Solid-state imaging element and imaging device with first pixel for gradation signal and second pixel for event detection having larger photoelectric conversion portion volume
A solid-state imaging element according to the present technology includes a pixel array unit in which a plurality of pixels each having a photoelectric conversion portion is arranged, the pixel array unit includes, as the pixels, a first pixel for obtaining a gradation signal indicating an intensity of received light and a second pixel for detecting that a change in an amount of received light exceeds a predetermined threshold value, and a volume of a photoelectric conversion portion included in the second pixel is larger than a volume of a photoelectric conversion portion included in the first pixel.
1 . A solid-state imaging element, comprising:
a pixel array unit comprising a plurality of pixels, wherein
each pixel of the plurality of pixels includes a photoelectric conversion portion,
the plurality of pixels includes a first pixel and a second pixel,
the first pixel is configured to obtain a gradation signal that indicates an intensity of received light,
the second pixel is configured to detect that a change in an amount of the received light exceeds a threshold value,
the first pixel includes a first volume of the photoelectric conversion portion,
the second pixel includes a second volume of the photoelectric conversion portion included in the second pixel, and
the second volume is larger than the first volume.
2 . The solid-state imaging element according to claim 1 , further comprising a semiconductor substrate, wherein the first pixel includes:
a floating diffusion region in the semiconductor substrate; and
a charge accumulation portion, different from the floating diffusion region, in the semiconductor substrate.
3 . The solid-state imaging element according to claim 2 , wherein
the second pixel comprises a first intra-pixel region and a second intra-pixel region,
the first intra-pixel region corresponds to a region where the photoelectric conversion portion is in the first pixel,
the second intra-pixel region corresponds to a region where the charge accumulation portion is in the first pixel, and
both the first intra-pixel region and the second intra-pixel region correspond to the photoelectric conversion portion.
4 . The solid-state imaging element according to claim 3 , wherein
the first pixel comprises a first trench,
the first trench separates a formation region of the photoelectric conversion portion in the first pixel and a formation region of the charge accumulation portion in the first pixel,
the second pixel comprises a second trench,
the second trench separates the first intra-pixel region and the second intra-pixel region, and
a depth of the second trench is shallower than a depth of the first trench.
5 . The solid-state imaging element according to claim 3 , wherein
the second pixel comprises an intra-region trench, and
the intra-region trench separates a first part of the second intra-pixel region and a second part of the second intra-pixel region.
6 . The solid-state imaging element according to claim 5 , wherein the intra-region trench has at least four surfaces.
7 . The solid-state imaging element according to claim 6 , wherein at least a part of a cross-sectional shape of the intra-region trench has a cross shape or a T shape.
8 . The solid-state imaging element according to claim 5 , wherein
the second pixel comprises a plurality of intra-region trenches, and
the plurality of intra-region trenches comprises the intra-region trench.
9 . The solid-state imaging element according to claim 2 , wherein, in the second pixel, a light incident surface of the semiconductor substrate has a moth-eye structure.
10 . The solid-state imaging element according to claim 1 , wherein
a size of the second pixel is equivalent to a size of a plurality of specific pixels, and
each pixel of the plurality of specific pixels is the first pixel.
11 . The solid-state imaging element according to claim 10 , wherein
the second pixel further includes a waveguide between a microlens and the photoelectric conversion portion, and
the waveguide is configured to guide light toward the photoelectric conversion portion of the second pixel.
12 . An imaging device, comprising:
a solid-state imaging element including
a pixel array unit comprising a plurality of pixels, wherein
each pixel of the plurality of pixels includes a photoelectric conversion portion,
the plurality of pixels includes a first pixel and a second pixel,
the first pixel is configured to obtain a gradation signal that indicates an intensity of received light,
the second pixel is configured to detect a change in an amount of the received light exceeds a threshold value,
the first pixel includes a first volume of the photoelectric conversion portion,
the second pixel includes a second volume of the photoelectric conversion portion included in the second pixel being, and
the second volume is larger than the first volume; and
a signal processing unit configured to:
receive a captured image; and
process the captured image based on the gradation signal obtained by the first pixel.
13 . A solid-state imaging element, comprising:
a semiconductor substrate;
a first pixel including:
a first photoelectric conversion portion in the semiconductor substrate in a cross-sectional view;
a first charge accumulation portion; and
a first trench between the first photoelectric conversion portion and the first charge accumulation portion;
a second pixel including:
a second photoelectric conversion portion, in the semiconductor substrate, adjacent to the first pixel in the cross-sectional view;
a third photoelectric conversion portion;
a fourth trench in the third photoelectric conversion portion; and
a second trench between the second photoelectric conversion portion and the third photoelectric conversion portion; and
a third trench between the first charge accumulation portion and the second photoelectric conversion portion in the cross-sectional view.
14 . The solid-state imaging element according to claim 13 , wherein the third trench penetrates the semiconductor substrate.
15 . The solid-state imaging element according to claim 13 , wherein the second pixel is configured to detect that a change in an amount of received light exceeds a specific threshold value.
16 . The solid-state imaging element according to claim 13 , wherein
the first pixel includes a floating diffusion region, and
the first charge accumulation portion is different from the floating diffusion region.
17 . The solid-state imaging element according to claim 13 , wherein the fourth trench is from a surface of the semiconductor substrate opposite to a light incident surface of the semiconductor substrate.
18 . The solid-state imaging element according to claim 13 , wherein the second pixel further includes:
a fourth photoelectric conversion portion; and
a fifth trench between the third photoelectric conversion portion and the fourth photoelectric conversion portion.
19 . The solid-state imaging element according to claim 13 , further comprising a moth-eye structure on the second photoelectric conversion portion and on a light incident surface of the semiconductor substrate.