Rare Earth Metal Silicides Synthesized by High Current Metal Ion Implantation

摘要

The YSi_2, LaSi_2, CeSi_2, PrSi_2, NdSi_2, SmSi_2, GdSi_2, TbSi_2, DySi_2, and ErSi_2 layers were formed on Si wafers by respective high current metal-ion implantation using a metal vacuum vapor arc (MEVVA) ion source and the formation temperature was considerable lower than the critical temperatures (300-350°C) required for the rare earth metal silicides by solid-state reaction. It was found that the crystalline structures could be improved with increasing slightly the formation temperature as well as the implantation dose. Concerning the growth kinetics, in some cases, fractal patterns were observed on Si surfaces and the branches of the fractals consisted of the grains of respective precipitated silicides. Interestingly, the fractal dimension increased with formation temperature and eventually approached to-a value of 2.0, corresponding to a continuous layer, which was required in practical application. The formation mechanism as well as the growth kinetics was discussed in terms of the far-from-equilibrium process involved in the MEVVA ion implantation.