Ruthenium CMP에서 Cerium Ammonium Nitrate와알루미나 연마 입자가 연마 거동에 미치는 영향

Abstract

Cerium ammonium nitrate (CAN) and nitric acid was used an etchant and an additive for Ru etching and polishing. pH and Eh values of the CAN and nitric acid added chemical solution satisfied the Ru etching condition. The etch rate increased linearly as the concentration of CAN increased. Nitric acid added solution had the high etch rate. But micro roughness of etched surfaces was not changed before and after etching. The removal rate of Ru film was the highest in 1 wt% abrasive added slurry, and not increased despite the concentration of alumina abrasive increased to 5 wt%. Even Ru film was polished by only CAN solution due to the friction. The highest removal rate of 120 nm/min was obtained in 1 M nitric acid and 1 wt% alumina abrasive particles added slurry. The lowest micro roughness value was observed in this slurry after polishing. From the XPS analysis of etched Ru surface, oxide layer was founded on the etched Ru surface. Therefore, Ru was polished by chemical etching of CAN solution and oxide layer abrasion by abrasive particles. From the result of removal rate without abrasive particle, the etching of CAN solution is more dominant to the Ru CMP.