| TIAN Qi-yuan,WANG Sheng-li,XIAO Yue,WANG Chen-wei,LIU Feng-xia,LIANG Ting-wei.Component Optimization of Polishing Slurry on Chemical Mechanical Planarization of Cobalt Contact[J],47(9):272-278 |
| Component Optimization of Polishing Slurry on Chemical Mechanical Planarization of Cobalt Contact |
| Received:May 17, 2018 Revised:September 20, 2018 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2018.09.036 |
| KeyWord:cobalt contact chemical-mechanical polishing removal rate removal selection ratio of Co/Ti electrochemical |
| Author | Institution |
| TIAN Qi-yuan |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
| WANG Sheng-li |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
| XIAO Yue |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
| WANG Chen-wei |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
| LIU Feng-xia |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
| LIANG Ting-wei |
School of Electronic Information Engineering, Hebei University of Technology, Tianjin , China |
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| Abstract: |
| The work aims to improve removal rate of Co and removal selection ratio of Co/Ti in global chemical mechanical polishing process of Very Large Scale Integration Circuit (VLSI), and describe removal mechanism of Co in detail. The effects of different concentrations of abrasives, polyhydroxypolyamine complexing agents (FA/O II) and oxidants, and different pH values on cobalt removal rate were studied. The mechanism of high Co removal rate was revealed by performing electrochemical experiments and surface chemical element analysis (XPS), and surface morphology of cobalt before and after polishing was observed by atomic force microscope (AFM). Optimum distribution ratio of polishing slurry was detected by performing orthogonal experiment. The removal rate of cobalt increased as the concentration of abrasive increased, and decreased as pH value increased. As oxidant concentration increased, removal rate of cobalt increased while removal selection ratio of Co/Ti firstly increased and then decreased. As the concentration of chelating agent increased, both removal rate of cobalt and removal selection ratio of Co/Ti firstly increased and then decreased. The orthogonal test found that the optimum distribution ratio of polishing slurry (3% abrasive, 20 mL/L polyamine chelating agent (FA/O II) and 5 mL/L oxidant (H2O2), pH=8) realized high removal rate of cobalt (~500 nm/min) and better removal selection ratio of Co/Ti (100:1). Besides, the planarization effect of surface was obviously improved. Atomic force microscope test results showed that Co surface roughness changed from 3.14 nm to 0.637 nm. The weakly alkaline polishing slurry can effectively improve removal rate of cobalt and ensure that corrosion is controllable. The combination of H2O2 and FA/O II in the polishing slurry could significantly improve polishing rate of cobalt and removal selection ratio of Co/Ti. It can be attributed to the strong complexation reaction on the surface of Co which results in the formation of the easily removable water-soluble complex. |
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