Thermal stress characteristics of Cu/oxide and Cu/low-k submicron interconnect structures

Thermal stress characteristics of single damascene Cu lines passivated with tetraethyl orthosilicate oxide and methyl silsesquioxane low-k dielectrics were investigated by x-ray diffraction method and finite element analysis. Lines with different aspect ratios were studied, and the effect of line geometry was evaluated. The stress characteristics of low-k passivated Cu lines indicate that the diffusion barrier plays an important role in controlling the stress behavior in damascene structure. The effect of material properties, process conditions, and interconnect structure were examined and the implications in Cu/low-k interconnect reliability are discussed.