The effect of elastic modulus on channel crack propagation in organosilicate glass films

Abstract The scaling demands of high-performance, silicon-based devices require the integration of low dielectric constant (low- κ ) materials for interconnecting structures. The group of materials known as organosilicate glass has emerged as the predominant choice for intermetal dielectrics in 65 and 90 nm node devices. The material has a characteristic tensile residual stress and low fracture toughness. A potential failure mechanism for this class of films during the manufacturing process is catastrophic fracture resulting from channel cracking. Channel crack velocity is dependent on several material properties, with the residual film stress, plane-strain modulus, and film bond density serving as key parameters. A model that predicts channel-crack propagation behavior in silica-based low-dielectric constant materials is described. Using a rigorous fracture mechanics analysis, we derive a set of fracture constants that govern channel cracking of organosilicate coatings on silicon substrates; these fracture parameters are used to predict crack behavior in six separate low- κ films with distinct elastic moduli in both ambient air conditions and de-ionized water. The analysis demonstrates that for a given film thickness, the crack propagation rate is extremely sensitive to the value of the elastic modulus, especially when the material is compliant.