Method for fabricating CMOS image sensor

• US 20060019425A1
• Filed: 07/18/2005
• Published: 01/26/2006
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: DONGBU ELECTRONICS CO., LTD. (DB HiTek Co., Ltd.)
• Original Assignee: Dongbuanam Semiconductor, Inc. (DB HiTek Co., Ltd.)
• Inventors: Su Kon, Kim
• Granted Patent: US 7,435,615 B2
• Time in Patent Office: Days
• US Class Current: 438/70
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

A method for fabricating a CMOS image sensor improves the characteristics of device by preventing a pad from being contaminated without damaging a micro-lens. The method includes steps of forming a device protection layer on a semiconductor substrate including at least one photo-sensing device and at least one metal pad disposed in a logic circuit area corresponding to the at least one photo-sensing device, the device protection layer covering the at least one metal pad; forming each of a first planarization layer, a color filter layer, and a second planarization layer in sequence on the device protection layer in correspondence with the at least one photo-sensing device; forming on the second planarization layer a material layer for micro-lens formation; exposing a predetermined portion of the metal pad by selectively etching the device protection layer; and forming a micro-lens for directing incident light onto the at least one photo-sensing device by reflowing, after the exposing step, the material layer for micro-lens formation.

Claims

1. A method for fabricating a CMOS image sensor, comprising:

forming a device protection layer on a semiconductor substrate including at least one photo-sensing device and at least one metal pad disposed in a logic circuit area corresponding to the at least one photo-sensing device, the device protection layer covering the at least one metal pad;

forming each of a first planarization layer, a color filter layer, and a second planarization layer in sequence on the device protection layer in correspondence with the at least one photo-sensing device;

forming on the second planarization layer a material layer for micro-lens formation;

exposing a predetermined portion of the metal pad by selectively etching the device protection layer; and

forming a micro-lens for directing incident light onto the at least one photo-sensing device by reflowing, after said exposing, the material layer for micro-lens formation.

2. The method of claim 1, wherein said material layer forming is performed before said exposing.

3. The method of claim 1, wherein said material layer forming is performed while the device protection layer covers the at least one metal pad.

4. The method of claim 1, said material layer forming comprising:

patterning the material layer for micro-lens formation according to a pixel size of the CMOS image sensor.

5. The method of claim 4, wherein said patterning is performed before said exposing.

6. The method of claim 1, wherein the reflowing of the material layer for micro-lens formation is performed with respect to the micro-lens material layer, thereby imparting the micro-lens with a convex upper surface for focusing incident light onto the at least one photo-sensing device.

7. The method of claim 1, wherein the reflowing of the material layer for micro-lens formation is performed after said sequential forming of each of a first planarization layer, a color filter layer, and a second planarization layer.

8. The method of claim 1, wherein the device protection layer has a deposition structure of an undoped silicate glass layer formed on the metal pad and a silicon nitride layer formed on the undoped silicate glass layer.

9. The method of claim 1, further comprising:

forming first and second barrier layers for improving conductivity with respect to lower and upper surfaces of the metal pad, respectively.

10. The method of claim 9, wherein the first and second barrier layers are formed of at least one of titanium and titanium nitride.

11. The method of claim 9, wherein the first and second barrier layers are formed using a chemical mechanical polishing process.

12. The method of claim 1, wherein the predetermined portion of the metal pad corresponds to a surface of the metal pad for enabling a wire bonding with respect to the metal pad during a packaging process of the CMOS image sensor.

13. The method of claim 1, wherein the at least one photo-sensing device is a photodiode.

14. A method for fabricating a CMOS image sensor, comprising:

forming a device protection layer on a semiconductor substrate including at least one photo-sensing device and at least one metal pad disposed in a logic circuit area corresponding to the at least one photo-sensing device, the device protection layer covering the at least one metal pad;

forming each of a first planarization layer, a color filter layer, and a second planarization layer in sequence on the device protection layer in correspondence with the at least one photo-sensing device;

forming on the second planarization layer a material layer for micro-lens formation;

exposing a predetermined portion of the metal pad by selectively etching the device protection layer; and

forming a micro-lens for directing incident light onto the at least one photo-sensing device, by reflowing the material layer for micro-lens formation,

wherein said sequential forming of each of a first planarization layer, a color filter layer, and a second planarization layer and said exposing are performed before the reflowing of said micro-lens forming.

15. The method of claim 14, wherein said material layer forming is performed before said exposing.

16. The method of claim 14, wherein said material layer forming is performed while the device protection layer covers the at least one metal pad.

17. The method of claim 14, said material layer forming comprising:

patterning the material layer for micro-lens formation according to a pixel size of the CMOS image sensor.

18. The method of claim 17, wherein said patterning is performed before said exposing.