Superjunction transistor device

A method and a transistor device are disclosed. The transistor device includes: a semiconductor body; first regions of a first doping type and second regions of a second doping type in an inner region and an edge region of the semiconductor body; transistor cells in the inner region of the semiconductor body, each transistor cell including a body region and a source region, the transistor cells including a common drain region; and a buffer region arranged between the drain region and the first and second regions. A dopant dose in the first and second regions decreases towards an edge surface of the semiconductor body. A dopant dose in the buffer region decreases towards the edge surface.