A method of fabricating a semiconductor device includes forming gate structures on PMOS and NMOS transistor regions of the semiconductor substrate, forming epitaxial blocking layers on source/drain regions of PMOS and NMOS transistor regions using a nitridation process, then selectively removing one of the epitaxial blocking layers, and using a SEG process to form an epitaxial layer on respective source/drain regions while shielding the other source/drain regions with a remaining epitaxial blocking layer.