Search

The properties of Cu(V) alloy films were investigated to evaluate its potential use as self-forming diffusion barrier in copper metallization. Cu(V) alloy films were deposited on SiO 2 /Si substrates by magnetron sputtering. Cu(V)/SiO 2 /Si systems were subsequently annealed at various temperatures and analyzed by four-point probe measurement (FPP), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). After annealed at 500 °C, the resistivity of the Cu(V) films reduced to 3.1 μΩ cm, there is no obvious increase in resistivity. XRD suggest that Cu alloy film has preferential (111) crystal orientation and no extra peak corresponding to Cu and Si even after annealed at 500 °C. According to TEM results, a self-formed thin layer with the thickness of about 8 nm is observed at the interface between Cu alloy and the SiO 2 /Si substrate in the sample annealed at400 °C. As XPS results, after annealed at 400 °C and 500 °C, V atoms are observed at the surface of the Cu(V) films and the interface of the Cu(V) and SiO 2 /Si. The formation of the self-formed thin layer is probably due to the separation of V at the interface. The sharp declines of the Cu and Si concentrations at the interface indicate a lack of inter-diffusion between Cu and SiO 2 /Si. Adding small amounts of V to Cu film can improve the barrier performance and thermal stability compared with pure Cu contact systems. [ABSTRACT FROM AUTHOR]

Synchrotron X-ray radiography was used to in situ study the interface diffusion behavior and microstructural evolution during the melting and solidification of Al/Cu bimetal. During the solidification, the dendritic growth around the interface is mainly dominated by the variation of Cu concentration and thermal field. Four transition zones of solute profile around the interface were identified to be I (α-Al), II (Al + Al 2 Cu), III (Al 2 Cu) and IV (AlCu, Al 3 Cu 4 and Al 2 Cu 3 ), respectively. During the melting, the concentration variations of Al and Cu around the interface were quantitatively analyzed through the extraction of gray level from sequenced X-ray images. The diffusion coefficients of Cu in liquid Al were calculated from the known concentration variations by an inverse method based on Fick’s second law. The diffusion coefficients of Cu in Al were found to follow linear Arrhenius equation dependencies with the pre-exponential factor of 2.83 × 10 −5 m 2 s −1 and the activation energy of 96.0 kJ mol −1 in a temperature range of 893–970 K. [ABSTRACT FROM AUTHOR]