By directing an ion beam with a beam divergence θ on a process surface of a semiconductor substrate, parallel electrode trenches are formed in the semiconductor substrate. A center axis of the directed ion beam is tilted to a normal to the process surface at a tilt angle α, wherein at least one of the tilt angle α and the beam divergence θ is not equal to zero. The semiconductor substrate is moved along a direction parallel to the process surface during formation of the electrode trenches. A conductive electrode is formed in the electrode trenches, wherein first sidewalls of the electrode trenches are tilted to the normal by a first slope angle φ1 with φ1 =(α+θ/2) and second sidewalls are tilted to the normal by a second slope angle φ2 with φ2 =(α−θ/2).