Solid state image sensing device and manufacturing and driving methods thereof

1. A manufacturing method of a solid state image sensing device in which a plurality of unit pixels containing a transistor for outputting a light signal having a ring shaped gate electrode and a photo diode is regularly arranged on a first conductive type substrate, the manufacturing method comprising steps of:

forming a first conductive type source neighborhood area in a prescribed area allocated in a second conductive type well area provided over a surface of the first conductive type substrate;

forming the ring shaped gate electrode on the second conductive type well area with sandwiching a gate insulative film, wherein a center opening of the ring shaped gate electrode is arranged to be allocated above the first conductive type source neighborhood area;

forming a first conductive type high concentration area in the first conductive type source neighborhood area by injecting first conductive type impurity in high concentration into the first conductive type source neighborhood area through the ring shaped gate electrode as a mask;

forming a second conductive type surface layer in high concentration by injecting second conductive type impurity into the first conductive type high concentration area through the ring shaped gate electrode as a mask;

forming a side wall spacer on an inner wall of the center opening of the ring shaped gate electrode; and

forming a second conductive type source area of the transistor for outputting a light signal on the second conductive type surface layer by injecting second conductive type impurity in high concentration into the second conductive type surface layer through the side wall spacer.