Solid-state imaging device, method of manufacturing the same, and electronic apparatus

Patent metadata

Field	Value
Publication number	US-2016351606-A1
Application number	US-201515113861-A
Country	US
Kind code	A1
Filing date	Feb 5, 2015
Priority date	Feb 18, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

The present disclosure relates to a solid-state imaging device that can be made smaller in size, a method of manufacturing the solid-state imaging device, and an electronic apparatus.
The solid-state imaging device includes a photoelectric conversion film that performs photoelectric conversion of light emitted from the back surface side of the semiconductor substrate. Also, in each pixel, a charge accumulation layer is formed to be in contact with the photoelectric conversion film on the back surface of the semiconductor substrate, a transfer path unit is formed to extend from the charge accumulation layer to a point near the front surface of the semiconductor substrate, and a memory unit is disposed near the back surface side of the semiconductor substrate, with a charge transfer gate being interposed between the memory unit and the transfer path unit. Then, the photoelectric conversion film is formed by stacking a layer formed with a material having a great light blocking effect on the back surface of the semiconductor substrate. The present technology can be applied to back-illuminated CMOS image sensors in global shutter mode.

First claim

1 . A solid-state imaging device comprising:
a semiconductor substrate having a plurality of pixels arranged in an array; and a photoelectric conversion film configured to perform photoelectric conversion of light emitted from a first surface side of the semiconductor substrate, wherein: each of the pixels includes: a charge accumulation layer configured to accumulate charge generated in the photoelectric conversion film, the charge accumulation layer being formed to be in contact with the photoelectric conversion film on the first surface of the semiconductor substrate; and a transfer path unit configured to serve as a path to transfer the charge accumulated in the charge accumulation layer, the transfer path unit being formed to extend from the charge accumulation layer to a point near a second surface, the second surface facing the opposite side from the first surface of the semiconductor substrate; and the photoelectric conversion film is formed by stacking a layer on the first surface of the semiconductor substrate, the layer being formed with a material having a great light blocking effect.

2 . The solid-state imaging device according to claim 1 , wherein the transfer path unit has a potential gradient, a potential becomes deeper in a direction from the charge accumulation layer toward the second surface of the semiconductor substrate.

3 . The solid-state imaging device according to claim 1 , wherein the transfer path unit is formed to have a smaller area than the charge accumulation layer when the semiconductor substrate is seen in a plan view.

4 . The solid-state imaging device according to claim 1 , wherein each of the pixels further includes
a memory unit configured to hold the charge transferred from the charge accumulation layer until the charge is read from the pixel, the memory unit being disposed near the second surface side of the semiconductor substrate, a charge transfer gate being interposed between the memory unit and the transfer path unit.

5 . The solid-state imaging device according to claim 4 , wherein each of the pixels further includes
an overflow drain formed on the first surface of the semiconductor substrate, the overflow drain being disposed on a different side of the transfer path unit from the side having the memory unit formed thereon, a discharge gate being interposed between the overflow drain and the transfer path unit.

6 . The solid-state imaging device according to claim 5 , further comprising
a drive circuit configured to drive the pixels, wherein the drive circuit drives the discharge gate of each of the pixels substantially at the same time, and collectively discharges the charge accumulated in the charge accumulation layers into the overflow drains.

7 . The solid-state imaging device according to claim 5 , wherein a cutoff potential of the discharge gate discharging the charge from the transfer path unit into the overflow drain is lower than a cutoff potential of the charge transfer gate transferring the charge from the transfer path unit to the memory unit.

8 . The solid-state imaging device according to claim 1 , wherein the photoelectric conversion film is a film formed with a compound lattice-matched to the semiconductor substrate.

9 . The solid-state imaging device according to claim 1 , wherein the photoelectric conversion film is a film formed with a silicide.

10 . The solid-state imaging device according to claim 1 , wherein the photoelectric conversion film is a film formed with an organic material.

11 . The solid-state imaging device according to claim 1 , further comprising
a buffer layer configured to reduce impurity diffusion, the buffer layer being disposed between the semiconductor substrate and the photoelectric conversion film.

12 . The solid-state imaging device according to claim 5 , wherein a pinning layer having a high concentration of an impurity is formed between the charge accumulation layer and the memory unit, the impurity being different from an impurity forming the charge accumulation layer and the memory unit.

13 . The solid-state imaging device according to claim 12 , wherein:
the charge accumulation layer and the pinning layer are formed on a silicon substrate forming the semiconductor substrate; and the memory unit is formed in an epitaxial layer through epitaxial growth of silicon on a front surface of the silicon substrate.

14 . The solid-state imaging device according to claim 12 , wherein the memory unit is formed to extend from a point near a front surface of the semiconductor substrate to a point in contact with the pinning layer.

15 . The solid-state imaging device according to claim 5 , wherein an electrode for reading the charge from the memory unit is formed to extend from a front surface of the semiconductor substrate toward the inside of the semiconductor substrate, the electrode being in contact with a side surface of the memory unit.

16 . The solid-state imaging device according to claim 12 , wherein part of the pinning layer is formed to extend toward a front surface side of the semiconductor substrate, the part of the pinning layer covering a side surface of the memory unit.

17 . The solid-state imaging device according to claim 16 , wherein the part of the pinning layer is formed to separate the memory unit and the transfer path unit from each other.

18 . The solid-state imaging device according to claim 5 , wherein the pixel has a layout in which the memory unit has the largest area among elements formed in a plane including the memory unit.

19 . A method of manufacturing a solid-state imaging device including: a semiconductor substrate having a plurality of pixels arranged in an array; and a photoelectric conversion film configured to perform photoelectric conversion of light emitted from a first surface side of the semiconductor substrate,
each of the pixels including: a charge accumulation layer configured to accumulate charge generated in the photoelectric conversion film; and a transfer path unit configured to serve as a path to transfer the charge accumulated in the charge accumulation layer, the method comprising the steps of: forming the charge accumulation layer near the first surface of the semiconductor substrate; forming the transfer path unit extending from the charge accumulation layer to a point near a second surface facing on the opposite side from the first surface of the semiconductor substrate; performing polishing until the charge accumulation layer is exposed through the first surface side of the semiconductor substrate; and forming the photoelectric conversion film by stacking a layer on the first surface of the semiconductor substrate, the layer being formed with a material having a great light blocking effect.

20 . An electronic apparatus comprising
a solid-state imaging device including: a semiconductor substrate having a plurality of pixels arranged in an array; and a photoelectric conversion film configured to perform photoelectric conversion of light emitted from a first surface side of the semiconductor substrate, wherein: each of the pixels includes: a charge accumulation layer configured to accumulate charge generated in the photoelectric conversion film, the charge accumulation layer being formed to be in contact with the photoelectric conversion film on the first surface of the semiconductor substrate; and a transfer path unit configured to serve as a path to transfer the charge accumulated in the charge accumulation layer, the transfer pat

Assignees

• Sony Corp

Inventors

• Azami Kenji
• Otake Yusuke
• Ohgishi Yuko
• Wakano Toshifumi
• Toda Atsushi

Classifications

• H04N25/77

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

• H04N25/76

  Addressed sensors, e.g. MOS or CMOS sensors · CPC title

• H01L27/1461

  Electricity · mapped topic

• H01L27/14687

  Electricity · mapped topic

• H04N5/374

  Electricity · mapped topic