BSI image sensor and method of forming same

Patent metadata

Field	Value
Publication number	US-11315972-B2
Application number	US-202017095994-A
Country	US
Kind code	B2
Filing date	Nov 12, 2020
Priority date	Mar 24, 2016
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

A backside illumination (BSI) image sensor and a method of forming the same are provided. A method includes forming a plurality of photosensitive pixels in a substrate, the substrate having a first surface and a second surface, the second surface being opposite the first surface, the substrate having one or more active devices on the first surface. A first portion of the second surface is protected. A second portion of the second surface is patterned to form recesses in the substrate. An anti-reflective layer is formed on sidewalls of the recesses. A metal grid is formed over the second portion of the second surface, the anti-reflective layer being interposed between the substrate and the metal grid.

First claim

What is claimed is:

1. A device comprising:
a substrate, the substrate having a first surface and a second surface opposite to the first surface;
at least one active device on the first surface of the substrate;
a plurality of photosensitive regions in the substrate;
a plurality of recesses in the second surface of the substrate, the plurality of recesses being disposed over the plurality of photosensitive regions;
an anti-reflective layer extending along sidewalls of the plurality of recesses;
a metal grid over the plurality of recesses; and
a metal shield adjacent to the metal grid, wherein a portion of the anti-reflective layer is interposed between the metal shield and the substrate.

2. The device of claim 1 , wherein a top surface of the metal shield is substantially level with a top surface of the metal grid.

3. The device of claim 1 , wherein a portion of the metal shield extends through the anti-reflective layer and physically contacts the second surface of the substrate.

4. The device of claim 1 , wherein portions of the substrate interposed between neighboring recesses are arranged in a rectangular array as viewed from top.

5. The device of claim 1 , wherein the metal grid comprises:
a first barrier layer comprising a first material; and
a first conductive layer over the first barrier layer, the first conductive layer comprising a second material different from the first material.

6. The device of claim 5 , wherein the metal shield comprises:
a second barrier layer comprising the first material; and
a second conductive layer over the second barrier layer, the second conductive layer comprising the second material.

7. The device of claim 6 , wherein the first barrier layer and the second barrier layer have a same thickness, and wherein the first conductive layer and the second conductive layer have a same thickness.

8. A device comprising:
a substrate having a pixel array region and a black level correction (BLC) region adjacent to the pixel array region;
a plurality of photosensitive regions in the substrate;
a plurality of protrusions on a first side of the substrate in the pixel array region, the plurality of protrusions being spaced apart from the plurality of photosensitive regions;
an anti-reflective layer over the first side of the substrate, a first portion of the anti-reflective layer extending along sidewalls of the plurality of protrusions;
a metal grid over the pixel array region of the substrate, the plurality of protrusions being interposed between the metal grid and the plurality of photosensitive regions; and
a metal shield over the BLC region of the substrate, wherein a second portion of the anti-reflective layer extends along a sidewall and a top surface of the metal shield.

9. The device of claim 8 , wherein the plurality of protrusions are arranged in a rectangular array.

10. The device of claim 8 , wherein the plurality of protrusions have a uniform width and a uniform pitch.

11. The device of claim 8 , further comprising a first dielectric layer interposed between the first side of the substrate and the metal shield, wherein a portion of the metal shield extends through the first dielectric layer and physically contacts the first side of the substrate.

12. The device of claim 11 , further comprising a second dielectric layer interposed between the top surface of the metal shield and the second portion of the anti-reflective layer, wherein the first dielectric layer and the second dielectric layer comprise different materials.

13. The device of claim 8 , wherein the metal grid and the metal shield comprise a same conductive material.

14. The device of claim 8 , wherein the anti-reflective layer comprises a dielectric material.

15. A device comprising:
a substrate having a pixel array region and a black level correction (BLC) region adjacent to the pixel array region;
an interconnect structure over the pixel array region and the BLC region of the substrate;
a plurality of photosensitive regions in the pixel array region and the BLC region of the substrate;
a plurality of protrusions on a first side of the substrate in the pixel array region, the plurality of photosensitive regions being interposed between the plurality of protrusions and the interconnect structure;
an anti-reflective layer extending along sidewalls of the plurality of protrusions;
a metal grid over the plurality of protrusions, wherein the anti-reflective layer extends along a sidewall and a top surface of the metal grid; and
a metal shield over the first side of the substrate in the BLC region, wherein the anti-reflective layer extends along a sidewall and a top surface of the metal shield.

16. The device of claim 15 , wherein the plurality of protrusions form a saw-tooth pattern in a cross-section view.

17. The device of claim 15 , further comprising a first dielectric layer interposed between the plurality of protrusions and the metal grid.

18. The device of claim 17 , further comprising a second dielectric layer interposed between the metal grid and the anti-reflective layer, wherein the first dielectric layer and the second dielectric layer comprise different materials.

19. The device of claim 15 , wherein the anti-reflective layer comprises an oxide material.

20. The device of claim 15 , wherein the metal grid and the metal shield have a same thickness.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Hsu Hung-Wen
• Lu Jiech-Fun
• Tu Yeur-Luen
• Chen U-Ting
• Tsai Shu-Ting
• Cheng Hsiu-Yu

Classifications

• H10F39/014

  of CMOS image sensors · CPC title

• H10F39/8057

  Optical shielding · CPC title

• H10F39/199

  Back-illuminated image sensors · CPC title

• H10F39/024

  of coatings or optical elements · CPC title

• H10F39/011

  Manufacture or treatment of image sensors covered by group H10F39/12 · CPC title