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

Abstract

Adsorption of the atomic layer deposition (ALD) precursor bis(N-tert-butyl-N′-ethylpropionamidinato) cobalt(II) (CoAMD) on SiO 2 , 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 SiO 2 and CDO, CoAMD chemisorbs on O containing moieties, primarily OH, to form Co 2+ . Accumulation of Co after three ALD cycles was greatest on Cu and least on CDO.

A State‐of‐the‐Art Heterogeneous Catalyst for Efficient and General Nitrile Hydrogenation

“…In particular, Co-N-C-700 displayed as ignal at 778.2 eV which is typical for cobalt in zero oxidations tate, while Co@MgO-700 showed signals at higherb inding energies (782.3 eV and 796.8 eV for Co2p3/2 and Co2p 1/2 ,r espectively) indicating oxidized Co species. [18] The material prepared with chitosan( Co-N-C(CH)@MgO-700) exhibited as imilarp attern to Co-N-C@MgO-700, whereas Co-N-C(CE)@MgO-700 prepared from cellulosed isplayed peaks slightly shiftedt owards lower binding energiesi ndicatingapossible reduction of Co II (Figure S5B). Deconvolution of the N1s regionf or Co-N-C@MgO-T revealed the presence of two signals at 398 eV (pyridinic nitrogen or Co-N x functionalities) and 400.8-401.2 eV (pyrrolic or graphitic Nc onfigurations) for each catalyst ( FigureS6a nd Figure 2D).…”

Surface Chemistry during Atomic-Layer Deposition of Nickel Sulfide from Nickel Amidinate and H2S

“…In situ XPS was first employed to study the surface chemistry during the ALD of NiS. XPS is highly sensitive to the surface chemical species and their valence/bonding states, and it could allow for directly monitoring the surface chemistry during ALD. ,− We first prepared the NiS substrates, in situ, by depositing 300 ALD cycles of NiS on flat SiO x /Si substrates at 200 °C. The SiO x /Si substrates were Si(100) wafer samples with native surface oxide, which were cleaned and subjected to heat treatment at 450 °C under vacuum for 4 h to completely remove any surface organic residue, as confirmed by XPS (Figure a).…”

Editors' Choice—Review—Cobalt Thin Films: Trends in Processing Technologies and Emerging Applications

“…Another emerging advantage of thermal Co ALD is its ability to enable or prevent area-specific or area-selective film growth, in what is commonly referred to as area-selective ALD. [59][60][61][62][63][64] Customized complexes (precursors) and surface assemblies or configurations can be made to react in a tightly controlled fashion so as to catalyze or inhibit Co deposition on specific areas of the underlying substrate surface, resulting in Co film formation only on the desired regions of the substrate. However, current ALD technologies suffer from high surface roughness and very limited growth rates (and thus low manufacturing throughput).…”

“…Elko-Hansen et al 61 examined area-selectivity in ALD Co using bis(N-t-butyl-N'-ethylpropionamidinato)Co (II) (CoAMD) (Co-209) and H 2 as co-reactant at a substrate temperature of 265 • C on Cu, SiO 2 and porous low-k (k∼2.6) C-doped oxide (CDO). Adsorption studies showed that Co growth occurred most preferentially on Cu and least preferentially on CDO, and that, similarly to other amidinate precursors, CoAMD (Co-209) readily dissociated on transition metal surfaces such as Cu via a complex dissociative chemisorption mechanism.…”