Atomic layer deposition

About: Atomic layer deposition is a research topic. Over the lifetime, 19821 publications have been published within this topic receiving 477332 citations. The topic is also known as: ALD.

Crystallinity of Inorganic Films Grown by Atomic Layer Deposition: Overview and General Trends

Abstract: 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.

Passivation method for improved uniformity and repeatability for atomic layer deposition and chemical vapor deposition

Abstract: A method to deposit a passivating layer of a first material on an interior reactor surface of a cold or warm wall reactor, in which the first material is non-reactive with one or more precursors used to form a second material. Subsequently when a film layer is deposited on a substrate by subjecting the substrate to the one or more precursors, in which at least one precursor has a low vapor pressure, uniformity and repeatability is improved by the passivation layer.

Plasma and thermal ALD of Al2O3 in a commercial 200 mm ALD reactor

Abstract: The deposition of Al 2 O 3 by remote plasma atomic layer deposition (ALD) in the Oxford Instruments FlexAL reactor was studied and compared with results from thermal ALD in the same reactor. Trimethylaluminum [Al(CH 3 ) 3 ] was used as the metal precursor and O 2 plasma and H 2 O were used as oxidizing agents for the plasma and thermal processes, respectively. For remote plasma ALD with a total cycle time of 4 s, the growth per cycle decreased monotonically with substrate temperature, from 1.7 A/cycle at 25°C to 1.0 A/cycle at 300°C. This growth per cycle was consistently higher than that obtained for thermal ALD. For the latter a maximum growth per cycle of ∼ 1.0 A/cycle was found at 200°C. The film properties investigated were nearly independent of oxidant source for temperatures between 100 and 300°C, with a slightly higher mass density for the remote plasma ALD Al 2 O 3 films. Films deposited at 200 and 300°C were stoichiometric with a mass density of 3.0 g/cm 3 and low C (< 1 atom %) and H (<3 atom %) contents. At lower substrate temperatures, oxygen-rich films were obtained with a lower mass density and higher H-content. Remote plasma ALD produced uniform Al 2 O 3 films with nonuniformities of less than ±2% over 200 mm diam substrates. Excellent conformality was obtained for films deposited in macropores with an aspect ratio of ∼8 (2.0-2.5 μm diam). Preliminary results on electrical properties of remote plasma deposited films showed high dielectric constants of 7.8 and 8.9 for as-deposited and forming gas annealed Al 2 O 3 , respectively.

Plasma atomic layer deposition system and method

Abstract: An improved gas deposition chamber includes a hollow gas deposition volume formed with a volume expanding top portion and a substantially constant volume cylindrical middle portion. The hollow gas deposition volume may include a volume reducing lower portion. An aerodynamically shaped substrate support chuck is disposed inside gas deposition chamber with a substrate support surface positioned in the constant volume cylindrical middle portion. The volume expanding top portion reduces gas flow velocity between gas input ports and the substrate support surface. The aerodynamic shape of the substrate support chuck reduces drag and helps to promote laminar flow over the substrate support surface. The volume reducing lower portion helps to increase gas flow velocity after the gas has past the substrate support surface. The improved gas deposition chamber is configurable to 200 mm diameter semiconductor wafers using ALD and or PALD coating cycles. An improved coating method includes expanding process gases inside the deposition chamber prior to the process gas reaching surfaces of a substrate being coated. The method further includes compressing the process gases inside the deposition chamber after the process gas has flowed past surfaces of the substrate being coated.