Semiconductor optical sensor having an inter-region light-shielding plug

1. A semiconductor optical sensor, comprising:

a substrate including a circuit element forming region and a photodiode forming region provided separately from said circuit element forming region, said substrate having a silicon substrate, an insulating layer formed on said silicon substrate, and a silicon layer formed on said insulating layer;

a photodiode formed in said silicon layer of said photodiode forming region;

a circuit element formed in said silicon layer of said circuit element forming region;

a first interlayer insulating film formed over said silicon layer of said substrate;

a first light-shielding film formed on said first interlayer insulating film of said circuit element forming region and comprising an opening exposing said photodiode forming region; and

a first inter-region light-shielding plug interposed between said circuit element forming region and said photodiode forming region, and extending through said insulating layer, said silicon layer, and said first interlayer insulating film so as to contact said first light-shielding film and said substrate at respectively opposite ends of said first inter-region light-shielding plug.

2. The semiconductor optical sensor according to claim 1 , wherein said first inter-region light-shielding plug surrounds a periphery of said photodiode forming region.

3. The semiconductor optical sensor according to claim 2 , further comprising a second inter-region light-shielding plug which surrounds a periphery of said first inter-region light-shielding plug, and which extends between and contacts said silicon substrate and said first light-shielding film.

4. The semiconductor optical sensor according to claim 3 , wherein said first inter-region light-shielding plug has a second opening between said circuit element forming region and said photodiode forming region;

said second inter-region light-shielding plug has a third opening between said circuit element forming region and said photodiode forming region; and

said semiconductor optical sensor further comprises a wiring portion for electrically connecting said circuit element formed in said circuit element forming region and said photodiode formed in said photodiode forming region, via said second opening and said third opening.

5. The semiconductor optical sensor according to claim 4 , wherein said second opening and said third opening are spaced apart from each other by a predetermined distance in a direction perpendicular to a direction in which said circuit element forming region and said photodiode forming region are located.

6. The semiconductor optical sensor according to claim 5 , wherein said predetermined distance is 10 μm or more.

7. The semiconductor optical sensor according to claim 4 , wherein said wiring portion is formed on a second interlayer insulating film located between said substrate and said first interlayer insulating film.

8. The semiconductor optical sensor according to claim 1 , wherein said first light-shielding film has a fourth opening;

and said semiconductor optical sensor further comprises a second light-shielding film formed on a third interlayer insulating film being an underlayer of said first interlayer insulating film;

and a fourth light-shielding plug which surrounds a periphery of said fourth opening, and which extends between and contacts said first light-shielding film and said second light-shielding film.

9. The semiconductor optical sensor according to claim 8 , wherein said fourth opening is rectangular and has a long side of 40 μm or more and a short side of 4 μm or more.

10. The semiconductor optical sensor according to claim 1 , wherein said insulating layer comprises silicon oxide.

11. The semiconductor optical sensor according to claim 1 , wherein said first light-shielding film is connected to ground.

12. The semiconductor optical sensor according to claim 1 , wherein the thickness of said silicon layer is 50 nm or less.