Core–Shell Structured Silica Nanoparticles as Abrasive for Tungsten Chemical Mechanical Planarization

Core–shell structured silica nanoparticles with different sizes were successfully prepared by the reaction between tetramethoxysilane (TMOS) and the SiO₂ core under a mild condition. The obtained silica nanoparticles have a unique structure with tight cores and loose shells, which showed superior performance during tungsten (W) chemical mechanical planarization (CMP) process. The material removal rate (MRR) increased significantly from 763 to 1631 Å/min (with ~ 100 nm particles) while the surface roughness decreased from 1.802 to 1.252 nm. A series of characterization indicates that the superior performance of core–shell structured silica nanoparticles can be attributed to the formation of the irregular loose shell, increasing the mechanical friction during the W CMP process. Meanwhile, the loose shell structure can also contribute to the improvement of the wafer surface quality after CMP process. This work provides a new strategy for designing high-efficient abrasives for CMP process.

Graphical Abstract