US Patent 10164006 LDMOS FinFET structures with trench isolation in the drain extension

Field-effect transistor structures for a laterally-diffused metal-oxide-semiconductor (LDMOS) device and methods of forming a LDMOS device. First and second fins are formed that extend vertically from a top surface of a substrate. A first isolation region is arranged between the first fin and the second fin. A body region of a first conductivity type is arranged partially in the substrate and partially in the second fin. A drain region of a second conductivity type is arranged partially in the substrate, partially in the first fin, and partially in the second fin. A source region is arranged within the body region in the first fin. A gate structure is arranged to overlap with a portion of the first fin. A second isolation region is arranged within the first fin, and is spaced along the first fin from the first isolation region.