Improved stability of thin cobalt disilicide films using BF2 implantation

The thermal stability of ∼50 nm CoSi2 and TiSi2 thin films after BF2+ implantation was investigated. The electrical characteristics of silicide films were evaluated after high temperature annealing as a function of implanted BF2+ energy. It was observed that implantation with a projected range near the silicide/silicon interface produced the most stable films. The silicide/silicon interface morphology was investigated using scanning tunneling microscopy, where with appropriate BF2 implantation conditions, smoother interfaces were seen after high temperature annealing. The stabilizing effect is attributed to fluorine segregation into the silicide grain boundaries and at the silicide/silicon interface.