A semiconductor device, including a device isolation layer arranged on a predetermined region of a semiconductor substrate to define an active region, the active region including a central top surface of a (100) crystal plane and an inclined edge surface extending from the central top surface to the device isolation layer, a semiconductor pattern covering the central top surface and the inclined edge surface of the active region, the semiconductor pattern including a flat top surface of a (100) crystal plane that is parallel with the central top surface of the active region and a sidewall that is substantially perpendicular to the flat top surface, and a gate pattern overlapping the semiconductor pattern.