A complementary metal oxide semiconductor (CMOS) device has a substrate 100, a gate structure 108 disposed atop the substrate, and spacers 250, deposited on opposite sides of the gate structure 108 to govern formation of deep source drain regions S, D in the substrate. Spacers 250 are formed of an oxynitride (SiOxNyCz) wherein x and y are non-zero but z may be zero or greater; such oxynitride spacers reduce parasitic capacitance, thus improving device performance. A method of fabricating a portion of a complementary metal oxide semiconductor (CMOS) device involves providing a substrate 100, forming a gate structure 108 over the substrate, depositing a first layer 104 atop the substrate on opposite sides of the gate structure to govern formation of deep source drain regions in the substrate, depositing an oxynitride (SiOxNyCz) layer 250 atop the first layer (in which x and y are non-zero but z may be zero or greater), depositing a second layer 112 atop the oxynitride layer, and depositing a nitride layer 114B atop the second layer.