Measurement of Intrinsic Hardness of Deposited Chromium Thin Films by Nanoindentation Method and Influencing Factors

Abstract

Materials with very small dimensions exhibit different physical and mechanical properties compared to their bulk counterparts. This becomes significantly important for the thin films that are widely used as components in micro-electronics and functional materials. In this study, a chromium (Cr) thin film was deposited on a silicon (Si) wafer by DC-magnetron sputtering. The intrinsic hardness of the Cr thin film on Si-wafer was evaluated by the nanoindentation method. We especially investigated ways of measuring the intrinsic hardness of the Cr thin film, and influential factors including the substrate effect and surface roughness effect. To further characterize the intrinsic hardness of the Cr thin film on Si-wafer, we used Xray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Two additional methods, the Meyer-plot and a profile for hardness versus indentation depth, were also employed. As a result of these two methods, we found that the profile for hardness versus indentation depth was valuable for evaluating the intrinsic hardness of Cr thin film on a Si-wafer substrate. The measured intrinsic hardness of the Cr thin film and Si wafer were about 900 Hv and 1143 Hv, respectively. The profile for hardness versus indentation depth can be widely used to evaluate the intrinsic hardness of metallic thin films on substrates.