A power semiconductor device includes a semiconductor-on-insulator island having a semiconductor region and an insulation structure, the insulation structure being formed by an oxide and separating the semiconductor region from a portion of a semiconductor body of the power semiconductor device. The insulation structure includes a sidewall that laterally confines the semiconductor region; a bottom that vertically confines the semiconductor region; and a local deepening that forms at least a part of a transition between the sidewall and the bottom, wherein the local deepening extends further along the extension direction as compared to the bottom.