US-12622074-B2 - Image sensor including an impurity injection region on a bottom surface of a trench and image sensing system including the image sensor

Abstract

An image sensor includes a semiconductor substrate having a first surface and a second surface opposing the first surface, a photodiode layer in the semiconductor substrate, a transfer gate on the photodiode layer, the transfer gate being on the first surface of the semiconductor substrate, a first trench recessed from the first surface of the semiconductor substrate at one side of the transfer gate, a first impurity injection region on at least a portion of a bottom surface of the first trench, the first impurity injection region not being on a sidewall of the first trench, and a lens on the second surface of the semiconductor substrate.

Inventors

• Chan Hee Lee
• Kyung Ho Lee
• Seung Ki Baek
• Seung Ki JUNG
• Tae Sub Jung

Assignees

• SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date

20260505

Application Date

20211201

Priority Date

20210412

Claims (20)

1. 1 . An image sensor, comprising: a substrate including a first surface and a second surface opposing the first surface; a pixel array region in the substrate; a first photodiode layer and a second photodiode layer in the pixel array region; a first separation trench between the first photodiode layer and the second photodiode layer; a transfer gate; a first trench recessed from the first surface of the substrate in the pixel array region and overlapping with the first photodiode layer in a first direction perpendicular to the first surface of the substrate; a first P type impurity injection region on a bottom surface of the first trench; a first contact connected to the bottom surface of the first trench and vertically overlapping with the bottom surface of the first trench; and a lens on the second surface of the substrate, wherein the first contact extends in the first direction, wherein a distance from the second surface of the substrate to the bottom surface of the first trench in the first direction is shorter than a distance from the second surface of the substrate to an uppermost surface of the first surface of the substrate, and wherein at least a portion of the transfer gate is on the uppermost surface of the first surface of the substrate.
2. 2 . The image sensor of claim 1 , wherein a distance from the uppermost surface of the first surface of the substrate to the bottom surface of the first trench in the first direction is from about 0.1 μm to about 0.2 μm.
3. 3 . The image sensor of claim 1 , wherein the first p type impurity injection region is connected with a ground terminal.
4. 4 . The image sensor of claim 3 , wherein the first contact comprises a first surface and a second surface opposing the first surface of the first contact, and wherein the first surface of the first contact is disposed in the first trench in a vertical view.
5. 5 . The image sensor of claim 4 , further comprises a second contact comprises a first surface and a second surface opposing the first surface of the second contact, wherein the second contact is connected to the transfer gate and vertically overlapping with the transfer gate in the first direction, wherein a length of the first contact from the first surface of the first contact to the second surface of the first contact is longer than a length of the second contact from the first surface of the second contact to the second surface of the second contact.
6. 6 . The image sensor of claim 5 , further comprises a floating diffusion in the substrate, a dual conversion gate, and a reset transistor, wherein the floating diffusion, the dual conversion gate, and the reset transistor are connected in series.
7. 7 . The image sensor of claim 5 , wherein the substrate further comprises a light-shielding region, wherein the light-shielding region comprises a third trench recessed from the first surface of the substrate and a second p type impurity injection region, wherein the second p type impurity injection region is on a bottom surface of the third trench.
8. 8 . The image sensor of claim 5 , wherein the first separation trench penetrates at least a part of the substrate from the first surface of the substrate.
9. 9 . The image sensor of claim 5 , further comprises a first N type impurity injection region on the uppermost surface of the first surface of the substrate and a third contact connecting to the first N type impurity injection region, and wherein the length of the first contact from the first surface of the first contact to the second surface of the first contact is longer than a length of the third contact from the first surface of the third contact to the second surface of the third contact.
10. 10 . The image sensor of claim 7 , further comprises a first N type impurity injection region on the uppermost surface of the first surface of the substrate in the light-shielding region.
11. 11 . The image sensor of claim 10 , further comprises a third contact connecting to the first N type impurity injection region, and wherein the length of the second contact from the first surface of the second contact to the second surface of the second contact is shorter than a length of the third contact from the first surface of the third contact to the second surface of the third contact.
12. 12 . The image sensor of claim 11 , wherein the height of the first contact in the first direction is equal to the height of the third contact in the first direction.
13. 13 . An image sensor, comprising: a substrate including a first surface and a second surface opposing the first surface; a pixel array region in the substrate; a first photodiode layer and a second photodiode layer in the pixel array region; a first separation trench between the first photodiode layer and the second photodiode layer; a transfer gate; a first trench recessed from the first surface of the substrate in the pixel array region and overlapping with the first photodiode layer in a first direction perpendicular to the first surface of the substrate; a first impurity injection region on a bottom surface of the first trench; a first contact connected to the bottom surface of the first trench and vertically overlapping with the bottom surface of the first trench; and a lens on the second surface of the substrate, wherein the first contact extends in the first direction, wherein a distance from the second surface of the substrate to the bottom surface of the first trench in the first direction is shorter than a distance from the second surface of the substrate to an uppermost surface of the first surface of the substrate, and wherein at least a portion of the transfer gate is on the uppermost surface of the first surface of the substrate.
14. 14 . The image sensor of claim 13 , wherein the first contact comprises a first surface and a second surface opposing the first surface of the first contact, and wherein the first surface of the first contact is disposed in the first trench in a vertical view.
15. 15 . The image sensor of claim 14 , further comprises a second contact comprises a first surface and a second surface opposing the first surface of the second contact, wherein the second contact is connected to the transfer gate and vertically overlapping with the transfer gate in the first direction, wherein a length of the first contact from the first surface of the first contact to the second surface of the first contact is longer than a length of the second contact from the first surface of the second contact to the second surface of the second contact.
16. 16 . The image sensor of claim 15 , wherein the first separation trench penetrates at least a part of the substrate from the first surface of the substrate.
17. 17 . The image sensor of claim 15 , further comprises a second impurity injection region on the uppermost surface of the first surface of the substrate and a third contact connecting to the second impurity injection region, wherein the length of the first contact from the first surface of the first contact to the second surface of the first contact is longer than a length of the third contact from the first surface of the third contact to the second surface of the third contact, and wherein the first impurity injection region is doped with a first type impurities and the second impurity injection region is doped with a second type impurities different from the first type impurities.
18. 18 . The image sensor of claim 15 , wherein the first impurity injection region is doped with P type impurities.
19. 19 . The image sensor of claim 17 , wherein the first impurity injection region is doped with P type impurities and the second impurity injection region is doped with N type impurities.
20. 20 . An image sensor, comprising: a substrate including a first surface and a second surface opposing the first surface; a pixel array region in the substrate; a first photodiode layer and a second photodiode layer in the pixel array region; a first separation trench between the first photodiode layer and the second photodiode layer; a transfer gate; a first trench recessed from the first surface of the substrate in the pixel array region and overlapping with the first photodiode layer in a first direction perpendicular to the first surface of the substrate; a P type impurity injection region on a bottom surface of the first trench; a first contact connected to the bottom surface of the first trench and vertically overlapping with the bottom surface of the first trench; and a lens on the second surface of the substrate, wherein a distance from the second surface of the substrate to the bottom surface of the first trench in the first direction is shorter than a distance from the second surface of the substrate to an uppermost surface of the first surface of the substrate, and wherein at least a portion of the transfer gate is on the uppermost surface of the first surface of the substrate.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority from Korean Patent Application No. 10-2021-0047140 filed on Apr. 12, 2021, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. 119, the contents of which in its entirety are herein incorporated by reference. BACKGROUND 1. Field The present disclosure relates to an image sensor and an image sensing system including the image sensor. 2. Description of the Related Art An image sensing device is a semiconductor element that converts optical information into an electrical signal. For example, the image sensing device may include a charge coupled device (CCD) image sensing device and a complementary metal-oxide semiconductor (CMOS) image sensing device. The CMOS image sensor may be abbreviated as a CIS (CMOS image sensor). The CIS may include a plurality of pixels arranged two-dimensionally. Each of the pixels may include, e.g., a photodiode (PD) layer. The photodiode layer may serve to convert incident light into an electrical signal. SUMMARY According to some embodiments, an image sensor may include a semiconductor substrate having a first surface and a second surface opposing the first surface, a photodiode layer in the semiconductor substrate, a transfer gate disposed on the photodiode layer and disposed on the first surface of the semiconductor substrate, a first trench recessed from the first surface of the semiconductor substrate at one side of the transfer gate, a first impurity injection region formed on at least a portion of a bottom surface of the first trench and not formed on a sidewall of the first trench and a lens disposed on the second surface of the semiconductor substrate. According to some embodiments, an image sensor may also include a semiconductor substrate having a first surface and a second surface opposing the first surface, a photodiode layer in the semiconductor substrate, a first trench disposed on the photodiode layer and recessed from the first surface of the semiconductor substrate, a transfer gate filling the first trench, a second trench spaced apart from the first trench and recessed from the first surface of the semiconductor substrate, at one side of the transfer gate, a first impurity injection region formed on at least a portion of a bottom surface of the second trench and a lens disposed on the second surface of the semiconductor substrate, wherein a first depth of the first trench is greater than a second depth of the second trench. According to some embodiments, an image sensing system may include an image sensor outputting an image signal and an image signal processor connected with the image sensor, processing the image signal provided from the image sensor, wherein the image sensor includes a semiconductor substrate including a first surface and a second surface opposing the first surface, a photodiode layer in the semiconductor substrate, a first trench disposed on the photodiode layer and recessed from the first surface of the semiconductor substrate, a transfer gate filling the first trench, a second trench spaced apart from the first trench and recessed from the first surface, at one side of the transfer gate, a first impurity injection region formed on at least a portion of a bottom surface of the second trench and not formed on a sidewall of the second trench and a lens disposed on the second surface of the semiconductor substrate, wherein a first depth of the first trench is greater than a second depth of the second trench. BRIEF DESCRIPTION OF THE DRAWINGS Features will become apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which: FIG. 1 is a block diagram of an image sensing system according to some embodiments of the present disclosure; FIG. 2 is a conceptual layout diagram of an image sensor of FIG. 1; FIG. 3 is a plan view of the image sensor layout of FIG. 2; FIG. 4 is a view of a sensor array region according to some embodiments of the present disclosure; FIG. 5 is a layout of a pixel array region according to some embodiments; FIG. 6 is a layout of a pixel array region according to some embodiments; FIG. 7 illustrates cross-sectional views along lines A-A, B-B, C-C and D-D of FIG. 3; FIG. 8 is an enlarged view of region R of FIG. 7; FIG. 9 is an exemplary circuit of a pixel of an image sensor according to some embodiments of the present disclosure; FIG. 10 is a view of an image sensor according to other embodiments of the present disclosure; FIG. 11 is a view of an image sensor according to still other embodiments of the present disclosure; FIG. 12 is a view of an image sensor according to yet other embodiments of the present disclosure; FIG. 13 is a view of an image sensor according to still other embodiments of the present disclosure; FIG. 14 is a view of an image sensor according to yet other embodiments of the present disclosure; FIG. 15 is a graph of an