Patent ID: 7439583

Claim:
A power metal-oxide-semiconductor field effect transistor (MOSFET) cell comprising: a semiconductor substrate having first and second main surfaces opposite to each other; a first electrode disposed on the first main surface of the semiconductor substrate; a voltage sustaining layer formed on the second main surface of the semiconductor substrate, the voltage sustaining layer including a first region of a first conductivity type and a second region of a second conductivity type, the second conductivity type being opposite to the first conductivity type; a highly doped active zone of the first conductivity type formed in the voltage sustaining layer opposite the semiconductor substrate, the highly doped active zone having a channel region included in the voltage sustaining layer; a source terminal region of the second conductivity type disposed in the voltage sustaining layer proximate the highly doped active zone, at least one of the highly doped active zone and the terminal region having a generally central aperture; and an extension region disposed in the voltage sustaining region at least partially within the generally central aperture.