Review–On Epitaxial Electrodeposition of Co, Cu, and Ru for Interconnect Applications

Epitaxial electrodeposition of Co, Cu and Ru is compared and contrasted. The seed layer for electrodeposition of all three metals was an epitaxial Ru(0001) film that was deposited at an elevated temperature onto a sapphire(0001) substrate and annealed post deposition. The epitaxial orientation relationship of the electrodeposited film and the seed layer, the epitaxial misfit strain, the role of symmetry of the seed layer versus the electrodepositing layer is addressed. In addition, the impact of underpotential deposition on film nucleation, and the growth morphology of the films is discussed. It is shown that epitaxial electrodeposition of metallic films to thicknesses of tens of nanometers is readily achievable.

This paper 1189 was presented during the 241st Meeting of the Electrochemical Society, May 29–June 2, 2022.

Authors:
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Award ID(s):
Publication Date:
NSF-PAR ID:
10369852
Journal Name:
Journal of The Electrochemical Society
Volume:
169
Issue:
8
Page Range or eLocation-ID:
Article No. 082517
ISSN:
0013-4651
Publisher:
The Electrochemical Society
1. The electrodeposition of Ru was investigated from solutions of ruthenium(III) nitrosyl sulfate and ruthenium(III) chloride onto seed layers of epitaxial and polycrystalline Ru and epitaxial Au. Using both galvanostatic and potentiostatic deposition modes, metallic Ru was found to electrodeposit as a porous layer comprised of (0001) oriented Ru crystallites, the presence of which was discovered and confirmed by X-ray and scanning transmission and transmission electron microscope (S/TEM) analyses. This finding was independent of the Ru salt and seed layer used. Using X-ray reflectivity (XRR), the average film density$ρeff$of the porous electrodeposited Ru layer was measured as less than the density of bulk Ru$ρRu,bulk$(14.414 g cm−3). Increasing the magnitude of the applied current density from −100μA cm−2to −10 mA cm−2in solutions of Ru nitrosyl sulfate increased the$ρeff$from 7.4 g cm−3to 9.7 g cm−2while the current efficiency decreased from 9.4% to 4.3%.