Synergistic Effect of Complexing Agent TAD and Corrosion Inhibitor PZ on BTA Removal in Copper Post-CMP Cleaning

Abstract

Benzotriazole (BTA) as a common corrosion inhibitor in the chemical mechanical polishing (CMP) process, can effectively protect the copper (Cu) surface, but its organic residues will form a passivation film on the wafer surface to prevent the contact between the cleaning solution and the wafer surface, so the removal of BTA is a major problem in the post-CMP cleaning. In this paper, N,N’-Bis(3-aminopropyl)−1,2-ethanediamine (TAD) and pyrazole (PZ) were used as the main components in the alkaline cleaning solution and fatty alcohol polyoxy ethylene ether (JFCE) was added as an auxiliary surfactant to investigate the removal of BTA. The complexation ability of TAD and the corrosion inhibition ability of PZ were verified by electrochemical experiments, and the reaction sites of the interaction between TAD and Cu surface were analyzed by quantum chemical calculations. Meanwhile, the mechanism of the synergistic removal of BTA by TAD and PZ was investigated by electrochemical methods. The final optimized cleaning solution consisted of 1 mmol L−1 TAD, 0.1 mmol L−1 PZ and 1 wt% JFCE and its good cleaning performance was verified by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), which provided guidance for the development of the cleaning solution.