Synthesis of Silica-Coated Ceria Particles for STI-CMP in a Single Step by Flame Spray Pyrolysis with an Emulsion

Abstract

Silica-coated ceria particles for STI-CMP (Shallow Trench Isolation Chemical Mechanical Planarization) were prepared in a single step by using a modified flame spray pyrolysis with an emulsion precursor solution. The prepared particles were characterized by using TEM and zeta potential measurement. The isoelectric points (IEPs) of the silica-coated ceria particles are decreased with increasing the amount of silica coating and approach to two, which is IEP of silica. This result macroscopically confirms that silica is reasonably coated on the ceria surface. TEM analysis also supports that the silica layer is indeed formed on ceria particle and the thickness is around 5 nm. The silica-coated ceria suspension was found to have lower viscosity compared with the bare ceria suspension. Therefore, dispersibility of CMP suspension is expected to be enhanced at the expense of decreased polishing rate. However, it is decreased by only 6.5% compared with the polishing rate of bare ceria when 5 wt % of silica is coated on ceria. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3597615] All rights reserved.