Imaging device, method of manufacturing imaging device, and electronic device
The present technology relates to an imaging device capable of preventing a decrease of sensitivity of the imaging device in a case where a capacitance element is provided in a pixel, a method of manufacturing an imaging device, and an electronic device. The imaging device includes, in a pixel, a photoelectric conversion element and a capacitance element accumulating an electric charge generated by the photoelectric conversion element. The capacitance element includes a first electrode including a plurality of trenches, a plurality of second electrodes each having a cross-sectional area smaller than a contact connected to a gate electrode of a transistor in the pixel, and buried in each of the trenches, and a first insulating film disposed between the first electrode and the second electrode in each of the trenches. The present technology can be applied, for example, to a backside irradiation-type CMOS image sensor.
1. An imaging device, comprising:
a pixel comprising:
a photoelectric conversion element configured to generate an electric charge;
a capacitance element configured to accumulate the electric charge generated by the photoelectric conversion element;
a first insulating film on the photoelectric conversion element;
a second insulating film;
a transistor, wherein
a gate electrode of the transistor is on the second insulating film,
the capacitance element includes a plurality of trench capacitors, and
the plurality of trench capacitors comprises:
a first electrode at a position that vertically overlaps the photoelectric conversion element via the first insulating film, wherein the first electrode is on an entire length of the first insulating film;
a plurality of second electrodes, wherein
the first electrode includes a plurality of trenches,
each second electrode of the plurality of second electrodes has a cross-sectional area smaller than a first contact connected to the gate electrode of the transistor in the pixel,
each second electrode of the plurality of second electrodes is buried in a respective one trench of the plurality of trenches,
a trench capacitor of the plurality of trench capacitors comprises the first electrode and a second electrode of the plurality of second electrodes, and
a distance between two adjacent trench capacitors of the plurality of trench capacitors is set equal to a diameter of the second electrode of the plurality of second electrodes;
a second contact connected to an upper surface of the first electrode, wherein the first electrode is connected to a negative power supply side of the pixel via the second contact; and
a third insulating film between the first electrode and each second electrode of the plurality of second electrodes in the plurality of trenches.
2. The imaging device according to claim 1 , wherein
the first electrode is in a wiring layer, and
the wiring layer is opposite to an incidence surface side of the photoelectric conversion element.
3. The imaging device according to claim 2 , wherein
each second electrode of the plurality of second electrodes is connected to a positive power supply side of the pixel.
4. The imaging device according to claim 1 , wherein a total area of a portion in which each second electrode of the plurality of second electrodes faces the first electrode is larger than an area of a region where the plurality of second electrodes are disposed in the first electrode.
5. The imaging device according to claim 1 , wherein each trench of the plurality of trenches is formed by directed self-assembly lithography.