Patent ID: 7535038

Claim:
A solid-state image pickup device comprising: a photosensor portion having first and second opposite sides, the photosensor portion being provided on the surface of a substrate to convert light incident on said first side into electric charges; a transfer portion formed on the surface of said substrate to transfer said electric charges read out from said photosensor portion; and an overflow barrier formed within said substrate and opposite the second side of said photosensor portion to discharge unnecessary electric charges of said electric charges, wherein potential under said transfer portion is formed smaller than that formed under said photosensor portion along the depth direction of said substrate in a range from the minimum potential position to said overflow barrier, wherein said transfer portion has one or a plurality of impurity regions formed at its second side, wherein one or a plurality of second impurity regions formed under said photosensor portion are formed with depths different from that of said impurity region, and wherein said impurity region is arranged in four layers along the depth direction of said substrate and said second impurity region is arranged in seven layers along the depth direction of said substrate.