The chemical states of Cu surfaces reacted with quinaldic acid (C10H7NO2) were investigated by using time-of-flight-secondary ion mass spectrometry (TOF-SIMS), paying a special attention to the reaction speed, pH of the acidic solution and the composition of the formed complex, in order to understand the mechanisms of Cu-chemical mechanical polishing (Cu-CMP) process. It was found from the evaluation of the secondary ion intensities from Cu, quinaldic acid molecules and Cu-quinaldic acid complexes that: (1) characteristic secondary ion peaks originating from the complex formed by the reaction between Cu and quinaldic acid were observed; (2) the intensities of these secondary ion peaks changed with the soaking time; (3) the reaction rate was dependent on the pH of the solution. It was also found that (4) the composition and the chemical states of the formed complex from the saturated surfaces were almost the same for each pH condition. (C) 2002 Published by Elsevier Science B.V.