A study of FTIR and XPS analysis of alkaline-based cleaning agent for removing Cu-BTA residue on Cu wafer

This study is to focus on the benzotriazole (BTA) residue problem in the postchemical mechanical planarization (post-CMP) cleaning process. The adsorption of BTA on copper surface was studied by analyzing the FTIR spectra; it indicates that the oxidation of the copper surface could affect the adsorption of BTA on the wafer surface. It used an alkaline-based chelating agent, ethylenediamine tetra acetic acid with four equivalents of 3,4-diaminobutane-1,1,2,2-tetraol, to deal with Cu-BTA film, compared with the tetraethyl ammonium hydroxide at the same pH of 10.3, and used X-ray photoelectron spectroscopy (XPS) analysis to characterize the BTA residue on Cu wafer. The results show that the alkaline-based chelating agent is very effective in removing the Cu-BTA from the Cu surface and leaving the cuprous species to passivate the Cu surface.