Interaction mechanism of Al2O3 abrasive in tantalum chemical mechanical polishing

• Published in: RSC advances Vol. 14; no. 40; pp. 29559 - 29568
• Main Authors: Lei, Rui, Jiang, Liang, Zhang, Honglin, Chen, Yushan, Zheng, Jiaxin, Sun, Junhui, Zhao, Qijian, Qian, Linmao
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 12.09.2024; The Royal Society of Chemistry
• Subjects: Aluminum oxide; Chemical bonds; Chemical reactions; Chemical-mechanical polishing; Chemistry; Hydrogen peroxide; Material removal rate (machining); Silicon dioxide; Slurries; Stability; Tantalum
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d4ra03743j

Al2O3 abrasive is expected to enhance chemical mechanical polishing (CMP) efficiency compared to the SiO2 abrasive. However, Al2O3 powder has dispersion issues and the material removal mechanism by Al2O3 remains unclear. This study investigated the role of Al2O3 abrasive in the tantalum CMP. It is revealed that (NaPO3)6 can effectively disperse Al2O3 powder in water. PO3− improves the stability while Na+ deteriorates it. The total Na+ concentration should be lower than the turning point to attain high stability. With stable Al2O3-containing slurries, a relatively high material removal rate of tantalum can be obtained at an alkaline pH. The characterization results indicate that the Ta element can be adsorbed on Al2O3 probably due to the chemical interaction between Al2O3 and the tantalum surface. Moreover, the Al2O3 microsphere tip starts to remove tantalum at 0.48 GPa, which is much lower than the yield strength of the tantalum surface film. For the mechanism, tantalum can be oxidized by H2O2 at alkaline pH. When Al2O3 presses and slides on the tantalum surface, tribochemical reactions occur, forming a chemical bond of Al–O–Ta at the interface. As Al2O3 moves, the bond is stretched and tantalum is detached. The findings provide mechanistic insight into Al2O3 abrasive in CMP.