Interfacial fracture for TiN/SiNx nano-multilayer coatings on Si(1 1 1) characterized by nanoindentation experiments

Fracture behavior for TiN/SiNx nano-multilayer coatings on Si(1 1 1) substrates, deposited using magnetron sputtering Ti and Si, is characterized by nanoindentation experiments, and the morphologies of the indentations are revealed by scanning electron microscopy, along with in situ atomic force microscopy (AFM) in nanoindentation experiments. During nanoindentation experiments, under the condition that the displacement limit mode is used and a strain rate is kept at 0.05/s, an interfacial (between the coating and substrate) fracture is observed as the maximum indenter displacement into the coating reaches 2500 nm, and the corresponding unloading segment in the load–displacement curve shows an obvious discontinuity. This discontinuity is attributed to the rebound of the detached film during unloading. The interfacial fracture toughness for TiN/SiNx nano-multilayer coating on Si(1 1 1), which is strongly dependent on the preferred orientation for the TiN layer as well as the interfaces between TiN and SiNx layer in the multilayer stack, is calculated.