A method produces a semiconductor device including a semiconductor body, an electrode thereon, and an insulating structure insulating the electrode from the semiconductor body. The semiconductor body includes a first contact region of a first conductivity type, a body region of a second conductivity type, a drift region of the first conductivity type, and a second contact region having a higher maximum doping concentration than the drift region. The insulating structure includes a gate dielectric portion forming a first horizontal interface. with the drift region and has a first maximum vertical extension A field dielectric portion forms with the drift region second and third horizontal interfaces arranged below the main surface. A second maximum vertical extension of the field dielectric portion is larger than the first maximum vertical extension. A third maximum vertical extension of the field dielectric portion is larger than the second maximum vertical extension.