Application of Extremely Thin ZrN Film as Diffusion Barrier between Cu and SiOC

As an extremely thin diffusion barrier applicable to Cu interconnects for the 45 nm technology nodes, we propose a barrier material without interface layers that can become a cause of barrier consumption owing to solid-phase reaction and/or intermixing. We examine the barrier properties of a reactively sputtered ZrN barrier as thin as 5 nm between Cu and SiOC. The ZrN barrier with a slightly N-rich composition tolerates annealing at 500 °C for 30 min. Transmission electron microscopy indicates the absence of interface layers adjoining the barrier. Using the ZrN barrier, we can demonstrate the effectiveness of the interface-layer-free characteristics for an extremely thin barrier of high performance.