PHOTODIODE AND METHOD OF MAKING THEREOF

• US 20190312169A1
• Filed: 04/05/2019
• Published: 10/10/2019
• Est. Priority Date: 04/09/2018
• Status: Abandoned Application

• Current Assignee: Huaian Imaging Device Manufacturer Corporation
• Original Assignee: Huaian Imaging Device Manufacturer Corporation
• Inventors: Ko, Tienchi, Liu, Shao Dong
• Application Number:
  US16/376,217
• Publication Number:
  US 20190312169A1
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/14607 Geometry of the photosensitive area
• CPC Class Codes: H01L 27/1461 characterised by the photosensitive area
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 27/14689 MOS based technologies
• CPC Class Codes: H01L 31/035281 Shape of the body
• CPC Class Codes: H01L 31/102 characterised by only one potential barrier
• CPC Class Codes: H01L 31/103 the potential barrier being of the PN homojunction type
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A photodiode in a CMOS image sensor and a method for making the photodiode are described. To make the photodiode, protrusions and trenches are alternately patterned on the surface of a semiconductor substrate. The protrusions and trenches are doped to form a first doped layer; and an upper portion of the first doped layer is doped to form a second doped layer, the first and second doped layers comprise dopants having opposite polarities. The photodiode further includes a dielectric layer on the second doped layer. A CMOS image sensor with the photodiode has an improved quantum efficiency and enhanced performance.

Claims

1. A photodiode, comprising:

a semiconductor substrate, wherein protrusions and trenches are alternately patterned on a surface of the semiconductor substrate;

a first doped layer disposed on the protrusions and trenches; and

a second doped layer formed on an upper portion of the first doped layer, wherein the first and second doped layers comprise opposite polarity dopants.

2. The photodiode according to claim 1, wherein the protrusions each has a trapezoid-like structure.

3. The photodiode according to claim 2, wherein an inclined surface each of the protrusions has inclined sidewalls, wherein the inclined sidewalls form angle with the substrate surface ranging from 30 to 90 degrees.

4. The photodiode according to claim 1, wherein a height of the protrusions is 1500 Å

to 2000 Å

.

5. The photodiode according to claim 1, wherein the first doped layer is N-doped, and the second doped layer is P-doped.

6. The photodiode according to claim 1, wherein the first doped layer is doped with a first ion implantation process.

7. The photodiode according to claim 1, wherein a depth of the first doped layer ranges from 100 Å

to 1000 Å

, and a depth of the second doped layer ranges from 100 Å

to 1000 Å

.

8. The photodiode according to claim 1, wherein the photodiode further comprises a dielectric layer on the second doped layer.

9. The photodiode according to claim 8, wherein the dielectric layer is a silicon oxide layer having a thickness ranging from 100 Å

to 1000 Å

.

10. A method for fabricating a photodiode, comprising:

providing a semiconductor substrate, comprising protrusions and trenches alternately patterned on a surface of the semiconductor substrate;

performing a first ion implantation process to form a first doped layer on the surface of the semiconductor substrate; and

performing a second ion implantation process to an upper portion of the first doped layer, to form a second doped layer, wherein the first doped layer has a doping type opposite to a doping type of the second doped layer.

11. The method for fabricating the photodiode according to claim 10, wherein the protrusion each has a trapezoid-like structure.

12. The method for fabricating the photodiode according to claim 10, wherein sidewalls of the protrusions form an inclined angle with the surface of the semiconductor substrate ranging from 30 to 90 degrees.

13. The method for fabricating the photodiode according to claim 10, wherein a height of the protrusions is 1500 Å

to 2000 Å

.

14. The method for fabricating the photodiode according to claim 10, wherein the alternating protrusions and the trenches are patterned by a lithography and an etching process.

15. The method for fabricating the photodiode according to claim 10, wherein the first ion implantation process applies N doping, and the second ion implantation process applies P doping.

16. The method for fabricating the photodiode according to claim 10, wherein a depth of the first doped layer ranges from 100 Å

to 1000 Å

, and a depth of the second doped layer ranges from 100 521 to 1000 Å

.

17. The method for fabricating the photodiode according to claim 10, further comprising:

forming a dielectric layer on the second doped layer.

18. The method for fabricating the photodiode according to claim 17, wherein the dielectric layer is a silicon oxide layer, having a thickness ranging from 100 Å

to 1000 Å

.

19. A semiconductor device, comprising a photodiode, a MOSFET, and a floating-gate diode, wherein the photodiode comprises:

a semiconductor substrate, wherein protrusions and trenches are alternately patterned on a surface of the semiconductor substrate;

a first doped layer disposed on the protrusions and trenches; and

a second doped layer formed on an upper portion of the first doped layer, wherein the first and second doped layers comprise opposite polarity dopants.