The influence of N content on the crystallization behavior of initially amorphous Ta-Si-N diffusion barriers deposited with a thickness of 10 nm between Cu and SiO2 was investigated by means of glancing angle X-ray diffraction (XRD), glow discharge optical emission spectroscopy (GD-OES), transmission electron microscopy (TEM), and graphite furnace atomic absorption spectrometry (GF-AAS) after annealing for various times at a temperature of T-an = 600 degreesC. For a Ta73Si27 film, only Ta silicide phases (Ta5Si3, Ta2Si) are formed, whereas all barriers containing nitrogen crystallize primarily into a Ta nitride. Si is not incorporated into this phase but diffuses mostly into the Cu film. Although the crystalline Ta nitride grows mainly within the original barrier region, it does not form a continuous layer. For barriers with a N content x(N) greater than or equal to 25 at.%, the annealing time necessary to start the crystallization increases and the formed Ta nitride phases become N-richer (Ta2N --> Ta5N6). A Ta30Si18N52 layer maintains its amorphous structure even after annealing for t(an) = 100 h. With increasing N content in the barrier, the thermal stability against Cu diffusion is improved. (C) 2004 Elsevier B.V All rights reserved.