Silicide formation and structural evolution in Fe-, Co-, and Ni-implanted silicon

ZHENGQUAN TAN, F. NAMAVAR, J. I. BUDNICK, F. H. SANCHEZ, A. FASIHUDDIN, S. M. HEALD, C. E. BOULDIN AND J. C. WOICIK

PHYSICAL REVIEW B - SOLID STATE

APS

Año: 1992 vol. 46 p. 4077 - 4085

0556-2805

Silicide formation and structural evolution in Fe-, Co-, and Ni-implanted silicon have been studiedwith use of extended x-ray-absorption fine-structure, x-ray-diffraction, and Rutherford backscattering spectrometry. Si(100) wafers were implanted at elevated temperatures, typically 350'C, to doses ranging from 1 X 10' to 1 X 10' ions/cm . In the Co-implanted system, CoSi2 forms with doses as low as 1 X 10' Co/cm and up to 3X10" Co/cm, where the CoSi phase starts to form. At higher doses (8X10' Co/cm ), ordered CoSi and a CoSi-like short-range-ordered phase coexist. The silicide formation observed in the Ni-implanted system is similar to that in the cobalt-implanted system. In the case of iron implantation, Fe is coordinated with about eight Si atoms in the (1?3)X10" Fe/cm range as in the tetragonal FeSi2. However, the FeSi2 phase forms only at around 5 X 10' Fe/cm'. At even higher doses, a substantial amount of iron is in disordered states in addition to the ordered FeSi phase. Upon annealing at 900 C, semiconducting P-Fesiz forms in all the Fe-implanted samples independent of the dose. Mechanisms for silicide formation in these ion-implanted systems are discussed with respect to crystal structure, diffusion, and implantation damage.