Scaling options for S/D extension junctions of MOS transistors by annealing temperature variation or by application of co-implantation were investigated. Blank wafer and test structure experiments showed that the main contribution to reduce junction depth and to fulfil the requirements of downscaled devices was temperature reduction. The implementation of co-implantation of F, C or N or of pre-amorphization provided another degree of junction depth variation. For p+n-junctions suppression of B diffusion was found from secondary ion mass spectrometric measurements when the parameters of the co-implantation were optimized to the dopant implantation. Also the use of different species for pre-amorphization influenced the electrical junction characteristics, shown by spreading resistance probe. For As implanted n+p-junctions a variation in electrical junction depth was observed that was related to the species implanted prior to the As dopant implantation.

Influence of Coimplantation on the Activation and Diffusion of Ultra-Shallow Extension Implantation. M.Herden, D.Gehre, T.Feudel, A.Wei, M.Bersani, G.Mannino, J.v.d. Berg: Nuclear Instruments and Methods in Physics Research Section B, 2005, 237[1-2], 203-7