MoS₂ as an Effective Cu Diffusion Barrier with a Back-End Compatible Process

This study demonstrates molybdenum disulfide (MoS₂) as a superior candidate as a diffusion barrier and liner. This research explores a newly developed process to show how effectively MoS₂ can be applied. First, a new approach is developed to prepare molybdenum disulfide (MoS₂) by microwave plasma-enhanced sulfurization (MW-PES). MW-PES can rapidly and directly grow on the target substrate at low temperatures, which is compatible with the back-end-of-line (BEOL) technology. Second, the performance of MW-PES MoS₂ as a diffusion barrier and liner is reported in the subsequent section. Through time-dependent dielectric breakdown (TDDB) measurements, MoS₂ is shown to have a barrier property better than that of the current material, Ta, with the same thickness. According to the model fitting, the lifetime of the device is about 45.2 times the lifetime under normal operating conditions. Furthermore, MoS₂ shows its superior thermal stability in maintaining the barrier properties. MoS₂ is proven to be an excellent interface as a liner as it can provide sufficient adhesion and wettability to further effectively reduce the surface scattering of copper (Cu) and significantly lower the circuit resistance.