Trench field electrode termination structure for transistor devices

A semiconductor device includes: a trench formed in a surface of a semiconductor substrate and extending lengthwise in a direction parallel to the surface; a body region adjoining the trench; a source region adjoining the trench above the body region; a drift region adjoining the trench below the body region; a field electrode in a lower part of the trench and separated from the substrate; and a gate electrode in an upper part of the trench and separated from the substrate and the field electrode. A first section of the field electrode is buried below the gate electrode in the trench. A second section of the field electrode transitions upward from the first section in a direction toward the surface. The separation between the second section and the gate electrode is greater than or equal to the separation between the first section and the gate electrode.