A semiconductor body has a first portion, a second portion, and an active area located between the first portion and the second portion. The first portion and the second portion are a shallow trench isolation region having an exposed surface extending above the surface of the active area. A first ion implantation is performed at a first angle such that a first shaded area defined by the exposed surface of the first portion and the first angle is exposed to fewer ions than a first unshaded area. A second ion implantation is performed at a second angle such that a second shaded area defined by the exposed surface of the second portion and the second angle is exposed to fewer ions than a second unshaded area.