Wang Ming, Duan Fangli
State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400044, China.
Langmuir. 2021 Feb 16;37(6):2161-2169. doi: 10.1021/acs.langmuir.0c03416. Epub 2021 Feb 2.
Reactive molecular dynamics (ReaxFF) simulations are performed to explore the atomistic mechanism of chemical mechanical polishing (CMP) processes on a Si(110) surface polished with an a-SiO particle. The Si surface is oxidized by reacting with water before the CMP process, and the O atoms of the oxidized Si surface mainly exist in the form of Si-O- dangling bonds and Si-O-Si bonds. In the CMP process, the insertion of O atoms into the surface, the formation of interfacial Si-O-Si and Si-Si bridge bonds, and the adsorption of H atoms on the surface-saturated Si atoms can all cause the surface bond breakage and even the Si atomic removal. The contributions of the four different kinds of tribochemical wear mechanisms to the surface wear decrease in turn and are much larger than that of mechanical wear. The results indicate that the material removal in the actual Si CMP process is the combined results of multiple atomic-level wear mechanisms. Furthermore, we find that the oxide layer of the Si surface plays an important role in the surface wear mainly by providing O atoms to insert into the surface, rather than by providing additional reaction pathways to form interfacial Si-O-Si bridge bonds. This work provides new and further insights into the process and mechanism of silicon removal during CMP.
进行反应分子动力学（ReaxFF）模拟，以探究用非晶硅颗粒抛光Si(110)表面的化学机械抛光（CMP）过程的原子机制。在CMP过程之前，Si表面通过与水反应被氧化，氧化Si表面的O原子主要以Si - O - 悬空键和Si - O - Si键的形式存在。在CMP过程中，O原子插入表面、界面Si - O - Si和Si - Si桥键的形成以及H原子在表面饱和Si原子上的吸附都可能导致表面键断裂，甚至Si原子去除。四种不同的摩擦化学磨损机制对表面磨损的贡献依次减小，且远大于机械磨损的贡献。结果表明，实际Si CMP过程中的材料去除是多种原子级磨损机制共同作用的结果。此外，我们发现Si表面的氧化层在表面磨损中起重要作用，主要是通过提供O原子插入表面，而不是通过提供额外的反应途径来形成界面Si - O - Si桥键。这项工作为CMP过程中硅去除的过程和机制提供了新的、更深入的见解。
