ADHESION AND ACOUSTIC-EMISSION ANALYSIS OF FAILURES IN NITRIDE FILMS WITH 14 METAL INTERLAYER

Interfacial fracture has been induced between a tantalum nitride film with an aluminum inter layer on a sapphire substrate using nanoindenta tion. To identify failures for which a model calculation is valid a co mmercial acoustic emission sensor has been used to study the details o f the failure event. The interfacial fracture energy of the system wit h an aluminum interlayer under the loading conditions at the crack tip is approximately 8 J/m(2). Within narrow bounds, this toughness value is reproducible using three different theoretical approaches. The aco ustic emission signal is used to determine a lower bound interfacial c rack velocity of 5 m/s. The majority of the failure occurs at the alum inum-sapphire interface, suggesting that the Fracture energy and crack velocity determined are related to the toughness of this interface an d not the nitride-aluminum interface.