Specimen size effect on elastic–plastic strength evaluation of interface between thin films

A specimen size effect on the adhesion strength of Cu/insulation layer interface was studied by means of a new elastic–plastic finite element simulation technique. By considering the influence of the plastic zone at the interface crack tip, the adhesion strength appeared almost independent of the specimen size. Since the Cu crystals were far smaller than the specimen dimensions and thus no significant difference should be expected in adhesion strength, it is speculated that an accurate estimation of the plastic zone is essential for micro-scale specimen evaluation.