Integrating bottom-up approach for ultra-thin copper diffusion barrier layers in interconnects

The Back-End-of-Line (BEOL) technology scaling is reaching its limits. For further scaling of the Cu interconnects for nano-scale CMOS, thermally stable, ultra-thin and conformal layers of barrier materials with a good adhesion to copper and the underlying low-K are required. Self-assembled monolayers (SAMs) with thicknesses < 2nm provide an ideal solution but wet chemistry is difficult to integrate into CMOS process flow. In this paper, we demonstrate the first vapor phase self-assembled monolayer (VPSAM) of Hydroxy-phenyl Zinc Porphyrin (ZnTPPOH) on inter-layer dielectric (ILD) materials with an application towards an effective copper diffusion barrier. The MOS devices with the ultra-thin barrier layer has been subjected to bias and temperature stress and successfully demonstrated to act as effective copper diffusion barrier.