Influence of source/drain formation process on resistance and effective mobility for scaled multi-channel MOSFET

The influence of doping process in selective epitaxial growth of source/drain, for vertically aligned three-dimensional multi-channel field-effect transistors (MCFETs), is examined. We show that the electrical performance of short devices strongly depends on the optimization of source drain regions. In situ doped epitaxial process results in a significant reduction in the series resistance. A further improvement, for both n- and p-MCFETs, is obtained by combination in situ doping with ion implantation. The effective mobility, however, is degraded by additional Coulomb scattering due to dopant diffusion into the channel. The detailed mobility analysis reveals the possibility for future process optimization based on the tight control of the activation annealing step during the source/drain formation.