Large-Area, Single-Layer Molybdenum Disulfide Synthesized at BEOL Compatible Temperature as Cu Diffusion Barrier

Abstract

The scaling limit of conventional Cu diffusion barriers has become the bottleneck for interconnect technology, which in turn limits the IC performance. Sub-nm diffusion barrier is urgently demanded to maintain the interconnect resistivity for ultra-scaled Cu interconnects. However, with this thickness, the blocking capabilities of conventional Cu diffusion barriers are lost. In this letter, sub-nm Cu diffusion barrier is realized by single-layer molybdenum disulfide (MoS2) grown at 400 °C using metal-organic chemical vapor deposition. MoS2 is directly grown on dielectrics without transfer processes and the continuous coverage in a large area (>1 cm2) is achieved. Its resistance to Cu diffusion is investigated by time-dependent dielectric breakdown (TDDB) measurements. Our results indicate that the MoS2 barrier can efficiently suppress Cu diffusion and enhance dielectric lifetime significantly. Although a few challenges, including Cu adhesion to the MoS2 surface and integration with the Damascene structure, have to be assessed before introducing this novel material to the back-end-of-line technology, our work lays the groundwork for further investigation.