Role of the Functional Groups of Complexing Agents in Copper Slurries

We investigate the role of – N H 2 and –COOH functional groups of complexing agents in H 2 O 2 -based slurries in controlling copper (Cu) removal rates. Slurries containing complexing agents with two of the same functional groups (succinic acid: H O O C – C H 2 C H 2 – C O O H , ethylene diamine: H 2 N – C H 2 C H 2 – N H 2 ) and a complexing agent containing one each of the functional groups (β-alanine: H 2 N – C H 2 C H 2 – C O O H ), all with the same carbon chain length, were investigated. Along with dissolution and disk polish experiments, potential–pH diagrams were constructed for these three systems in the presence of H 2 O . The dissolution and polish rates are consistent with the known activity of carboxylic acids (with –COOH groups) at acidic conditions and that of amines (with – N H 2 groups) in an alkaline environment. The observed trends in the removal rates with all these slurries are explained using potential–pH diagrams, UV/visible spectra, and electrochemical experiments. When compared to glycine ( H 2 N – C H 2 – C O O H ) , β-alanine ( H 2 N – C H 2 C H 2 – C O O H ) produced higher removal rates at acidic pH values and lower removal rates at alkaline pH values. Finally, succinic acid and β-alanine-based slurries were found to result in lower dissolution rates and higher polish rates compared to glycine-based slurries at pH 4.