Investigation of deplating behavior of Pt contact pins in semiconductor Cu electroplating process

In wet-contact Cu electroplating processes, the Pt contact pins are deposited with Cu films. In order to maintain the contact quality, the Pt contact pins should be deplated to remove extra Cu films. However, a deplating potential/current that is too large easily causes the water electrolysis reaction to generate micro bubbles, whereas a deplating potential/current that is too small results in inefficient Cu removal. In this study, an electrochemistry analysis system is employed to characterize the behavior of Pt deplating process. It was found that the correlation between deplating efficiency and potential is not linear due to the electric field distribution caused by the electrode resistance. Higher applied potential aggravates the uniformity of electric field distribution so that the effective deplating area decreases. Cu oxides also limit the deplating rate. Based on these results, the dissolution rate of Cu oxides is an important factor in deplating efficiency.