Void formation during silicidation and its influence on the thermal stability of cobalt silicide

초록

Void formation during silicidation and its influence on the thermal stability of CoSi2 on the poly-Si were investigated. Visible voids were found at the interface Of CoSi2/poly-Si on the BF2 doped poly-Si but not on the boron doped one. Void formation during silicidation could be suppressed effectively by two methods: preventing oxidation of poly-Si during dopant activation annealing or removing surface SiOx(F-y) compounds sufficiently in dilute HF before cobalt deposition. It was' found that the thermal stability of CoSi2 on the BF2 doped poly-Si with the interface voids was much better than that on the boron doped one or BF2 doped one, without the interface voids. It is verified that interface void formation during silicidation improves the thermal stability Of CoSi2 by suppressing the grain grooving from the interface due to the increase of interface energy. (C) 2002 American Vacuum Society.

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