Abstract
The combination of FA/OII chelating agent and double complexing agent ammonium citrate can shift the ionization to the right (the dissolution of Cu-BTA), effectively break the Cu-N bond, and accelerate BTA removal on the copper surface. • Ammonium citrate's nucleophilic attack may occur near C2 and O4 atoms. • The electrophilic attack may occur near N22 and N26 atoms. • The pH value of the cleaning solution is stable at 10.24 for optimal removal of BTA. • Effect and mechanism of composite complex agent were studied by electrochemical, contact angle, SEM, FTIR and XPS. • Composite complex agent can complex copper ions, form copper amine complex and break the ionization balance of Cu-BTA. Benzotriazole (BTA) is a common corrosion inhibitor in chemical mechanical polishing (CMP). It is also the main pollutant to be removed in post CMP cleaning. In this paper, a new type of alkaline cleaning solution based on composite complexing agent was proposed for BTA removal. The optimal concentration and pH value of the cleaning solution were explored using electrochemical measurement and contact angle measurement. When the components were 200 ppm FA/OII chelating agent and 0.1 vol% ammonium citrate (pH = 10.24), BTA residue on copper surface can be effectively removed. Density Functional Theory (DFT) proved that ammonium citrate's nucleophilic attack may occur around C2 and O4 atoms, respectively. The electrophilic attack of ammonium citrate may occur around N22 and N26 atoms, respectively. The results of scanning electron microscopy (SEM) showed that a lower surface roughness was obtained after cleaning. Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed that the cleaning solution could complex copper ions, break the ionization balance of Cu-BTA and accelerate its dissolution, so as to remove BTA effectively.
Published Version
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