Trace Metals Optimization in Ceria Abrasive for Material Removal Rate Enhancement during ILD CMP

Abstract

Ceria abrasive has been widely used in chemical mechanical planarization (CMP) to achieve a high material removal rate. To achieve optimum CMP performance, Ce3+ ions need to be generated on the ceria particle surface so they can react with SiO2. Based on the redox reaction, trace metals can be good candidates for forming the required ions. In this study, FeCl2 and CrCl2 trace metals with ceria were evaluated in terms of their CMP performance and effectiveness. The role of oxygen vacancies formed on the ceria surface using trace metals was experimentally investigated. Compared to FeCl2, CrCl2 exhibits better CMP performance. We observed that with the addition of CrCl2 trace metals in the ceria abrasive, the removal rate of SiO2 was enhanced by 1.3 times that of only ceria abrasive. Further, in the presence of CrCl2, the SiO2 wafer surface roughness was reduced from 0.473 nm to 0.390 nm.