| Thin films are critical for various industrial applications. Proper measurement of the mechanical properties of thin films is the first step in analyzing the mechanics of thin films. Industry has long relied on indentation techniques for measuring the hardness and stiffness of a wide range of bulk materials. Recently, low-load and depth-sensing indentation, commonly referred to as nanoindentation, has been used to study the mechanical properties of thin films on substrates.; In this study, both the conventional Knoop microhardness and nanohardness measurements were applied to Cu and Cr thin films on single crystal sapphire substrates. The hard sapphire substrate was used to investigate the substrate contribution to the thin film hardness.; The microhardness measurements revealed that the hardnesses depend upon the thin film thickness as well as the thin film material. Microhardness anisotropy from the substrate was detected for several different very thin films of Cu and Cr which is a result of the sapphire substrate contribution. The nanoharndesses, when measured within the thin film itself are quite different than the film/substrate composite Knoop microhardnesses.; Energy balance analysis was applied to the Knoop microhardnesses of Cu and Cr thin films. The resulting energy balance coefficient enabled derivation of the load independent microhardness for each of the films. |
