Nanohardness measurement of carbon nitride thin films

A nanohardness measurement method using an atomic force microscope equipped with a diamond tip is described and applied to carbon nitride thin films. These films were prepared by radiofrequency magnetron sputtering at various substrate temperatures. Based on the general hardness definition, the hardness of thin films was determined directly from the indentation force and the (residual) indentation depth using fused silica as a standard reference. The hardnesses measured by this technique are quite reproducible. The hardnesses of the carbon nitride thin films with a thickness of similar to 35 nm were in the range 31-35 GPa, increasing slightly with substrate temperature. This increase is in good correlation with the film density changes as measured by grazing-incidence x-ray reflectivity. Copyright (C) 2001 John Wiley & Sons, Ltd.