Imaging device with improved short-wavelength sensitivity

Patent metadata

Field	Value
Publication number	US-12100722-B2
Application number	US-201917250834-A
Country	US
Kind code	B2
Filing date	Sep 17, 2019
Priority date	Sep 21, 2018
Publication date	Sep 24, 2024
Grant date	Sep 24, 2024

Abstract

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.

First claim

The invention claimed is:

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.

Assignees

• Sony Semiconductor Solutions Corp

Inventors

• Furumi Koji
• Manda Shuji
• Matsumoto Ryosuke
• Hirano Tomoyuki

Classifications

• H10F30/225

  the potential barrier working in avalanche mode, e.g. avalanche photodiodes · CPC title

• H10F39/18

  Complementary metal-oxide-semiconductor [CMOS] image sensors; Photodiode array image sensors · CPC title

• H10F39/811

  Interconnections · CPC title

• H10F39/807

  Pixel isolation structures · CPC title

• H10F39/802 Primary

  Geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes · CPC title