Lateral trench transistor device

A method of manufacturing a semiconductor device includes: forming a trench in a first side of a semiconductor layer, the semiconductor layer including a drift zone of a first conductivity; forming a drain region of the first conductivity type in the first side of the semiconductor layer and laterally adjoining the drift zone; forming a body region of a second conductivity type opposite the first conductivity type and laterally adjoining the drift zone at a side of the drift zone opposite the drain region; and forming source regions of the first conductivity type and body contact regions of the second conductivity type in a sidewall of the trench and arranged in an alternating manner along a length of the trench, using a dopant diffusion process which includes diffusing dopants of both conductivity types from oppositely-doped dopant source layers which are in contact with different regions of the sidewall.