"These spherical, single-crystal Ti-doped CeO2 nanoparticles reduce CMP defects by 80% and increase the silica removal rate by 50%, which will facilitate precise and reliable mass-manufacturing of chips for microelectronics and nanoelectronics," ZL Wang of Georgia Institute of Technology, Peking University, China, and the National Center for Nanoscience and Technology, China, told nanotechweb.org.

Wang and colleagues from Ferro Corporation, US, Cranfield University, UK, Georgia Institute of Technology, US, and Nanocerox, US, made the nanoparticles by liquid-phase flame spray pyrolysis. They doped the ceria system with titanium and used flame temperatures that enabled crystallization of the ceria but kept the resulting titania molten.

"The inner CeO2 core evolves a single-crystal spherical-shape, without faceting, because throughout the crystallization it is completely encapsulated by a molten 1–2 nm shell of TiO2," said Wang. "In liquid state the TiO2 shell forms a spherical shape to minimize its surface energy."

The technique can produce up to 300 g of ceria nanoparticles per hour. The researchers believe they may be able to adapt the approach for other oxide systems. This could bring applications in photonics, magnetics, inorganic pigments, catalysis and other fields, in addition to CMP.

"CMP is used to isolate and connect individual transistors on a chip," said ZL Wang. "The CMP process has been the fastest-growing semiconductor operation in the last decade. Currently 60% of chips use CMP in their manufacturing and its future growth is expected to be equally explosive because of the introduction of copper-based interconnects in advanced microprocessors and other novel applications of CMP for next-generation nanoscale devices."

The spherical ceria nanoparticles are currently under evaluation in the CMP of next-generation chips. The team is now looking to boost the yield of the process and to produce monosize nanospheres.

The researchers reported their work in Science.