A photo sensor with pinned photodiode structure integrated with a trench isolation structure. The photo sensor includes a substrate of a first conductivity type, at least one trench in the substrate, at least one doped region of the first conductivity type, and at least one doped region of a second conductivity type. Each doped region of the first conductivity type is beneath a corresponding trench. Each doped region of the second conductivity type is sandwiched between the corresponding doped region and the substrate of the first conductivity type. No edge of any doped region of the first or second conductivity type extends to the trench corners. A method of fabricating the photo sensor is also provided.