A method of fabricating a semiconductor device according to an example embodiment may include forming an isolation layer defining an active region in a semiconductor substrate, forming a silicon pattern and a sacrificial pattern on the active region, the sacrificial pattern including a semiconductor material different from the silicon pattern, forming a gate spacer on a sidewall of the silicon pattern and a sidewall of the sacrificial pattern, removing the sacrificial pattern to expose a top surface of the silicon pattern, and/or forming a gate silicide on the silicon pattern.