A semiconductor device is provided as follows. A first fin is formed on a first region of a substrate, extending in a first direction. A second fin is formed on a second region of the substrate, extending in a second direction. A first dual liner is formed on a lateral surface of the first fin. The first dual liner includes a first liner and a second liner. The first liner is interposed between the second liner and the lateral surface of the first fin. A second dual liner is formed on a lateral surface of the second fin. The second dual liner includes a third liner and a fourth liner. The third liner is interposed between the fourth liner and the lateral surface of the second fin. An epitaxial layer surrounds a top portion of the second fin. The first liner and the third liner have different thicknesses.