XPS Investigation of the Atomic Layer Deposition Half Reactions of Bis(N-tert-butyl-N′-ethylpropionamidinato) Cobalt(II)

Adsorption of the atomic layer deposition (ALD) precursor bis(N-tert-butyl-N'-ethylpropionamidinato) cobalt(II) (CoAMD) on SiO2, carbon-doped oxide (CDO), and Cu is reported. Adsorption was performed under ALD cycling conditions with and without H-2 coreactant to mimic the first and second ALD half reactions on the substrates. Resultant surface chemistries were evaluated by X-ray photoelectron spectroscopy. Adsorption of CoAMD proved self-limiting and the precursor reduced readily on Cu with and without H-2 coreactant to form Co-0. Residual C and N signals on Cu suggest that amidinate ligands and decomposition fragments from CoAMD adsorb on the Cu surface. On SiO2 and CDO, CoAMD chemisorbs on O containing moieties, primarily OH, to form Co2+. Accumulation of Co after three ALD cycles was greatest on Cu and least on CDO.