Investigation on boron transient enhanced diffusion induced by the advanced P+/N ultra-shallow junction fabrication processes

In this paper, we propose to characterize boron transient enhanced diffusion (TED) for processes currently used for P+/N ultra-shallow junctions (USJ) fabrication. Indeed, the fundamental understanding of boron diffusion for low energy boron implantation is mandatory to evaluate the scalability of such processes for the coming complementary metal-oxide-semiconductor (CMOS) transistor generations. In these experiments, we characterize the boron anomalous diffusion, thanks to boron buried marker-layers obtained by epitaxial growth. B+ and BF2+ ultra-low energy (ULE) implantations and plasma doping (PLAD) using BF3 as precursor gas are carried out to compare the two techniques used for advanced USJ fabrication. Boron diffusion behaviors are analyzed via secondary ion mass spectrometry for annealing at 700 °C for 5 min and 15 min. Finally this paper brings some physical insights explaining the technological benefit coming from PLAD technique over standard ion implantation that have been demonstrated in recent publications [F. Lallement et al., Proceedings of VLSI, Honolulu, Hawaii, USA, in press [1]].