Enhancing Cu-barrier properties of 2D-WS2 barriers: The role of grain size and surface passivation

Two-dimensional (2D) films, such as tungsten disulfide (WS2), are being considered by the microelectronics industry as promising barrier and liner systems for the back-end-of-line (BEOL) metal interconnects. To maximize their efficiency, processes to integrate large grain size 2D barriers in BEOL should be explored. In this work, we investigate the use of large grain WS2 films, which are obtained by the epitaxy of the 2D film on sapphire substrates and then transferred into the dielectric. After demonstrating that a hydrogen disulfide passivation technique can help overcome film transfer challenges, we show that large grain size 2D films have enhanced barrier efficiency. Our results are benchmarked against commercially available TaN systems, proving that thin 2D films are advantageous in reducing metal diffusion in BEOL dielectrics.