Enhanced trench isolation structure

Patent metadata

Field	Value
Publication number	US-12581762-B2
Application number	US-202318355467-A
Country	US
Kind code	B2
Filing date	Jul 20, 2023
Priority date	Oct 19, 2020
Publication date	Mar 17, 2026
Grant date	Mar 17, 2026

Abstract

The present disclosure relates to an image sensor comprising a substrate. A photodetector is in the substrate. A trench is in the substrate and is defined by sidewalls and an upper surface of the substrate. A first isolation layer extends along the sidewalls and the upper surface of the substrate that define the trench. The first isolation layer comprises a first dielectric material. A second isolation layer is over the first isolation layer. The second isolation layer lines the first isolation layer. The second isolation layer comprises a second dielectric material. A third isolation layer is over the second isolation layer. The third isolation layer fills the trench and lines the second isolation layer. The third isolation layer comprises a third material. A ratio of a first thickness of the first isolation layer to a second thickness of the second isolation layer is about 0.17 to 0.38.

First claim

What is claimed is:

1 . An image sensor comprising:
a substrate; a photodetector in the substrate; a first isolation layer laterally surrounding the photodetector and extending along sidewalls and an upper surface of the substrate, the first isolation layer comprising a first metal-oxide; a second isolation layer comprising a second metal-oxide, different than the first metal-oxide, over the first isolation layer, the second metal-oxide contacting a sidewall and an upper surface of the first metal-oxide; and a third isolation layer over the second isolation layer and lining the second isolation layer, the third isolation layer comprising a third dielectric different than the first metal-oxide and the second metal-oxide, wherein a thickness of the first isolation layer is greater than 100 angstroms.

2 . The image sensor of claim 1 , wherein hydrogen atoms are arranged along an interface between the substrate and the first isolation layer.

3 . The image sensor of claim 1 , wherein the thickness of the first isolation layer is greater than 100 angstroms between sidewalls of the first isolation layer and wherein the thickness of the first isolation layer is greater than 100 angstroms between upper surfaces and lower surfaces of the first isolation layer.

4 . The image sensor of claim 3 , wherein the first isolation layer has a density less than 3.05 g/cm3.

5 . The image sensor of claim 1 , wherein the first metal-oxide consists of aluminum oxide and the second metal-oxide consists of tantalum pentoxide.

6 . The image sensor of claim 1 , wherein an interlayer dielectric layer is on the sidewalls of the substrate and the upper surface of the substrate, wherein the interlayer dielectric layer separates the substrate from the first isolation layer, wherein the interlayer dielectric layer comprises a second dielectric different than the first metal-oxide, and wherein the first metal-oxide contacts a sidewall and an upper surface of the second dielectric, and wherein the dielectric of the third isolation layer contacts a sidewall and an upper surface of the second metal-oxide.

7 . The image sensor of claim 6 , wherein a thickness of the interlayer dielectric layer is less than 20 angstroms.

8 . The image sensor of claim 1 , wherein a ratio of the thickness of the first isolation layer to a thickness of the second isolation layer is about 0.17 to 0.38.

9 . An image sensor comprising:
a substrate; a photodetector in the substrate; a trench in the substrate that is formed by sidewalls and an upper surface of the substrate; a first isolation layer extending over the photodetector and laterally surrounding the photodetector, the first isolation layer comprising a first metal-oxide, the first isolation layer extending along the sidewalls of the substrate and the upper surface of the substrate that form the trench, and the first isolation layer filling a first portion of the trench; a second isolation layer over the first isolation layer and laterally surrounding the photodetector, the second isolation layer comprising a second metal-oxide different than the first metal-oxide, the second isolation layer extending along sidewalls and an upper surface of the first isolation layer, and the second isolation layer filling a second portion of the trench; and a third isolation layer over the second isolation layer and laterally surrounding the photodetector, the third isolation layer comprising a dielectric different than the first metal-oxide and the second metal-oxide, the third isolation layer extending along sidewalls and an upper surface of the second isolation layer, and the third isolation layer filling a remainder of the trench, wherein the second metal-oxide extends from a sidewall of the dielectric to a sidewall of the first metal-oxide, wherein the first isolation layer has a density less than 3.05 g/cm3, and wherein a distance between a topmost surface of the substrate and a topmost surface of the first isolation layer is greater than 100 angstroms.

10 . The image sensor of claim 9 , wherein an interlayer dielectric layer is directly between the substrate and the first isolation layer along the sidewalls of the substrate and the upper surface of the substrate, wherein the interlayer dielectric layer comprises a second dielectric, wherein the first metal-oxide extends from a sidewall of the second dielectric to a sidewall of the second metal-oxide.

11 . The image sensor of claim 10 , wherein a ratio of a thickness of the interlayer dielectric layer to a thickness of the first isolation layer is less than 0.2.

12 . The image sensor of claim 9 , wherein the first metal-oxide consists of aluminum oxide and hydrogen.

13 . The image sensor of claim 9 , wherein hydrogen atoms are arranged along an interface between the substrate and the first isolation layer.

14 . The image sensor of claim 9 , wherein the density of the first isolation layer is less than a density of the second isolation layer, and wherein a ratio of the density of the first isolation layer to the density of the second isolation layer is about 0.35 to 0.37.

15 . The image sensor of claim 9 , wherein a distance between the substrate and the second isolation layer along the sidewalls of the substrate and the upper surface of the substrate is greater than 100 angstroms.

16 . An image sensor comprising:
a substrate, the substrate having a first sidewall, a second sidewall, and a top surface that extends from the first sidewall to the second sidewall; a photodetector in the substrate between the first sidewall and the second sidewall of the substrate and under the top surface of the substrate; a first metal-oxide layer comprising a first metal-oxide, the first metal-oxide extending along the first sidewall of the substrate, the second sidewall of the substrate, and the top surface of the substrate; a second metal-oxide layer comprising a second metal-oxide different than the first metal-oxide, the second metal-oxide on a first sidewall of the first metal-oxide, a second sidewall of the first metal-oxide, a top surface of the first metal-oxide; and an isolation layer comprising a dielectric different than the first metal-oxide and the second metal-oxide, the dielectric on a first sidewall of the second metal-oxide, a second sidewall of the second metal-oxide, a top surface of the second metal-oxide, wherein a thickness of the first metal-oxide layer along the first sidewall of the substrate, the second sidewall of the substrate, and the top surface of the substrate is greater than 100 angstroms, and wherein a density of the first metal-oxide layer is less than 3.05 g/cm3.

17 . The image sensor of claim 16 , wherein a distance between the top surface of the substrate and the top surface of the first metal-oxide layer is greater than 100 angstroms.

18 . The image sensor of claim 16 , wherein a distance between the first sidewall of the substrate and the first sidewall of the first metal-oxide is greater than 100 angstroms.

19 . The image sensor of claim 16 , wherein hydrogen is directly between the first metal-oxide and the substrate along the first sidewall of the substrate, the second sidewall of the substrate, and the top surface of the substrate.

20 . The image sensor of claim 16 , further comprising:
an interlayer dielectric layer comprising a second dielectric different than the first metal-oxide, the second dielectric on the first sidewall of the substrate, the second sidewall of the substrate, and the top surface o

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Tsai Min-Ying
• Lee Cheng-Te
• Chu Rei-Lin
• Li Ching I
• Yu Chung-Yi

Classifications

• H10F39/028

  performed after manufacture of the image sensors, e.g. annealing, gettering of impurities, short-circuit elimination or recrystallisation · CPC title

• H10F39/014

  of CMOS image sensors · CPC title

• H10F39/8053

  Colour filters · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• H10F39/18

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