Nd-doped porous CeO2 abrasives for chemical mechanical polishing of SiO2 films

Chemical mechanical polishing (CMP) is a crucial step in integrated circuit manufacturing, and as chip feature sizes continue to shrink, there is an escalating demand for improved polishing performance. In this study, monodisperse porous CeO2 nanospheres were synthesized and then modified through Nd doping. The structural and chemical characterization confirmed the enrichment effect on surface defects (Ce3+ and oxygen vacancies) due to the doping, with the percentage of Ce3+ in pCeO2-Nd materials (39%) being higher than that of pCeO2 (31%). Furthermore, for the CMP application on silicon wafers, the material removal rate (MRR) of pCeO2-Nd reached 126.3 +/- 17.5 nm/min, which is a 56% improvement over that of pCeO2. In addition, the surface roughness (Ra) of the localized area (3 x 3 mu m2) was reduced from initially 0.813 +/- 0.02 nm to 0.296 +/- 0.02 nm after polishing with pCeO2. The chemical bonding of Ce-O-Si is considered to be the bridge between the structural characteristics of the abrasive and the polishing properties, whose presence makes the CMP process more efficient and high-quality.