Solid state image pickup device and method of producing solid state image pickup device
Forming a back-illuminated type CMOS image sensor, includes process for formation of a registration mark on the wiring side of a silicon substrate during formation of an active region or a gate electrode. A silicide film using an active region may also be used for the registration mark. Thereafter, the registration mark is read from the back-side by use of red light or near infrared rays, and registration of the stepper is accomplished. It is also possible to form a registration mark in a silicon oxide film on the back-side (illuminated side) in registry with the registration mark on the wiring side, and to achieve the desired registration by use of the registration mark thus formed.
1. A solid state image pickup device comprising:
a photo-electric conversion device configured to convert a spectrum of incident light into a signal charge, said photo-electric conversion region being in a pixel region of a semiconductor substrate;
a light-shielding film configured to inhibit transmission of said incident light onto said semiconductor substrate, an opening through the light-shielding film being between a micro-lens and said photo-electric conversion device;
wirings in an insulating layer, said semiconductor substrate being between said light-shielding film and said insulating layer;
a metallic alignment mark within said semiconductor substrate at a first surface of the semiconductor substrate, said first surface being between said insulating layer and a light receiving surface of the semiconductor substrate.
2. The solid state image pickup device according to claim 1 , wherein said metallic alignment mark is a silicide.
3. The solid state image pickup device according to claim 1 , wherein said insulating layer touches and said metallic alignment mark.
4. The solid state image pickup device according to claim 1 , wherein said wirings are metallic.
5. The solid state image pickup device according to claim 1 , wherein said insulating layer is silicon oxide.
6. The solid state image pickup device according to claim 1 , wherein said semiconductor substrate has a thickness, said thickness correlating to said spectrum.
7. The solid state image pickup device according to claim 1 , wherein said incident light through said micro-lens is transmissible onto said photo-electric conversion device through said opening.
8. The solid state image pickup device according to claim 1 , further comprising:
a pixel configured to detect a black level, said pixel being in said pixel region.
9. The solid state image pickup device according to claim 8 , wherein said light-shielding film is configured to inhibit said incident light from reaching said pixel.
10. The solid state image pickup device according to claim 1 , further comprising:
a registration mark between said metallic alignment mark and a portion of the light-shielding film.
11. The solid state image pickup device according to claim 10 , further comprising:
an insulator film between said semiconductor substrate and said light-shielding film, said registration mark being within said insulator film.
12. The solid state image pickup device according to claim 11 , wherein said insulator film is silicon oxide.
13. The solid state image pickup device according to claim 11 , wherein said light-shielding film is within a passivation layer.
14. The solid state image pickup device according to claim 13 , wherein said passivation layer is silicon nitride.
15. The solid state image pickup device according to claim 1 , wherein a photo-electric conversion region of the photo-electric conversion device is between a backside layer of the photo-electric conversion device and said first surface, said backside layer having a conductivity type opposite to said photo-electric conversion region.
16. The solid state image pickup device according to claim 15 , wherein said backside layer touches said photo-electric conversion region and said light receiving surface.
17. The solid state image pickup device according to claim 15 , further comprising:
a charge accumulation region of the photo-electric conversion device between said photo-electric conversion region and a photodiode region of the photo-electric conversion device, said photodiode region touching said first surface and said charge accumulation region.
18. The solid state image pickup device according to claim 17 , wherein said charge accumulation region has a conductivity type opposite to said photodiode region, said photodiode region and said backside layer being of a same conductivity type.
19. The solid state image pickup device according to claim 17 , further comprising:
a channel region between said photodiode region and a floating diffusion portion, said first surface touching said floating diffusion portion and said channel region.
20. The solid state image pickup device according to claim 19 , wherein said floating diffusion portion has a conductivity type opposite to said photodiode region.