Scratch-free dielectric CMP slurry with 5-nm colloidal ceria abrasive

We present a novel polishing slurry with 5-rmu colloidal ceria abrasive. The new slurry exhibited a high oxide removal rate even at the low abrasive concentrations and superior performance in reducing micro scratches. We developed a practical polishing process using the new slurry, where a soft pad is used for fast pattern polishing and a hard pad with polymer additives is used for planarization. We fabricated STI and low-capacitance interconnect structures with remarkably improved quality.