Development of Zr- and Gd-doped porous ceria (pCeO(2)) abrasives for achieving high-quality and high-efficiency oxide chemical mechanical polishing

摘要

Porous ceria (pCeO(2)), Zr-doped pCeO(2) (pCeZrO(2)), and Gd-doped pCeO(2) (pCeGdO(2)) abrasives for both surface quality and removal rate improvements were developed using a facile one-pot solvothermal approach. The resulting products were characterized via XRD, SEM, TEM, HRTEM, Raman spectroscopy, UV-visible spectros-copy, and N-2 adsorption-desorption measurements. Raman spectra revealed that oxygen vacancies were the dominant defects in pCeO(2) nanospheres. Zr-and Gd-doping treatments contributed to oxygen vacancy enrichment, thus leading to an increased content of trivalent cerium (Ce3+) formed on the pCeO(2) surfaces. Oxide-CMP capability of pure pCeO(2), pCeZrO(2), and pCeGdO(2) abrasives were compared in terms of surface morphology/roughness/defect, topographical variation, as well as material removal rate (MRR). Atomic force microscopy and interferometric microscopy investigations showed that both pCeO(2), pCeZrO(2), and pCeGdO2 abrasives achieved high-quality surfaces with ultra-low roughness (0.11-0.14 nm Ra, 0.13-0.17 nm RMS). As expected, the MRR was accelerated by 78.7 in alkaline slurries containing pCeGdO(2) abrasives compared to the undoped pCeO(2). The improved CMP performance might be attributed to the reduced modulus, the expend pore size, as well as the enriched Ce3+ and oxygen vacancy. Furthermore, the interfacial action and removal mechanism of the pCeO(2) abrasives were discussed on the basis of their structure feature and surface chemistry.