Initial stages of cobalt-disilicide formation in mesotaxy

We present results on the formation of buried silicide layers at ion implan tation doses in the range of 1-60% of the critical dose for formation of a uniform layer We emphasize observations for the low-dose range of 1-5% wher e the precipitate density is quite dilute. The Co redistribution during pos t-implant annealing is measured using Rutherford backscattering techniques and secondary ion mass spectrometry. Experimental observations during posti mplantation annealing at 1000 degrees C involves (i) a contraction of the C o depth profile for all doses, (ii) shifting of the peak of the profile tow ards the hulk, and (iii) formation of a secondary Co peak near the surface. The secondary peak is only present in samples implanted to greater than 3% of the critical dose. The interpretation of the shift of the main peak and the occurrence of the secondary peak requires a model exceeding the standa rd ripening model used previously to describe mesotaxy. We suggest that mor e recent ripening-based concepts allow for a full description of these obse rvations with a minimum of parameters, particularly not requiring interacti on with the complex defect profiles formed initially during implantation. E ssential for this model is a proper inclusion of precipitate-precipitate in teractions and the role of diffusion screening.