BACKSIDE ILLUMINATED IMAGE SENSOR AND METHOD OF MANUFACTURING THE SAME

• US 20190319054A1
• Filed: 04/09/2019
• Published: 10/17/2019
• Est. Priority Date: 04/11/2018
• Status: Active Grant

• Current Assignee: DB HiTek Co., Ltd.
• Original Assignee: DB HiTek Co., Ltd.
• Inventors: Han, Chang Hun
• Granted Patent: US 10,957,734 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/1461 characterised by the photosensitive area
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/14638 Structures specially adapted for transferring the charges across the imager perpendicular to the imaging plane
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

A backside illuminated image sensor includes pixel regions disposed in a substrate, a light-blocking pattern disposed on a backside surface of the substrate and having openings corresponding to the pixel regions, a color filter layer disposed on the light-blocking pattern, a micro lens array disposed on the color filter layer, and refraction patterns respectively disposed in the openings to condense light passing through the micro lens array and the color filter layer into the pixel regions.

Claims

1. A backside illuminated image sensor having a backside surface and a frontside surface arranged opposite one another, the backside illuminated image sensor comprising:

a plurality of pixel regions disposed in a substrate that defines the frontside surface and the backside surface;

a light-blocking pattern disposed on the backside surface and defining a plurality of openings, each of the plurality of openings corresponding to one of the plurality of pixel regions;

a color filter layer disposed on the light-blocking pattern;

a micro lens array disposed on the color filter layer; and

a plurality of refraction patterns, each one of the plurality of refraction patterns disposed in a corresponding one of the plurality of openings to condense light passing through the micro lens array and the color filter layer into the pixel regions.

2. The backside illuminated image sensor of claim 1, wherein each of the refraction patterns has inclined side surfaces so that a width of the refraction patterns is thicker proximal to the backside surface and thinner distal to the backside surface.

3. The backside illuminated image sensor of claim 1, further comprising a planarization layer disposed on the light-blocking pattern and the refraction patterns, wherein the color filter layer is disposed on the planarization layer.

4. The backside illuminated image sensor of claim 3, wherein the refraction patterns have a refractive index higher than that of the planarization layer.

5. The backside illuminated image sensor of claim 1, wherein the refraction patterns comprise silicon nitride.

6. The backside illuminated image sensor of claim 1, further comprising an anti-reflective layer disposed on the backside surface of the substrate.

7. The backside illuminated image sensor of claim 6, wherein the anti-reflective layer comprises:

a metal oxide layer disposed on the backside surface of the substrate;

a silicon oxide layer disposed on the metal oxide layer; and

a silicon nitride layer disposed on the silicon oxide layer.

8. The backside illuminated image sensor of claim 7, further comprising an insulating layer disposed on the anti-reflective layer, wherein the light-blocking pattern and the refraction patterns are disposed on the insulating layer.

9. The backside illuminated image sensor of claim 1, wherein each of the pixel regions comprises:

a charge accumulation region disposed in the substrate; and

a frontside pinning layer disposed between the frontside surface and the charge accumulation region.

10. The backside illuminated image sensor of claim 9, wherein the each of the pixel regions further comprises a backside pinning layer disposed between the backside surface and the charge accumulation region.

11. A method of manufacturing a backside illuminated image sensor, the method comprising:

forming a plurality of pixel regions in a substrate that defines a frontside surface and a backside surface;

forming a light-blocking pattern defining a plurality of openings on the backside surface, each of the plurality of openings corresponding to one of the plurality of pixel regions;

forming a plurality of refraction patterns, wherein each of the plurality of refraction patterns is arranged in a corresponding one of the plurality of openings;

forming a color filter layer on the light-blocking pattern and the plurality of refraction patterns; and

forming a micro lens array on the color filter layer,

wherein the plurality of refraction patterns are configured to condense light passing through the micro lens array and the color filter layer into the pixel regions.

12. The method of claim 11, wherein forming the refraction patterns comprises:

forming preliminary refraction patterns in the openings; and

removing edge portions of the preliminary refraction patterns to form the refraction patterns,

wherein each of the refraction patterns has inclined side surfaces so that it is thicker proximal to the backside surface and thinner distal to the backside surface.

13. The method of claim 12, wherein forming the refraction patterns further comprises:

forming photoresist patterns each having inclined side surfaces on the preliminary refraction patterns,

wherein the edge portions of the preliminary refraction patterns are removed by an anisotropic etching process using the photoresist patterns as an etching mask.

14. The method of claim 13, wherein the photoresist patterns are removed at the same rate as the preliminary refraction patterns during the anisotropic etching process.

15. The method of claim 11, further comprising forming a planarization layer on the light-blocking pattern and the refraction patterns, wherein the color filter layer is formed on the planarization layer.

16. The method of claim 15, wherein the refraction patterns have a refractive index higher than a refractive index of the planarization layer.

17. The method of claim 11, wherein the refraction patterns comprise silicon nitride.

18. The method of claim 11, further comprising performing a heat treatment process to remove defects of the refraction patterns.

19. The method of claim 11, further comprising forming an anti-reflective layer on the backside surface of the substrate.

20. The method of claim 19, further comprising forming an insulating layer on the anti-reflective layer, wherein the light-blocking pattern and the plurality of refraction patterns are formed on the insulating layer.