Phosphorus implant for S/D extension formation: Diffusion and activation study after spacer and spike anneal

Abstract

Formation of highly activated S/D extension is one of the key issues to meet the requirements for further downscaling of CMOS devices. Germanium-preamorphization implant (Ge-PAI) followed by solid phase epitaxial regrowth (SPER) is capable of forming abrupt and shallow junctions with activation levels well above solid solubility. In this paper, we demonstrate a possible alternative by using phosphorus (P) with the Ge-PAI and boron (B) Halo implant to form the S/D extension of NMOS. The anomalous diffusion and activation of P after the conventional spacer and spike anneals were studied. We observed that a highly activated and shallow junction can be formed via Ge-PAI after spacer anneal which is equivalent to a low temperature SPER. The level of P activation is enhanced even more when B Halo is considered. It is postulated that this is due to the competing interactions of B and P with the emitted interstitials of the end-of-range (EOR) defects. However, improvement in junction depth and electrical properties due to B halo implant decreases when annealing temperature increases. © 2006 American Institute of Physics.