DIFFUSION BARRIER PERFORMANCE OF THIN CR FILMS IN THE CU CR/SI STRUCTURE/

The Cu/Cr/Si structure was studied for thermal stability using thin Cr layers as a barrier in the range of 10 to 40 nm, between 250 and 500 degrees C for 30 min. Investigations using sheet resistance method, de ep level transient spectroscopy (DLTS), X-ray diffraction (XRD) analys is, Rutherford backscattering spectroscopy (RBS), and adhesion tests w ere carried out, to reveal the behavior of Cu and Cr in the Cu/Cr/Si s tructures. It is shown that even a IO-nm thin Cr layer preserves the m ultilayer structure up to 400 degrees C and that Cu silicide formation is observed only after annealing at 450 degrees C. However, as found by DLTS, compared with the conventional characterization techniques, C u migration into the structure reduces the effectiveness of the Cr lay ers as a diffusion barrier at 50 degrees C. (C) 1998 Elsevier Science Ltd.