Microstructural difference between platinum and silver trapped in hydrogen induced cavities in silicon

The gettering of implanted Pt and Ag to hydrogen-induced cavities in Si has been compared for doses from 1×10¹³ to 1×10¹⁵cm^-2. After annealing at 850°C for 1 h, almost 100% of both implanted metals were relocated to the cavity band for doses less than 1×10¹⁴cm^-2. At higher doses, large differences were observed in the gettering behaviour of Pt and Ag, where the amount of Pt was saturated at close to a monolayer coverage of cavity walls, whereas the Ag accumulation at cavities continually increased with dose. Cross-sectional transmission electron microscopy revealed strong differences in the ability of Pt and Ag to form a bulk phase at the cavities. The results indicate that stable silicide formation at the near-surface and trapping of Ag to implantation damage are the main processes which limit gettering at the higher doses.