Cu ECMP 공정에서 전해액이 연마거동에 미치는 영향

Abstract

The purpose of this study is to characterize various electrolytes on electrochemical mechanical planarization (ECMP). The ECMP system was modified from conventional CMP system to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat for the evaluation of the polishing behavior on ECMP. KOH (alkaline) and NaNO3 (salt) were selected as electrolytes which have high conductivity. In static and dynamic states, the corrosion potential decreased and the corrosion current increased as a function of the electrolyte concentration. But, the electrochemical reaction was prevented by mechanical polishing effect in the dynamic state. The static etch and removal rate were measured as functions of concentration and applied voltage. When NaNO₃was used, the dissolution was much faster than that of KOH. It was concluded that the removal rate was strongly depended on electrochemical dissolution. The removal rate increased up to 350nm/min in NaNO₃based electrolyte.