A study on thermal stability of CoSi2 employing novel fine-grained polycrystalline silicon/CoSi2/Si (001) system

The cobalt silicide/fine-grained polycrystalline silicon (poly-Si) structur e has been employed as gate electrodes in silicon-based very large-scale in tegration circuits. We have constructed a novel fine-grained poly-Si/cobalt silicide/silicon (001) structure to investigate the thermal stability of c obalt silicide at elevated temperatures. The dissociated cobalt atoms are o bserved to diffuse from fine-grained poly-Si/cobalt silicide and cobalt sil icide/silicon (001) interfaces into the fine-grained poly-Si layer through poly-Si grain boundaries and the bulk cobalt silicide layer. The dissociate d Si atoms at the cobalt silicide/silicon (001) interface are observed to g row epitaxilly on the silicon (001) substrate. This observation is consiste nt with previous results for circuits that employed amorphous Si instead of fine-grained poly-Si.