Solid-state imaging device, fabrication method for the same, and electronic apparatus

Abstract

A solid-state imaging device includes a photodetector which is formed on a substrate and is configured to generate signal charge by photoelectric conversion, a floating diffusion configured to receive the signal charge generated by the photodetector, a plurality of MOS transistors including a transfer transistor that transfers the signal charge to the floating diffusion and an amplification transistor that outputs an pixel signal corresponding to a potential of the floating diffusion, a multi-wiring layer which is formed in a layer higher than the substrate and is composed of a plurality of wiring layers electrically connected to the MOS transistors via contact portions, and a light-shielding film that is constituted by a bottom wiring layer disposed in a layer higher than the substrate and lower than the multi-wiring layer.

1 . A solid-state imaging device comprising:
 a photodetector formed on a substrate, the photodetector being configured to generate signal charge by converting incident light into electricity;   a floating diffusion configured to receive the signal charge generated by the photodetector;   a plurality of MOS (metal oxide semiconductor) transistors including a transfer transistor that transfers the signal charge to the floating diffusion and an amplification transistor that outputs an pixel signal corresponding to a potential of the floating diffusion;   a multi-wiring layer formed in a layer higher than the substrate, the multi-wiring layer being composed of a plurality of wiring layers electrically connected to the MOS transistors via contact portions; and   a light-shielding film constituted by a bottom wiring layer disposed in a layer higher than the substrate and lower than the multi-wiring layer, the light-shielding film being formed at a region that shields at least the floating diffusion from the light, the light-shielding film being electrically connected to the floating diffusion via a contact portion.   
   
   
       2 . The solid-state imaging device of  claim 1 ,
 wherein the light-shielding film is electrically connected to a gate electrode of the amplification transistor via a contact portion.   
   
   
       3 . The solid-state imaging device of  claim 2 ,
 wherein the light-shielding film is formed so as to surround the photodetector except in a region directly above an aperture of the photodetector.   
   
   
       4 . The solid-state imaging device of  claim 1 ,
 wherein the MOS transistors are electrically connected to the wiring layers in the multi-wiring layer by contact portions via an intermediate film constituted by the bottom wiring layer.   
   
   
       5 . A method for fabricating a solid-state imaging device, the method comprising the steps of:
 forming a photodetector and a floating diffusion on a substrate;   forming a first insulating layer on the substrate;   forming an aperture in the first insulating layer so that the floating diffusion is exposed;   forming a contact portion by filling the aperture with a metallic material;   forming a light-shielding film constituted by a bottom wiring layer at a region on the first insulating layer including the contact portion, the region shielding the floating diffusion from light;   forming a second insulating layer on the first insulating layer including the light-shielding film; and   forming a multi-wiring layer having a plurality of wiring layers on the second insulating layer.   
   
   
       6 . The method of  claim 5 , further comprising the step of forming the light-shielding film so as to surround the photodetector except in a region directly above the aperture of the photodetector. 
   
   
       7 . A method for fabricating a solid-state imaging device, the method comprising the steps of:
 forming a photodetector, a floating diffusion, and an impurity region on a substrate, the impurity region constituting a predetermined source or drain of a MOS transistor;   forming apertures for exposing the floating diffusion and the impurity region by removing respective portions of the first insulating layer above the floating diffusion and the impurity region;   forming contact portions by filling the apertures formed in the first insulating layer with a metallic material;   forming a light-shielding layer constituted by a bottom wiring layer at a region on the first insulating layer including the contact portion formed on the floating diffusion, the region shielding the floating diffusion from the light, and forming an intermediate film constituted by the bottom wiring layer on the first insulating layer including the contact portion formed on the impurity region;   forming a second insulating layer on the first insulating layer including the light-shielding film and the intermediate film;   forming an aperture in the second insulating layer so that the intermediate film is exposed;   forming a contact portion by filling the aperture formed in the second insulating layer with a metallic material; and   forming a multi-wiring layer having a plurality of wiring layers including a wire connected to the contact portion formed in the second insulating layer.   
   
   
       8 . The method of  claim 7 , further comprising the step of forming the light-shielding film so as to surround the photodetector except in a region directly above the aperture of the photodiode. 
   
   
       9 . An electronic apparatus comprising:
 an optical lens;   a solid-state imaging device configured to receive light collected by the optical lens, the solid-state imaging device including a photodetector formed on a substrate, the photodetector being configured to generate signal charge by converting incident light into electricity, a floating diffusion configured to receive the signal charge generated by the photodetector, a plurality of MOS (metal oxide semiconductor) transistors including a transfer transistor that transfers the signal charge to the floating diffusion and an amplification transistor that outputs an pixel signal corresponding to a potential of the floating diffusion, a multi-wiring layer formed in a layer higher than the substrate, the multi-wiring layer being composed of a plurality of wiring layers electrically connected to the MOS transistors via contact portions, and a light-shielding film constituted by a bottom wiring layer disposed in a layer higher than the substrate and lower than the multi-wiring layer, the light-shielding film being formed at a region that shields at least the floating diffusion from the light, the light-shielding film being electrically connected to the floating diffusion via a contact portion; and   a signal processing circuit configured to process a signal output from the solid-state imaging device.