Patent ID: 7767528

Claim:
A method for fabricating a double diffused metal oxide semiconductor field effect transistor, the method comprising the following implemented without any restriction by the order specified: forming a trench in a drift region of a substrate, the trench having a sidewall and a base, at least the sidewall adjoining the drift region; filling the trench with an insulating material; patterning the insulating material to produce a first cutout for a control region, and a second cutout for a drain region, the first and second cutouts isolated by the insulating material, the drain region being connected to the drift region; providing an electrically conductive material in the first and second cutouts; forming a source region outside the trench before or after forming the trench, and an inversion channel region before or after forming the trench, the inversion channel adjoining the drift region and the source region, wherein the inversion channel and the drift region are separate components; wherein the first trench is deeper below the control region than below the drain region; insulating material is disposed between a bottom of the first trench below the control region and the control region; deepening the trench in at least one partial region and maintaining the trench depth in at least one other partial region, wherein trench regions with mutually different trench depths arise; and a deepest boundary between the control region and the insulating material is disposed in an upper half of the first trench containing the control region.