A semiconductor device includes first and second gate electrode structures and a connection plug. The first gate electrode structure is buried in a semiconductor portion and has array stripes inside a first cell array of transistor cells and a contact stripe outside the first cell array, the contact stripe structurally connected with the array stripes. The second gate electrode structure is buried in the semiconductor portion and has array stripes inside a second cell array of transistor cells. An array isolation region of the semiconductor portion separates the first and second gate electrode structures. The connection plug extends between a first surface of the semiconductor portion and the contact stripe of the first gate electrode structure.