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 nanoindentation. To identify failures for which a model calculation is valid a commercial acoustic emission sensor has been used to study the details of the failure event. The interfacial fracture energy of the system with 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 acoustic emission signal is used to determine a lower bound interfacial crack velocity of 5 m/s. The majority of the failure occurs at the aluminum-sapphire interface, suggesting that the Fracture energy and crack velocity determined are related to the toughness of this interface and not the nitride-aluminum interface.