Patent ID: 7323373

Claim:
A method of forming a semiconductor device, the method comprising: patterning a semiconductor layer of silicon to form a vertical active region and a horizontal active region, wherein the horizontal active region is adjacent the vertical active region and the semiconductor layer overlies an insulating layer; forming a spacer adjacent the vertical active region and over a portion of the horizontal active region; forming a mask layer over the vertical active region; implanting oxygen into the horizontal active region, the horizontal active region chemically remaining silicon removing the spacer and the mask layer with a chemical etchant that removes the spacer and mask layer without removing the horizontal active region or the vertical active region; forming a gate dielectric over the vertical active region after removing the spacer; forming a gate electrode over the gate dielectric and a portion of the horizontal active region; and annealing the oxygen after removing the spacer to make the horizontal active region chemically change from silicon to an insulating oxide material to electrically insulate the gate electrode, wherein the insulating oxide material electrically insulates the gate electrode from the insulating layer, which is a buried oxide layer, and the vertical active region is in direct contact with the buried oxide layer.