Disclosed is a method of fabricating a semiconductor device. The method includes forming a lower layer on a substrate, forming on the lower layer a sacrificial layer and an etching pattern, forming a first spacer layer on the sacrificial layer and the etching pattern, etching the sacrificial layer and the first spacer layer to form a sacrificial pattern and a first spacer on at least a portion of a top surface of the sacrificial pattern, forming a second spacer layer on the sacrificial pattern and the first spacer, etching the second spacer layer and the first spacer to form a second spacer on a sidewall of the sacrificial pattern, and partially etching the lower layer to form a pattern. The second spacer is used as an etching mask to partially etch the lower layer.