Strained Si has been realized as one of the most promising candidates of next generation complementary metal-oxide-semiconductor technology. Since the carrier mobility can be significantly increased with strained Si lattice, the device speed can be further increased without reducing the critical dimensions. However, ultrashallow junction engineering becomes more challenging due to much complicated dopant diffusion behavior. We have used scanning capacitance microscopy and dopant selective etching to characterize such differences by comparing the devices fabricated with strained Si channel and with conventional unstrained Si. The devices we used are p-type channel complementary metal-oxide-semiconductor field effect transistors fabricated with 130 nm technology, with strained Si channel built on SiGe pseudosubstrate. Significant differences were observed in the formation of source/drain (S/D) extensions. The junction profile shows abrupt transition from S/D extension to S/D comparing with unstrained Si. Meanwhile, halo implant was much suppressed. These differences can be explained with retarded B diffusion and enhanced As diffusion in tensile strained Si and relaxed SiGe lattices, which is consistent with the calculation using lattice expansion theory. (C) 2004 American Vacuum Society.