Abstract
Bottom-electrode Ru films were fabricated on barrier metal TiN films by the reaction of tris-(2,4-octanedionato)ruthenium [Ru(od)3, Ru(C8H13O2)3] precursor and O2 gas. It was observed that the film incorporated the undesirable impurity of oxygen that could oxidize the TiN underlayer during postthermal treatments. To evaluate the oxidation characteristics of barrier metal TiN by the incorporated oxygen, samples with the Ru/TiN film stack were annealed in N2 ambient up to 700°C for 60 s by rapid thermal processing (RTP). No sign of TiN oxidation was observed in analyses by X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy. This was also confirmed by measuring the electrical resistance of a contact hole plugged with poly-Si and connected to the Ru/TiN stack, which shows an acceptable value below 1.3×103 Ω. We also investigated the oxidation characteristics of the Ru/TiN stack by atmospheric O2 gas. The samples were annealed in O2 ambient by RTP at 500°C, 600°C, and 700°C for 60 s. The Ru film began to oxidize to RuO2 at 500°C. With increasing temperature, further oxidations of Ru and TiN occurred simultaneously. Finally, at 700°C, Ru and TiN oxidized completely to RuO2 and rutile TiO2 phases, respectively. These results demonstrate the ease of oxidation of Ru and TiN films in O2 ambient.
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