Photoelectric conversion device having a semiconductor region arranged in a substrate and having a plurality of regions along a surface of the substrate
A photoelectric conversion device includes a substrate, a photoelectric conversion unit arranged in the substrate and configured to generate charges corresponding to incident light, and a pixel isolation portion arranged in the substrate and isolating the photoelectric conversion unit from other elements. A sidewall of the pixel isolation portion has a plurality of depressions and protrusions in a cross-sectional view. A period of at least a part of the plurality of depressions and protrusions is greater than ½ of a wavelength of light to which the photoelectric conversion unit has sensitivity.
1 . A photoelectric conversion device comprising:
a substrate;
a photoelectric conversion unit arranged in the substrate and configured to generate charges corresponding to incident light;
a pixel isolation portion arranged in the substrate and isolating the photoelectric conversion unit from other elements; and
a semiconductor region arranged in the substrate and having a conductivity type different from a conductivity type of the charges,
wherein the pixel isolation portion is arranged inside the semiconductor region,
wherein the semiconductor region includes a plurality of regions along a normal direction of a surface of the substrate,
wherein a sidewall of the pixel isolation portion has a plurality of depressions and protrusions in a cross-sectional view,
wherein a period of at least a part of the plurality of depressions and protrusions is greater than ½ of a wavelength of light to which the photoelectric conversion unit has sensitivity, and
wherein a length of one region of the plurality of regions along the normal direction is greater than a distance between adjacent protrusions of the plurality of depressions and protrusions.
2 . The photoelectric conversion device according to claim 1 , wherein the plurality of depressions and protrusions is two-dimensionally arranged in a cross-sectional view from a direction perpendicular to the sidewall.
3 . The photoelectric conversion device according to claim 1 , wherein the substrate has depressions and protrusions arranged on an incident surface of the photoelectric conversion unit.
4 . The photoelectric conversion device according to claim 1 , wherein the photoelectric conversion unit includes an avalanche photodiode.
5 . The photoelectric conversion device according to claim 4 , wherein the plurality of depressions and protrusions is arranged at least at a depth at which avalanche multiplication occurs in the avalanche photodiode.
6 . The photoelectric conversion device according to claim 1 , wherein the pixel isolation portion has a rectangular shape surrounding the photoelectric conversion unit in a plan view with respect to the substrate.
7 . The photoelectric conversion device according to claim 6 , wherein the plurality of depressions and protrusions is arranged at least in a center of one side of the rectangular shape.
8 . The photoelectric conversion device according to claim 1 , wherein the pixel isolation portion is arranged so as to penetrate the substrate.
9 . The photoelectric conversion device according to claim 1 , wherein material whose light transmittance, at a wavelength in which the photoelectric conversion unit has sensitivity, is lower than that of material of the substrate is buried in at least a part of the pixel isolation portion.
10 . The photoelectric conversion device according to claim 9 , wherein metal is buried in at least a part of the pixel isolation portion.
11 . The photoelectric conversion device according to claim 9 , wherein polysilicon is buried in at least a part of the pixel isolation portion.
12 . The photoelectric conversion device according to claim 1 further comprising a light shielding layer arranged on at least one of a side of an incident surface of the incident light and a side opposite to the incident surface.
13 . The photoelectric conversion device according to claim 1 , wherein a period of at least a part of the plurality of depressions and protrusions is greater than 325 nm.
14 . The photoelectric conversion device according to claim 1 , wherein a period of at least a part of the plurality of depressions and protrusions is less than 4 μm.
15 . A light detection system comprising:
the photoelectric conversion device according to claim 1 ; and
a signal processing unit configured to process a signal output from the photoelectric conversion device.
16 . A movable body comprising:
the photoelectric conversion device according to claim 1 ;
a distance information acquisition unit configured to acquire distance information to an object from a signal output from the photoelectric conversion device; and
a control unit configured to control the movable body based on the distance information.
17 . The photoelectric conversion device according to claim 1 , wherein the distance between adjacent protrusions of the plurality of depressions and protrusions is greater than ½ of the wavelength of light to which the photoelectric conversion unit has sensitivity.
18 . The photoelectric conversion device according to claim 1 , wherein the plurality of depressions and protrusions has a periodic depressions and protrusions structure, and a periodic distance of at least a part of the depressions and protrusions structure is greater than ½ of the wavelength of light to which the photoelectric conversion unit has sensitivity.