A semiconductor substrate having a first main surface and a transistor cell includes a drift region, a body region between the drift region and the first main surface, an active trench at the first main surface extending into the drift region, a gate insulating layer at sidewalls and a bottom side of the active trench, a gate conductive layer in the active trench, a source region in the body region, and adjacent to the active trench, a body trench at the first main surface extending into the drift region, the body trench being adjacent to the body region and to the drift region, an insulating layer at sidewalls and at a bottom side of the body trench, the insulating layer being asymmetric with respect to an axis extending perpendicular to the first main surface at a center of the body trench, and a conductive layer in the body trench.