Solid-state imaging device, method of manufacturing the same, and electronic apparatus

Abstract

Solid-state imaging devices, methods of producing a solid-state imaging device, and electronic apparatuses are provided. More particularly, a solid-state image device ( 1 ) includes a silicon substrate ( 22 ), and at least a first photodiode ( 33 ) formed in the silicon substrate. The device also includes an epitaxial layer ( 21 ) with a first surface adjacent a surface of the silicon substrate, and a transfer transistor ( 31 ) with a gate electrode ( 41 ) that extends from the at least a first photodiode to a second surface of the epitaxial layer opposite the first surface. In further embodiments, a solid-state imaging device with a plurality of pixels formed in a second semiconductor substrate wherein the pixels are symmetrical with respect to a center point is provided. A floating diffusion is formed in an epitaxial layer, and a plurality of transfer gate electrodes that are each electrically connected to the floating diffusion by one of the transfer gate electrodes is provided.

What is claimed is: 
     
         1 . A solid-state imaging device, comprising:
 a silicon substrate;   at least a first photodiode, wherein the first photodiode is formed in the silicon substrate;   an epitaxial layer, wherein a first surface of the epitaxial layer is adjacent a surface of the silicon substrate;   a transfer transistor, wherein a gate electrode of the transfer transistor extends from the at least a first photodiode to a second surface of the epitaxial layer opposite the first surface.   
     
     
         2 . The solid-state imaging device of  claim 1 , further comprising:
 a floating diffusion, wherein the floating diffusion is formed in the epitaxial layer and is in electrical contact with the gate electrode of the transfer transistor.   
     
     
         3 . The solid-state imaging device of  claim 1 , further comprising:
 a plurality of pixel transistors, wherein the plurality of pixel transistors are formed on the epitaxial layer.   
     
     
         4 . The solid-state imaging device of  claim 3 , wherein the plurality of pixel transistors overlay at least a portion of the silicon substrate in which the at least a first photodiode is formed. 
     
     
         5 . The solid-state imaging device of  claim 1 , further comprising:
 a second photo diode, wherein the second photodiode is formed in the epitaxial layer.   
     
     
         6 . The solid-state imaging device of  claim 5 , wherein the second photodiode is in electrical contact with the gate electrode of the transfer transistor. 
     
     
         7 . The solid-state imaging device of  claim 1 , further comprising:
 a plurality of photodiodes formed in the epitaxial layer.   
     
     
         8 . The solid-state imaging device of  claim 7 , wherein the first photodiode and the photodiodes formed in the epitaxial layer are in electrical contact with the gate electrode of the transfer transistor. 
     
     
         9 . The solid-state imaging device of  claim 8 , further comprising:
 a plurality of pinning layers, wherein the plurality of photodiodes formed in the epitaxial layer are laminated in a depth direction with the plurality of pinning layers.   
     
     
         10 . The solid-state imaging device of  claim 9 , wherein an area of at least one of the plurality of epitaxial layers formed in the epitaxial layer has an area in a plane parallel to the first surface of the epitaxial layer that is different than at least one of the other of the plurality of photodiodes formed in the epitaxial layer. 
     
     
         11 . The solid state imaging device of  claim 10 , wherein the photodiodes formed in the epitaxial layer overlay at least a portion of the photodiode formed in the silicon substrate. 
     
     
         12 . The solid state imaging device of  claim 11 , further comprising:
 a floating diffusion, wherein at least a portion of the floating diffusion overlays at least a portion of the first photodiode.   
     
     
         13 . The solid state imaging device of  claim 12 , further comprising:
 a plurality of pixel transistors, wherein the plurality of pixel transistors are formed on the epitaxial layer and overlay at least a portion of the first photodiode.   
     
     
         14 . A solid-state imaging device, comprising:
 a plurality of pixels, wherein each pixel in the plurality of pixels is formed in a semiconductor substrate, and wherein the pixels are symmetrical with respect to a center point;   an epitaxial layer on the semiconductor substrate;   a floating diffusion, wherein the floating diffusion is formed in the epitaxial layer;   a plurality of transfer gate electrodes, wherein each of the pixels is electrically connected to the floating diffusion by one of the transfer gate electrodes.   
     
     
         15 . The solid-state imaging device of  claim 14 , wherein the plurality of pixels are arranged symmetrically about the floating diffusion. 
     
     
         16 . The solid-state imaging device of  claim 15 , further comprising:
 a plurality of pixel transistors, wherein the pixel transistors are formed in the epitaxial layer.   
     
     
         17 . The solid-state imaging device of  claim 15 , wherein the plurality of transfer gate electrodes are arranged symmetrically about the floating diffusion. 
     
     
         18 . A method of producing a solid-state imaging device, comprising:
 forming a photodiode in a silicon substrate;   forming an epitaxial layer on the silicon substrate;   forming an excavated portion by excavating from a surface of the epitaxial layer to the silicon substrate, wherein the excavated portion reaches a P-well surrounding N-type regions of the photodiode;   forming a gate electrode by forming a gate oxide film on an inside surface of the excavated portion.   
     
     
         19 . An electronic apparatus, comprising:
 an optical system;   an image capture element including a solid-state imaging device, wherein the solid-state imaging device receives light from the optical system, the solid-state imaging device including   an on chip lens;   an antireflection film;   a silicon substrate, wherein the antireflection film is connected to a first surface of the silicon substrate, and wherein the on chip lens is separated from the first surface of the silicon substrate by at least the antireflection film;   at least a first photodiode, wherein the first photodiode is formed in the silicon substrate;   an epitaxial layer, wherein a first surface of the epitaxial layer is adjacent a surface of the silicon substrate;   a transfer transistor, wherein a gate electrode of the transfer transistor extends from the at least a first photodiode to a second surface of the epitaxial layer opposite the first surface;   a signal processing circuit, wherein the signal processing circuit receives a signal from the image capture element.   
     
     
         20 . An electronic apparatus, comprising:
 an optical system;   an image capture element including a solid-state imaging device, wherein the solid-state imaging device receives light from the optical system, the solid-state imaging device including:   a plurality of pixels, wherein each of the plurality of pixels is formed in a semiconductor substrate, wherein the pixels are symmetrical with respect to a center point;   an epitaxial layer on the semiconductor substrate;   a floating diffusion, wherein the floating diffusion is formed in the epitaxial layer;   a plurality of transfer gate electrodes, wherein each of the pixels is electrically connected to the floating diffusion by one of the transfer gate electrodes;   a signal processing circuit, wherein the signal processing circuit receives a signal from the image capture element.