<i>In situ</i> XPS study on atomic layer etching of Fe thin film using Cl2 and acetylacetone

Lin, Xi; Chen, Meixi; Janotti, Anderson; Opila, R. L.

doi:10.1116/1.5039517

Cited by 22 publications

(26 citation statements)

References 54 publications

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“…24 A mixed Cl-containing compound was also proposed as a possible desorbing product in ALE of chlorinated iron surface. 25 Thus, the role of mixed Co 3+ -containing metalorganic species in ALE processes may need to be explored further.…”

Section: Thermal Desorption Investigationsmentioning

confidence: 99%

Molecular mechanisms of atomic layer etching of cobalt with sequential exposure to molecular chlorine and diketones

Konh

Lin

et al. 2019

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The mechanism of thermal dry etching of cobalt films is discussed for a thermal process utilizing sequential exposures to chlorine gas and a diketone [either 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (hexafluoroacetylacetone, hfacH) or 2,4-pentanedione (acetylacetone, acacH)]. The process can be optimized experimentally to approach atomic layer etching (ALE); a sequential exposure to Cl 2 and hfacH dry etchants at 140°C is shown to proceed efficiently. The use of acacH as a diketone does not result in ALE with chlorine even at 180°C, but the decrease of surface chlorine concentration and chemical reduction of cobalt is noted. However, thermal desorption analysis suggests that the reaction of chlorinated cobalt surface exposed to the ambient conditions (oxidized) with hfacH does produce volatile Co-containing products within the desired temperature range and the products contain Co 3+. The effect of adsorption of ligands on the energy required to remove surface cobalt atoms is evaluated using the density functional theory.

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Section: Thermal Desorption Investigationsmentioning

confidence: 99%

Molecular mechanisms of atomic layer etching of cobalt with sequential exposure to molecular chlorine and diketones

Konh

Lin

et al. 2019

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…In 2018, Lin et al published the etching of Fe by alternately reacting chlorine and acetylacetone (acac) to form volatile metal complexes at low temperatures [146]. The whole Fe ALE process is shown in Figure 11.…”

Section: Signal Element Metalsmentioning

confidence: 99%

“…The gases A and B are a halogen precursor Cl 2 and an organic precursor acetylacetone (acac). Reprint with permission from Ref [146]…”

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confidence: 99%

Recent Progress of Atomic Layer Technology in Spintronics: Mechanism, Materials and Prospects

Tsai

2022

Nanomaterials

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The atomic layer technique is generating a lot of excitement and study due to its profound physics and enormous potential in device fabrication. This article reviews current developments in atomic layer technology for spintronics, including atomic layer deposition (ALD) and atomic layer etching (ALE). To begin, we introduce the main atomic layer deposition techniques. Then, in a brief review, we discuss ALE technology for insulators, semiconductors, metals, and newly created two-dimensional van der Waals materials. Additionally, we compare the critical factors learned from ALD to constructing ALE technology. Finally, we discuss the future prospects and challenges of atomic layer technology in the field of spinronics.

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“…The majority of current ALE approaches to fabricate thin films of magnetic metals are based on a two-step scheme, where the first step is kinetically controlled formation of metal oxides, , nitrides, , or chlorides. − The second step is then based on a selective self-limiting reaction of the produced activated layer with the co-reactant, often delivering an organic ligand that can form a volatile metal-containing compound. If the metal-containing products are volatile and thermally stable, they can be removed by simply controlling the process temperature.…”

Section: Introductionmentioning

confidence: 99%

Molecular Mechanism of Thermal Dry Etching of Iron in a Two-Step Atomic Layer Etching Process: Chlorination Followed by Exposure to Acetylacetone

2021

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Controlling thickness and morphology of transition-metal thin films used in magnetic random-access memory fabrication is a major challenge. Thermal dry etching has emerged as a method of choice for preparing the desired films; however, the mechanisms of the underlying surface processes are very difficult to assess. In this work, thermal dry etching of metallic iron by using sequential exposure to chlorine gas and 2,4-pentanedione (acetylacetone, acacH) was investigated. The mechanism of reacting acacH with chlorine-modified iron surface was studied by following the fragments desorbing from the surface in temperature-programmed desorption experiments in half-cycle processes that compared the chlorinated, oxidized, mixed (Cl and O), and clean (sputtered) iron films. In situ Auger electron spectroscopy and ex situ X-ray photoelectron spectroscopy of each sample after each etching step confirmed that the surface is activated by chlorine and then the chlorine-containing iron species are removed from the top layer of the sample, resulting in a metallic iron surface. No etching of clean (sputtered) surface was observed with acacH. The complete mechanism of acacH reaction with chlorinated iron samples is complicated, and etch products can contain both Fe2+ and Fe3+. However, a number of major conclusions, including the formation of surface intermediates and the final products of etching, primarily removal of Fe(acac) x Cl y , are inferred by comparing the results of these experiments with the computational investigation of selected surface processes using density functional theory calculations.

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In situ XPS study on atomic layer etching of Fe thin film using Cl2 and acetylacetone

Cited by 22 publications

References 54 publications

Molecular mechanisms of atomic layer etching of cobalt with sequential exposure to molecular chlorine and diketones

Molecular mechanisms of atomic layer etching of cobalt with sequential exposure to molecular chlorine and diketones

Recent Progress of Atomic Layer Technology in Spintronics: Mechanism, Materials and Prospects

Molecular Mechanism of Thermal Dry Etching of Iron in a Two-Step Atomic Layer Etching Process: Chlorination Followed by Exposure to Acetylacetone

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