HIGH-ENERGY HIGH-DOSE NI IRRADIATION OF SOI STRUCTURES

Si/Si3N4/Si(100) silicon on insulator (SOI) structures formed by keV i on beam synthesis have been irradiated with 6 MeV Ni ions at doses of 1 to 13 x 10(17) Ni/cm2. The microstructure as well as the composition of unirradiated, as-implanted and furnace annealed layer systems are studied using x-sectional TEM and AES. After Ni implantation, an unexp ected amorphization is observed, which starts at the Si/Si3N4 interfac es and leads to extended interfacial a-Si and a-Si3N4 layers, the amor phization mechanisms obviously being different. Oriented NiSi2 precipi tates are formed in the (100) Si substrates with morphologies and dept h distributions comparable to those observed earlier in (111) Si. Anne aling leads to recrystallization of the a-Si layers and to redistribut ion of the implanted Ni, the buried nitride layer acting as a diffusio n barrier. At the highest dose a layer system of Si/Si3N4/Si...Si/NiSi 2/Si is formed.