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Novel Sn precursors, Sn(tbip)2, Sn(tbtp)2, and Sn(tbta)2, were synthesized and characterized using various analytical techniques and density functional theory calculations. These precursors contained cyclic amine ligands derived from iminopyrrolidine. X-ray crystallography revealed the formation of monomeric Sn L 2 with distorted seesaw geometry. Thermogravimetric analysis demonstrated the exceptional volatility of all complexes. Sn(tbtp)2 showed the lowest residual weight of 2.7% at 265 °C. Sn3N4 thin films were successfully synthesized using Sn(tbtp)2 as the Sn precursor and NH3 plasma. The precursor exhibited ideal characteristics for atomic layer deposition, with a saturated growth per cycle value of 1.9 Å cy−1 and no need for incubation when the film was deposited at 150–225 °C. The indirect optical bandgap of the Sn3N4 film was approximately 1–1.2 eV, as determined through ultraviolet–visible spectroscopy. Therefore, this study suggests that the Sn3N4 thin films prepared using the newly synthesized Sn precursor are suitable for application in thin-film photovoltaic devices. [ABSTRACT FROM AUTHOR]

Ru films are grown on Pt, TiN, and SiO2 substrates via atomic layer deposition (ALD) using Ru(II)(η5‐C7H7O)(η5‐C7H9) as the novel Ru metalorganic precursor and O2 as the reactant. The ALD self‐limiting film growth is confirmed at the low temperature of 200 °C by manipulating the injection time and purge time of the Ru precursor and O2, and the saturated growth per cycle is 0.22 Å cy−1. It is confirmed that the combustion reaction occurs during the deposition process from the formation of the H2O and CO2 by‐products. Thin films with a low resistivity of 17–19 µΩ cm are grown at a thickness of ≈15 nm. The Ru incubation times are remarkably short at 200 °C (negligible on Pt, ≈30 cycles on TiN and SiO2), but increase with increasing temperature. The energy dispersive X‐ray mapping image of the Ru film on the pattern in which TiN is formed on SiO2 shows that the Ru film with a novel precursor has the intrinsic substrate selectivity at the deposition temperature of 300 °C. Furthermore, the substrate affects the properties of the Ru film. Particularly because Ti serves as an oxygen reservoir, a relatively large amount of RuOx is produced on the TiN substrate. [ABSTRACT FROM AUTHOR]

As semiconductor devices are miniaturized (to dimensions of nanometers), the accurate alignment of each layer on the desired location poses a challenge in the fabrication of multilayer-stacked devices. Area-selective deposition has attracted interest in resolving alignment issues in nanoelectronics. Herein, we demonstrate the area-selective atomic layer deposition (ALD) of SnS2, a promising two-dimensional channel material for the application of back-end-of-line (BEOL)-compatible transistors, on SiO2 (growth area) and Al2O3 (nongrowth area). We employed a super cycle comprising acetylacetone injection as an inhibitor, SnS ALD cycles, and H2S plasma for the area-selective deposition of SnS2. Although SnS ALD possesses good selectivity, the H2S plasma used for the transformation of SnS to SnS2 deteriorated the Al2O3 surface and resulted in nucleation in the nongrowth area. The acetylacetone injection in the super cycle was selectively adsorbed by Al2O3 and protected it from the H2S plasma. The synergistic effects of the selectivity of the SnS ALD process and protection of the Al2O3 surface exhibited excellent selectivity for SnS2. In the super cycle, the increase in the number of SnS cycles enhanced growth incubation on Al2O3 and induced the appearance of the SnS phase on SiO2 as the growth area. By optimizing the super-cycle conditions, ∼7 nm of selective SnS2 deposition was achieved on Al2O3 and SiO2. The proposed strategy will help enhance the area-selective deposition technology for two-dimensional semiconductors in BEOL-compatible transistors. [ABSTRACT FROM AUTHOR]

New heteroleptic indium complexes, i. e. [MeIn(mdpa)(tmhd)]2 (2), [MeIn(mdpa)(acac)]2 (3), [MeIn(edpa)(tmhd)]2 (4), and [MeIn(edpa)(acac)]2 (5), with three different ligands, bearing N‐alkoxy carboxamide and β‐diketonate were designed and synthesized as indium precursors for indium oxide thin films by atomic layer deposition (ALD) using [Me2In(edpa)]2 and [Me2In(mdpa)]2 (1) as starting materials. The resulting complexes were characterized by NMR and FT‐IR spectroscopy, elemental analysis (EA), thermogravimetric analysis (TGA), and single crystal X‐ray diffraction. TGA curves of all the complexes showed clear single‐step weight losses, with low residual masses of 7–13 %. Among them, complex 5 was volatile and thermally stable, and thus, it can be used as potential indium precursor for indium oxide‐based thin films. [ABSTRACT FROM AUTHOR]

New heteroleptic complexes of zinc were designed and synthesized using aminoalkoxide and β‐diketonate ligands. The complexes, [Zn(dmamp)(tmhd)]2 (1), [Zn(dmamp)(acac)]2 (2), [Zn(dmamp)(hfac)]2 (3), [Zn(dmamb)(tmhd)]2 (4), [Zn(dmamb)(acac)]2 (5), and [Zn(dmamb)(hfac)]2 (6), were synthesized by controlled acid‐base reactions between [EtZn(aminoalkoxide)]2 and β‐diketonate ligands. Single crystal x‐ray diffraction showed that complexes 1−4 and 6 exist as dimeric molecular structures with the zinc metal centers interconnected by the alkoxy oxygen atom via μ2‐O bonding and their gemetries exhibit distorted trigonal bipyrimidal. TGA curves of complexes 3 and 6 showed sharp weight losses in a single step with very low residues, which confirmed the excellent vaporization and thermal stability. [ABSTRACT FROM AUTHOR]

(GeTe2)(1–x)(Sb2Te3)x(GST) layerswere deposited via atomic layer deposition (ALD) at growth temperaturesranging from 50 to 120 °C using Ge(OCH3)4or Ge(OC2H5)4, Sb(OC2H5)3, and [(CH3)3Si]2Te as the metal–organic precursors of the Ge, Sb, andTe elements, respectively. The GST layers with compositions lyingon the GeTe2–Sb2Te3tie linescould be obtained by varying the ratio of the Ge–Te and Sb–TeALD cycles. Although the incorporation of an Sb–Te layer intothe GST film occurred in a genuine ALD manner, that of the Ge–Telayer was governed by the kinetically limited physisorption of Geprecursors. The incorporation behavior of the Ge precursor with differentligands was explained by the adsorption and desorption kinetics based on the Brunauer–Emmett–Tellerisotherm. The ALD-like film growth behavior could be well-explainedby the kinetically limited incorporation of Ge atoms. [ABSTRACT FROM AUTHOR]

Phase change random access memory appears to be the strongestcandidatefor next-generation high density nonvolatile memory. The fabricationof ultrahigh density phase change memory (≫1 Gb) depends heavilyon the thin film growth technique for the phase changing chalcogenidematerial, most typically containing Ge, Sb and Te (Ge–Sb–Te).Atomic layer deposition (ALD) at low temperatures is the most preferredgrowth method for depositing such complex materials over surfacespossessing extreme topology. In this study, [(CH3)3Si]2Te and stable alkoxy-Ge (Ge(OCH3)4) and alkoxy-Sb (Sb(OC2H5)3) metal–organic precursors were used to deposit variouslayers with compositions lying on the GeTe2–Sb2Te3tie lines at a substrate temperature as lowas 70 °C using a thermal ALD process. The adsorption of Ge precursorwas proven to be a physisorption type while other precursors showeda chemisorption behavior. However, the adsorption of Ge precursorwas still self-regulated, and the facile ALD of the pseudobinary solidsolutions with composition (GeTe2)(1-x)(Sb2Te3)xwereachieved. This chemistry-specific ALD process was quite robust againstprocess variations, allowing highly conformal, smooth, and reproduciblefilm growth over a contact hole structure with an extreme geometry.The detailed ALD behavior of binary compounds and incorporation behaviorsof the binary compounds in pseudobinary solid solutions were studiedin detail. This new composition material showed reliable phase changeand accompanying resistance switching behavior, which were slightlybetter than the standard Ge2Sb2Te5material in the nanoscale. The local chemical environment was similarto that of conventional Ge2Sb2Te5materials. [ABSTRACT FROM AUTHOR]

The electrical switching behavior of the GeTe phase-changing material grown by atomic layer deposition is characterized for the phase change random access memory (PCRAM) application. Planar-type PCRAM devices are fabricated with a TiN or W bottom electrode (BE). The crystallization behavior is characterized by applying an electrical pulse train and analyzed by applying the Johnson–Mehl–Avrami kinetics model. The device with TiN BE shows a high Avrami coefficient (>4), meaning that continuous and multiple nucleations occur during crystallization (set switching). Meanwhile, the device with W BE shows a smaller Avrami coefficient (~3), representing retarded nucleation during the crystallization. In addition, larger voltage and power are necessary for crystallization in case of the device with W BE. It is believed that the thermal conductivity of the BE material affects the temperature distribution in the device, resulting in different crystallization kinetics and set switching behavior. [ABSTRACT FROM AUTHOR]

Highlights: [•] The uncommon aspects of the atomic layer deposition (ALD) reactions are addressed. [•] Influences of metal precursors, non-metal precursors, and substrates are reviewed. [•] Selected functional materials of TiO2, SrTiO3, Ge–Sb–Te, Ru, RuO2, NiO are discussed. [•] Desirable directions for ALD are suggested based on the non-ideal aspects. [Copyright &y& Elsevier]

Series of niobium precursors with imido group and N -alkoxy carboxamide ligands were synthesized and fully analyzed by NMR, FT-IR, EA and TGA. All prepared complexes were able to be distilled and sublimed under reduced pressure, and expected potential precursors for niobium containing films. [Display omitted] A series of novel Nb(V) t Bu-imido/ N -alkoxy carboxamide complexes, NbCl 2 (N t Bu)(pyridine)(edpa) (1), NbCl 2 (N t Bu)(pyridine)(mdpa) (2), and Nb(N t Bu)(mdpa) 3 (3), were successfully synthesized by metathesis reaction between Nb(N t Bu)Cl 3 (py) 2 and several equivalents of Na(edpa) (edpaH = Nethoxy-2,2-dimethylpropanamide) and Na(mdpa) (mdpaH = N -methoxy-2,2-dimethylpropanamide). These complexes could potentially serve as precursors for Nb-containing thin films. Compounds 1 – 3 were characterized by FT-IR and 1H and 13C NMR spectroscopies, elemental analysis, and thermogravimetric analysis (TGA). Single crystal X-ray diffraction analysis suggested that complex 3 has a distorted pentagonal bipyramidal geometry around the central Nb atom, with three bidentate mdpa ligands and one t Bu imido group saturating the coordination. TGA analysis revealed that the thermal characteristics of 3 were superior to those of 1 and 2. All prepared complexes were able to be distilled or sublimed and expected potential precursors for the fabrication of thin films. [ABSTRACT FROM AUTHOR]