A power semiconductor transistor includes: a semiconductor body coupled to a load terminal; a drift region in the semiconductor body and having dopants of a first conductivity type; a first trench extending into the semiconductor body along a vertical direction and including a control electrode electrically insulated from the semiconductor body by an insulator; a second trench extending into the semiconductor body along the vertical direction; a mesa region arranged between the trenches and including a source region electrically connected to the load terminal and a channel region separating the source and drift regions; and a portion of a contiguous plateau region of a second conductivity type arranged in the semiconductor drift region and extending below the trenches and below the channel and source regions, the contiguous plateau region having a plurality of openings aligned below the channel region in a widthwise direction of the channel region.