Area-selective atomic layer deposition of Ru thin films by chemo-selective inhibition of alkyl aldehyde molecules on nitride surfaces

Abstract

Area-selective atomic layer deposition (AS-ALD) on pre-defined areas is of crucial importance nowadays in significantly reducing complexities associated with current top-down fabrication processes. In this work, we report the effects of surface modification using various alkyl aldehyde inhibitors with different chain lengths—hexanal, decanal, and undecanal—on nitride surfaces such as TiN and SiN to achieve AS-ALD. On the basis of density functional theory calculations and experimental analysis, including water contact angle and X-ray photoelectron spectroscopy, it is evident that aldehydes would chemo-selectively react with the –NH2 functional groups present on the nitride surfaces. Then, we further investigate their blocking ability against subsequent Ru ALD, a promising next-generation electrode material. It is worth noting that the Ru deposition thickness decreased by 4–10 nm with the presence of undecanal adsorbed on SiN and TiN substrates. Finally, we successfully demonstrate AS-ALD of Ru thin films over 8 nm on a patterned TiN/SiO2 substrate. These results hold potential for applications in bottom-up nanofabrication techniques for next-generation nanoelectronic applications. © 2024 Elsevier B.V.