Abstract
Interfacial reactions and thermal stability of ultrahigh vacuum deposited multilayered Mo/Si structures have been investigated by high resolution transmission electron microscopy in conjunction with fast Fourier transform and autocorrelation function analysis. For samples with nominal atomic ratios Mo:Si= 1:2 and 3:1, well defined multilayered Mo/Si structures were obtained after annealing at 250°C for 30 min. On the other hand, distinct multilayered MoSi 2 /Si structure was formed only for Mo:Si=1:2 samples after annealing at 650°C for 1 h. Multiphases were observed to simultaneously form in samples annealed at 400-500°C. After 600°C annealing for 1 h, tetragonal MoSi 2 was the only suicide phase observed for the Mo:Si=1:2 samples, whereas both tetragonal and hexagonal MoSi 2 were present in Mo:Si-3:1 samples. The stability of the multilayered Mo/Si structures was found to depend critically on the atomic ratios of constituent elements, bilayer period, and annealing conditions. The results are interpreted in terms of the delicate balance among intermixing of constituent atoms, suicide formation, and crystallization of silicon. © 1996 American Institute of Physics.