Optimizing boron junctions through point defect and stress engineering using carbon and germanium co-implants

We report the fabrication of p + ∕ n junctions using Ge + , C + , and B + co-implantation and a spike anneal. The best junction exhibits a depth of 26 nm , vertical abruptness of 3 nm ∕ decade , and sheet resistance of 520 Ohm ∕ square . The junction location is defined by where the boron concentration drops to 10 18 cm − 3 . These junctions are close to the International Technology Roadmap specifications for the 65 nm technology node and are achieved by careful engineering of amorphization, stresses, and point defects. Advanced simulation of boron diffusion is used to understand and optimize the process window. The simulations show that the optimum process completely suppresses the transient-enhanced diffusion of boron and the formation of boron-interstitial clusters. This increases the boron solubility to 20% above the equilibrium solid-state solubility.