SOLID-STATE IMAGE SENSOR AND MANUFACTURING METHOD THEREOF

• US 20060278948A1
• Filed: 06/07/2006
• Published: 12/14/2006
• Est. Priority Date: 06/08/2005
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: MURATA, Takahiko, KASUGA, Shigetaka, YAMAGUCHI, Takumi
• Granted Patent: US 7,968,888 B2
• Time in Patent Office: Days
• US Class Current: 257/444
• 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 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14632 Wafer-level processed structures
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 27/14687 Wafer level processing

Abstract

An object of the present invention is to provide a small solid-state image sensor which realizes significant improvement in sensitivity. The solid-state image sensor of the present invention includes a semiconductor substrate in which photoelectric conversion units are formed, a light-blocking film which is formed above the semiconductor substrate and has apertures formed so as to be positioned above respective photoelectric conversion units, and a high refractive index layer formed in the apertures. Here, each aperture has a smaller aperture width than a maximum wavelength in a wavelength of light in a vacuum converted from a wavelength of the light entering the photoelectric conversion unit through the apertures, and the high refractive index is made of a high refractive index material having a refractive index which allows transmission of light having the maximum wavelength through the aperture.

Claims

1. A solid-state image sensor comprising:

a semiconductor substrate;

a photoelectric conversion unit formed in said semiconductor substrate;

a light-blocking film which is formed above said semiconductor substrate and has an aperture formed so as to be positioned above said photoelectric conversion unit; and

a high refractive index layer formed in the aperture.

2. The solid-state image sensor according to claim 1,

wherein the aperture has an aperture width which is smaller than a maximum wavelength in a wavelength of light in a vacuum converted from a wavelength of the light entering said photoelectric conversion unit through the aperture, and

said high refractive index layer is made of a high refractive index material having a refractive index which allows light of the maximum wavelength to transmit, the light entering said photoelectric conversion unit through the aperture.

3. The solid-state image sensor according to claim 1,

wherein the aperture is filled with said high refractive index layer.

4. The solid-state image sensor according to claim 1,

wherein said high refractive index layer is made of a high refractive index material having a refractive index of 1.8 or higher.

5. The solid-state image sensor according to claim 1,

wherein said high refractive index layer is as thick as or thicker than said light-blocking film.

6. The solid-state image sensor according to claim 1,

wherein said high refractive index layer has a convex lens shape, and condenses light entering said photoelectric conversion unit through the aperture.

7. The solid-state image sensor according to claim 1,

wherein the high refractive index material is one of titanium oxide, tantalum oxide, and niobium oxide.

8. The solid-state image sensor according to claim 1,

wherein the aperture width is 1.0 μ

m or less.

9. The solid-state image sensor according to claim 1, further comprising

a filter film which is formed above said light-blocking film so as to be positioned above the aperture, and allows transmission of light in a predetermined wavelength band,

wherein the aperture has an aperture width smaller than a maximum wavelength of the light which is transmitted through said filter film.

10. A camera comprising a solid-state image sensor,

wherein said solid-state image sensor includes:

a semiconductor substrate;

a photoelectric conversion unit formed in the semiconductor substrate;

a light-blocking film which is formed above the semiconductor substrate and has an aperture formed so as to be positioned above the photoelectric conversion unit; and

a high refractive index layer formed in the aperture,

wherein the aperture has an aperture width which is smaller than a maximum wavelength in a wavelength of light in a vacuum converted from a wavelength of the light entering said photoelectric conversion unit through the aperture, and

said high refractive index layer is made of a high refractive index material having a refractive index which allows light of the maximum wavelength to transmit, the light entering said photoelectric conversion unit through the aperture.

14. The method of manufacturing a solid-state image sensor according to claim 10, further comprising

processing the high refractive index layer positioned above the aperture into a convex lens shape.

11. A method of manufacturing a solid-state image sensor, said method comprising:

forming a light-blocking film above a semiconductor substrate in which a photoelectric conversion unit is formed and forming an aperture in the light-blocking film so as to be positioned above the photoelectric conversion unit; and

forming a high refractive index layer in the aperture and on the light-blocking film,

wherein said forming of the high refractive index layer includes forming the high refractive index layer with a thickness which makes a surface of the high refractive index layer flat.

12. The method of manufacturing a solid-state image sensor according to claim 11,

wherein said forming of the high refractive index layer includes forming the high refractive index layer with a thickness which is half or more of a width of the aperture.

13. The method of manufacturing a solid-state image sensor according to claim 11, further comprising

planarizing the surface of the high refractive index layer.

15. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate;

microlenses formed above said semiconductor substrate so as to be positioned above the respective photoelectric conversion units; and

a color filter which includes filter films arranged in a two-dimensional array and which is formed above said semiconductor substrate so that the filter films are positioned above the respective photoelectric conversion units,

wherein said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, said second photoelectric conversion unit being positioned below one of the filter films transmitting light of a longer wavelength than a wavelength of light transmitted by another one of the filter films positioned above said first photoelectric conversion unit, and

one of the microlenses positioned above said second photoelectric conversion unit has a higher refractive index than another one of the microlenses positioned above said first photoelectric conversion unit.

16. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate;

microlenses formed above said semiconductor substrate so as to be positioned above the respective photoelectric conversion units; and

a color filter which includes filter films arranged in a two-dimensional array and which is formed above said semiconductor substrate so that the filter films are positioned above the respective photoelectric conversion units,

wherein each microlens is made of a low refractive index material and a high refractive index material,

said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, said second photoelectric conversion unit being positioned below one of the filter films transmitting light of a longer wavelength than a wavelength of the light transmitted by another one of the filter films positioned above said first photoelectric conversion unit, and

a volume of a high refractive index material included in one of the microlenses positioned above said second photoelectric conversion unit is greater than a volume of a high refractive index material included in another one of the microlenses positioned above said first photoelectric conversion unit.

17. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate;

a high refractive index film formed above said semiconductor substrate; and

a color filter which includes filter films arranged in a two-dimensional array and which is formed above said semiconductor substrate so that the filter films are positioned above said respective photoelectric conversion units,

said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, said second photoelectric conversion unit being positioned below one of the filter films transmitting light of a longer wavelength than a wavelength of the light transmitted by another one of the filter films positioned above said first photoelectric conversion unit, and

said refractive index film positioned above said second photoelectric conversion unit has a higher refractive index than said refractive index film positioned above said first photoelectric conversion unit.

18. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate; and

microlenses formed above said semiconductor substrate so as to be positioned above the respective photoelectric conversion units,

wherein said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, in which light enters at a greater incident angle than an incident angle at which light enters said first photoelectric conversion unit,

one of said microlenses positioned above said second photoelectric conversion unit has a higher refractive index than another one of said microlenses positioned above said first photoelectric conversion unit.

19. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate; and

microlenses formed above said semiconductor substrate so as to be positioned above the respective photoelectric conversion units,

wherein each microlens is made of a low refractive index material and a high refractive index material,

said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, in which light enters at a greater incident angle than an incident angle at which light enters said first photoelectric conversion unit, and

a volume of a high refractive index material included in one of the microlenses positioned above said second photoelectric conversion unit is greater than a volume of a high refractive index material included in another one of the microlenses positioned above said first photoelectric conversion unit.

20. A solid-state image sensor comprising:

a semiconductor substrate;

photoelectric conversion units formed in said semiconductor substrate; and

a high refractive index film formed above said semiconductor substrate,

wherein said photoelectric conversion units are a first photoelectric conversion unit and a second photoelectric conversion unit, in which light enters at a greater incident angle than an incident angle at which light enters said first photoelectric conversion unit, and

said refractive index film positioned above said second photoelectric conversion unit has a higher refractive index than said refractive index film positioned above said first photoelectric conversion unit.

21. A solid-state image sensor comprising:

a semiconductor substrate;

light-receiving cells which are formed in said semiconductor substrate, and have photoelectric conversion units which generate signal charge in accordance with a luminance of incident light; and

microlenses formed above the respective photoelectric conversion units,

wherein said light-receiving cells are a first light-receiving cell having a first aperture width, and a second light-receiving cell having a second aperture width which is greater than the first aperture width, and

a refractive index of one of said microlenses in said first light-receiving cell is higher than a refractive index of another one of said microlenses in said second light-receiving cell.

22. A solid-state image sensor comprising:

a semiconductor substrate;

light-receiving cells which are formed in said semiconductor substrate, and have photoelectric conversion units which generate signal charge in accordance with a luminance of incident light; and

microlenses formed above the respective photoelectric conversion units,

wherein one of said microlenses of said first light-receiving cell and another one of said microlenses of said second light-receiving cell are respectively made of at least a low refractive index material and a high refractive index material, and

a volume of the high refractive index material included in said microlens of said first light-receiving cell is greater than a volume of the high refractive index material included in said microlens of said second light-receiving cell.

23. A solid-state image sensor comprising:

a semiconductor substrate;

light-receiving cells which are formed in said semiconductor substrate, and have photoelectric conversion units which generate signal charge in accordance with a luminance of incident light; and

microlenses formed above the respective photoelectric conversion units,

wherein said light-receiving cells are a first light-receiving cell having a first aperture width, and a second light-receiving cell having a second aperture width which is greater than the first aperture width, and

said solid-state image sensor further comprises;

a first high refractive index interlayer film positioned above said first light-receiving cell; and

a second high refractive index interlayer film positioned above said second light-receiving cell,

wherein said first high refractive index interlayer film has a higher refractive index than said second high refractive index interlayer film.

24. A solid-state image sensor comprising:

a semiconductor substrate;

light-receiving cells which are formed in said semiconductor substrate, and have photoelectric conversion units which generate signal charge in accordance with a luminance of incident light; and

microlenses positioned above the respective photoelectric conversion units,

wherein said light-receiving cells are a first light-receiving cell having a first aperture width, and a second light-receiving cell having a second aperture width which is greater than the first aperture width, and

one of said microlenses of said first light-receiving cell is higher in height than another one of said microlenses of said second light-receiving cell.