Superconformal Copper Electroplating on an Ultrathin Cobalt Seed in an Acidic Copper Sulfate Electrolyte
| Autor: | Y. Liu, L. J. Brogan, M. A. Rigsby, M. M. Huie, E. C. Opocensky, T. A. Spurlin, J. D. Reid |
|---|---|
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Journal of The Electrochemical Society. 169:082508 |
| ISSN: | 1945-7111 0013-4651 |
| DOI: | 10.1149/1945-7111/ac862d |
| Popis: | Cu electroplating on an ultrathin Co seed has been developed for superconformal filling of advanced interconnects, in an acidic CuSO4 electrolyte containing plating additives, i.e., halide, suppressor, accelerator, and leveler. A suppressor-halide adlayer is found to play a bifunctional role in both suppressing Cu growth and inhibiting Co dissolution. Corrosion inhibition is attributed to adsorption of hydrophobic suppressor molecules on a halide-terminated Co surface that blocks water from interacting with Co, thereby retarding the formation of Co(OH)+, a corrosion immediate with which hydronium from the electrolyte would react to form soluble Co2+. With enhanced suppression, Co loss is mainly confined to the removal of native Co oxides in acid. Correspondingly, galvanic Cu deposition forms a monolayer shortly after immersion at open-circuit potential, becoming self-limited with growth of a second layer over the next 20 s as dynamic surface processes make more underlying Co available for the displacement reaction. Growth of the first Cu layer is controlled by the receding of native oxides in an exponential-decay manner. Native Co oxides, if not removed, promote Cu protrusions in electroplating. The proposed process produces void-free fill on a 22 nm wide feature with a Co liner about 20 Å thick after fill. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|