Low-Temperature Radiation Enhanced Diffusion of Implanted Platinum in Silicon with Increased Controllability

Abstract

The in-diffusion of platinum into a low-doped n-type float zone silicon guided and enhanced by radiation damage produced by co-implantation of helium ions was investigated. The implantation of 1 MeV platinum ions at different doses ranging from 5×1011 to 3×1014 cm-2 was used to produce a finite source for platinum diffusion. Single and multiple energy implantation of helium ions with energies 7, 9, 11 and 13 MeV and doses from 5×1011 to 1×1013 cm-2 were applied to enhance and shape the diffusion of platinum atoms performed by 20 minutes annealing at 725°C in vacuum. Results show that diffusion of platinum at these conditions is fast enough to reach an equilibrium decoration of vacancy-related defects up to the depth of hundred micrometers. Analysis of the resulting platinum profiles indicates, that transformation of diffusing platinum interstitials to stable substitutional position is mainly given by Frank-Turnbull mechanism controlled by vacancy-related defects while the kick-out mechanism may play role at the peak of the radiation damage and at higher doses of helium implantation (>1012 cm-2). It is also shown that an extra annealing performed prior to helium implantation substantially increases the amount and localization of in-diffused platinum.