Comparative analysis of extended defect depth profiles in silicon by rutherford backscattering, X-rays and electron microscopy

Abstract

Buried layers of perfect dislocation loops were generated in silicon by 6×10 15 Si + /cm 2 , 100 keV ion implantation and furnace annealing at 950°C for 30, 60 and 120 min. The samples were analyzed by Rutherford backscattering (RBS) channeling technique, planar and cross-section transmission electron microscopy (TEM) observation and computer simulation of double crystal X-ray diffraction (DCD) rocking curves. As for RBS, it was experimentally confirmed that the λ diameter of the perturbed cylinder coaxial with the dislocation loop increases linearly with the square root of the ion energy up to a certain energy value ( E s ), beyond which saturation occurs. The λ saturation value (λ s ) resulted proportional to the loop radius. From TEM observations it was possible to deduce the relationship linking λ s and E s to the average loop radius ( R̄ ). Once these relationship are known it is possible, at least in obtain the damage depth profile in the case of dislocation loops by performing measurements at different ion energies. The damage depth profiles obtained on the samples examined in the present work were compared with those obtained by TEM observation and X-ray diffraction, showing a very good agreement. In particular the energy to depth conversion functions, used for RBS analyses, have been computed by using three different stopping power data reported in the literature. A detailed discussion on the precision of the stopping power data is reported on the basis of the TEM cross-section observations.