FINFET ICs and methods for their fabrication are provided. In accordance with one embodiment a FINFET IC is fabricated by forming in a substrate a region doped with an impurity of a first doping type. The substrate region is etched to form a recess defining a fin having a height and sidewalls and the recess adjacent the fin is filled with an insulator having a thickness less than the height. Spacers are formed on the sidewalls and a portion of the insulator is etched to expose a portion of the sidewalls. The exposed portion of the sidewalls is doped with an impurity of the first doping type, the exposed sidewalls are oxidized, and the sidewall spacers are removed. A gate insulator and gate electrode are formed overlying the fin, and end portions of the fin are doped with an impurity of a second doping type to form source and drain regions.