Study of diffusion barrier properties of ionized metal plasma (IMP) deposited TaN between Cu and SiO₂

The diffusion barrier properties of IMP deposited TaN between Cu and SiO₂ have been investigated in the Cu (200 nm)/TaN (30 nm)/SiO₂ (250 nm)/Si multi-layer structure. The IMP-TaN thin film shows better Cu diffusion barrier properties than chemical vapor deposition (CVD) and conventional physical vapor deposition (PVD) deposited TaN films. The thermal stability was evaluated by electrical measurement and X-ray diffraction (XRD) analysis. As a main part of thermal stability studies, the atomic intermixing, new compound formation and phase transitions in the test structure were also studied. Furthermore, a failure mechanism was also examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), secondary ion mass spectroscopy (SIMS) and Rutherford backscattering spectroscopy (RBS) in conjunction with electrical measurements. The 30 nm thick IMP-TaN was found to be stable up to 800 °C for 35 min.