Converting Ceria Polyhedral Nanoparticles into Single-Crystal Nanospheres
Xiangdong Feng,1*
Dean C. Sayle,2
Zhong Lin Wang,3,4,5*
M. Sharon Paras,6
Brian Santora,1
Anthony C. Sutorik,6
Thi X. T. Sayle,2
Yi Yang,1
Yong Ding,3
Xudong Wang,3
Yie-Shein Her1
Ceria nanoparticles are one of the key abrasive materials for
chemical-mechanical planarization of advanced integrated circuits.
However, ceria nanoparticles synthesized by existing techniques
are irregularly faceted, and they scratch the silicon wafers
and increase defect concentrations. We developed an approach
for large-scale synthesis of single-crystal ceria nanospheres
that can reduce the polishing defects by 80% and increase the
silica removal rate by 50%, facilitating precise and reliable
mass-manufacturing of chips for nanoelectronics. We doped the
ceria system with titanium, using flame temperatures that facilitate
crystallization of the ceria yet retain the titania in a molten
state. In conjunction with molecular dynamics simulation, we
show that under these conditions, the inner ceria core evolves
in a single-crystal spherical shape without faceting, because
throughout the crystallization it is completely encapsulated
by a molten 1- to 2-nanometer shell of titania that, in liquid
state, minimizes the surface energy. The principle demonstrated
here could be applied to other oxide systems.
2 Cranfield University, Defense Academy of the United Kingdom, Shrivenham, Swindon SN6 8LA, UK.
3 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332–0245, USA.
4 Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, 100871 Beijing, China.
5 National Center for Nanoscience and Technology, Beijing 100080, China.
6 Nanocerox, Inc., 712 State Circle, Ann Arbor, MI 48108, USA.
Present address: James Hardie Building Products, 10901 Elm Avenue, Fontana, CA 92337, USA.
* To whom correspondence should be addressed. E-mail: shawn.feng{at}jhresearchusa.com (X.D.F.); zhong.wang{at}mse.gatech.edu (Z.L.W.)
