CHARACTERIZATION OF CU CHEMICAL-MECHANICAL POLISHING BY ELECTROCHEMICAL INVESTIGATIONS

In order to investigate the chemical etching and passivating effects o f Cu in the polishing slurry and to give some insights of the polishin g process itself, the influence of the oxidizing agent (H2O2) was stud ied. The interaction between the Cu surface and the slurry was investi gated by potentiodynamic measurements applied during the polishing pro cess as well as under static conditions. It was shown that with increa sing H2O2 concentration the wet etch rate and also the polish rate of Cu decreases. That can be explained by changes in the structure of the passivating layer and the dominating role of the dynamic repassivatio n during polishing. In addition, W-TI used as a barrier/adhesion layer in Cu chemical mechanical polishing (CMP) was also investigated in te rms of electrochemical interaction with the polishing slurry and Cu. T he observed acceleration of the W-Ti polish rate in the presence of Cu ions is caused by the galvanic interaction between Cu and W-Ti.