SIMULTANEOUS OCCURRENCE OF MULTIPHASES IN THE INTERFACIAL REACTIONS OF ULTRAHIGH-VACUUM DEPOSITED HF AND CR THIN-FILMS ON (111)SI

Simultaneous occurrence of multiphases were observed in the interfacial reactions of ultrahigh vacuum deposited Hf and Cr thin films on (111) Si by high-resolution transmission electron microscopy in conjunction with fast Fourier transform diffraction analysis and image simulation. For Hf/Si system, an amorphous interlayer, Hf5Si3 as well as FeB and CrB types of HfSi were found to form simultaneously in samples annealed at 530-degrees-C for 40-80 min. For Cr/Si system, an amorphous interlayer, Cr5Si3, CrSi, and CrSi2 were observed to form in samples annealed at 375-degrees-C for 30 min. The formation of multiphases appeared to be quite general in the initial stages of interfacial reactions of ultrahigh vacuum deposited refractory thin films. The results called for a reexamination of generally accepted ''difference'' in reaction sequence between bulk and thin-film couples.