Assessing Ultrathin Wafer-Scale WS2 as a Diffusion Barrier for Cu Interconnects

Abstract

To maintain the scaling trends in the complementary metal oxide semiconductor (CMOS) technology, the thickness of barrier/liner systems used in back-end-of-line (BEOL) fabrication of metal interconnects needs to be sub-2 nm. However, reducing the thickness of the traditional barrier and liner systems necessary for the dimensional scaling of future interconnects is extremely challenging. Hence, ultrathin two-dimensional (2D) transition-metal dichalcogenide (TMD) films can be an alternative to current barrier/liner systems. However, the processes used to grow these films are generally not BEOL-compatible. Here, using the plasma-free metal–organic chemical vapor deposition (MOCVD) process, we grow BEOL-compatible tungsten disulfide (WS2) film, which has a clear advantage over current diffusion barrier/liner systems used in Cu-interconnects. Our results show that these WS2 films not only block Cu diffusion but also reduce the effective resistance of the Cu film by suppressing the grain boundary and interface scattering of electrons.