THERMAL-STABILITY OF COBALT SILICIDE THIN-FILMS ON SI(100)

The thermal stability of blank and BF2--implanted cobalt silicide (CoSi2) films annealed in a furnace with flowing nitrogen was investigated. It was found that BF2+ implantation can significantly stabilize thin silicide films during high-temperature annealing. This result can be attributed to an increase in surface and interface energy. For a CoSi2 film with a thickness of 350 angstrom, the silicide releases its high surface energy through low-energy silicon surface exposure at elevated annealing temperatures (greater-than-or-equal-to 800-degrees-C). The optimal BF2+ implantation energy for a cobalt silicide layer 350 angstrom thick is 50 keV. At this energy, a dose of 2 X 10(15) cm-2 is sufficient to improve the high-temperature stability Of CoSi2 film. The highest annealing temperature without degrading the CoSi2 film can be increased by 100-degrees-C using the optimal implantation conditions.