| 摘要 |
PROBLEM TO BE SOLVED: To lower the voltage VT for reading electric charges without further developing white blemish and degrading such characteristics as a blooming margin. SOLUTION: Prior to implantation of n-type impurity ions for forming an electric charge accumulation region of a photo diode (photoelectric conversion section), a gate insulation film is made thin and is formed with steps along both sides of a photo detection region of the photo diode. On both sides of the photo detection region, thick film portions are formed which are formed thicker than the other parts to attenuate ion implantation energy. By implanting n-type impurity ions under this condition, both side portions of an N layer which will become the electric charge accumulation region can be formed at a shallow position of a semiconductor substrate than the other portions due to the existence of the thick film portions of the gate insulation film. Consequently, the doping concentration of a P layer in the front surface of the substrate can be lowered near an electric charge reading section without damaging the whole structure, resulting in facilitating the read-out of electric charges. COPYRIGHT: (C)2004,JPO
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