Atomic Layer Deposition: An Overview

Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
Chemical Reviews (Impact Factor: 46.57). 11/2009; 110(1):111-31. DOI: 10.1021/cr900056b
Source: PubMed


Atomic layer deposition (ALD) which has emerged as an important technique for depositing thin films for a variety of applications has been reported. The necessity for continuous and pinhole-free films in semiconductor devices has driven the advancement of ALD. ALD is able to meet the needs for atomic layer control and conformal deposition using sequential, self-limiting surface reactions. The ALD of Al2O3 has developed as a model ALD system. ALD processing is also extendible to very large substrates and to parallel processing of multiple substrates. ALD is a gas phase method based on sequential, selflimiting surface reactions. ALD can deposit very conformal and ultrathin films on substrates with very high aspect ratios. ALD on high aspect ratio structures was then considered including an examination of the times required for conformal growth on high aspect ratio structures. The number of applications for ALD also continues to grow outside of the semiconductor arena.

    • "However, titanium dioxide films production seems to be more difficult than that of powders and is based on dip coating in an aqueous peroxotitanate solution (Gao et al., 2003) or on the sol–gel technique (Ghorashi et al., 2013; Pakdel et al., 2013; Sobczyk-Guzendan et al., 2013). Now, the atomic layer deposition is employed for the formation of thin films (George, 2010). To improve the stability of the deposited layers, some authors proposed plasma treatment. "
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    ABSTRACT: Porous polypropylene membranes were coated with plasma polymerized titanium isopropoxide in a 75 kHz plasma reactor. It was noted that the presence of air in the plasma chamber in the amount of deposited polymer. Selection of the process parameters enabled obtaining membranes with up to 300 mu g cm(-2) of polymerized titanium isopropoxide. Deposition of the titanium oxide layer resulted in the reduction of permeate flux but it significantly improved the membrane photocleaning ability The recovery index reached the level of 95 % for membranes with the highest amount of the titanium oxide deposit. (C) 2015 Institute of Chemistry, Slovak Academy of Sciences
    No preview · Article · Mar 2016 · Chemical Papers- Slovak Academy of Sciences
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    • "The results of the scanning electron microscopy and EDS analysis conducted to observe the morphologies of the bare silk fabric and TiO 2 -coated silk fabrics subjected to 800 and 1600 ALD cycles are shown in Fig. 2. Fig. 2a, e, and i shows that the silk fabrics had tightly woven, fibrous structures and that the microstructures of the bare silk fabric and TiO 2 -coated silk fabrics subjected to different numbers of ALD cycles appeared the same at low magnification, which is consistent with the conformal characteristics of the ALD process[24]. Fig. 2bshows that a single fiber of the bare silk fabric at a high magnification was smooth, in clear contrast to single fibers of the TiO 2 -coated silk fabrics subjected to 800 and 1600 ALD cycles, as shown in Fig. 2fand j. "
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    ABSTRACT: Highly hydrophobic silk fabric surfaces were successfully fabricated using a simple one-step atomic layer deposition (ALD) process. The surface morphology, chemical composition, and structure of bare silk fabric and silk fabrics coated with titanium dioxide (TiO2) subjected to 800 and 1600 ALD cycles were measured using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning probe microscopy (SPM). The surface wettability of the silk fabrics was evaluated by determining their static water contact angles (WCAs) and roll-off angles. The results suggest that the good hydrophilicity of the surfaces of bare silk fabrics can be changed to high hydrophobicity by the application of TiO2 nanoparticles to their surfaces using ALD. The high hydrophobicity achieved can be attributed to the increase in roughness of the silk fabric surface. The laundering durability of TiO2-coated silk fabrics is greatly improved by increasing the thickness of the ALD TiO2 films.
    Full-text · Article · Oct 2015 · Applied Surface Science
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    • "ALD is one of the most rapidly developing fields of thin film technology belonging to the general class of chemical vapor deposition (CVD) techniques [4]. Typical applications for ALD-films include semiconductor devices such as high dielectric constant gate oxides in the MOSFET structure, copper diffusion barriers in backend interconnects , energy applications as well as micro-and nanoelectromechanical systems (MEMS/NEMS) [5] [6]. TiO 2 thin films are used in a wide variety of applications: photovoltaic devices such as solar cells [7] [8], corrosion resistance [9], self-cleaning [10], water purification [11], anti-fogging [12], superhydrophilicity [13], as well as anti-bacterial [14], -fungal [15] and -algal [16] applications. "
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    ABSTRACT: For every coating it is critical that the coatings are sufficiently durable to withstand practical applications and that the films adhere well enough to the substrate. In this paper the nanotribological, nanomechanical and interfacial properties of 15 - 100 nm thick atomic layer deposited (ALD) TiO2 coatings deposited at 110 - 300 °C were studied using a novel combination of nanoscratch and scanning nanowear testing. Thin film wear increased linearly with increasing scanning nanowear load. The film deposited at 300 °C was up to 58 ± 11 %-points more wear-resistant compared to the films deposited at lower temperatures due to higher hardness and crystallinity of the film. Amorphous/nanocrystalline composite structure with agglomerated crystallites was observed with TiO2 deposited at 200 °C and the agglomerates were up to 37 ± 10 %-points more wear-resistant than the amorphous/nanocrystalline matrix. All of the tested films had excellent interfacial properties and no delamination was observed with the films outside of the scanned regions. These findings may prove useful in the development of tribological and mechanical characterization methods, and in developing thin film materials with enhanced properties tailored to their function. This will also help in the development and tuning of ALD processes.
    Full-text · Article · Sep 2015 · Wear
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