Scaling Down Diffusion Barriers: Performance and Thickness Dependence of TaN and Two-Dimensional-Material-Based Barrier Layers

Two-dimensional (2D) materials have been suggested to offer a viable route towards further miniaturization of interconnect technology as new diffusion barriers (DBs), replacing current industry standards at low thickness regime. We investigate new copper DBs to be used in back end of line (BEOL) interconnect structures, based on 2D materials grown on a large scale. The films are characterized using transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy to verify their structural quality and chemical composition. An experimental protocol is presented to assess the performance of these films as DBs, including a device fabrication scheme and a measurement scheme that both allow for the comparison of different barriers. This study establishes the difference in barrier properties as a function of film thickness based on their different crystal structure, comparing 2D materials with industry standard TaN barriers, thus evaluating the potential of 2D materials for future, scaled down, interconnect technology. This screening protocol also enables optimization of the growth conditions for improved DBs.