Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

For thermal ALD Ta_xN_yC_z films improved growth behaviour and Cu diffusion barrier performance are demonstrated by applying a plasma treatment prior to film deposition, in particular on low-k dielectrics. Two different kinds of ALD processes for depositing thermal ALD Ta_xN_yC_z films are applied in this study, involving either TBTDET or PDMAT as a precursor. Ammonia is used as a reactant and Ar as a purging gas in both processes. Within the experiment, two types of pre-treatments prior to ALD are investigated: a wet-chemical pre-treatment using diluted (0.5%) HF, and plasma pre-treatments using Ar/H₂ or N₂ plasmas. It is examined by transmission electron microscopy (TEM) from a microstuctural perspective whether improved growth behaviour of thermal ALD Ta_xN_yC_z films can be achieved by applying a plasma treatment prior to film deposition. The Cu diffusion barrier properties of 10-15 nm ALD TaNC films are then evaluated by bias temperature stress (BTS) and triangular voltage sweep (TVS) measurements on metal-insulator-semiconductor (MIS) test structures, after annealing at up to 600 °C under H₂/N₂ atmosphere. The results imply that, from a process side, thermal ALD TaNC films can intrinsically achieve a Cu diffusion barrier performance similar to PVD TaN. However, if no treatment was applied, Cu drift occurred.