https://cyberleninka.org/article/n/247805.pdf

A brief review of atomic layer deposition: from fundamentals to applications

Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.

Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends

Atomic layer deposition (ALD) is an attractive method to deposit thin films for advanced technological applications such as microelectronics and nanotechnology. One material group in ALD that has matured in 10 years and proven to be of wide technological importance is noble metals. In this paper, thermal ALD of noble metals and their oxides is reviewed. Noble metal films are mostly grown using O2 as the nonmetal precursor in a combustion-type chemistry. Alternatively, lower growth temperatures can be reached via noble metal oxide growth with consecutive reactions with ozone and H2. The use of true reducing chemistry (i.e., H2) is typical only for ALD of palladium at low temperatures. On the other hand, ALD of noble metal oxides has been limited with reactants such as ozone and O2 gas. In this review, reaction mechanisms in various types of processes are discussed and issues in nucleation are addressed. Deposition temperatures, film growth rates, and purities as well as evaporation temperatures used for no...

Atomic Layer Deposition of Noble Metals and Their Oxides

Films are deposited on a substrate by a process in which atomic layer deposition (ALD) is used to deposit one layer of the film and pulsed chemical vapor deposition (CVD) is used to deposit another layer of the film. During the ALD part of the process, a layer is formed by flowing sequential and alternating pulses of mutually reactive reactants that deposit self-limitingly on a substrate. During the pulsed CVD part of the process, another layer is deposited by flowing two CVD reactants into a reaction chamber, with at least a first of the CVD reactants flowed into the reaction chamber in pulses, with those pulses overlapping at least partially with the flow of a second of the CVD reactants. The ALD and CVD parts of the process ca be used to deposit layers with different compositions, thereby forming, e.g., nanolaminate films. Preferably, high quality layers are formed by flowing the second CVD reactant into the reaction chamber for a longer total duration than the first CVD reactant. In some embodiments, the pulses of the third reactant at separated by a duration at least about 1.75 times the length of the pulse. Preferably, less than about 8 monolayers of material are deposited per pulse of the first CVD reactant.

Method for depositing thin films by mixed pulsed CVD and ALD

We review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest. Recongnizing that this is a vast area, the focus of this treatment is mainly on high-κ dielectric, ferroelectric, magnetic, and multiferroic materials. Also, we consider ferrimagnetic oxides in the context of the new, rapidly developing field of negative-index metamaterials. This review is motivated by the recent resurgence of interest in complex oxides owing to their coupling of electrical, magnetic, thermal, mechanical, and optical properties, which make them suitable for a wide variety of applications, including heat, motion, electric, and magnetic sensors; tunable and compact microwave passive components; surface acoustic wave devices; nonlinear optics; and nonvolatile memory, and pave the way for designing multifunctional devices and unique applications in spintronics and negative refraction-index media. For most of the materials treated here, structural and physical propertie...

Oxides, Oxides, and More Oxides: High-κ Oxides, Ferroelectrics, Ferromagnetics, and Multiferroics

-di- tert-butylacetamidinato "ruthenium !II" dicarbonyl. The CVD Þlms were grownwithout any coreactant, while the ALD Þlms used ammonia as a coreactant. The Þ lms are Þne-grained polycrystalline rutheniumwith high purity !! 0.2% impurities ".R u grew as a continuous, electrically conductive, pinhole-free Þlm on tungsten nitride !WN "Þlms even for Þlms as thin as 2 nm. The resistivities of the Þlms match those of pure sputtered ruthenium of the same thickness.Roughness is ! 2% of the Þlm thickness. The Þ lms are very conformal, with 80% step coverage over holes with high aspect ratios!40:1 ". T his thermal process does not use any oxidant or plasma as a second reagent, thereby avoiding damage to sensitivesubstrates. The ALD growth rate can reach 1.5  /cycle at a substrate temperature of 300 iC .© 2007 The Electrochemical Society . #DOI: 10.1 149/1.2789294 $ All rights reserved.Manuscript submitted May 9, 2007; revised manuscript received August 9, 2007. A vailable electronically October 11, 2007.

/pdf/vapor-deposition-of-ruthenium-from-an-amidinate-precursor-3n02xjf89s.pdf

Vapor Deposition of Ruthenium from an Amidinate Precursor

A novel thermally-stable zirconium amidinate ALD precursor for ZrO2 thin films

Smooth and continuous films of nickel nitride (NiNx) with excellent step coverage were deposited from a novel nickel amidinate precursor, Ni(MeC(NtBu)2)2, and either ammonia (NH3) or a mixture of NH3 and hydrogen (H2) gases as co-reactants. The reactants were injected together in direct-liquid-injection chemical vapor deposition (DLI-CVD) processes at substrate temperatures of 160−200 °C. Depending on the ratio of NH3 to H2 gases during deposition, the Ni:N atomic ratio in DLI-CVD NiNx films could be varied from ∼3:1 to ∼15:1, having either a cubic nickel structure or a mixture of hexagonal Ni3N and cubic Ni4N crystal structures with an incorporation of nitrogen as low as 6%. The chemical vapor deposition (CVD) growth rates of NiNx could be increased to more than 5 nm/min. The CVD films were smooth and continuous, and they had ∼100% step coverage in high-aspect-ratio (>50:1) holes. The as-deposited NiNx films had resistivities as low as ∼50 μΩ cm for film thicknesses of ∼25 nm. Annealing of the films in H...

https://faculty.chemistry.harvard.edu/files/gordon/files/cvd_ninx_chemmater2230602010.pdf

Direct-Liquid-Injection Chemical Vapor Deposition of Nickel Nitride Films and Their Reduction to Nickel Films

Electrical properties of atomic-layer-deposited La2O3 films using a novel La formamidinate precursor and ozone

Lanthanum-based ternary oxide La x M 2-x O 3 (M = Sc, Lu, or Y) films were deposited on HF-last Si substrates by atomic layer deposition. Both LaScO 3 and LaLuO 3 films are amorphous while the as-deposited La x Y 2-x O 3 films form a polycrystalline layer/ amorphous layer structure on Si. Transmission electron microscopy and electrical analysis show the absence of interfacial layers. The dielectric constants for LaScO 3 , LaLuO 3 , and La 1.23 Y 0.77 O 3 films are ∼23, 28 ± 1, and 17 ± 1.3, respectively, with leakage current density up to 6 orders of magnitude lower than that of thermal SiO 2 with the same effective oxide thickness. Conformal coating thickness is demonstrated on holes with aspect ratio ∼80:1.

/pdf/atomic-layer-deposition-of-lanthanum-based-ternary-oxides-1bvztuu1ns.pdf

Huazhi Li

Papers

Vapor Deposition of Ruthenium from an Amidinate Precursor

A novel thermally-stable zirconium amidinate ALD precursor for ZrO2 thin films

Direct-Liquid-Injection Chemical Vapor Deposition of Nickel Nitride Films and Their Reduction to Nickel Films

Electrical properties of atomic-layer-deposited La2O3 films using a novel La formamidinate precursor and ozone

Atomic Layer Deposition of Lanthanum-Based Ternary Oxides