Patent ID: 7361527

Claim:
A method for fabricating an image sensor, comprising: forming a gate structure on a semiconductor layer of a first conductive type; performing a first ion implantation process to form a first impurity region of a second conductive type aligned with one side of the gate structure and extending to a predetermined depth from a surface portion of the semiconductor layer; performing a first blanket ion implantation process to form a second impurity region of the first conductive type aligned with the one side of the gate structure and extending to a predetermined depth from the surface portion of the semiconductor layer; forming spacers on sidewalls of the gate structure; performing a second blanket ion implantation process to form a third impurity region of the first conductive type aligned with one of the spacers and extending to a predetermined depth from the surface portion of the semiconductor layer; forming an ion implantation mask exposing the surface portion of the semiconductor layer apart from the one side of the gate structure with a predetermined distance which is larger than a thickness of the one of the spacers; and performing a second ion implantation process using the ion implantation mask, thereby obtaining a fourth impurity region of the first conductive type extending to a predetermined depth from the surface portion of the semiconductor layer.