Influence of nitrogen content on the crystallization behavior of thin Ta–Si–N diffusion barriers

• Published in: Thin solid films Vol. 468; no. 1; pp. 183 - 192
• Main Authors: Hübner, R., Hecker, M., Mattern, N., Voss, A., Acker, J., Hoffmann, V., Wetzig, K., Engelmann, H.-J., Zschech, E., Heuer, H., Wenzel, Ch
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.12.2004; Elsevier Science
• Subjects: Chemical interdiffusion; diffusion barriers; Condensed matter: structure, mechanical and thermal properties; Cu metallization; Diffusion in solids; Exact sciences and technology; Glow discharge optical emission spectroscopy; Physics; Ta–Si–N diffusion barriers; Transport properties of condensed matter (nonelectronic); X-ray diffraction; Ta–Si–N diffusion barriers; X-ray diffraction; Cu metallization; Glow discharge optical emission spectroscopy; Amorphous material; Annealing; Inorganic compounds; Atomic absorption spectroscopy; Ternary compounds; Transition element compounds; Crystallization; Composition effect; Optical emission spectroscopy; XRD; Experimental study; Thermal stability; Ta-Si-N diffusion barriers; Thickness; Time dependence; Transmission electron microscopy; Diffusion barriers; Silicon nitrides; Tantalum nitrides; Glow discharges
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2004.04.026

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 SiO 2 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 °C. For a Ta 73Si 27 film, only Ta silicide phases (Ta 5Si 3, Ta 2Si) 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≥25 at.%, the annealing time necessary to start the crystallization increases and the formed Ta nitride phases become N-richer (Ta 2N→Ta 5N 6). A Ta 30Si 18N 52 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.