A method for forming a transistor device includes forming a field electrode arrangement by forming a trench in a first surface of a semiconductor body, forming a protection layer on sidewalls of the trench in an upper trench section, forming a dielectric layer on a bottom of the trench and on sidewall sections uncovered by the protection layer, and forming a field electrode at least on the dielectric layer. The method further includes forming a gate electrode and a gate electrode dielectric horizontally spaced apart from the field electrode arrangement with respect to the first surface, forming a body region adjacent the gate electrode and dielectrically insulated from the gate electrode by the gate dielectric, and forming a source region in the body region.