As extensions have been up till now always used in N-MOS transistors with an activation anneal. Here, we show that also alternative doping by P can result in junction extensions that are extremely abrupt and shallow thus suitable for upcoming transistor technologies. P extensions are manufactured by amorphization, carbon co-implantation and conventional rapid thermal annealing (RTA). The impact of Si interstitials (Sii) flux suppression on the formation of P junction extensions during RTA is demonstrated. We have concluded that optimization of implants followed by RTA spike offers excellent extensions with depth Xj = 20 nm (taken at 5 × 1018 at./cm3), abruptness 3 nm/dec. and Rs = 326 Ω. Successful implementation of these junctions is straightforward for N-MOS devices with 30 nm gate length and results in an improved short channel effects with respect to the As reference.