(Invited) Chemistry Effects on the Electrodeposition of Re, Co, and Alloys

Abstract

Electrodeposition has been adopted in various metallization processes. It allows conformal and super-conformal deposition on curved and recessed substrates, enables the fabrication of metals and alloys with well controlled composition, impurity, and grain structure, and provides fast growth rate, high throughput, and low cost of ownership. Organic additives have been used in electrolytes to tune not only the growth behavior, but also the impurity and grain structure of the deposited material. The most well-known cases are those used for magnetic alloy plating[1,2] in storage and MEMS industry and for damascene copper plating[3,4] in microelectronic industry. On the other hand, the electrolyte itself has largely remained aqueous for most cases. Organic solvents, room temperature ionic liquids, and deep eutectic systems have been widely studied with, however, relatively limited success in large scale adoption.The first part of this talk will introduce some studies on the electrodeposition of Cobalt as an alternative metal for semiconductor interconnect applications. Organic additives that tailor the deposition rate of cobalt are used to enable the Co filling in sub-micron structures. The effect of such additives on the impurity incorporation and film grain structure will be discussed. The second part of the talk will discuss some recent studies on the electrodeposition from “water-in-salt” electrolytes, where the hydration of a super high concentration of supporting salt depletes the free water molecules in the aqueous solution, thus limiting the hydrogen evolution reaction. The discussion will be in a context of Re and ReCo alloy deposition for superconducting connector applications for quantum devices. REFERENCES T. Osaka, M. Takai, K. Hayashi, K. Ohashi, M. Saito, and K. Yamada, A soft magnetic CoNiFe film with high saturation magnetic flux density and low coercivity, Nature, 1998, 392(6678), 796. E.I. Cooper, C. Bonhôte, J. Heidmann, Y. Hsu, P. Kern, J.W. Lam, M. Ramasubramanian, N. Robertson, L.T. Romankiw, and H. Xu, Recent developments in high-moment electroplated materials for recording heads, IBM Journal of Research and Development, 2005, 49(1), 103. P. Andricacos, C. Uzoh, J. Dukovic, J. Horkans, and H. Deligianni, Damascene copper electroplating for chip interconnections, IBM Journal of Research and Development, 1998, 42(5), 567. T.P. Moffat, J.E. Bonevich, W.H. Huber, A. Stanishevsky, D.R. Kelly, G.R. Stafford, and D. Josell, Superconformal Electrodeposition of Copper in 500–90 nm Features, Journal of The Electrochemical Society, 2000, 147, 4524.