Determination of the absolute hardness of electrolytically produced copper coatings by application of the Chicot-Lesage composite hardness model

Abstract

In this study, a novel procedure, based on application of the Chicot–Lesage (C–L) composite hardness model, was proposed for the determination of an absolute hardness of electrolytically produced copper coatings. The Cu coatings were electrodeposited on the Si(111) substrate by the pulsating current (PC) regime with a variation of the following parameters: the pause duration, the current density amplitude and the coating thickness. The topography of produced coatings was characterized by atomic force microscope (AFM), while a hardness of the coatings was examined by Vickers microindentation test. Applying the C–L model, the critical relative indentation depth (RID)c of 0.14 was determined, which is independent of all examined parameters of the PC regime. This RID value separated the area in which the composite hardness of the Cu coating corresponded to its absolute hardness (RID <0.14) from the area in which the application of the C–L model was necessary for a determination of the absolute coating hardness (RID ≥ 0.14). The obtained value was in a good agreement with the value already published in the literature.

Keywords

• electrodeposition
• the pulsating current
• topography
• hardness
• relative indentation depth