A semiconductor device comprises a transistor formed in a semiconductor body having a first main surface. The transistor comprises a source region, a drain region, a channel region, a drift zone, a source contact electrically connected to the source region, a drain contact electrically connected to the drain region, and a gate electrode at the channel region. The channel region and the drift zone are disposed along a first direction between the source region and the drain region, the first direction being parallel to the first main surface. The channel region has a shape of a first ridge extending along the first direction. One of the source contact and the drain contact is adjacent to the first main surface, the other one of the source contact and the drain contact is adjacent to a second main surface that is opposite to the first main surface.