Copper Chemical Mechanical Polishing Performances of Polystyrene/Ceria Hybrid Abrasives with a Core/Shell Structure
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The core/shell structured hybrid abrasives, featuring polystyrene (PS, 280–300 nm in size) cores and ceria (CeO2, 10–20 nm in thickness) shells, were introduced into copper chemical mechanical polishing (CMP) processes. The slurry chemistry based on the synergy among glycine–hydrogen peroxide-benzotriazole was used in combination with the obtained polystyrene/ceria (PS/CeO2) abrasives. Moreover, the use of a medium/high-hardness pad (IC-1000) was compared to the use of a soft pad (MD-Chem). The copper CMP characteristics were evaluated in terms of material removal rate, surface roughness as well as cross-sectional profile analyses. After CMP with PS/CeO2 hybrids in combination with a soft pad, the average roughness of copper layer decreased from 1.89 to 0.56 nm, and a mean removal rate of 254 nm/min was achieved. With respect to conventional ceria particles, the PS/CeO2 hybrid abrasives contributed to the reduction of the mechanical damage and the number/depth of scratch/pit. The improved copper CMP performances might result from the reduced overall hardness and elastic modulus of PS/CeO2 hybrid particles. These experimental results revealed that the PS/CeO2 composite abrasives further presented potential CMP applications for mechanically challenging materials such as copper and low-k dielectrics.
KeywordsHybrid particle Core/shell structure Polystyrene Copper Chemical mechanical polishing
The work was supported financially by the National Natural Science Foundation of China (51405038, 51575058), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
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