Methods of manufacturing a color image sensor having an array of pixels with color filters

1. A method of manufacturing a color image sensor, the method comprising:

forming an array of pixels in a semiconductor layer having a back side to receive an illumination, wherein insulated conductive walls penetrate into the semiconductor layer from the back side and separate the pixels from one another;

forming an optically transparent antireflective coating over each of the pixels; and

forming a plurality of color filters, each color filter overlying an associated pixel and separated therefrom by the antireflective coating, each color filter penetrating into the semiconductor layer from 5 to 30% of a thickness of the semiconductor layer from the back side and occupying at least 90% of a surface area delimited by the insulated conductive walls.

2. The method of claim 1 , wherein each pixel includes a first semiconductor region of a first conductivity type overlying a second semiconductor region of a second conductivity type, which in turn overlies a third semiconductor region of the first conductivity type, each color filter overlying the first semiconductor region of the associated pixel.

3. The method of claim 1 , wherein the insulated conductive walls comprise an electrically-conductive material coated with an insulating layer, the electrically-conductive material being opaque to light.

4. The method of claim 1 , wherein the insulated conductive walls penetrate into at least three quarters of the thickness of the semiconductor layer.

5. A method of manufacturing a color image sensor, the method comprising:

etching trenches in a semiconductor layer, the trenches defining an array of pixels of the color image sensor;

depositing an insulating coating along sidewalls of the trenches;

filling the trenches with an electrically-conductive material;

for each pixel, etching a cavity between adjacent trenches; and

filling each cavity with a color filtering material so that the electrically-conductive material extends along sidewalls of the color filtering material filling the cavity into the semiconductor layer to a depth that is deeper than the color filtering material filling the cavity.

6. The method of claim 5 , wherein each pixel includes a first semiconductor region of a first conductivity type overlying a second semiconductor region of a second conductivity type, which in turn overlies a third semiconductor region of the first conductivity type.

7. The method of claim 5 , wherein etching the cavity for each pixel comprises removing a portion of the electrically-conductive material.

8. The method of claim 5 , wherein the electrically-conductive material is opaque to light.

9. The method of claim 8 , wherein the electrically-conductive material comprises metal.

10. The method of claim 5 , further comprising depositing an electrically-conductive coating layer opaque to light on the insulating coating before depositing the electrically-conductive material, wherein each cavity is etched through the electrically-conductive coating layer.

11. The method of claim 10 , wherein the electrically-conductive coating layer comprises a metal or a metal nitride.

12. The method of claim 5 , wherein the trenches penetrate into at least three quarters of the thickness of the semiconductor layer.

13. The method of claim 5 , wherein filling each cavity with a color filtering material comprises filling some cavities with a color filtering material of a first color and filling other cavities with a color filtering material of a second color that is different than the first color.

14. The method of claim 5 , further comprising lining each cavity with an antireflection coating before filling the cavity with the color filtering material.

15. The method of claim 5 , wherein each cavity penetrates from 5 to 30% of a thickness of the semiconductor layer, and occupying at least 90% of a surface area delimited by the trenches.

16. A method of manufacturing a color image sensor, the method comprising:

etching a trench structure in a semiconductor layer that includes a first semiconductor region of a first conductivity type overlying a second semiconductor region of a second conductivity type, which in turn overlies a third semiconductor region of the first conductivity type;

depositing an insulating coating along sidewalls of the trench structure;

filling the trench structure with an electrically-conductive material;

etching a first cavity and a second cavity in the first semiconductor region of the semiconductor layer, the first and second cavities being separated by a trench of the trench structure;

lining the first and second cavities with an optically transparent antireflective coating;

filling the first cavity with a color filtering material of a first color; and

filling the second cavity with a color filtering material of a second color that is different than the first color.

17. The method of claim 16 , wherein each cavity penetrates from 5 to 30% of a thickness of the semiconductor layer, and occupies at least 90% of a surface area delimited by the trench structure.

18. The method of claim 17 , wherein the trench structure penetrates into at least three quarters of the thickness of the semiconductor layer.

19. The method of claim 16 , further comprising forming a first microlens over the first cavity and a second microlens over the second cavity.

20. The method of claim 16 , wherein etching the trench structure comprises etching a trench structure to define an array for pixels of the color image sensor.

21. The method of claim 16 , wherein the semiconductor layer overlies an interconnect structure.

22. The method of claim 16 , wherein the electrically-conductive material comprises a metal that is opaque to light.