Investigation of the impact of environmental conditions on the mechanical properties of thin-film copper wafers

Abstract

Thin-film copper offers excellent film texture for multilevel interconnections in integrated circuit fabrication due to its superior resistance to electromigration and high electrical conductivity. To perform a chemical mechanical planarization process during semiconductor fabrication of copper, 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 wafers 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 (DI) water and polishing slurry environments compared to thin-film copper exposed to ambient air. Interestingly, variations in temperature within wet environments do not significantly affect the properties of thin-film copper wafers; but changes in properties are largely driven by chemical processes. The insights gained from this study emphasize the significance of considering both the passivation layers and wet environments in semiconductor fabrication processes, which contributes to the advancement of copper-based interconnect materials and optimization of the chemical mechanical planarization process in semiconductor manufacturing.