Provided are methods for fabricating semiconductor devices incorporating a fin-FET structure that provides body-bias control, exhibits some characteristic advantages associated with SOI structures, provides increased operating current and/or reduced contact resistance. The methods for fabricating semiconductor devices include forming insulating spacers on the sidewalls of a protruding portion of a first insulation film; forming a second trench by removing exposed regions of the semiconductor substrate using the insulating spacers as an etch mask, and thus forming fins in contact with and supported by the first insulation film. After forming the fins, a third insulation film is formed to fill the second trench and support the fins. A portion of the first insulation film is then removed to open a space between the fins in which additional structures including gate dielectrics, gate electrodes and additional contact, insulating and storage node structures may be formed.