Preparation of three-dimensional dendritic-like mesoporous silica particles and their pore size-dependent polishing behavior and mechanism
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The type and structure of abrasive particles play a key role in the involved friction and wear processes during chemical mechanical polishing (CMP). This work aims to develop silica-based abrasives that improve both surface finish and removal rate. The uniform, three-dimensional, and dendritic-like mesoporous silica (D-mSiO2) spheres with sub-100 nm size were synthesized in a heterogeneous oil–water biphase reaction system. The pore size of 3D-dendritic channels could be adjusted by regulating hydrophobic solvents in the upper oil phase. The improvements of root-mean-square roughness (0.18–0.26 nm) and removal rate (192–260 nm/min) were achieved for the D-mSiO2 particles compared to colloidal silica abrasives (0.37 nm, 112 nm/min). A reduction from 2.90 to 0.48 and 2.60 to 0.42 nm for the maximum asperity height and the maximum valley depth respectively was also observed after CMP with D-mSiO2 abrasives. Furthermore, the D-mSiO2 particles with an enlarged pore size achieved a reduced surface roughness and an enhanced removal rate. The improved polishing performance may be attributed to the enlarged real contact area, the promoted tribo-chemical wear, and the enhanced adhesion effect between particles and surfaces. The contact area mechanism and the contact-penetration-adhesion model may be predominant and significant for D-mSiO2 abrasives, rather than the traditional the indentation-based mechanism and the indentation-sliding model. The unique three-dimensional mesopores of D-mSiO2 abrasives are expected to play key role in material removal processes, and it will have more hopeful prospects in CMP performance improvements.
KeywordsMesoporous silica 3D-dendritic silica Pore size Particle abrasive Chemical mechanical polishing Mechanism
The project is supported by National Natural Science Foundation of China (Grant Nos. 51405038, 51575058, 51875052), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
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Conflict of interest
The authors declare no conflict of interest.
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