Three types of cracks associated with interfacial failure of a tungsten fine line on silicon oxide (SiO2) have been observed in microwedge scratch testing (MWST) of free lines. They were identified by carefully controlling scratch conditions in a continuous microindenter system, in conjunction with SEM micrographs. The first type is a hinge crack, which is responsible for nucleating an interfacial crack. The driving force for the hinge crack is the difference in stress conditions in the middle on the line (plane strain) and the outside of the line (plane stress). The second type is the interfacial crack, which is driven by the movement of the microwedge. This crack is modelled by the finite element method (FEM) to obtain an interfacial work of adhesion value. The third type of crack is a spallation crack, and is driven by tensile strains associated with buckling of the thin film once the interfacial crack becomes sufficiently long. Tensile strains in the film at the maximum crack length are calculated by FEM in order to arrive at a value of thin film fracture strength. A brittle failure mechanism has been confirmed by a micrograph of a spalled piece exhibiting no perceptible plastic deformation.
|Original language||English (US)|
|Number of pages||6|
|Journal||Materials Research Society Symposium - Proceedings|
|State||Published - Dec 1 1994|
|Event||Proceedings of the 1994 MRS Spring Meeting - San Francisco, CA, USA|
Duration: Apr 5 1994 → Apr 8 1994