The field effect transistor device comprises a substrate (1) of semiconductor material, a body well of a first type of electric conductivity in the substrate, a source region in the body well, the source region having an opposite second type of electric conductivity, a source contact (3) on the source region, a body contact region of the first type of electric conductivity in the body well, a body contact (5) on the body contact region, and a gate electrode layer (2) partially overlapping the body well. A portion (2*) of the gate electrode layer (2) is present between the source contact (3) and the body contact (5).

Performances of a semiconductor device are improved. The semiconductor device has: a gate electrode formed on an SOI layer of an SOI substrate via a gate insulating film having a charge storage film therein; an n-type semiconductor region and a p-type semiconductor region respectively formed on SOI layers on both sides of the gate electrode. A memory cell MC serving as a non-volatile memory cell is formed of the gate insulating film, the gate electrode, the n-type semiconductor region and the p-type semiconductor region.

According to one aspect of the present disclosure, a semiconductor device includes a substrate having a first type dopant. In some embodiments, the semiconductor device also includes an epitaxial layer above the substrate, having a second type dopant and a top region. In some embodiments, the semiconductor device also includes a trench in the top region of the epitaxial layer; at least one doped ring implanted in the epitaxial layer below the trench; and a dielectric material filling within the trench. In some embodiments, there is a twelve-sided body tie in the epitaxial layer, wherein the sides of the twelve-sided body tie are not all equal to each other.