WAFER LEVEL ELECTRODEPOSION OF Fe-Ni NOVEL UBM FILMS

Using customized wafer electroplating system, the electrodeposition process of Fe-Ni under bump metallization (UBM) thin film has been developed by modified Watts bath. The major factors which can affect the Fe content in the final UBM films, including the concentration of Fe 2+ , electrodeposition temperature and current density, were investigated systematically. The growth rate of Fe-Ni film under different electroplating conditions was measured in order to provide a reference for actual production. The microstructure and morphology of obtained Fe-Ni films were characterized by XRD and TEM. Multiple kinds of analytical methods including titration and inductive coupled plasma emission spectrometer (ICP) were used to monitor the content change of bath component under working or storage conditions. Regulations were put forward to maintain the bath daily including the keeping of the main salt content and the inhibition of Fe 3+ concentration.