3-DIMENSIONAL SIMULATION OF IMPURITY DIFFUSION IN THIN-FILM DIFFUSION-BARRIERS

Three-dimensional (3D) simulation of combined lattice and grain-bounda ry diffusion of impurities in thin-film diffusion barriers for semicon ductor device metallizations is performed. Calculated results of impur ity concentration profiles demonstrate quantitatively an obvious under estimation of the frequently used two-dimensional (2D) analysis with r espect to the influence of film geometry and grain-boundary diffusion coefficient. As for the average concentration at the backside of diffu sion barriers, approximately a factor of two difference between the 2D and 3D simulation results is found over an interesting range of times and grain size structures. Graphs for predicting the effectiveness of diffusion barriers are presented with several normalized parameters a ssociated with position and time. Particular application examples of a luminum diffusion in titanium nitride films justify the use of this ma terial as an effective diffusion barrier in silicon microelectronic de vices.