Regensburg 2007 – scientific programme
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DS: Fachverband Dünne Schichten
DS 15: Poster Session
DS 15.41: Poster
Tuesday, March 27, 2007, 15:00–17:00, Poster B
Spectroscopic ellipsometry study of thin diffusion barriers of TaN and Ta for Cu interconnects in integrated circuits — •Sukumar Rudra1, Marion Friedrich1, Sindu Louis1, Ovidiu Gordan1, Thomas Wächtler2, and Dietrich Zahn1 — 1Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany — 2Chemnitz University of Technology, Centre for Microtechnologies, D-09107 Chemnitz, Germany
The objective of this work is to study the optical and electrical properties of tantalum nitride and tantalum barrier thin films against the copper diffusion in integrated circuits using spectroscopic ellipsometry in the VUV and UV-Visible range. Single layers of tantalum nitride, bilayer of Ta/TaN and tri-layer of Cu/Ta/TaN were produced on Si (111) substrates with a native oxide layer using the technique of sputtering. The dielectric functions were modelled using effective medium approximation (EMA) and Drude-Lorentz model to obtain informations regarding film thickness, film composition, surface roughness, mean free path and electrical resistivity. It was observed that for the thicker layer of Ta on TaN, contribution of α-phase is higher than that of the β-phase of Tantalum. Depositions of Cu on Ta were also done using other techniques of chemical vapour deposition (CVD) and atomic layer deposition (ALD) at different temperatures and ambient. It was observed that a small change in deposition temperature give rise to a pronounced change in the dielectric functions and hence in the film morphology.