Experimental And Density Functional Theory Study Of Complexing Agents On Cobalt Dissolution In Alkaline Solutions

Glycine (GLY), potassium tartrate (PT), and hydroxyethylidene diphosphonic acid (HEDP) have been used as effective complexing agents for chemical mechanical polishing (CMP) of a cobalt (Co) barrier layer, but the most suitable of these three complexing agents is still unclear. In this paper, the density functional theory (DFT) method is employed to predict the complexing capability of the three complexing agents to Co ions. The prediction results show that the complexing capability of the three complexing agents is in the order of: HEDP > GLY > PT. Then, electrochemical experiments, static corrosion tests, UV-Vis spectra, and XPS analysis successfully prove the effectiveness of the DFT method for molecular activity prediction. The experimental results show that regardless of the presence or absence of H2O2, PT has the weakest complexing capability, which results in sufficient Co removal rate without causing unnecessary Co dissolution. In addition, the complexation capability of HEDP is stronger than that of GLY when the oxidation of the Co surface is not a limiting factor. (C) 2021 Elsevier Ltd. All rights reserved.