an fet with a source - substrate connection and a trench gate includes a drain zone of a first conductivity type provided on a first surface of a semiconductor layer of the first conductivity type that is disposed on a semiconductor substrate of the first conductivity type . the trench gate substantially penetrates the semiconductor layer . a source zone of the first conductivity type is provided at an end of the trench on a second surface of the semiconductor layer . a semiconductor zone of the second conductivity type is provided in a region next to the trench on the second surface of the semiconductor layer . the semiconductor zone has a surface which forms the second surface of the semiconductor layer together with the surface of the source zone . a method for producing the fet is also provided .