Electrochemical and Frictional Behaviors of Cu Surface in Organic Acid Based Slurries During Copper CMP

摘要

Copper CMP process is widely researched for the next generation of interconnection because of lower electrical resistivity of copper compared with aluminum and higher resistance to electro-migration [1]. During CMP process, Cu surface was chemically removed by the etching of chemicals in slurry and mechanically removed by abrasive particles and CMP pads. Generally, the removal rate of surface is expressed by the Preston equation, which is, removal rate (R) is dependent on the Preston coefficient (Kp), the applied pressure (P) and linear velocity (V) between pad and surface [2]. During Cu CMP, mechanical abrasion is strongly dependent on the applied pressure and linear velocity. The other hand, Preston coefficient mainly includes chemical parameters such as slurry composition, abrasive types and additives in slurry. The chemical and mechanical removal mechanisms of Cu are very important to obtain the suitable removal rate of Cu. In this study, the removal rates of Cu surfaces were evaluated in terms of frictional and electrochemical aspects. Also, the surface properties of Cu were characterized in Cu CMP slurries containing various additives.