Abstract: The effect of CO2-3 on copper electrodeposits from 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA) baths was investigated over a wide range of concentration by electrochemical measurements, XRD, and IR spectra of the complex. It could be seen from potentiodynamic polarization curves that CO2-3 in the bath could not only enhance the cathodic polarization but also promote anodic dissolution. The X-ray diffraction results indicated the changing of preferred orientation of the copper deposits, from a preferential growth orientation (222) plane containing little CO2-3 to (111) plane containing more CO2-3. The IR spectra of the solid complex purified from the bath showed that CO2-3 could enter the complex and stabilize Cu2+ in the structure as the second ligand, so the potential of copper deposition was negatively shifted and the (111) plane orientation was preferred.

Key words: 1-Hydroxyethylidene-1,1-diphosphonic acid, Copper deposits, Preferred orientation