A method of fabricating a semiconductor device includes forming a gate pattern on a substrate, forming an amorphous silicon (a-Si) region adjacent to the gate pattern by implanting a dopant containing a Group IV or VIII element into portions of the semiconductor substrate, forming gate spacers on sidewalls of the gate pattern, forming a first cavity by etching the a-Si region and the substrate using a first etching process, forming a second cavity by etching the substrate, such that the second cavity expands a profile of the first cavity in lateral and vertical directions, and forming a strained semiconductor region in the second cavity.