The Study on Action Mechanism of 2-Phosphonobutane -1,2,4-Tricarboxylic Acid in Cu Chemical Mechanical Planarization Process

In this study, 2-Phosphonobutane -1,2,4-Tricarboxylic acid (PBTCA) was found and utilized as a superior complexing agent in a Cu chemical mechanical polishing (CMP) slurry, which significantly accelerated the dissolution of Cu and increased the removal rate of Cu. The reaction mechanism of PBTCA lies in its ability to react with Cu 2+ , forming a Cu(II)-PBTCA complex. This process occurs because O atoms on the carboxyl and phosphonic groups form chemical bonds with Cu 2+ . Molecular dynamics results showed that the complexation ability of the phosphate groups is more potent than that of the carboxylate group. The removal rate of Cu reached 280.6 Å min −1 was obtained in an optimized slurry containing 4 wt% SiO 2 , 0.6 wt% H 2 O 2 , 0.3 wt% PBTCA, and 0.03 wt% 5-Methyl-1H-benzotriazole, while the Sq is 0.82 nm and Ra is 0.106 nm. It meets the needs of the CMP of the low-size Cu interconnection. PBTCA, as a highly efficient and environmentally friendly low-cost complexant, has great application potential in chip manufacturing, especially at a low-technology node.