Surface Corrosion Inhibition Effect and Action Mechanism Analysis of 5-Methyl-Benzotriazole on Cobalt-Based Copper Film Chemical Mechanical Polishing for GLSI

Abstract

With integrated circuit (IC) technology nodes below 20 nm, the chemical mechanical polishing (CMP) of cobalt (Co)-based copper (Cu) interconnection has been gradually changed to one-step polishing, which requires rapid removal rate (RR) of Cu while controlling the height differences of concave and convex areas on the Cu surface, and finally achieving global planarization. Co as the barrier material is also required a lower RR to ensure a high Cu/Co removal rate selection ratio. Therefore, choosing the appropriate inhibitor in the slurry is extremely important. The corrosion inhibitor 5-methyl-benzotriazole (TTA) was thoroughly examined in this study for its ability to prevent corrosion on Cu film as well as its mode of action. The experimental results showed that TTA can effectively inhibit the removal of Cu under both dynamic and static conditions, which was also confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) tests. The corrosion inhibition effect and mechanism of TTA was further revealed by open circuit potential (OCP), polarization curve, adsorption isotherm, quantum chemical calculation, UV–Visible and X-ray photoelectron spectroscopy (XPS) tests. It was found that TTA can inhibit the corrosion of Cu by physical and chemical adsorption on the Cu surface, which is conductive to obtain excellent planarization properties. At the same time, it was also found TTA can also inhibit the corrosion of Co by forming Co-TTA and promoting the conversion of Co(OH)2 to Co3O4, and a Cu/Co removal rate selection ratio of 104 was obtained, which provides a suitable corrosion inhibitor for the polishing of Co-based Cu interconnection CMP and has a broad application prospect.