Diffusion barrier performance of thin Cr films in the Cu/Cr/Si structure

We have studied the thermal stability of thin (from 10 to 40nm) sputter deposited Cr layers as a diffusion barrier in Cu/Cr/Si structure. Sheet resistance measurements, DLTS, X-Ray Diffraction analysis (XRD), Rutherford Backscattering Spectroscopy (RBS), Auger Electron Spectroscopy (AES) and adhesion tests were carried out in order to reveal the behaviour of Cu and Cr in the Cu/Cr/Si structures. It is shown that even the 10 nm thin Cr layer preserves the multilayer structure up to 400 degrees C, and Cu silicide formation is observed only after annealing. at 450 degrees C for 30 min. DLTS measurements revealed the Cu migration into the structure at lower temperatures (in this case at 350 degrees C) than the other characterization techniques.