Corrosion inhibition effect of benzimidazole and two derivatives on copper in alkaline environments: Experimental and theoretical analyses

Copper (Cu) is an important interconnect metal material in the semiconductor field. While removing excess copper in the chemical mechanical polishing process, it is necessary to add corrosion inhibitors to the slurry to protect copper from excessive corrosion. Numerous studies have shown that the heteroatoms and functional groups of corrosion inhibitors are crucial factors affecting their corrosion inhibition ability. The corrosion inhibition performance of benzimidazole (BI) and its two derivatives, 5-methyl benzimidazole (MBI) and 5-methyl benzotriazole (MBTA), on copper in glycine + N-methylglycine solution at pH 9 was studied, and their structure-activity relationship was revealed. Electrochemical measurements and adsorption isotherm fittings show that the three corrosion inhibitors cover the copper surface mainly through the chemisorption to prevent the anodic reaction of copper. The corrosion inhibition efficiencies of BI, MBI, and MBTA were 97.22 %, 98.00 % and 98.73 % at the concentration of 8 mM, respectively, reaching their maximum values. The contact angle testing reveals that MBI and MBTA containing methyl groups are relatively more hydrophobic. X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and scanning electron microscope (SEM) results confirm that the three corrosion inhibitors were successfully adsorbed on the copper surface and formed a dense passivation film to protect the copper from corrosive solutions. In addition, a multi-module collaboration with density functional theory (DFT) and molecular dynamics (MD), further demonstrates that BI, MBI, and MBTA are all adsorbed on the copper layer in a mixed way, and MBTA has the strongest binding capacity to copper. The introduction of the methyl and N atom increased the adsorption area and attachment sites between the corrosion inhibitor and copper, which coincides with the experimental results.