Abstract: Electrochemical mechanical planarization (ECMP) is considered as one of the most potential planarizaiton techniques for Cu/low-k surface with low strength, and the transport of the electrolyte solution and contact pressure distribution are the two dominated factors for improving efficiency and profile accuracy of ECMP. Mixed soft elastohydrodynamic lubrication model is used to simulate the flow and contact behaviors on the surface of ECMP pad with conducting hole. For the pad analyzed here, the results show that the local contact pressure, which directly affects the surface integrity of Cu/low-k structure, is around 70 kPa, although, the mean value is only 6.895 kPa. Moreover, from the results considering different position of the conducting holes, no significant differences are observed in the distribution of electrolyte solution pressure and contact pressure, the orientation of wafer is also without obvious change. Therefore, in order to improve the uniformity of the contact pressure and increase the machining efficiency and profile accuracy of ECMP, beside the research on the distribution of the conducting hole, the pad and wafer carrier also should be studied and improved further. The simulation approach of mixed soft elastohydrodynamic lubrication behavior of ECMP pad and the conclusion obtained here is helpful to the development of ECMP technique.

Key words: Elastohydrodynamic lubrication, Electrochemical mechanical planarization(ECMP), Rough surface