A dummy gate electrode layer and a dummy gate mask layer may be formed on a substrate. The dummy gate mask layer may be patterned to form a dummy gate mask so that a portion of the dummy gate electrode layer is exposed. Ions may be implanted into the exposed portion of the dummy gate electrode layer and a portion of the dummy gate electrode layer adjacent thereto by an angled ion implantation to form a growth blocking layer in the dummy gate electrode layer. The dummy gate electrode layer may be etched using the dummy gate mask as an etching mask to form a dummy gate electrode. A spacer may be formed on side surfaces of a dummy gate structure including the dummy gate electrode and the dummy gate mask. An SEG process may be performed to form an epitaxial layer.