Showing papers on "Atomic layer deposition published in 2005"

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

Abstract: 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.

Resistive switching mechanism of TiO2 thin films grown by atomic-layer deposition

Abstract: The resistive switching mechanism of 20- to 57-nm-thick TiO2 thin films grown by atomic-layer deposition was studied by current-voltage measurements and conductive atomic force microscopy. Electric pulse-induced resistance switching was repetitively (> a few hundred times) observed with a resistance ratio ⪢102. Both the low- and high-resistance states showed linear log current versus log voltage graphs with a slope of 1 in the low-voltage region where switching did not occur. The thermal stability of both conduction states was also studied. Atomic force microscopy studies under atmosphere and high-vacuum conditions showed that resistance switching is closely related to the formation and elimination of conducting spots. The conducting spots of the low-resistance state have a few tens times higher conductivity than those of the high-resistance state and their density is also a few tens times higher which results in a ∼103 times larger overall conductivity. An interesting finding was that the area where the ...

Nucleation and Growth during Al2O3 Atomic Layer Deposition on Polymers

Abstract: Nucleation and growth during Al2O3 atomic layer deposition (ALD) were explored on a variety of polymer films at 85 °C. Al2O3 ALD was performed using sequential exposures of Al(CH3)3 [trimethylalumi...

Surface passivation of III-V compound semiconductors using atomic-layer-deposition-grown Al2O3

Abstract: Al2O3 was deposited on In0.15Ga0.85As∕GaAs using atomic-layer deposition (ALD). Without any surface preparation or postthermal treatment, excellent electrical properties of Al2O3∕InGaAs∕GaAs heterostructures were obtained, in terms of low electrical leakage current density (10−8 to 10−9A∕cm2) and low interfacial density of states (Dit) in the range of 1012cm−2eV−1. The interfacial reaction and structural properties studied by high-resolution x-ray photoelectron spectroscopy (HRXPS) and high-resolution transmission electron microscopy (HRTEM). The depth profile of HRXPS, using synchrotron radiation beam and low-energy Ar+ sputtering, exhibited no residual arsenic oxides at interface. The removal of the arsenic oxides from Al2O3∕InGaAs heterostructures during the ALD process ensures the Fermi-level unpinning, which was observed in the capacitance-voltage measurements. The HRTEM shows sharp transition from amorphous oxide to single crystalline semiconductor.

HfO2 and Al2O3 gate dielectrics on GaAs grown by atomic layer deposition

Abstract: High-performance metal-oxide-semiconductor field effect transistors (MOSFETs) on III–V semiconductors have long proven elusive. High-permittivity (high-κ) gate dielectrics may enable their fabrication. We have studied hafnium oxide and aluminum oxide grown on gallium arsenide by atomic layer deposition. As-deposited films are continuous and predominantly amorphous. A native oxide remains intact underneath HfO2 during growth, while thinning occurs during Al2O3 deposition. Hydrofluoric acid etching prior to growth minimizes the final interlayer thickness. Thermal treatments at ∼600°C decompose arsenic oxides and remove interfacial oxygen. These observations explain the improved electrical quality and increased gate stack capacitance after thermal treatments.

Localized surface plasmon resonance nanosensor: a high-resolution distance-dependence study using atomic layer deposition.

Abstract: Atomic layer deposition (ALD) is used to deposit 1−600 monolayers of Al2O3 on Ag nanotriangles fabricated by nanosphere lithography (NSL). Each monolayer of Al2O3 has a thickness of 1.1 A. It is demonstrated that the localized surface plasmon resonance (LSPR) nanosensor can detect Al2O3 film growth with atomic spatial resolution normal to the nanoparticle surface. This is approximately 10 times greater spatial resolution than that in our previous long-range distance-dependence study using multilayer self-assembled monolayer shells. The use of ALD enables the study of both the long- and short-range distance dependence of the LSPR nanosensor in a single unified experiment. Ag nanoparticles with fixed in-plane widths and decreasing heights yield larger sensing distances. X-ray photoelectron spectroscopy, variable angle spectroscopic ellipsometry, and quartz crystal microbalance measurements are used to study the growth mechanism. It is proposed that the growth of Al2O3 is initiated by the decomposition of tr...

ATOMIC LAYER DEPOSITION OF Zrx Hfy Sn1-x-y O2 FILMS AS HIGH k GATE DIELECTRICS

Abstract: The use of atomic layer deposition (ALD) to form a nanolaminate dielectric of zirconium oxide (ZrO 2 ), hafnium oxide (HfO 2 ) and tin oxide (SnO 2 ) acting as a single dielectric layer with a formula of Zr X Hf Y Sn 1-X-Y O 2 , and a method of fabricating such a dielectric layer is described that produces a reliable structure with a high dielectric constant (high k). The dielectric structure is formed by depositing zirconium oxide by atomic layer deposition onto a substrate surface using precursor chemicals, followed by depositing hafnium oxide onto the substrate using precursor chemicals, followed by depositing tin oxide onto the substrate using precursor chemicals, and repeating to form the thin laminate structure. Such a dielectric may be used as a gate insulator, a capacitor dielectric, or as a tunnel insulator in non-volatile memories, because the high dielectric constant (high k) provides the functionality of a much thinner silicon dioxide film.

Plasma enhanced atomic layer deposition system having reduced contamination

Abstract: A plasma enhanced atomic layer deposition (PEALD) system is described, wherein the system comprises a processing space and a high vacuum, ultra-clean transfer space. During processing, the substrate to which the thin conformal film is formed is exposed to the processing space. During substrate transfer, the substrate is exposed to the high vacuum space. Processing gases are introduced sequentially and alternately to the process chamber and the pressures and gas flows within, to and from, and between the process chamber and the high vacuum transfer space are controlled to keep the transfer space ultra-clean.

Leakage current and breakdown electric-field studies on ultrathin atomic-layer-deposited Al2O3 on GaAs

Abstract: Atomic-layer deposition (ALD) provides a unique opportunity to integrate high-quality gate dielectrics on III-V compound semiconductors. We report detailed leakage current and breakdown electric-field characteristics of ultrathin Al2O3 dielectrics on GaAs grown by ALD. The leakage current in ultrathin Al2O3 on GaAs is comparable to or even lower than that of state-of-the-art SiO2 on Si, not counting the high-k dielectric properties for Al2O3. A Fowler-Nordheim tunneling analysis on the GaAs∕Al2O3 barrier height is also presented. The breakdown electric field of Al2O3 is measured as high as 10MV∕cm as a bulk property. A significant enhancement on breakdown electric field up to 30MV∕cm is observed as the film thickness approaches to 1nm.

Apparatuses and methods for atomic layer deposition of hafnium-containing high-k dielectric materials

Abstract: Embodiments of the invention provide methods for depositing dielectric materials on substrates during vapor deposition processes, such as atomic layer deposition (ALD). In one example, a method includes sequentially exposing a substrate to a hafnium precursor and an oxidizing gas to deposit a hafnium oxide material thereon. In another example, a hafnium silicate material is deposited by sequentially exposing a substrate to the oxidizing gas and a process gas containing a hafnium precursor and a silicon precursor. The oxidizing gas contains water vapor formed by flowing a hydrogen source gas and an oxygen source gas through a water vapor generator.

Low-Temperature Growth of SiO2 Films by Plasma-Enhanced Atomic Layer Deposition

Abstract: Silicon dioxide (SiO 2 ) films prepared by plasma-enhanced atomic-layer deposition were successfully grown at temperatures of 100 to 250 °C, showing self-limiting characteristics. The growth rate decreases with an increasing deposition temperature. The relative dielectric constants of SiO 2 films are ranged from 4.5 to 7.7 with the decrease of growth temperature. A SiO 2 film grown at 250 °C exhibits a much lower leakage current than that grown at 100 °C due to its high film density and the fact that it contains deeper electron traps.

Plasma enhanced atomic layer deposition system and method

Abstract: A plasma enhanced atomic layer deposition (PEALD) method and system, the system including a process chamber and a substrate holder provided within the processing chamber and configured to support a substrate on which a predetermined film will be formed. A first process material supply system is configured to supply a first process material to the process chamber, and a second process material supply system configured to supply a second process material to the process chamber in order to provide a reduction reaction with the first process material to form the predetermined film on the substrate. Also included is a power source configured to couple electromagnetic power to the process chamber to generate a plasma within the process chamber to facilitate the reduction reaction, and a chamber component exposed to the plasma and made from a film compatible material that is compatible with the predetermined film deposited on the substrate.

Absence of magnetism in hafnium oxide films

Abstract: We establish the limits of magnetism in thin, electronic grade, hafnium oxide, and hafnium silicate films deposited onto silicon wafers by chemical vapor deposition and atomic layer deposition. To the limits of sensitivity of our measurement techniques, no ferromagnetism occurs in these samples. Contamination by handling with stainless-steel tweezers leads to a measurable magnetic signal. The magnetic properties of this contamination are similar to those attributed to ferromagnetic HfO2 in a recent report, including the magnitude of moment, magnetization field dependence, and spatial asymmetry.

Atomic layer deposition of metal oxynitride layers as gate dielectrics

Abstract: A metal oxynitride layer formed by atomic layer deposition of a plurality of reacted monolayers, the monolayers comprising at least one each of a metal, an oxide and a nitride. The metal oxynitride layer is formed from zirconium oxynitride, hafnium oxynitride, tantalum oxynitride, or mixtures thereof. The metal oxynitride layer is used in gate dielectrics as a replacement material for silicon dioxide. A semiconductor device structure having a gate dielectric formed from a metal oxynitride layer is also disclosed.

Method of forming a layer and forming a capacitor of a semiconductor device having the same layer

Abstract: In a method of forming a layer using an atomic layer deposition process, after a substrate is loaded into a chamber, a first reactant is provided onto the substrate. The first reactant is partially chemisorbed on the substrate. A second reactant is introduced into the chamber to form a preliminary layer on the substrate by chemically reacting the second reactant with the chemisorbed first reactant. Impurities in the preliminary layer and unreacted reactants are simultaneously removed using a plasma for removing impurities to thereby form the layer on the substrate. The impurities in the layer may be effectively removed so that the layer may have reduced leakage current.

Method to perform selective atomic layer deposition of zinc oxide

Abstract: A method for selective ALD of ZnO on a wafer preparing a silicon wafer; patterning the silicon wafer with a blocking agent in selected regions where deposition of ZnO is to be inhibited, wherein the blocking agent is taken from a group of blocking agents includes isopropyl alcohol, acetone and deionized water; depositing a layer of ZnO on the wafer by ALD using diethyl zinc and H 2 O at a temperature of between about 140° C. to 170° C.; and removing the blocking agent from the wafer.

ALD of Hafnium Oxide Thin Films from Tetrakis(ethylmethylamino)hafnium and Ozone

Abstract: Hafnium oxide (HfO 2 ) thin films were deposited from tetrakis(ethylmethylamino)hafnium (TEMAH) and ozone (O 3 ) by atomic layer deposition (ALD) on 200 mm silicon wafers. The O 3 half-reaction shows good saturation behavior. However, gradual surface saturation is observed for the TEMAH half-reaction. Within wafer non-uniformity of less than 1% and step coverage of about 100% were achieved for trenches with aspect ratio of around 40:1. The film thickness increased linearly as the number of cycles increased. From susceptor temperatures of 160-420°C, the lowest deposition rate (A/cycle) and the highest refractive index is observed at 320°C. The atomic ratio of hafnium to oxygen determined by Rutherford backscattering is 1:2.04 for the films deposited at 320°C. The carbon and hydrogen content determined by secondary ion mass spectroscopy (SIMS) decreased as the susceptor temperature increased from 200 to 320°C. Lower carbon and hydrogen levels were obtained in the control films made with H 2 O than the films made with O 3 . A reaction mechanism of the TEMAH + O 3 ALD process is discussed. The results show that an O 3 -based ALD HfO 2 deposition is promising for microelectronic applications.

Electronic apparatus with deposited dielectric layers

Abstract: An atomic layer deposited dielectric layer and a method of fabricating such a dielectric layer produce a reliable dielectric layer having an equivalent oxide thickness thinner than attainable using SiO2. Depositing a hafnium metal layer on a substrate surface by atomic layer deposition and depositing a hafnium oxide layer on the hafnium metal layer by atomic layer deposition form a hafnium oxide dielectric layer substantially free of silicon oxide. Dielectric layers containing atomic layer deposited hafnium oxide are thermodynamically stable such that the hafnium oxide will have minimal reactions with a silicon substrate or other structures during processing.

Nanolaminate film atomic layer deposition method

Abstract: An atomic layer deposition method to deposit an oxide nanolaminate thin film is provided. The method employs a nitrate ligand in a first precursor as an oxidizer for a second precursor to form the oxide nanolaminates. Using a hafnium nitrate precursor and an aluminum precursor, the method is well suited for the deposition of a high k hafnium oxide/aluminum oxide nanolaminate dielectric for gate dielectric or capacitor dielectric applications on a hydrogen-terminated silicon surface.

Methods of forming a capacitor using an atomic layer deposition process

Abstract: Methods for forming a capacitor using an atomic layer deposition process include providing a reactant including an aluminum precursor onto a substrate to chemisorb a portion of the reactant to a surface of the substrate. The substrate has an underlying structure including a lower electrode. An ammonia (NH 3 ) plasma is provided onto the substrate to form a dielectric layer including aluminum nitride on the substrate including the lower electrode. An upper electrode is formed on the dielectric layer. A second dielectric layer may be provided oil the first dielectric layer.

Atomic layer deposition in nanometer-level replication of cellulosic substances and preparation of photocatalytic TiO2/cellulose composites.

Abstract: TiO2 replicas of filter paper with nanometer-level accuracy were prepared by atomic layer deposition of thin conformal TiO2 coating, followed by a removal of the paper by air-anneal at 450 °C. Photocatalytic anatase TiO2/cellulose composites were also made by leaving the paper intact. The TiO2 films were deposited from Ti(OMe)4 and H2O at 150−250 °C. The photocatalytic activity of the TiO2/cellulose composite was verified by photocatalytic reduction of Ag(I) from an aqueous solution to Ag nanoparticles on the TiO2 surface. The TiO2/cellulose composites are mechanically more stable than the free-standing TiO2 replicas and are therefore potentially suitable as lightweight, high surface area photocatalysts.

Method of forming a layer and method of forming a capacitor of a semiconductor device having the same

Abstract: In a method of forming a layer using an atomic layer deposition process, after a substrate is loaded into a chamber, a reactant is provided onto the substrate to form a preliminary layer. Atoms in the preliminary layer are partially removed from the preliminary layer using plasma formed from an inert gas such as an argon gas, a xenon gas or a krypton gas, or an inactive gas such as an oxygen gas, a nitrogen gas or a nitrous oxide gas to form a desired layer. Processes for forming the desired layer may be simplified. A highly integrated semiconductor device having improved reliability may be economically manufactured so that time and costs required for the manufacturing of the semiconductor device may be reduced.

Low zirconium hafnium halide compositions

Abstract: This invention relates to hafnium halide compositions having a zirconium concentration of less than about 1000 parts per million, a process for producing the hafnium halide compositions having a zirconium concentration of less than about 1000 parts per million, organometallic compound precursors, a process for producing the organometallic compound precursors, and a method for producing a film or coating from the organometallic compound precursors. The organometallic compounds are useful in semiconductor applications as chemical vapor or atomic layer deposition precursors for film depositions.

Methods of forming a thin film structure, and a gate structure and a capacitor including the thin film structure

Abstract: A thin film structure is formed that includes hafnium silicon oxide using an atomic layer deposition process. A first reactant including tetrakis ethyl methyl amino hafnium (TEMAH) is introduced onto a substrate. A first portion of the first reactant is chemisorbed to the substrate, whereas a second portion of the first reactant is physorbed to the first portion of the first reactant. A first oxidant is provided onto the substrate. A first thin film including hafnium oxide is formed on the substrate by chemically reacting the first oxidant with the first portion of the first reactant. A second reactant including amino propyl tri ethoxy silane (APTES) is introduced onto the first thin film. A first portion of the second reactant is chemisorbed to the first thin film, whereas a second portion of the second reactant is physorbed to the first portion of the second reactant. A second oxidant is provided onto the first thin film. A second thin film including silicon oxide is formed on the first thin film by chemically reacting the second oxidant with the first portion of the second reactant.

Forming capping layer over metal wire structure using selective atomic layer deposition

Abstract: Methods of forming a capping layer over a metal wire structure of a semiconductor device are disclosed. In one embodiment, the method includes providing a partially fabricated semiconductor device having exposed surfaces of the metal (e.g., copper) wire structure and a dielectric around the metal wire structure. The exposed surface of the metal wire structure is then activated by forming a seed layer thereon. The capping layer is then formed over the exposed surface of the metal wire structure by performing a selective atomic layer deposition (ALD) of a capping layer material onto the metal wire structure. As an alternative, the dielectric may be masked off to further assist the selectivity of the ALD. The invention also includes a semiconductor structure including the metal wire structure having an atomic layer deposition capping layer over an upper surface thereof.

Method of producing thin films

Abstract: A process for producing metal nitride thin films comprising doping the metal nitride thin films by atomic layer deposition (ALD) with silicon or boron or a combination thereof. The work function of metal nitride thin films, which are used in metal electrode applications, can efficiently be tuned.