Investigation of polyvinylpyrrolidone as an inhibitor for trench super-filling of cobalt electrodeposition

• Published in: Journal of the Taiwan Institute of Chemical Engineers 2020-07, Vol.112, p.232-239
• Main Authors: Ni, Xiuren, Chen, Yuanming, Jin, Xiaofeng, Wang, Chong, Huang, Yunzhong, Hong, Yan, Su, Xinhong, Zhou, Guoyun, Wang, Shouxu, He, Wei, Chen, Qingguo
• Format: Article
• Language: English
• Subjects: Cobalt electrodeposition; Suppressor; Trench filling
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2020.06.010

•PVP increases inhibition of cobalt deposition, and the inhibition is accelerated with existence of chloride ions.•chloride ion displays a certain synergistic effect with PVP to promote the suppression in cobalt electroplating and can make the adsorption of PVP more stable.•Quantum chemical calculations implied the amide group of PVP is the reaction site of suppression.•High aspect ratio trench filling was achieved by cobalt electro-deposition with PVP. Polyvinylpyrrolidone (PVP) is studied in this paper as an inhibitor of cobalt electrodeposition. The suppression effect of PVP was analyzed through electrochemical methods, including cyclic voltammetry (CV) and galvanostatic measurements (GM) tests. It is indicated that PVP effectively suppresses the electrodeposition of cobalt and chloride ion accelerates this suppression. Further experiments verify that PVP inhibits the deposition of cobalt through the adsorption on the electrode surface. Quantum chemical calculations were employed to calculate the molecular orbitals of PVP and the electrostatic potential (ESP) energy of the involved molecules. The simulation results imply that the amide group acts as the main electrophilic attack region and facilitates nucleophilic reactions to bond with cobalt. High aspect ratio trench filling on silicon wafer was achieved with the addition of PVP, which confirms that PVP is an applicable inhibitor for the practical electrodeposition of cobalt filling. The mechanism of cobalt trench filling was proposed to explain the role of PVP in the electroplating filling. Besides, crystalline and morphological characterizations reveal that PVP is able to inhibit the specific crystal growth of cobalt, especially the growth of 220 crystal plane, affect the crystal morphology of cobalt and improve surface compactness.