BEOL compatible 2D layered materials as ultra-thin diffusion barriers for Cu interconnect technology

摘要

Diffusion barriers based on Ta and Ti related materials have been used in Cu interconnect technology to mitigate Cu diffusion into damascene structures. Along with the scaling of VLSI circuits, Cu interconnects scaling is demanded as well. To maximize the Cu volume in its trench for lower line resistance, the thickness of the diffusion barrier should be reduced accordingly. However, conventional barrier materials lose their capabilities of blocking Cu diffusion as their thicknesses are reduced below ~3nm, as illustrated in Fig. 1(a), which can result in malfunctioning of integrated circuits. In this work, 2D layered materials, which have the potential to be scaled below sub-1 nm, are explored as alternative diffusion barriers. In addition, the resistivity of the Cu/2D barrier hybrid is also studied. Furthermore, back-end-of-line (BEOL)-compatible graphene directly grown on a low-k dielectric is demonstrated, indicating the feasibility of introducing 2D materials into interconnect technology.