond to portions of third and fourth parallel polysilicon strips, the sum of the surface areas exposed to light of the third and fourth parallel polysilicon strips being substantially equal to the sum of the surface areas exposed to light of the first and second polysilicon strips.
Dependencies are inferred from the claim text.