Copper seed layer using atomic layer deposition for Cu interconnect

Cu has replaced Al for interconnection material in ultra large integrated circuit (ULSI), resulting in reducing the RC delay and achieving higher electro-migration reliability. However, it becomes more difficult to form reliable Cu wire as the feature size more decreases. For successful electrochemical plating (ECP) filling, continuous Cu seed layer with low resistivity and conformallity is essentially required. We have studied a Cu seed layer deposited using plasma enhanced atomic layer deposition (PE-ALD). The electrical property of sub-10 nm thickness Cu thin film was determined by the continuity and morphology of thin film. Based on these results, Cu seed layers were deposited on the 32 nm sized Ta/SiO₂ trench substrate, and ECP was performed under the conventional conditions. It was observed that the continuous seed layer was deposited using PE-ALD and the trench was perfectly filled.