Imaging device with improved short-wavelength sensitivity
There is provided an imaging device including a first semiconductor layer formed on a semiconductor substrate, a second semiconductor layer formed on the first semiconductor layer and having an opposite conductivity type to the first semiconductor layer, a pixel separation portion that demarcates a pixel region including the first semiconductor layer and the second semiconductor layer, a first electrode connected to the first semiconductor layer from one surface side of the semiconductor substrate, and a metal layer connected to the second semiconductor layer from a light irradiation surface side which is the other surface of the semiconductor substrate and buried in the pixel separation portion in at least a part of the semiconductor substrate in a thickness direction.
1. An imaging device, comprising:
a first semiconductor layer on a semiconductor substrate;
a second semiconductor layer on the first semiconductor layer, wherein the second semiconductor layer has an opposite conductivity type to the first semiconductor layer;
a pixel separation portion configured to demarcate a pixel region including the first semiconductor layer and the second semiconductor layer;
a first electrode connected to the first semiconductor layer from a first surface side of the semiconductor substrate;
a metal layer connected to the second semiconductor layer from a light irradiation surface side which is a second surface side of the semiconductor substrate, wherein the metal layer is buried in the pixel separation portion in at least a part of the semiconductor substrate; and
a second electrode connected to the second semiconductor layer from the light irradiation surface side, wherein
the second electrode corresponds to a position of the pixel separation portion, and
the metal layer is electrically connected to the second semiconductor layer via the second electrode.
2. The imaging device according to claim 1 , wherein the second electrode is along a periphery of the pixel region.
3. The imaging device according to claim 1 , wherein the second electrode is in a region of a part of a periphery of the pixel region.
4. The imaging device according to claim 3 , wherein
the pixel region is a rectangular pixel region; and
the second electrode is in at least one of four corners of the rectangular pixel region.
5. The imaging device according to claim 3 , wherein the second electrode is buried in a hole in the second semiconductor layer.
6. The imaging device according to claim 3 , wherein the second electrode and the metal layer are formed of the same material.
7. The imaging device according to claim 1 , further comprising:
an insulation film along the pixel separation portion and the light irradiation surface side, wherein
the second electrode is buried in an opening in the second semiconductor layer; and
a specific region in which an end of the insulation film retreats more than a wall surface of the opening, wherein the specific region is filled with the second electrode.
8. The imaging device according to claim 1 , further comprising:
an insulation film along the pixel separation portion; and
a specific region in which an end of the insulation film retreats in a thickness direction of the pixel separation portion, wherein the specific region is filled with the second electrode.
9. The imaging device according to claim 1 , wherein a voltage for multiplying electrons is applied between the first electrode and the metal layer.
10. The imaging device according to claim 1 , further comprising a third semiconductor layer on the second semiconductor layer, wherein the third semiconductor layer and the second semiconductor layer have the same conductivity type.
11. The imaging device according to claim 1 , wherein the second electrode is on an upper surface of the pixel separation portion.
12. The imaging device according to claim 1 , wherein
the pixel separation portion and the second electrode have a planar shape of a grid shape surrounding a plurality of pixel regions, and
the plurality of pixel regions comprises the pixel region.