Atomic layer deposition of Ru onto organic monolayers: Shifting metal effective work function using monolayer structure

Organic thin films are integrated with metal atomic layer deposition metallization to adjust and tune the electronic properties of metal/dielectric junctions. Specifically, 3-aminopropyltriethoxysilane (APTES) and undecenyltrichlorosilane (UDTS) self-assembled monolayers on hafnia-based dielectrics produce a shift in the effective work function of ruthenium metal deposited by atomic layer deposition at 325 degrees C onto the monolayer/oxide heterostructure. Based on infrared analysis, the molecular monolayer is relatively stable upon heating above 300 degrees C. The effective work function extracted from measurements of flat band voltage versus oxide thickness shift by +0.1 and -0.6 V when the metal is deposited on APTES and UDTS, respectively, consistent with expected organic interface dipoles on the dielectric surface. Results suggest various nucleation mechanisms for ALD growth on organic monolayers, and demonstrate that low temperature ALD is useful for metallization of organic modified surfaces for a range of applications. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3671938]