Atomic layer deposition(ALD), a chemical vapor deposition technique based on sequential self-terminating gas–solid reactions, has for about four decades been applied for manufacturing conformal inorganic material layers with thickness down to the nanometer range. Despite the numerous successful applications of material growth by ALD, many physicochemical processes that control ALD growth are not yet sufficiently understood. To increase understanding of ALD processes, overviews are needed not only of the existing ALD processes and their applications, but also of the knowledge of the surface chemistry of specific ALD processes. This work aims to start the overviews on specific ALD processes by reviewing the experimental information available on the surface chemistry of the trimethylaluminum/water process. This process is generally known as a rather ideal ALD process, and plenty of information is available on its surface chemistry. This in-depth summary of the surface chemistry of one representative ALD process aims also to provide a view on the current status of understanding the surface chemistry of ALD, in general. The review starts by describing the basic characteristics of ALD, discussing the history of ALD—including the question who made the first ALD experiments—and giving an overview of the two-reactant ALD processes investigated to date. Second, the basic concepts related to the surface chemistry of ALD are described from a generic viewpoint applicable to all ALD processes based on compound reactants. This description includes physicochemical requirements for self-terminating reactions,reaction kinetics, typical chemisorption mechanisms, factors causing saturation, reasons for growth of less than a monolayer per cycle, effect of the temperature and number of cycles on the growth per cycle (GPC), and the growth mode. A comparison is made of three models available for estimating the sterically allowed value of GPC in ALD. Third, the experimental information on the surface chemistry in the trimethylaluminum/water ALD process are reviewed using the concepts developed in the second part of this review. The results are reviewed critically, with an aim to combine the information obtained in different types of investigations, such as growth experiments on flat substrates and reaction chemistry investigation on high-surface-area materials. Although the surface chemistry of the trimethylaluminum/water ALD process is rather well understood, systematic investigations of the reaction kinetics and the growth mode on different substrates are still missing. The last part of the review is devoted to discussing issues which may hamper surface chemistry investigations of ALD, such as problematic historical assumptions, nonstandard terminology, and the effect of experimental conditions on the surface chemistry of ALD. I hope that this review can help the newcomer get acquainted with the exciting and challenging field of surface chemistry of ALD and can serve as a useful guide for the specialist towards the fifth decade of ALD research.

Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

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

Process gas discharged from a bypass pipe to a gas exhaust system can be prevented from diffusing back to the inside of a process chamber without having to install a dedicated vacuum pump at the downstream side of the bypass pipe. The substrate processing apparatus includes a process chamber accommodating a substrate, a gas supply system supplying process gas from a process gas source to the process chamber for processing the substrate, a gas exhaust system configured to exhaust the process chamber, two or more vacuum pumps installed in series at the gas exhaust system, and a bypass pipe connected between the gas supply system and the gas exhaust system. The most upstream one of the vacuum pumps is a mechanical booster pump, and the bypass pipe is connected between the mechanical booster pump and the rest vacuum pumps located at a downstream side of the mechanical booster pump.

Substrate Processing Apparatus

Embodiments of the invention provide an apparatus configured to form a material during an atomic layer deposition (ALD) process, such as a plasma-enhanced ALD (PE-ALD) process. In one embodiment, a lid assembly for conducting a vapor deposition process within a process chamber is provided which includes an insulation cap and a plasma screen. In one example, the insulation cap has a centralized channel configured to flow a first process gas from an upper surface to an expanded channel and an outer channel configured to flow a second process gas from an upper surface to a groove which is encircling the expanded channel. In one example, the plasma screen has an upper surface containing an inner area with a plurality of holes and an outer area with a plurality of slots. The insulation cap may be positioned on top of the plasma screen to form a centralized gas region with the expanded channel and a circular gas region with the groove.

Apparatus and process for plasma-enhanced atomic layer deposition

The present invention provides systems and methods for mixing precursors such that a mixture of precursors are present together in a chamber during a single pulse step in an atomic layer deposition (ALD) process to form a multi-component film. The precursors are comprised of at least one different chemical component, and such different components will form a mono-layer to produce a multi-component film. In a further aspect of the present invention, a dielectric film having a composition gradient is provided.

System and method for forming multi-component dielectric films

A method of depositing a hafnium-based dielectric film is provided. The method comprises atomic layer deposition using ozone and one or more reactants comprising a hafnium precursor. A semiconductor device is also provided. The device comprises a substrate, a hafnium-based dielectric layer formed atop the substrate, and an interfacial layer formed between the substrate and the hafnium-based dielectric layer, wherein the interfacial layer comprises silicon dioxide and has a crystalline structure.

Atomic layer deposition of hafnium-based high-k dielectric

A method is provided for forming films comprising Fe, Ru or Os employing the techniques of chemical vapor deposition to decompose a vapor comprising an organometallic compound of the formula (a): (CO)4 ML or (b): M2 [μ-η:η4 -C4 ](CO)6 ; wherein L is a two-electron donor ligand and each R is H, halo, OH, alkyl, perfluoroalkyl or aryl; so as to deposit a coating comprising one or more of said metals on the surface of a substrate.

Chemical vapor deposition of iron, ruthenium, and osmium

Atomic layer deposition (ALD) processes for HfO2 and HfxSi1−xO2 high-k dielectric thin films using liquid precursors and ozone were evaluated. Tetrakis(ethylmethylamino)hafnium (TEMAHf) precursor provides HfO2 films with superior quality as compared to Hf(t-butoxide)4 precursor in terms of deposition rate, purity, and electrical properties of the films. ALD processes for hafnium silicate films have been developed by co-injection of TEMAHf and tetrakis(ethylmethylamino) silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400 °C to grow HfxSi1−xO2 film. The Hf and Si precursors can be converted to vapor for delivery to the deposition chamber either by bubbling an inert carrier gas separately through each liquid or by using a liquid vaporization unit. The co-injection process enables the formation of homogeneous single-layer hafnium silicate films as deposited.

Atomic layer deposition of hafnium oxide and hafnium silicate thin films using liquid precursors and ozone

A novel class of volatile liquid precursors based on amino substituted disilane compounds is used to form silicon nitride dielectric materials on the surface of substrates. This class of precursors overcomes the issues of high deposition temperatures and the formation of undesirable by-products that are inherent in the present art. In another aspect, methods of depositing silicon nitride films on substrates are provided.

Yoshihide Senzaki

Papers

System and method for forming multi-component dielectric films

Atomic layer deposition of hafnium-based high-k dielectric

Chemical vapor deposition of iron, ruthenium, and osmium

Atomic layer deposition of hafnium oxide and hafnium silicate thin films using liquid precursors and ozone

Low temperature deposition of silicon nitride