Solid-state image pickup device

Abstract

A solid-state image pickup device 1 is back surface incident type and includes a semiconductor substrate 10 , a semiconductor layer 20 and a light receiving unit 30 . The solid-state image pickup device 1 photoelectrically converts light incident on the back surface S 2 of the semiconductor substrate 10 into signal electrical charges to image an object. The semiconductor substrate 10 has a resistivity ρ 1 . A semiconductor layer 20 is provided on the surface S 1 of the semiconductor substrate 10 . The semiconductor layer 20 has a resistivity ρ 2 . Where, ρ 2>ρ1 . A light receiving unit 30 is formed in the semiconductor layer 20 . The light receiving unit 30 receives signal charges produced by the photoelectric conversion.

What is claimed is: 
     
         1 . A solid-state image pickup device photoelectrically converting light incident on a back surface of a semiconductor substrate into signal electric charges to image an object, the solid-state image pickup device comprising:
 a first semiconductor layer forming a part of the semiconductor substrate and having a first resistivity;   a second semiconductor layer provided on a front surface of the semiconductor substrate and having a second resistivity higher than the first resistivity;   a light receiving unit provided in the second semiconductor layer and receiving the signal electric charges produced by the photoelectric conversion; and   wherein the first resistivity is 0.1 ohm cm or less, wherein the second resistivity is from 5 ohm cm or more to 100 ohm cm or less,   wherein the first semiconductor layer is an impurity diffusion layer formed on the surface layer on side of the back surface of the semiconductor substrate and having an impurity concentration higher than that of the other part of the semiconductor substrate.   
     
     
         2 . A solid-state image pickup device photoelectrically converting light incident on a back surface of a semiconductor substrate into signal electric charges to image an object, the solid-state image pickup device comprising:
 a first semiconductor layer forming a part of the semiconductor substrate and having a first resistivity;   a second semiconductor layer provided on a front surface of the semiconductor substrate and having a second resistivity higher than the first resistivity;   a light receiving unit provided in the second semiconductor layer and receiving the signal electric charges produced by the photoelectric conversion; and   wherein the first resistivity is 0.1 ohm cm or less,   wherein the second resistivity is from 5 ohm cm or more to 100 ohm cm or less,   wherein the semiconductor substrate includes a silicon substrate and an epitaxial layer being provided on the silicon substrate and corresponding to the first semiconductor layer,   wherein the silicon substrate is p type or p− type,   wherein the epitaxial layer is p+ type.   
     
     
         3 . The solid-state image pickup device according to  claim 1 , wherein a distance between a face of the first semiconductor layer on side of the semiconductor layer and the back surface of the semiconductor substrate is not greater than an absorption length of the light. 
     
     
         4 . The solid-state image pickup device according to  claim 1 , wherein a predetermined fixed electric potential is applied to the semiconductor substrate. 
     
     
         5 . The solid-state image pickup device according to  claim 4 , wherein the predetermined fixed electric potential is ground potential. 
     
     
         6 . The solid-state image pickup device according to  claim 1 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         7 . The solid-state image pickup device according to  claim 2 , wherein a distance between a face of the first semiconductor layer on side of the semiconductor layer and the back surface of the semiconductor substrate is not greater than an absorption length of the light. 
     
     
         8 . The solid-state image pickup device according to  claim 2 , wherein a predetermined fixed electric potential is applied to the semiconductor substrate. 
     
     
         9 . The solid-state image pickup device according to  claim 3 , wherein a predetermined fixed electric potential is applied to the semiconductor substrate. 
     
     
         10 . The solid-state image pickup device according to  claim 2 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         11 . The solid-state image pickup device according to  claim 3 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         12 . The solid-state image pickup device according to  claim 4 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         13 . The solid-state image pickup device according to  claim 5 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         14 . The solid-state image pickup device according to  claim 7 , wherein a predetermined fixed electric potential is applied to the semiconductor substrate. 
     
     
         15 . The solid-state image pickup device according to  claim 8 , wherein the predetermined fixed electric potential is ground potential. 
     
     
         16 . The solid-state image pickup device according to  claim 9 , wherein the predetermined fixed electric potential is ground potential. 
     
     
         17 . The solid-state image pickup device according to  claim 14 , wherein the predetermined fixed electric potential is ground potential. 
     
     
         18 . The solid-state image pickup device according to  claim 7 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         19 . The solid-state image pickup device according to  claim 8 , wherein the second semiconductor layer is an epitaxial layer. 
     
     
         20 . The solid-state image pickup device according to  claim 10 , wherein the second semiconductor layer is an epitaxial layer.