| 摘要 |
PURPOSE:To smooth a flow of a signal charge that is converted by a photo diode and prevent the development of the residual image phenomenon by preparing more than two sorts of an impurity concentration of the photo diode, thereby causing a potential distribution to be in a state of stepped form. CONSTITUTION:A P/N-type photo diode 40 and an electric charge transfer part 50 which are surrounded by element isolation regions 31 of SiO2 and others on a semiconductor substrate 30 are formed. The P/N-type photo diode 40 where an incident light H is converted into an electrical signal charge Q is composed of a gate insulating film 41 that is formed at the surface of the semiconductor substrate 30 and the first and second N<-> type impurity layers 42 and 43 that are formed below the gate insulating film 41. And the above impurity layers 42 and 43 are formed so that their impurity concentrations, for example, will be low enough to be 10<16>cm<-3> or less and further, the impurity concentration of the N<-> type impurity layer 43 that is in the vicinity of the electric charge transfer part 50 will be slightly higher than that of the N<-> type impurity layer 42. |
