Zhao Feng, Zhang Zhenyu, Deng Xingqiao, Feng Junyuan, Zhou Hongxiu, Liu Zhensong, Meng Fanning, Shi Chunjing
State Key Laboratory of High-performance Precision Manufacturing, Dalian University of Technology, Dalian 116024, China.
School of Mechanical and Electrical Engineering, Chengdu University of Technology, Chengdu 610059, China.
Nanoscale. 2024 Feb 1;16(5):2318-2336. doi: 10.1039/d3nr05278h.
Chemical mechanical polishing (CMP) is widely used to achieve an atomic surface globally, yet its cross-scale polishing mechanisms are elusive. Moreover, traditional CMP normally employs toxic and corrosive slurries, resulting in potential pollution to the environment. To overcome these challenges, a novel cross-scale model from the millimeter to nanometer scale is proposed, which was confirmed by a newly developed green CMP process. The developed CMP slurry consisted of hydrogen peroxide, sodium carbonate, sodium hydroxycellulose, and silica. Prior to CMP, fused silica was polished by a ceria slurry. After CMP, the surface roughness () was 0.126 nm, the material-removal rate was 88.3 nm min, and the thickness of the damaged layer was 8.8 nm. The proposed model was built by fibers, through integrating Eulerian and Lagrangian models and reactive force field-molecular dynamics. The results predicted by the model were in good agreement with those of CMP experimentally. A model for large-sized fibers revealed that a direct contact area of 11.12% was obtained for a non-woven polishing pad during the CMP experiments. Another model constructed combining Eulerian and Lagrangian functions showed that the stress at the intersections of the fibers varied mainly from 0.1 to 0.01 MPa and was higher than the stress at other parts. An increase in viscosity led to a decrease in the areas with low stress, demonstrating that viscosity enhanced the stress and facilitated the removal of material. At the microscale and nanoscale, the stress of the abrasive surface exposed to the workpiece changed from 2.21 to 6.43 GPa. Stress at the interface contributed to the formation of bridging bonds, further promoting the removal of material. With increasing the compressive stress, the material-removal form was transformed from a single atom to molecular chains. The proposed model and developed green CMP offer new insights to understand the cross-scale polishing mechanism, as well as for designing and manufacturing novel polishing slurries, pads, and setups.
化学机械抛光（CMP）被广泛用于在全球范围内获得原子级光滑表面，但其跨尺度抛光机制仍不清楚。此外，传统的CMP通常使用有毒且腐蚀性的研磨液，这会对环境造成潜在污染。为了克服这些挑战，提出了一种从毫米到纳米尺度的新型跨尺度模型，该模型通过新开发的绿色CMP工艺得到了证实。所开发的CMP研磨液由过氧化氢、碳酸钠、羟丙基甲基纤维素和二氧化硅组成。在进行CMP之前，先用氧化铈研磨液对熔融石英进行抛光。CMP之后，表面粗糙度为0.126纳米，材料去除率为88.3纳米/分钟，损伤层厚度为8.8纳米。所提出的模型是通过纤维构建的，整合了欧拉模型和拉格朗日模型以及反作用力场-分子动力学。该模型预测的结果与CMP实验结果吻合良好。一个针对大型纤维的模型表明，在CMP实验期间，非织造抛光垫的直接接触面积为11.12%。另一个结合欧拉函数和拉格朗日函数构建的模型表明，纤维交叉处的应力主要在0.1至0.01兆帕之间变化，且高于其他部位的应力。粘度的增加导致低应力区域减少，这表明粘度增强了应力并促进了材料去除。在微观和纳米尺度上，与工件接触的磨料表面应力从2.21吉帕变化到6.43吉帕。界面处的应力有助于形成桥连键，进一步促进材料去除。随着压缩应力的增加，材料去除形式从单个原子转变为分子链。所提出的模型和开发的绿色CMP为理解跨尺度抛光机制以及设计和制造新型研磨液、抛光垫和装置提供了新的见解。
