Nucleation and growth of cobalt disilicide precipitates during in situ transmission electron microscopy implantation

Abstract

The paper is aimed at getting deeper insight into the fundamental mechanisms that govern CoSi(2) precipitate nucleation and growth during Co ion implantation at high temperatures (500-650 degrees C). Information about nucleation and growth of metal silicides as a function of temperature and implantation flux is provided by experiments on cobalt implantation in silicon, performed directly by in situ transmission electron microscopy. The main attention is paid to the nucleation of B-type precipitates, which dominate under ion implantation conditions. The obtained quantitative behavior of precipitate number density and size and the scaling of these values with implantation flux are discussed and rationalized in terms of analytical and simulation approaches. An atomistic model of B-type precipitate nucleation based on the first-principles calculations of relative energetic efficiency of different Co clusters is proposed. (C) 2008 American Institute of Physics

In situ TEM study of cubic zirconia implanted with caesium ions

“…In both case the damage created by ion implantation is visible from the edge of the TEM foil over the depth. No denuded zone appear near the edge (i.e., in very thin parts, when the free surfaces are close), contrary to experiments in which the free surface plays a significant role (see, e.g., the defects induced in Si by self ion irradiation [17]). Since no surface effects exist in TEM thin foils, and since RBS/C experiments have shown no diffusion of the Cs in the sample [18], in situ TEM results can be compared to RBS/C results performed on bulk samples.…”

Sensitivity of CoSi2 precipitation in silicon to extra-low dopant concentrations. II. First-principles calculations

“…6 The computational setup was the same as used earlier in Ref. 2 in order to guarantee the overall compatibility of the data. Namely, 3 Â 3 Â 3 (216 atoms) silicon supercells with the fixed lattice parameter of 5.46 Å were used.…”

“…For comparison purpose, Table I and the subsequent tables in this section include also relevant energies for matching Co n V clusters. 2 The strongest binding of cobalt atom is in clusters CoV 2 (B) and CoV 2 (A S ). This is due to the formation of chemical bonds between the cobalt atom and nearby Si atoms, which are clearly seen in the plots of the electron density distribution in the simulation supercell, see Figs.…”

“…2,8 Interstitial cobalt atoms only weakly interact with the surrounding Si atoms, which are covalently bound between them. An encounter of a cobalt atom with a vacancy (V) results in the formation of a strongly bound pair Co-V.…”

“…First of all, we study the mechanism of interstitial cobalt accumulation on divacancies and the transformation of thus formed agglomerates of cobalt interstitials into Co-Si phase nuclei. This allows us to extend the earlier suggested model, 2,5 where only vacancies were considered as nucleation centers for Btype CoSi 2 clusters. Second, we consider in detail various aspects of phosphorus atom interaction with self point defects (interstitials, vacancies, and divacancies) in silicon, which are directly relevant to the model suggested in Paper I, but not sufficiently clarified in the literature.…”