Phase analysis of TaN/Ta barrier layers in sub-micrometer trench structures for Cu interconnects

The resistance behavior of TaN/Ta diffusion barrier bilayers has been investigated. The dependence of the Ta-phase on the TaN layer thickness was examined by means of X-ray micro-diffraction and resistivity measurements. Furthermore, the influence of the geometry of a damascene trench structure on the Ta-phase of the deposited TaN/Ta barrier bilayers has been studied and compared to the results obtained with blanket wafers. The influence of the Ta-phase on the via resistance of Cu interconnects is discussed.