A semiconductor device formed in a semiconductor substrate having a first main surface comprises a transistor array and a termination region. The transistor array comprises a source region, a drain region, a body region, a drift zone, and a gate electrode at the body region. The gate electrode is configured to control a conductivity of a channel formed in the body region. The gate electrode is disposed in first trenches. The body 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 body region has a shape of a first ridge extending along the first direction. The termination region comprises a termination trench, a portion of the termination trench extending in the first direction, a length of the termination trench being larger than a length of the first trenches, the length being measured along the first direction.