A model of interdiffusion occurring during the formation of thin metal films on single-crystal silicon under conditions of limited solubility of the components

Abstract

Thin metal films are used in semiconductor and microelectronic devices to form ohmic and non-ohmic contacts to singlecrystal silicon. A common feature of the used Ме–Si systems is the low mutual solubility of elements and the polycrystalline nature of metal films. Solid-phase interactions during the deposition of metals on single-crystal silicon and the subsequent vacuum annealing results in the redistribution of the elements near the Me/Si interface. An important task facing the material science of solid-state electronics is to develop a mechanism of solid-phase interaction of metal thin films and single-crystal silicon. The aim of our study – was to develop a quantitative model of interdiffusion in the Ме–Si system under conditions of limited solubility of the components. The article suggests a mechanism of formation of Me–Si systems based on the diffusion and segregation of silicon near the intergrain boundaries of the metal and the limited formation of complexes during the diffusion-induced penetration of metal into silicon. The article suggests a model of reactive interdiffusion in thin metal film – single-crystal silicon systems under conditions of limited solubility of the components. Mathematical modelling was used to study the interaction of magnetron-sputtered metals Ti, W, and Nb with single-crystal silicon during isothermal vacuum annealing. The numerical analysis of experimental distributions of concentrations of Me and Si obtained by Rutherford backscattering spectroscopy allowed us to determine their individual diffusion coefficients in Me-Si systems. The model can be used for empirical studies of the redistribution of the elements of two-layer systems with limited solubility, as well as to forecast the technological conditions for the production of electronic devices.