A 2-nm-Thick Mn Oxide on a Nitrogen-Stuffed Porous Carbon-Doped Organosilica as a Barrier of Cu Films

Abstract

An ultrathin (e.g., ≤ 2 nm) barrier is needed for fabricating Cu interconnects associated with porous low-k (p-SiOCH) dielectrics with a high aspect ratio trenches/vias in the ultra large scale integrated circuits. To implement successfully the ultrathin Mn oxide barrier on the p-SiOCH dielectric for Cu interconnection, understanding is needed of how the Mn oxide is formed. This study investigated a 2-nm-thick Mn oxide film, deposited by sputtering with a biased-filter intermediating, as the barrier layer to prevent Cu from diffusion. Phase formation of the as-deposited Mn oxide was examined by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy to confirm the formation of Mn2O3. The experimental results indicated that the formation of Mn2O3 barrier is highly effective in preventing the Cu film from diffusion and agglomeration. Thermal stability of the Cu film increased up to 550°C, 250°C greater than the p-SiOCH dielectric without the Mn2O3 film, when combining the nitrogen-stuffed treatment on the p-SiOCH dielectric and annealed the Mn2O3 before the Cu deposition. The structures of Mn2O3 barrier and p-SiOCH dielectric after nitrogen-stuffing treatments were analyzed to evaluate their applicability in Cu interconnects.