Study on Effects of Slurry Key Factors on Advanced Oxide CMP Performance

With the advancement of technology nodes, the demands on oxide CMP have become more stringent. Defectivity, rate, profile, selectivity to various films (in special applications), planarization efficiency, process window, as well as costs, are the main considerations in an advanced oxide CMP process. Polishing rate and profile tuning by slurry formulations are challenging in certain silica based slurry systems. In this paper, various designed, novel additives are explored to enhance oxide CMP performance. The effects of key factors including abrasive types, chemistry, and pH range on within wafer non-uniformity, especially on the wafer edge rate drop, have been studied. The results indicated that a controlled removal rate and desired wafer edge profile can be achieved through the optimum combination of functional chemistry compositions, abrasive type and properties, and pH. A number of possible mechanisms will also be discussed.