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+, Fe+, Co+ and Ni+ were implanted at room temperature. For the Cr+, Fe+ and Ni+ 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 CrSi2 after the Cr-Si samples were annealed 4 hours at 550°C. In the case of the Fe+ and Ni+ implants, FeSi2 and NiSi2 were identified by XRD after annealing the implanted samples half an hour at 400°C. A layer of CoSi of about 1000 Å was observed in the as implanted Co-Si samples by both RBS and XRD.
Ni+ ions accelerated to 150 keV were implanted at 350°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.