Optical sensor, signal reading method therefor, solid-state imaging device, and signal reading method therefor

Patent metadata

Field	Value
Publication number	US-10154222-B2
Application number	US-201815923136-A
Country	US
Kind code	B2
Filing date	Mar 16, 2018
Priority date	Nov 17, 2014
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

One problem addressed by the present invention is to provide an optical sensor, a solid-state imaging device, and methods for reading the signals therefrom, which contribute greatly to the development of industry and the realization of a safer and more secure society. One solution according to the present invention is an optical sensor having a light-receiving element, storage capacitors that store a charge, and a transfer switch for transferring to the storage capacitors a charge generated by light input to the light-receiving element, wherein the storage capacitors are a floating diffusion capacitor and a lateral overflow integration capacitor, and the transfer switch is a non-LDD/MOS transistor, that is, a non-LDD/MOS transistor for which the impurity concentration of the drain region is reduced by 50%.

First claim

What is claimed is:

1. A signal reading method for an optical sensor comprising:
(1) a sensor portion having pixel portions, each of the pixel portions includes a light-receiving element, storage capacitors that store a charge, and a transfer switch for transferring to the storage capacitors a charge generated by light input to the light-receiving element, the storage capacitors are a floating diffusion capacitor and a lateral overflow integration capacitor, and the transfer switch is a MOS transistor;
(2) a pixel signal output line connected to each of the pixel portions; and
(3) a signal reading path connected to the pixel signal output line;
the signal reading method comprising the steps of:
(a) keeping the pixel signal output line in a floating capacitance state after resetting,
(b) while the pixel signal output line is kept in the floating capacitance state,
(b-1) forming a first pixel output signal by converting a charge of a charge amount that contributes to reading by the floating diffusion capacitor to voltage,
(b-2) forming a second pixel output signal by combining the floating diffusion capacitor and the lateral overflow integration capacitor and converting a charge of a charge amount that contributes to reading to voltage; and
(b-3) inputting these two pixel output signals to the signal reading path;

wherein the first pixel output signal is amplified in the signal reading path by a plurality of amplifiers that include at least one amplifier having an amplification factor greater than 1.

2. A signal reading method for an imaging device comprising:
(1) a plurality of pixel portions, each of the pixel portions in which a light-receiving element (PD), a transfer switch (T), an overflow switch (S) and a reset switch (R) are connected in series in that order, which have a floating diffusion capacitor (CFD) and a source follower switch (SF) connected to wiring between the transfer switch (T) and the overflow switch (S), and a lateral overflow integration capacitor (CLOFIC) connected to wiring between the overflow switch (S) and the reset switch (R), the source follower switch (SF) is a MOS transistor, and the transfer switch (T) is a MOS transistor,
(2) the light-receiving elements (PD) of the plurality of pixel portions are arranged two-dimensionally to constitute a pixel array,
(3) the plurality of pixel portions is sequentially connected to a pixel column output signal line, and
(4) the pixel column output signal line is connected to a column circuit portion; the signal reading method comprising the steps of:
(a) keeping the pixel column output signal line in a floating capacitance state after resetting,
(b) while the pixel column output signal line is kept in the floating capacitance state,
(b-1) forming a first pixel output signal by converting a charge of a charge amount that contributes to reading by the floating diffusion capacitor to voltage,
(b-2) forming a second pixel output signal by combining the floating diffusion capacitor and the lateral overflow integration capacitor and converting a charge of a charge amount that contributes to reading to voltage, and
(b-3) inputting these two pixel output signals to the column circuit portion;

wherein the first pixel output signal is amplified in the column circuit portion by a plurality of amplifiers that include at least one amplifier having an amplification factor greater than 1.

Assignees

• Univ Tohoku

Inventors

• Sugawa Shigetoshi
• Kuroda Rihito
• Wakashima Shunichi

Classifications

• H04N25/59 Primary

  by controlling the amount of charge storable in the pixel, e.g. modification of the charge conversion ratio of the floating node capacitance · CPC title

• H04N25/771

  comprising storage means other than floating diffusion · CPC title

• H04N25/77

  Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components · CPC title

• H04N5/378 Primary

  Electricity · mapped topic

• H01L27/14616

  Electricity · mapped topic