Classification of processes for the atomic layer deposition of metals based on mechanistic information from density functional theory calculations

Abstract

Original citationElliott Reaction cycles for the atomic layer deposition (ALD) of metals are presented, based on the incomplete data that exist about their chemical mechanisms, particularly from density functional theory (DFT) calculations. ALD requires self-limiting adsorption of each precursor, which results from exhaustion of adsorbates from previous ALD pulses and possibly from inactivation of the substrate through adsorption itself. Where the latter reaction does not take place, an "abbreviated cycle" still gives self-limiting ALD, but at a much reduced rate of deposition. Here, for example, ALD growth rates are estimated for abbreviated cycles in H 2 -based ALD of metals. A wide variety of other processes for the ALD of metals are also outlined and then classified according to which a reagent supplies electrons for reduction of the metal. Detailed results on computing the mechanism of copper ALD by transmetallation are summarized and shown to be consistent with experimental growth rates. Potential routes to the ALD of other transition metals by using complexes of non-innocent diazadienyl ligands as metal sources are also evaluated using DFT. Published by AIP Publishing.

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

“…Elliott et al 7 performed a multi-phase theoretical study of the underlying mechanisms in ALD Co from t-Bu-allyl)Co(CO) 3 (Co-108) and zero-valent Co complexes containing "non-innocent" ligands such as the diazadienyl molecules tBu 2 DAD (Co-208) and Me 2 DAD (C 4 H 8 N 2 ). Employing mechanistic information from density functional theory calculations for shortened cycles of precursor interactions with co-reactants such as H 2 , the authors investigated how ligands can be cleanly eliminated to yield pure Co, as well as what effects side-reactions could have on the incorporation of impurities (such as C) and other unwanted products (such as CoO).…”

Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

“…Density functional theory (DFT) calculations have successfully applied to reveal the reaction mechanism of O-plasma in PE-ALD. [40][41][42] However, limited theoretical studies are available that discuss N-plasma PE-ALD. 43 Delabie et al 44,45 have simulated the ALD of Ru on Ru surfaces focusing on Ru precursor reactions with bare Ru surface and H-terminated Ru surfaces.…”

Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

“…Density functional theory (DFT) calculations have successfully applied to reveal the reaction mechanism of O-plasma in PE-ALD. [40][41][42] However, limited theoretical studies are available that discuss N-plasma PE-ALD. 43 Delabie et al 44,45 have simulated the ALD of Ru on Ru 5 surfaces focusing on Ru precursor reactions with bare Ru surface and H-terminated Ru surfaces.…”