(Invited) Effect of Gravitational Level on the Initial Stage of Cu Electrodeposition

Abstract

Material tailoring of nanostructured devices emphasizes the importance to separately control the nucleation rate from the growth process. It is indispensable to uniquely create the heterogeneous interface to result in the required electronic or physical properties. Then, the multi-scale modeling to link the atomic scale process on the heterogeneous interface with the shape evolution phenomena based on the continuous media process is required. It is well known that natural convection is accompanying with physicochemical reactions under ground level (1 G). Microgravity experiments are conducted over 10 s with JAMIC drop tower in order to understand the effect of gravitational level on electrodeposition as well as electrochemical dissolution. Less nucleation rate was observed in μ-G. On the other hand, a centrifugal field has been applied widely in order to create high G environment in electrochemical processing. Various differences in physical and chemical properties were found as well as morphological variations. The main purpose of this study is to clarify the effect of gravitational level from m-G to high G level on the coupling phenomena between the ionic mass transfer rate and the morphological variations of the electrodeposits. The possibility to control the nucleation phenomena, film morphology and nanostructure is explored. In particularly, the effects on the electrodeposited copper are analyzed in a cavity-type electrolytic cell from microgravity field in parabolic flight to high G field in centrifugal field. Cathode over anode configuration simulates the ionic mass transfer rate under quasi-microgravity environment because no macroscopic natural convection is induced in this cell configuration. Copper electrodeposition is conducted in order to examine the nucleation rate of copper on TiN substrate. The effects of cell configuration and gravitational level are focused on these phenomena.