Fiducial mark and nanocrack zone formation during thin-film delamination

Abstract Carbon fiducial marks are formed during thin-film local delamination processes induced either by superlayer indentation forming circular blisters, or by residual stress relief through telephone cord blister formation. Hydrocarbons are sucked into the crack tip during the delamination process, outlining the crack-tip-opening angle, which can be used to back calculate thin-film adhesion using either elastic or plastic analyses presented here. Fiducial marks have been observed in two different thin-film systems, namely Cu/SiO2 and TiW x N y /GaAs. Cu/SiO2 delamination blisters have been cross-sectioned using the focused-ion-beam method, and high-resolution scanning electron microscopy of the cross-sections revealed crack renucleation ahead of the original crack tip. This is attributed to the stress redistribution process due to the dislocation shielding mechanism. At stress intensity levels of 0.33 MPa m½, it is found that four emitted dislocations can account for crack arrest, with renucleation of 100 nm sized nanocracks dependent on the antishielding stresses.