As technology nodes continue to decrease, traditional Copper (Cu) interconnects in the back end of the line (BEOL) will encounter more and more problems. Ruthenium (Ru) is expected to be a barrier layer or even as a novel type of interconnection material because of its good electrical properties. However, because of its high chemical inertness, Ru is challenging to achieve a higher removal rate in the chemical mechanical polishing (CMP) process. In this study, the synergist effect of potassium periodate (KIO₄) and potassium persulfate (K₂S₂O₈) on the removal rate of Ru during CMP was investigated. The theory of advanced oxidation process (AOPs) is used to explain the reaction process of Ru with KIO₄ and K₂S₂O₈. X-ray photoelectron spectroscopy (XPS) combined with electrochemical are applied to explore the removal machanism and chemical reaction mechanism of Ru under the synergistic effect of KIO₄ and K₂S₂O₈. The CMP tests shows that the Ru removal rate (1123 Å/min) in the presence of KIO₄ and K₂S₂O₈ composite could be increased by more than 221% compared to the removal rate (507 Å/min) of KIO₄ alone. In addition, Ru oxidation process is more affected by diffusion-controlled. Excessive oxidant concentration will reduce the removal rate of Ru. The mechanism analysis shows that the RuO₃-activated persulfate generates sulfate radical (SO₄⁻•), which can further generate more oxides on the Ru surface, and Ru oxide is easily removed under the CMP process. Therefore, the Ru removal rate will be significantly improved. Simultaneously, the surface roughness Sq can be reduced to 0.667 nm after polishing.

随着技术节点的不断减少，线路后端（BEOL）中的传统铜（Cu）互连将遇到越来越多的问题。钌（Ru）由于其良好的电性能，有望成为阻挡层甚至是新型互连材料。然而，由于其化学惰性高，Ru在化学机械抛光（CMP）工艺中实现更高的去除速率具有挑战性。在这项研究中，研究了高碘酸钾（KIO ₄）和过硫酸钾（K ₂ S ₂ O ₈）对CMP过程中Ru去除率的协同作用。使用高级氧化过程（AOPs）的理论来解释Ru与KIO ₄和K的反应过程₂ S ₂ O ₈。利用X射线光电子能谱（XPS）结合电化学研究了在KIO ₄和K ₂ S ₂ O ₈协同作用下Ru的去除机理和化学反应机理。CMP测试表明，与KIO的去除率（507Å/ min）相比，在KIO ₄和K ₂ S ₂ O ₈复合材料存在下，Ru去除率（1123Å/ min）可以提高221％以上。₄单独。另外，Ru的氧化过程受扩散控制的影响更大。氧化剂浓度过高会降低Ru的去除率。该机制分析表明的RuO ₃活化过硫酸盐生成硫酸根（SO ₄ ^- •），其可以进一步生成钌表面上多种氧化物，和Ru氧化物容易在CMP工艺除去。因此，Ru去除率将显着提高。同时，可以在抛光后将表面粗糙度Sq减小到0.667nm。