Semiconductor devices may include first and second fins that protrude from a substrate, extend in a first direction, and are separated from each other in the first direction. Semiconductor devices may also include a field insulating layer that is disposed between the first and second fins to extend in a second direction intersecting the first direction, an etch-stop layer pattern that is formed on the field insulating layer and a dummy gate structure that is formed on the etch-stop layer pattern.