SEMICONDUCTOR STRUCTURE

A semiconductor structure includes a semiconductor substrate, first to third isolation structures, and a conductive feature. The first to third isolation structures are over the semiconductor substrate and spaced apart from each other. The semiconductor substrate comprises a region surrounded by a sidewall of the first isolation structure and a first sidewall of the second isolation structure. The conductive feature extends vertically in the semiconductor substrate and between the between the second and third isolation structures, wherein the conductive feature has a rounded corner adjoining a second sidewall of the second isolation structure opposite the first sidewall of the second isolation structure.