Deformation and fracture of TiN coating on a Si(1 1 1) substrate during nanoindentation

The deformation mechanisms and fracture behavior of TiN coating on a Si(111) substrate, deposited using magnetron sputtering Ti target, is characterized by nanoindentation experiments. The morphologies of the indentations are revealed by scanning electron microscopy, coupled with in situ atomic force microscopy in nanoindentation experiments. The results show that permanent trigonal impressions and radial plastic grooves are confined within the contact regions even though the peak indenter displacement increases to 1500 nm. Local cracks of TiN appear around the indent marks making the edges of the indentations irregular. The cracks increase with an increase of the indenter displacement until the indenter arrives at (or approaches) the Si(1 1 1) substrate at a critical displacement. As the peak indenter displacement increases to 2500 nm, an interfacial fracture between the TiN coating and the Si(1 1 1) substrate is observed using both scanning electron microscopy micrograph and in situ atomic force microscopy images. The diameter of the interfacial fracture determined by scanning electron microscopy micrographs is more accurate than that determined by in situ atomic force microscopy images in nanoindentation experiments. The failure mechanism of the TiN coating is also investigated by means of a standard nanoscratch test.