Photoelectric conversion element, image sensing device, and imaging system

Patent metadata

Field	Value
Publication number	US-12446346-B2
Application number	US-202217678304-A
Country	US
Kind code	B2
Filing date	Feb 23, 2022
Priority date	Aug 30, 2019
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A photoelectric conversion element includes a substrate and an optical element. The substrate has a first surface on which reflected light reflected from an object is incident, and includes a first semiconductor region and a second semiconductor region, the second semiconductor region being formed in a direction perpendicular to the first surface and extended from the first surface toward an inside of the substrate. The optical element is positioned on a first surface side of the substrate and collects the reflected light to the second semiconductor region. The first semiconductor region includes a first conductive type semiconductor, the second semiconductor region includes a second conductive type semiconductor. The substrate and the optical element are structured such that a relational expression 0.95*exp(−α(λ)*z)≤B(z)/A1≤1.05*exp(−α(λ)*z) is established at a distance z=z0 when A1≥A2 is satisfied and a distance z0=In(2)/α(λ) is established.

First claim

What is claimed is:

1. A photoelectric conversion element, comprising:
a substrate having a first surface on which reflected light reflected from an object is incident, and including a first semiconductor region and a second semiconductor region, the second semiconductor region being formed in a direction perpendicular to the first surface and extended from the first surface toward an inside of the substrate; and
an optical element positioned on a first surface side of the substrate and configured to collect the reflected light to the second semiconductor region,
wherein the first semiconductor region comprises a first conductive type semiconductor, the second semiconductor region comprises a second conductive type semiconductor whose conductive type is different from that of the first conductive type semiconductor, and
the substrate and the optical element are configured such that a relational expression 0.95*exp(−α(λ)*z)≤B(z)/A1≤1.05*exp(−α(λ)*z) is established at a distance z=z0 when A1≥A2 is satisfied and a distance z0=In(2)/α(λ) is established,
where I is incident energy of the reflected light incident on the photoelectric conversion element,
α(λ) is an absorption coefficient of the reflected light in the substrate where λ is an average wavelength of a light source,
A1 is incident energy of the reflected light in a predetermined region on the first surface,
A2 is incident energy of the reflected light in the predetermined region on the first surface in a case where the photoelectric conversion element does not include the optical element, and
B(z) is incident energy of the reflected light in a region translated from the predetermined region by a predetermined distance z in a thickness direction of the substrate.

2. The photoelectric conversion element according to claim 1 , wherein the predetermined region is defined by perpendicularly projecting the second semiconductor region to the first surface.

3. The photoelectric conversion element according to claim 1 , wherein the light source emits light in a near infrared wavelength band.

4. The photoelectric conversion element according to claim 1 , wherein the light source emits light in a wavelength range of 850 nm to 940 nm.

5. A photoelectric conversion element, comprising:
a substrate having a first surface on which reflected light reflected from an object is incident, and including a first semiconductor region and a second semiconductor region, the second semiconductor region being formed in a direction perpendicular to the first surface and extended from the first surface toward an inside of the substrate; and
an optical element positioned on a first surface side of the substrate and configured to collect the reflected light to the second semiconductor region,
wherein the first semiconductor region comprises a first conductive type semiconductor, the second semiconductor region comprises a second conductive type semiconductor whose conductive type is different from that of the first conductive type semiconductor, and
the substrate and the optical element are configured such that a relational expression 0.95*exp(−α(λ)*z)≤B(z)/A1≤1.05*exp(−α(λ)*z) is established at a distance z satisfying 0≤z≤z0 when A1≥A2 is satisfied and a distance z0=In(2)/α(λ) is established,
where I is incident energy of the reflected light incident on the photoelectric conversion element,
α(λ) is an absorption coefficient of the reflected light in the substrate where λ is an average wavelength of a light source,
A1 is incident energy of the reflected light in a predetermined region on the first surface,
A2 is incident energy of the reflected light in the predetermined region on the first surface in a case where the photoelectric conversion element does not include the optical element, and
B(z) is incident energy of the reflected light in a region translated from the predetermined region by a predetermined distance z in a thickness direction of the substrate.

6. The photoelectric conversion element according to claim 5 , wherein the predetermined region is defined by perpendicularly projecting the second semiconductor region to the first surface.

7. The photoelectric conversion element according to claim 5 , wherein the light source emits light in a near infrared wavelength band.

8. The photoelectric conversion element according to claim 5 , wherein the light source emits light in a wavelength range of 850 nm to 940 nm.

9. An image sensing device, comprising:
a plurality of pixels two-dimensionally formed in a matrix in a light-receiving region, each of the pixels including the photoelectric conversion element of claim 1 ,
wherein the pixels are arrayed in a first direction and a second direction which are orthogonal to each other, and
the optical elements are configured to have a first height and a second height different from each other, where the first height is a height of a trough between two adjacent optical elements in a cross section of the optical elements along the first direction and the second direction, and the second height is a height of a trough between two adjacent optical elements in a cross section of the optical elements along a diagonal line direction of the pixels.

10. An imaging system, comprising:
a light source that emits light in a wavelength band;
the image sensing device of claim 9 ; and
a light-receiving device that receives light reflected from an object.

11. The imaging system according to claim 10 , wherein the wavelength band is a near infrared wavelength band.

12. The imaging system according to claim 10 , wherein the wavelength band is in a range of 850 nm to 940 nm.

13. An image sensing device, comprising:
a plurality of pixels two-dimensionally formed in a matrix in a light-receiving region, each of the pixels including the photoelectric conversion element of claim 5 ,
wherein the pixels are arrayed in a first direction and a second direction which are orthogonal to each other, and
the optical elements are configured to have a first height and a second height different from each other, where the first height is a height of a trough between two adjacent optical elements in a cross section of the optical elements along the first direction and the second direction, and the second height is a height of a trough between two adjacent optical elements in a cross section of the optical elements along a diagonal line direction of the pixels.

14. An imaging system, comprising:
a light source that emits light in a wavelength band;
the image sensing device of claim 13 ; and
a light-receiving device that receives light reflected from an object.

15. The imaging system according to claim 14 , wherein the wavelength band is a near infrared wavelength band.

16. The imaging system according to claim 14 , wherein the wavelength band is in a range of 850 nm to 940 nm.

Assignees

• Toppan Inc

Inventors

• Ookubo Yu
• Nakagome Tomohiro

Classifications

• H10F39/8057

  Optical shielding · CPC title

• H10F39/184

  Infrared image sensors · CPC title

• G02B3/0037

  characterized by the distribution or form of lenses · CPC title

• G01S7/4863

  Detector arrays, e.g. charge-transfer gates · CPC title

• G01S7/4816

  of receivers alone · CPC title