Development of Planarity Improved Abrasive-Free Copper CMP Slurry and Practical Non-Selective Barrier CMP Slurry Based on Electrochemical Study

Abstract:
In order to reduce microscratches and obtain minimized dishing and erosion, we have developed new abrasive-free Cu CMP slurries through electrochemical study using rotary Cu disk electrode under pressure which will imitate CMP process intentionally. It was considered that the ratio of current density with pressure to that without pressures will be a promising guideline for designing an excellent abrasive free solution for excellent planarity. Based on these studies, new abrasive-free Cu CMP slurry with high removal rate and excellent planarity has been developed. For the second-step CMP, we have developed a slurry for barrier metal which has not only controllable selectivity but also corrosion improved based on electrochemical study. Whereas required selectivity was performed on blanket wafer, there are several planarity issues on a patterned wafer for example Cu protrusion, seam & fang and Cu corrosion. Through chemical optimization and the electrochemical study, practical non-selective barrier CMP slurry has been successfully developed.