Image pickup device and method for manufacturing image pickup device

Abstract

An image pickup device having a pixel region in which pixels are arranged, and in which a multilayer wiring structure is disposed. Each pixel includes a photoelectric conversion unit, a charge accumulation unit, a floating diffusion, a light shielding portion covering the charge accumulation unit and opening above the photoelectric conversion unit, and a waveguide which overlaps at least partially a portion at which the light shielding portion opens in a plan view. The device includes an insulating film disposed below the optical waveguide. The insulating film has a refractive index higher than that of an interlayer insulating film. The insulating film is disposed closer to the photoelectric conversion unit than to the lowermost wiring layer among wiring layers of the multilayer wiring structure. The insulating film extends to a portion above the light shielding portion. The insulating film is wider than a lower portion of the optical waveguide.

What is claimed is: 
     
         1 . An image pickup device which has a pixel region in which a plurality of pixels are arranged, and a multilayer wiring structure is disposed in a pixel region, each of the pixels including
 a photoelectric conversion unit,   a charge accumulation unit configured to accumulate signal charge transferred from the photoelectric conversion unit,   a floating diffusion to which the signal charge of the charge accumulation unit is transferred,   a light shielding portion configured to cover at least a part of the charge accumulation unit and opening above the photoelectric conversion unit, and   an optical waveguide disposed above the photoelectric conversion unit,   the device comprising an insulating film disposed below the optical waveguide,   wherein the insulating film has a refractive index higher than that of a portion of an interlayer insulating film of the multilayer wiring structure disposed above the charge holding portion, and the insulating film extends from below the optical waveguide to a portion above the light shielding portion at a portion closer to the photoelectric conversion unit than to the lowermost wiring layer among wiring layers of the multilayer wiring structure.   
     
     
         2 . The image pickup device according to  claim 1 , wherein the insulating film covers the entire charge accumulation unit. 
     
     
         3 . The image pickup device according to  claim 1 , wherein an incident surface area of an upper portion of the optical waveguide is larger than an emission surface area. 
     
     
         4 . The image pickup device according to  claim 1 , wherein an antireflection film is disposed above the photoelectric conversion unit, the antireflection film has an opening, and the insulating film is disposed above the opening of the antireflection film. 
     
     
         5 . A method for manufacturing an image pickup device which has a pixel region in which a plurality of pixels are arranged, each of the pixels including
 a photoelectric conversion unit,   a charge accumulation unit configured to accumulate signal charge transferred from the photoelectric conversion unit,   a floating diffusion to which the signal charge of the charge accumulation unit is transferred,   a light shielding portion configured to cover at least a part of the charge accumulation unit and opening above the photoelectric conversion unit, and   a waveguide disposed above the photoelectric conversion unit,   the method comprising:   preparing a semiconductor substrate on which the charge accumulation unit and the photoelectric conversion unit are arranged;   forming the light shielding portion;   forming an interlayer insulating film so as to cover the light shielding portion and the photoelectric conversion unit;   forming an opening which at least partially overlaps the photoelectric conversion unit in the interlayer insulating film by etching; and   forming the optical waveguide in the opening,   wherein an etching stop film used in the etching is formed to extend continuously from at least a part of a portion above the photoelectric conversion unit to at least a part of a portion above the light shielding portion in a plan view.   
     
     
         6 . The method for manufacturing an image pickup device according to  claim 5 , further comprising forming a multilayer wiring structure on the pixel region,
 wherein the etching stop film is removed in a region in which a contact plug which connects between the semiconductor substrate and a wire included in the wiring layer of the multilayer wiring structure exists.   
     
     
         7 . The method for manufacturing an image pickup device according to  claim 5 , further comprising forming an insulating film between the light shielding portion and the etching stop film. 
     
     
         8 . The method for manufacturing an image pickup device according to  claim 7 , further comprising removing at least a part of the insulating film, wherein the etching stop film is left in a region from which the insulating film is removed.