Erratum: “Formation and desorption of nickel hexafluoroacetylacetonate Ni(hfac)2 on a nickel oxide surface in atomic layer etching processes” [J. Vac. Sci. Technol. A 38, 052602 (2020)]

HfO2 is a high-k material that is used in semiconductor devices. Atomic-level control of material processing is required for the fabrication of thin films of high-k materials at nanoscale device sizes. Thermal atomic layer etching (ALE) of metal oxides, in which up to one monolayer of material can be removed, can be achieved by sequential self-limiting (SL) fluorination and ligand-exchange reactions at elevated temperatures. First-principles based atomic-level simulations using density functional theory (DFT) can give deep insights into the precursor chemistry and the reactions that drive the etch of metal oxides. A previous study examined the hydrogen fluoride (HF) pulse in the first step in the thermal ALE process of crystalline HfO2 and ZrO2. This study examines the HF pulse on amorphous HfO2 using first-principles simulations. The Natarajan-Elliott analysis, a thermodynamic methodology is used to compare reaction models representing the self-limiting and spontaneous etch processes taking place during an ALE pulse. For the HF pulse on amorphous HfO2, we found that thermodynamic barriers impeding spontaneous etching are present at ALE relevant temperatures. HF adsorption calculations on the amorphous oxide surface is studied to understand the mechanistic details of the HF pulse. A HF molecule adsorbs dissociatively by forming Hf-F and O-H bonds. HF coverages ranging from 1.1 ± 0.3 to 18.0 ± 0.3 HF/nm2 are investigated and a mixture of molecularly and dissociatively adsorbed HF molecules is present at higher coverages. A theoretical etch rate of -0.82 ± 0.02 Å/cycle for amorphous HfO2 was calculated using a maximum coverage of 9.0 ± 0.3 Hf-F/nm2. This theoretical etch rate is greater than the theoretical etch rate for crystalline HfO2 that we previously calculated at -0.61 ± 0.02 Å/cycle. Undercoordinated atoms and void regions in amorphous HfO2 allows for more binding sites during fluorination whereas crystalline HfO2 has a limited number of adsorption sites.

Download Full-text

Molecular dynamics simulation of atomic layer etching of silicon

Journal of Vacuum Science & Technology A Vacuum Surfaces and Films ◽

10.1116/1.579659 ◽

1995 ◽

Vol 13 (3) ◽

pp. 966-971 ◽

Cited By ~ 70

Author(s):

Satish D. Athavale ◽

Demetre J. Economou

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Atomic Layer ◽

Dynamics Simulation ◽

Atomic Layer Etching

Download Full-text

Atomic Layer Deposition of Ni-Co-O Thin-Film Electrodes for Solid-State LIBs and the Influence of Chemical Composition on Overcapacity

Nanomaterials ◽

10.3390/nano11040907 ◽

2021 ◽

Vol 11 (4) ◽

pp. 907

Author(s):

Yury Koshtyal ◽

Ilya Mitrofanov ◽

Denis Nazarov ◽

Oleg Medvedev ◽

Artem Kim ◽

...

Keyword(s):

Chemical Composition ◽

Atomic Layer Deposition ◽

Nickel Oxide ◽

Cobalt Oxide ◽

Lithium Ion ◽

Atomic Layer ◽

Metallic Nickel ◽

Uniform Density ◽

Oxide Content ◽

Layer Deposition

Nanostructured metal oxides (MOs) demonstrate good electrochemical properties and are regarded as promising anode materials for high-performance lithium-ion batteries (LIBs). The capacity of nickel-cobalt oxides-based materials is among the highest for binary transition metals oxide (TMOs). In the present paper, we report the investigation of Ni-Co-O (NCO) thin films obtained by atomic layer deposition (ALD) using nickel and cobalt metallocenes in a combination with oxygen plasma. The formation of NCO films with different ratios of Ni and Co was provided by ALD cycles leading to the formation of nickel oxide (a) and cobalt oxide (b) in one supercycle (linear combination of a and b cycles). The film thickness was set by the number of supercycles. The synthesized films had a uniform chemical composition over the depth with an admixture of metallic nickel and carbon up to 4 at.%. All samples were characterized by a single NixCo1-xO phase with a cubic face-centered lattice and a uniform density. The surface of the NCO films was uniform, with rare inclusions of nanoparticles 15–30 nm in diameter. The growth rates of all films on steel were higher than those on silicon substrates, and this difference increased with increasing cobalt concentration in the films. In this paper, we propose a method for processing cyclic voltammetry curves for revealing the influence of individual components (nickel oxide, cobalt oxide and solid electrolyte interface—SEI) on the electrochemical capacity. The initial capacity of NCO films was augmented with an increase of nickel oxide content.

Download Full-text