In situ study of effects of ion irradiation on solid-state crystallization of cobalt disilicide thin films

Results of a continuing in situ study of the ion-irradiation-modified crystallization of amorphous CoSi2 thin films are discussed. 1.5 MeV Kr ion irradiation is employed at 90 K to ''mix'' nominally amorphous, as-deposited material for subsequent epitaxial regrowth at 450 K. The ion irradiation is also employed at 300 K to produce ion-assisted crystallization. The average degree of transformation per ion is approximately 4x10-20 cm3. The resultant number density of crystals, however, depends sensitively on prior treatment of the film. For example, 300 kV electron irradiation at 300 K prior to ion irradiation may result in a large number density of crystal nuclei. Low-dose Kr irradiation at 300 K may also cause a slight increase in the number density of crystals formed subsequently at 450 K, while larger Kr doses at 300 K (>3x1014cm-2) may double to subsequent thermal growth rate at 450 K. These results are discussed qualitatively in terms of nucleation and growth theory. (orig.)