A STUDY OF THERMALLY ACTIVATED INTERFACIAL REACTIONS IN AN NI CR/SI MULTILAYER STRUCTURE/

Differential scanning calorimetry (DSC) with Auger electron spectrosco py (AES) and transmission electron microscopy (TEM) were used to study interfacial reactions, diffusion zones and barriers in a multilayer s tructure composed of Ni, Cr and Si thin films deposited on smooth (111 ) single-crystal Si. AES depth profiles of the samples before and afte r DSC measurements at two different scanning rates between room temper ature and 550-degrees-C revealed a strong reaction between the Si and Ni layers, resulting in silicide formation, and a much less pronounced reaction between Cr and Si. The type of Ni silicide depended on the t hickness of the Si layer and on the amount of Ni which was available f or the reaction, and the kinetics was controlled by interfacial reacti ons. The reaction between Ni and Cr was diffusion controlled, and the Ni/Cr multilayer exhibited a decreasing diffusion flux with increasing layer thickness. The combination of DSC, AES and TEM analysis of the multilayer structures and the relevant thermodynamic and kinetic data enabled the identification of reaction products in the Ni/Cr/Si multil ayer formed by thermal treatment during DSC measurements.