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Magnetic Materials for 3-D Damascene Metallization: Void-free Electrodeposition of Ni and Ni_(subscript 70)Fe_(subscript 30) Using 2-Mercapto-5-benzimidazolesulfonic Acid

Published

Author(s)

Chang H. Lee, John E. Bonevich, Thomas P. Moffat

Abstract

Superconformal filling of sub-micrometer trenches with Ni is demonstrated using NiSO_(subscript 4)-NiCl_(subscript 2)-FeSO_(subscript 4) electrolyte containing 2-mercapto-5-bensimidazolesulfonic acid (MBIS). The process offers the ability to build three dimensional magnetically active structures that may be easily integrated with other state-of-the art metallization schemes. MBIS acts to inhibit Ni(Fe) electrodeposition although under certain conditions rapid, autocatalytic breakdown accompanies the onset of Ni deposition. Optimal trench filling is associated with the positive feedback process, moderated by electrolyte iR losses, and manifests as a hysteretic voltammetric response on planar electrodes for MBIS concentration 100  mol/L/  On freshly immersed substrates, trench filling is characterized by an initial period of uniform growth followed by the development of a v-notch geometry associated with transient depletion of MBIS within the recessed feature. Interestingly, the finest sub-micrometer features are filled while only minimal deposition occurs on the neighboring free surface. Continued growth of the MBIS derived v-notch geometry also results in void-free filling of the larger features by geometrical leveling. The same behavior is observed for soft magnetic alloys such as Ni-rich Ni-Fe alloys. Preliminary experiments indicated that MBIS does not significantly perturb the low coercivity of Ni-Fe alloys, an important attribute for prospective technical applications.
Citation
Journal of the Electrochemical Society
Volume
155
Issue
7

Citation

Lee, C. , Bonevich, J. and Moffat, T. (2008), Magnetic Materials for 3-D Damascene Metallization: Void-free Electrodeposition of Ni and Ni_(subscript 70)Fe_(subscript 30) Using 2-Mercapto-5-benzimidazolesulfonic Acid, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/1.2907433 (Accessed March 4, 2024)
Created June 30, 2008, Updated October 12, 2021