Semiconductor device

Abstract

A transistor device includes a semiconductor substrate having a first major surface and one or more transistor cells. Each transistor cell may include a columnar trench in the semiconductor substrate. The columnar trench includes a field dielectric, base, and a side wall. The side wall may extend from the base to the first major surface. The field dielectric may line the base and side wall of the columnar trench. A first thickness of the field dielectric at a first distance from the base is smaller than a second thickness of the field dielectric at a second distance from the base. The first distance is greater than the second distance. A columnar field plate with a cavity may be arranged in the columnar trench. A first perimeter of the columnar field plate at the first distance is greater than a second perimeter of the columnar field plate at the second distance.

Dependencies are inferred from the claim text.