Abstract Thin film copper offers excellent film texture for multilevel interconnections in integrated circuits fabrication because of its superior resistivity to electromigration and high electricelectrical conductivity. To perform a semiconductor fabrication of copper during chemical mechanical planarization process, it is necessary to have a thorough understanding of the nanomechanical properties of thin film copper. In this study, thin film copper and reacted passivation layers on silicon substrate wafer are investigated for their nanomechanical properties under various environmental conditions. The results of this study indicate that thin film copper passivation layers have different properties in deionized water and polishing slurry environments compared to thin film copper exposed to ambient air. The insights gained from this study emphasize the significance of considering both the passivation layers and wet environments in semiconductor fabrication processes, contributing to the advancement of copper-based interconnect materials and optimization of the chemical mechanical planarization process in semiconductor manufacturing.