Patent ID: 7358108

Claim:
A method for fabricating a CMOS image sensor comprising: forming a trench in a field region of a first conductive type semiconductor substrate having a first conductive type low concentration epitaxial layer; forming a first conductive type heavily doped impurity ion regions in the first conductive type low concentration epitaxial layer, at sidewalls of the trench by implanting first conductive type heavily doped impurity ions into both sides of the trench at a predetermined tilt angle θ against the substrate, the tilt angle θ being chosen such that the first conductive type heavily doped impurity ions are not implanted into a bottom of the trench, wherein the tilt angle θ depends on tan θ=W/(H 1 +H 2 ), with W representing a width of the trench at a top surface of the trench, H 1 representing a height of a sacrificial layer formed on the substrate, and H 2 representing a depth of the trench; forming a first insulating film in the trench such that the first insulating film covers the first conductive type impurity ion regions; forming a device isolation film by depositing a second insulating film in the trench; sequentially forming a gate insulating film and a gate electrode on the semiconductor substrate; and forming a second conductive type impurity ion region for a photodiode at a predetermined portion of an active region in the first conductive type low concentration epitaxial layer.