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Research on weakly alkaline bulk slurries relevant to chemical mechanical polishing for cobalt interconnects

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Abstract

Recently, the technology node shrunk below 7 nm and beyond; cobalt (Co) and its low resistivity, superior adhesion property, and excellent electro-migration performance pledge to transform the integrated circuits’ landscape in several areas, especially in interconnects and logic contacts. The present work proposes a weakly alkaline polishing slurry for Co interconnects, mainly consisting of colloidal silica, hydrogen peroxide, glycine, and 1,2,4-triazole at pH 8.1. The feature of tunable high material removal rate (greater than 1000–2000 Å/min) and fitting removal selectivity (~ 160) between Co and oxide dielectric could be realized by a moderately variable concentration of glycine complexing agent. Moreover, several analytical techniques, including electrochemical analysis, X-ray photoelectron spectroscopy survey, and adsorption isotherm characterization, were used to understand the interaction mechanism during Co material removal process. The results reveal that 1,2,4-triazole could adsorb on the Co oxide layers via physisorption, achieving an inhibition effect to avoid Co excessive corrosion. Furthermore, the oxidization of hydrogen peroxide, the complexation of glycine zwitterions, and the abrasive mechanical action are critical to maintaining the appropriate material removal rate. Based on the results with research-level wafers, the optimized Co bulk slurry was ultimately applied to the production-level of Co and oxide dielectric wafers. The residual particle, haze condition, and surface profile after polishing have been researched simultaneously.

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Data availability

The datasets generated and/or analyzed during the current study are available from the first author on reasonable request.

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The authors are thankful to the editors and reviewers.

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Authors and Affiliations

  1. State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China

    Lifei Zhang, Tongqing Wang & Xinchun Lu

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  1. Lifei Zhang
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  2. Tongqing Wang
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Contributions

Lifei Zhang contributed to the study conception, design, material preparation, data collection and data analysis. The first draft of the manuscript was written by Lifei Zhang, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Xinchun Lu.

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Zhang, L., Wang, T. & Lu, X. Research on weakly alkaline bulk slurries relevant to chemical mechanical polishing for cobalt interconnects. Int J Adv Manuf Technol 125, 4549–4559 (2023). https://doi.org/10.1007/s00170-023-10824-4

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