SILICIDE FORMATION BY HIGH DOSE TRANSITION METAL IMPLANTS INTO Si.

We report preliminary results of a study on silicide formation by means of high dose transition metal implants into Si (100) single crystals. 100 keV Cr** plus , Fe** plus , Co** plus and Ni** plus were implanted at room temperature. For the Cr** plus , Fe** plus and Ni** plus implants, no silicide formation was observed after implantation. However, both Rutherford Backscattering Spectrometry (RBS) and X-Ray Diffraction (XRD) results clearly indicated the existence of CrSi//2 after the Cr-Si samples were annealed 4 hours at 550 degree C. In the case of the Fe** plus and Ni** plus implants, FeSi//2 and NiSi//2 were identified by XRD after annealing the implanted samples half an hour at 400 degree C. A layer of CoSi of about 1000 Angstrom was observed in the as-implanted Co-Si samples by both RBS and XRD. Ni** plus ions accelerated to 150 keV were implanted at 350 degree C. A much broader distribution and higher retention of Ni was obtained in this case, showing evidence of long range atomic diffusion. NiSi and polycrystalline silicon were observed by XRD in the as-implanted samples. The possibility of high dose ion implantation as a suitable technique for producing transition metal silicides is discussed.