Optical sensor and signal readout method therefor, and solid-state image pickup device and signal readout method therefor

Patent metadata

Field	Value
Publication number	US-2020043971-A1
Application number	US-201616339438-A
Country	US
Kind code	A1
Filing date	Oct 7, 2016
Priority date	Oct 7, 2016
Publication date	Feb 6, 2020
Grant date	—

Abstract

One of the problems addressed by the present invention is to provide an optical sensor, a solid-state imaging device, and a signal readout method drive therefor that greatly contribute to a further development of industry and to the realization of a more secure and safe society. One of the solutions provided by the present invention is an optical sensor comprising a light reception element, a storage capacitor for storing charges, and a transfer switch for transferring, to the storage capacitor, a charge generated by light input into the light reception element. The storage capacitor includes a floating diffusion capacitor and a lateral overflow integration capacitor. The transfer switch is an LDD-MOS transistor of which a drain area has a specific impurity concentration.

First claim

1 . An optical sensor, comprising:
a light receiving element; a storage capacitor configured to store a charge; a transfer switch configured to transfer, to the storage capacitor, a charge generated by light input to the light receiving element; and a pixel signal output line, wherein the pixel signal output line has a signal readout path connected thereto, wherein the storage capacitor includes a floating diffusion capacitor (C FD ) and a lateral overflow integration capacitor (C LOFIC ), wherein the transfer switch includes an LDD-MOS transistor, wherein a concentration (N D ) of semiconductor impurities in a drain region of the LDD-MOS transistor and a concentration (N) of semiconductor impurities in a diffusion region provided adjacent to the drain region satisfy the following relationships:
1< N/N D 100   (1); and

0< N≤ 1.0×10 ° cm −3   (2),

wherein a first pixel output signal subjected to charge-to-voltage conversion by the floating diffusion capacitor (C FD ) and a second pixel output signal subjected to charge-to-voltage conversion by a combination of the floating diffusion capacitor (C FD ) and the lateral overflow integration capacitor (C LOFIC ) are input to the signal readout path, and wherein the first pixel output signal is amplified by an amplification factor larger than 1 when the first pixel output signal is an ultra-high sensitive signal.

2 . A multi-pixel optical sensor, comprising:
a row of plurality of two-dimensionally arranged pixel units, each including:
a light receiving element;
a storage capacitor configured to store a charge; and
a transfer switch configured to transfer, to the storage capacitor, a charge generated by light input to the light receiving element,
the storage capacitor including a floating diffusion capacitor (C FD ) and a lateral overflow integration capacitor (C LOFIC ),
the transfer switch including an LDD-MOS transistor,
a concentration (N D ) of semiconductor impurities in a drain region of the LDD-MOS transistor and a concentration (N) of semiconductor impurities in a diffusion region provided adjacent to the drain region satisfying the following relationships:
1< N/N D 100   (1); and

0< N≤ 1.0×10 ° cm −3   (2),

a pixel signal output line, to which each of the plurality of two-dimensionally arranged pixel units is sequentially connected; and a signal readout path unit configured to execute amplification by using an amplification factor larger than 1 and another amplification factor different from the amplification factor in a different manner, the signal readout path unit being connected to the pixel signal output line at a position downstream of a position at which a last pixel unit in the row of plurality of two dimensionally arranged pixel units is connected to the pixel signal output line, wherein a first pixel output signal subjected to charge-to-voltage conversion by the floating diffusion capacitor (C FD ) and a second pixel output signal subjected to charge-to-voltage conversion by a combination of the floating diffusion capacitor (C FD ) and the lateral overflow integration capacitor (C LOFIC ) are input to the signal readout path.

3 . A signal readout method to be executed by an optical sensor, the optical sensor including, for each pixel unit:
a light receiving element; a storage capacitor configured to store a charge; and a transfer switch configured to transfer, to the storage capacitor, a charge generated by light input to the light receiving element, the storage capacitor including a floating diffusion capacitor and a lateral overflow integration capacitor, the transfer switch including an LDD-MOS transistor, a concentration (N D ) of semiconductor impurities in a drain region of the LDD-MOS transistor and a concentration (N) of semiconductor impurities in a diffusion region provided adjacent to the drain region satisfying the following relationships:
1< N/N D 100   (1); and

0< N≤ 1.0×10 ° cm −3   (2),

the optical sensor further including:
a pixel signal output line, to which each pixel unit is connected; and
a signal readout path connected to the pixel signal output line, the signal readout method comprising:
subjecting, by the floating diffusion capacitor, an amount of charges that contribute to readout to charge-to-voltage conversion so as to form a first pixel output signal; subjecting, by a combination of the floating diffusion capacitor and the lateral overflow integration capacitor, the amount of charges that contribute to readout to charge-to-voltage conversion so as to form a second pixel output signal; inputting the first pixel output signal and the second pixel output signal to the signal readout path; and amplifying the first pixel output signal in the signal readout path by a plurality of amplifiers including at least one amplifier having an amplification factor larger than 1.

4 . An image pickup device, comprising:
a plurality of pixel units each including:
a light receiving element (PD);
a switch for transfer (T);
a switch for overflow (S);
a switch for resetting (R);
the light receiving element (PD), the switch for transfer (T), the switch for overflow (S), and the switch for resetting (R) are connected in series in the stated order,
a floating diffusion capacitor (C FD ) and a source-follower switch (SF), which are connected to a line between the switch for transfer (T) and the switch for overflow (5); and
a lateral overflow integration capacitor (C LOFIC ), which is connected to a line between the switch for overflow (S) and the switch for resetting (R),
the source-follower switch (SF) including a MOS transistor, a concentration (N D ) of semiconductor impurities in a drain region in the switch for transfer (T) and a concentration (N) of semiconductor impurities in a diffusion region provided adjacent to the drain region satisfying the following relationships:
1< N/N D 100   (1); and

0< N≤ 1.0×10 ° cm −3   (2),

the light receiving elements (PD) of the plurality of pixel units forming an array of two-dimensionally arranged pixels;
a pixel row output signal line, to which the plurality of pixel units are sequentially connected; and a reading unit connected to the pixel row output signal line, wherein a first pixel output signal subjected to charge-to-voltage conversion by the floating diffusion capacitor (C FD ) and a second pixel output signal subjected to charge-to-voltage conversion by a combination of the floating diffusion capacitor (C FD ) and the lateral overflow integration capacitor (C LOFIC ) are input to the reading unit, and wherein the first pixel output signal is amplified in a signal readout path by a plurality of amplifiers including at least one amplifier having an amplification factor larger than 1.

5 . A signal readout method for an image pickup device, the signal readout method comprising:
preparing an image pickup device including:
a plurality of pixel units each including:
a light receiving element (PD);
a switch for transfer (T);
a switch for overflow (S);
a switch for resetting (R);
the light receiving element (PD), the switch for transfer (T), the switch for overflow (S), and the switch for resetting (R) are connected in series in the stated order,
a floating diffusion capacitor (C FD ) and a source-follower switch (SF), which are connected to a line between the switch for transfer (T) and the switch for overflow (S); and
a lateral overflow integration capacitor (C LOFIC ), which is connected to a line between the switch for overflow (S) and the switch for resetting (R),
the source-follower switch (SF) including a MOS transistor,
a concentration (N D ) of semiconductor impurities in a drain region in the switch for transfer (T) and a concentration (N) of semiconductor impurities in a dif

Assignees

• Univ Tohoku

Inventors

• Sugawa Shigetoshi
• Kuroda Rihito
• Wakashima Shunichi

Classifications

• H04N25/59

  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

• H04N25/778

  comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself · CPC title

• H04N25/621

  for the control of blooming · CPC title

• H04N5/37455

  Electricity · mapped topic

• H04N5/37457

  Electricity · mapped topic