Solubility of Carbon in Nanocrystalline -Iron

A thermodynamic model for nanocrystalline interstitial alloys is presented. The equilibrium solid solubility of carbon in -iron is calculated for given grain size. Inside the strained nanograins local variation of the carbon content is predicted. Due to the nonlinear relation between strain and solubility, the averaged solubility in the grain interior increases with decreasing grain size. The majority of the global solubility enhancement is due to grain boundary enrichment however. Therefore the size effect on carbon solubility in nanocrystalline -iron scales with the inverse grain size.

Optimisation of Junctions formed by Solid Phase Epitaxial Regrowth for sub-70nm CMOS

For the 70nm CMOS node, it is anticipated that conventional implantation and spike annealing approaches, even with pre-amorphisation and co-implantation, are unlikely to provide pMOS junctions consistent with the ITRS requirements. Here the junction performance is limited by equilibrium solid solubility.As laser annealing and in-situ doping techniques currently have unsolved integration problems, there is a renewed interest in using solid phase epitaxial regrowth (SPER) to form ultra-shallow metastable junctions. Such junctions have the potential to have an active dopant profile similar to the as-implanted profile. This offers above equilibrium solid solubility and abrupt profiles compatible with 70nm and even 45nm nodes. However there are concerns about residual defects, deactivation, diffusion and uniformity.In this paper we show how the Ge, F and B implant and SPER anneal can be optimised for abrupt, uniform and highly activated B junctions. There is latitude for higher doses and energies than conventional implants, however results show that this may lead to clustering causing enhanced deactivation and reduced mobility. We give attention to the probing issues involved in characterising partially annealed junctions.With this approach, p-type junctions having a sheet resistance of 265 ohms/sq and depth of 22nm are realised which are compatible with 70nm and potentially 45nm CMOS nodes.

A Perspective on Nitrogen in Silicon

This is the first symposium to explicitly include nitrogen in discussions on nondopant light impurities in Si. Ordering of the impurity listing (oxygen, carbon, hydrogen and nitrogen) deserves examination. It is obvious that the impurities are not listed alphabetically nor are they listed in the order they appear in the periodic table. Presumably the ordering does not simply reflect a bias of the organizing chairmen. The impurities are, in fact, listed in an order of recognition on a chronological scale of their importance in Si technology. Equilibrium solid solubility for the different impurities, as well as concentrations of the impurities in the processing environment, probably determined the chronology. Based upon published literature, the importance of oxygen was recognized in the mid 50's, carbon in the mid 60's and hydrogen in the mid 70's. Now in the mid 80's nitrogen is receiving increased attention as an impurity in Si.

Study of Metastable Fe-W Films

ABSTRACTXenon irradiation of Fe-W multilayers at room temperature (R.T.) can produce two types of metastable states: low doses (< 1 × 1016 Xe/cm2 ) extend the equilibrium solid solubility of W in Fe and vice versa, maintaining the equilibrium b.c.c. lattice structure of Fe and W; at high doses (> 1 × 1016 Xe/ cm2 ) and in the vicinity of the composition Fe70W30, amorphization can occur. In comparison, RF sputter-deposited FexWl-x films were amorphous over the whole range (0.35<x < 0.79) investigated. The recrystallization temperatures of these amorphous layers exceed 600°C for 15 min vacuum annealing. Whereas Fe-W compounds always form during thermal annealing, these compounds are normally not found after Xe-irradiation of multilayers.