A calculation of diffusion parameters for Cu/Ta and Ta/Si interfaces in Cu/Ta/Si(1 1 1) structure

Abstract

In this investigation, we have studied the elemental diffusion coefficients of the Cu/Ta and Ta/Si interfaces in the Cu/Ta/Si(1 1 1) structure. The diffusion parameters for Cu diffusion into the Ta barrier layer, Ta diffusion into the Si substrate and diffusion of Si atoms into the Ta layer have been calculated using conversion of RBS data to concentration-depth profile curves and the solution of Fick's equation based on a constant diffusing amount boundary conditions. Furthermore, by calculating grain boundary diffusion coefficients, we have estimated grain boundary slabs of the Ta layer at different temperatures. It was shown that, the width of grain boundary slabs in the Ta layer at 700°C allows a fast diffusion of Cu and Si atoms through the Ta barrier layer resulted in the copper silicide and TaSi 2 formation and consequently the barrier failure was observed at the temperature of 700°C in an N 2 environment for 30 min .