Showing papers on "Atomic layer deposition published in 2006"

ZnO-Al2O3 and ZnO-TiO2 core-shell nanowire dye-sensitized solar cells

Abstract: We describe the construction and performance of dye-sensitized solar cells (DSCs) based on arrays of ZnO nanowires coated with thin shells of amorphous Al2O3 or anatase TiO2 by atomic layer deposition. We find that alumina shells of all thicknesses act as insulating barriers that improve cell open-circuit voltage (VOC) only at the expense of a larger decrease in short-circuit current density (JSC). However, titania shells 10−25 nm in thickness cause a dramatic increase in VOC and fill factor with little current falloff, resulting in a substantial improvement in overall conversion efficiency, up to 2.25% under 100 mW cm-2 AM 1.5 simulated sunlight. The superior performance of the ZnO−TiO2 core−shell nanowire cells is a result of a radial surface field within each nanowire that decreases the rate of recombination in these devices. In a related set of experiments, we have found that TiO2 blocking layers deposited underneath the nanowire films yield cells with reduced efficiency, in contrast to the beneficial...

Ultralow surface recombination of c-Si substrates passivated by plasma-assisted atomic layer deposited Al2O3

Abstract: Excellent surface passivation of c-Si has been achieved by Al2O3 films prepared by plasma-assisted atomic layer deposition, yielding effective surface recombination velocities of 2 and 13cm∕s on low resistivity n- and p-type c-Si, respectively. These results obtained for ∼30nm thick Al2O3 films are comparable to state-of-the-art results when employing thermal oxide as used in record-efficiency c-Si solar cells. A 7nm thin Al2O3 film still yields an effective surface recombination velocity of 5cm∕s on n-type silicon.

Apparatus and process for plasma-enhanced atomic layer deposition

Abstract: 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.

Ca test of Al2O3 gas diffusion barriers grown by atomic layer deposition on polymers

Abstract: Quantitative Ca tests were used to determine the water vapor transmission rate (WVTR) through 25nm thick Al2O3 gas diffusion barriers grown on plastic by atomic layer deposition (ALD). The measured WVTRs were 1.7×10−5g∕m2day at 38°C and 6.5×10−5g∕m2day at 60°C. Based on the apparent activation energy, the WVTR at 23°C is estimated to be only 6×10−6g∕m2day. The WVTR values for the Al2O3 ALD film are very similar to the WVTR value for the glass control. These Ca tests indicate that Al2O3 ALD gas diffusion barriers should enable display and lighting applications of highly moisture sensitive organic light-emitting diodes on plastic.

Ultrastable substrates for surface-enhanced Raman spectroscopy: Al2O3 overlayers fabricated by atomic layer deposition yield improved anthrax biomarker detection.

Abstract: A new method to stabilize and functionalize surfaces for surface-enhanced Raman spectroscopy (SERS) is demonstrated. Atomic layer deposition (ALD) is used to deposit a sub-1-nm alumina layer on silver film-over-nanosphere (AgFON) substrates. The resulting overlayer maintains and stabilizes the SERS activity of the underlying silver while presenting the surface chemistry of the alumina overlayer, a commonly used polar adsorbent in chromatographic separations. The relative affinity of analytes for alumina-modified AgFON substrates can be determined by their polarity. On the basis of SERS measurements, dipicolinic acid displays the strongest binding to the ALD alumina-modified AgFON among a set of pyridine derivatives with varying polarity. This strong affinity for carboxylate groups makes the SERS substrate an ideal candidate for bacillus spores detection using the dipicolinate biomarker. The SERS signal from extracted dipicolinate was measured over the spore concentration range 10-14−10-12 M to determine t...

Gas diffusion barriers on polymers using Al2O3 atomic layer deposition

Abstract: Thin films of Al2O3 grown by atomic layer deposition (ALD) were investigated as gas diffusion barriers on flexible polyethylene naphthalate and Kapton® polyimide substrates Al2O3 ALD films with thicknesses of 1–26nm were grown at 100–175°C For Al2O3 ALD films with thicknesses ⩾5nm, oxygen transmission rates were below the MOCON instrument test limit of ∼5×10−3cc∕m2∕day Applying a more sensitive radioactive tracer method, H2O-vapor transmission rates of ∼1×10−3g∕m2∕day were measured for single-sided Al2O3 ALD films with thicknesses of 26nm on the polymers Ultrathin gas diffusion barriers grown by Al2O3 ALD may enable organic displays and electronics on permeable, flexible polymer substrates

High-performance ZnO thin-film transistors on gate dielectrics grown by atomic layer deposition

Abstract: We fabricated high-performance ZnO thin-film transistors on gate dielectrics of HfO2, HfSiOx, and Al2O3, grown by atomic layer deposition (ALD). Devices on HfO2 had a mobility of 12.2cm2∕Vs with a threshold voltage of 2.6V and subthreshold slope of 0.5V∕decade. Device performance on Al2O3 depended on synthesis temperature. For 100nm thick Al2O3, synthesized at 200°C, ZnO devices had a mobility of 17.6cm2∕Vs with a threshold voltage of 6V and less than ∼0.1nA gate leakage at 20V. The overall trends were that devices on Hf oxides had a lower threshold voltage, while the gate leakage current density was lower on Al2O3. Device characteristics for all ALD dielectrics exhibited negligibly small hysteresis, suggesting a low defect density at the interface of ZnO with the gate dielectric.

Zn(O,S) buffer layers by atomic layer deposition in Cu(In,Ga)Se2 based thin film solar cells: Band alignment and sulfur gradient

Abstract: Thin film solar cells with the structure sodalimeglass∕Mo∕Cu(In,Ga)Se2∕Zn(O,S)∕ZnO∕ZnO:Al are studied for varying thickness and sulfur content of the Zn(O,S) buffer layer. These Zn(O,S) layers were deposited by atomic layer deposition (ALD) at 120°C. Devices with no or small concentrations of sulfur in the buffer layer show low open-circuit voltages. This is explained by the cliff, or negative conduction-band offset (CBO), of −0.2eV measured by photoelectron spectroscopy (PES) and optical methods for the Cu(In,Ga)Se2 (CIGS)∕ZnO interface. Devices with ZnS buffer layers exhibit very low photocurrent. This is expected from the large positive CBO (spike) of 1.2eV measured for the CIGS∕ZnS interface. For devices with Zn(O,S) buffer layers, two different deposition recipes were found to yield devices with efficiencies equal to or above reference devices in which standard CdS buffer layers were used; ultrathin Zn(O,S) layers with S∕Zn ratios of 0.8–0.9, and Zn(O,S) layers of around 30nm with average S∕Zn ratios...

Ald metal oxide deposition process using direct oxidation

Abstract: Embodiments of the invention provide methods for forming hafnium materials, such as oxides and nitrides, by sequentially exposing a substrate to hafnium precursors and active oxygen or nitrogen species (e.g., ozone, oxygen radicals, or nitrogen radicals). The deposited hafnium materials have significantly improved uniformity when deposited by these atomic layer deposition (ALD) processes. In one embodiment, an ALD chamber contains an expanding channel having a bottom surface that is sized and shaped to substantially cover a substrate positioned on a substrate pedestal. During an ALD process for forming hafnium materials, process gases form a vortex flow pattern while passing through the expanding channel and sweep across the substrate surface. The substrate is sequentially exposed to chemical precursors that are pulsed into the process chamber having the vortex flow.

Plasma-assisted atomic layer deposition of Al2O3 moisture permeation barriers on polymers

Abstract: Thin Al2O3 films of different thicknesses (10–40nm) were deposited by plasma-assisted atomic layer deposition on substrates of poly(2,6-ethylenenaphthalate) (PEN), and the water vapor transmission rate (WVTR) values were measured by means of the calcium test. The permeation barrier properties improved with decreasing substrate temperature and a good WVTR of 5×10−3gm−2day−1 (WVTRPEN=0.5gm−2day−1) was measured for a 20nm thick Al2O3 film deposited at room temperature using short purging times. Such ultrathin, low-temperature deposited, high-quality moisture permeation barriers are an essential requirement for the implementation of polymeric substrates in flexible electronic and display applications.

Atomic layer deposition on suspended single-walled carbon nanotubes via gas-phase noncovalent functionalization.

Abstract: Alternating exposures of nitrogen dioxide gas and trimethylaluminum vapor are shown to functionalize the surfaces of single-walled carbon nanotubes with a self-limited monolayer. Functionalized nanotube surfaces are susceptible to atomic layer deposition of continuous, radially isotropic material. This allows for the creation of coaxial nanotube structures of multiple materials with precisely controlled diameters. Functionalization involves only weak physical bonding, avoiding covalent modification, which should preserve the unique optical, electrical, and mechanical properties of the nanotubes.

Hafnium aluminium oxynitride high-K dielectric and metal gates

Abstract: Electronic apparatus and methods of forming the electronic apparatus may include a tantalum aluminum oxynitride film for use in a variety of electronic systems and devices. The tantalum aluminum oxynitride film may be structured as one or more monolayers. The tantalum aluminum oxynitride film may be formed using atomic layer deposition. Metal electrodes may be disposed on a dielectric containing a tantalum aluminum oxynitride film.

Treatment processes for a batch ald reactor

Abstract: Embodiments of the invention provide treatment processes to reduce substrate contamination during a fabrication process within a vapor deposition chamber. A treatment process may be conducted before, during, or after a vapor deposition process, such as an atomic layer deposition (ALD) process. In one example of an ALD process, a process cycle, containing an intermediate treatment step and a predetermined number of ALD cycles, is repeated until the deposited material has a desired thickness. The chamber and substrates may be exposed to an inert gas, an oxidizing gas, a nitriding gas, a reducing gas, or plasmas thereof during the treatment processes. In some examples, the treatment gas may contain ozone, water, ammonia, nitrogen, argon, or hydrogen. In one example, a process for depositing a hafnium oxide material within a batch process chamber includes a pretreatment step, an intermediate step during an ALD process, and a post-treatment step.

Atomic layer deposition method of depositing an oxide on a substrate

Abstract: The invention includes atomic layer deposition methods of depositing an oxide on a substrate. In one implementation, a substrate is positioned within a deposition chamber. A first species is chemisorbed onto the substrate to form a first species monolayer within the deposition chamber from a gaseous precursor. The chemisorbed first species is contacted with remote plasma oxygen derived at least in part from at least one of O2 and O3 and with remote plasma nitrogen effective to react with the first species to form a monolayer comprising an oxide of a component of the first species monolayer. The chemisorbing and the contacting with remote plasma oxygen and with remote plasma nitrogen are successively repeated effective to form porous oxide on the substrate. Other aspects and implementations are contemplated.

Hafnium tantalum oxynitride high-k dielectric and metal gates

Abstract: Electronic apparatus and methods may include a hafnium tantalum oxynitride film on a substrate for use in a variety of electronic systems. The hafnium tantalum oxynitride film may be structured as one or more monolayers. The hafnium tantalum oxynitride film may be formed using atomic layer deposition. Metal electrodes may be disposed on a dielectric containing a hafnium tantalum oxynitride film.

Cyclopentadienyl type hafnium and zirconium precursors and use thereof in atomic layer deposition

Abstract: Precursors suitable for chemical vapour deposition, especially ALD, of hafnium oxide or zirconium oxide, have the general formula (I): (R1Cp)2MR2 R3 wherein Cp represents a cyclopentadienyl ligand, R1 is H or a substituting alkyl group, alkoxy group or amido group of the Cp ligand, R2 and R3 is an alkyl group, an alkoxy group or an amido group and M is hafnium or zirconium.

LOW TEMPERATURE ALD SiO2

Abstract: The present invention generally comprises a silicon dioxide atomic layer deposition method. By providing pyridine as a catalyst, water may be utilized as the oxidization source while depositing at a low temperature. Prior to exposing the substrate to the water, the substrate may be exposed to a pyridine soak process. Additionally, the water may be co-flowed to the chamber with the pyridine through separate conduits to reduce interaction prior to entering the chamber. Alternatively, the pyridine may be co-flowed with a silicon precursor that does not react with pyridine.

ALD and Characterization of Aluminum Oxide Deposited on Si ( 100 ) using Tris(diethylamino) Aluminum and Water Vapor

Abstract: © The Electrochemical Society, Inc. 2006. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Katamreddy, R., R. Inman, G. Jursich, A. Soulet, and C. Takoudis, 2006, ALD and characterization of aluminum oxide deposited on Si (100) using tris(diethylamino) aluminum and water vapor: Journal of the Electrochemical Society, v. 153, no. 10, p. C701-C706.

Ald of silicon films on germanium

Abstract: The use of atomic layer deposition (ALD) to form a semiconductor structure of a silicon film on a germanium substrate is disclosed. An embodiment includes a tantalum nitride gate electrode on a hafnium dioxide gate dielectric on the silicon film (TaN/HfO2/Si/Ge), which produces a reliable high dielectric constant (high k) electronic structure having higher charge carrier mobility as compared to silicon substrates. This structure may be useful in high performance electronic devices. The structure is formed by ALD deposition of a thin silicon layer on a germanium substrate surface, and then ALD forming a hafnium oxide gate dielectric layer, and a tantalum nitride gate electrode. Such a structure may be used as the gate of a MOSFET, or as a capacitor. The properties of the dielectric may be varied by replacing the hafnium oxide with another gate dielectric such as zirconium oxide (ZrO2), or titanium oxide (TiO2).

Atomic Layer Deposition of Ultrathin Copper Metal Films from a Liquid Copper(I) Amidinate Precursor

Abstract: We report a method for producing thin, completely continuous and highly conductive copper films conformally inside very narrow holes with aspect ratios over 35:1 by atomic layer deposition (ALD). Pure copper thin films were grown from a novel copper(I) amidinate precursor, copper(I) N,N'-di-sec-butylacetamidinate, and molecular hydrogen gas as the reducing agent. This copper precursor is a liquid during vaporization because its melting point (77°C) is lower than its vaporization temperature (90-120°C). Thus, the transport of the precursor vapor is very reproducible and controllable. Carbon and oxygen impurities were below 1 atom %. The growth per cycle varied from 1.5-2 A/cycle on SiO 2 or Si 3 N 4 surfaces but was only 0.1-0.5 A/cycle on metallic Ru, Cu, and Co surfaces. On oxide surfaces, copper atoms form isolated copper crystallites that merge into rough polycrystalline films after more deposition cycles. On Ru and Co metal surfaces ALD Cu nucleates densely, forming smooth and strongly adherent films that are continuous even for films as thin as 4 atomic layers. With 4 nm Cu deposited on 2 nm Ru substrates, the sheet resistance is below 50 Ω/□, which is low enough for making seed layers for electroplating Cu interconnect wires.

System for depositing a film by modulated ion-induced atomic layer deposition (MII-ALD)

Abstract: The present invention relates to an enhanced sequential atomic layer deposition (ALD) technique suitable for deposition of barrier layers, adhesion layers, seed layers, low dielectric constant (low-k) films, high dielectric constant (high-k) films, and other conductive, semi-conductive, and non-conductive films. This is accomplished by 1) providing a non-thermal or non-pyrolytic means of triggering the deposition reaction; 2) providing a means of depositing a purer film of higher density at lower temperatures; and, 3) providing a faster and more efficient means of modulating the deposition sequence and hence the overall process rate resulting in an improved deposition method.

Plasma pre-treating surfaces for atomic layer deposition

Abstract: Method and structures are provided for conformal lining of dual damascene structures in integrated circuits Preferred embodiments are directed to providing conformal lining over openings formed in porous materials Trenches are formed (100) in insulating layers The layers are then adequately treated with a particular plasma process (101) Following this plasma treatment a self-limiting, self-saturating atomic layer deposition (ALD) reaction (115) can occur without significantly filling the pores forming improved interconnects

DNA Functionalization of Carbon Nanotubes for Ultrathin Atomic Layer Deposition of High κ Dielectrics for Nanotube Transistors with 60 mV/Decade Switching

Abstract: For single-walled carbon nanotube (SWNT) field effect transistors, vertical scaling of high κ dielectrics by atomic layer deposition (ALD) currently stands at ∼8 nm with a subthreshold swing S ≈ 70−90 mV/decade at room temperature. ALD on as-grown pristine SWNTs is incapable of producing a uniform and conformal dielectric layer due to the lack of functional groups on nanotubes and because nucleation of an oxide dielectric layer in the ALD process hinges upon covalent chemisorption on reactive groups on surfaces. Here, we show that by noncovalent functionalization of SWNTs with poly-T DNA molecules (dT40-DNA), one can impart functional groups of sufficient density and stability for uniform and conformal ALD of high κ dielectrics on SWNTs with thickness down to 2−3 nm. This enables approaching the ultimate vertical scaling limit of nanotube FETs and reliably achieving S ≈ 60 mV/decade at room temperature, and S ≈ 50 mV/decade in the band-to-band tunneling regime of ambipolar transport. We have also carried ...

Atomic layer deposition on biological macromolecules: metal oxide coating of tobacco mosaic virus and ferritin.

Abstract: Decoration of nanoparticles, in particular biomolecules, gathered high attention in recent years.1-7 Of special interest is the potential use of biomolecules as templates for the fabrication of semiconducting or metallic nanostructures.1-7,26 In this work we show the application of atomic layer deposition, a gas-phase thin film deposition process, to biological macromolecules, which are frequently used as templates in nanoscale science, and the possibility to fabricate metal oxide nanotubes and thin films with embedded biomolecules.1-13

Vapor deposition of metal carbide films

Abstract: Methods of forming metal carbide thin films are provided. According to preferred embodiments, metal carbide thin films are formed in an atomic layer deposition (ALD) process by alternately and sequentially contacting a substrate in a reaction space with spatially and temporally separated vapor phase pulses of a metal source chemical, a reducing agent and a carbon source chemical. The reducing agent is preferably selected from the group consisting of excited species of hydrogen and silicon-containing compounds.

In-situ atomic layer deposition

Abstract: An in situ method for forming a HfO2 high-k dielectric layer in a batch wafer processing system (1, 100). The method comprises first loading a plurality of wafers (40, 110) into a process chamber (10, 102), and then pre-treating the plurality of wafers (40, 110) in the process chamber (10, 102) with a first oxidizer. After pre-treating the wafers (40, 110), and without removing the wafers (40, 110) from the process chamber (10, 102), the method then comprises depositing HfO2 on the plurality of wafers (40, 110) by atomic layer deposition, which comprises a plurality of deposition cycles, each cycle comprising alternating exposure of the plurality of wafers (40, 110) in the process chamber (40, 110) to a second oxidizer and a hafnium precursor. The hafnium precursor is selected from hafnium tert-butoxide (HTB) or hafnium tetra-diethylamide (TDEAH).

Methods for fabricating hafnium tantalum oxide dielectrics

Abstract: A dielectric layer containing hafnium tantalum film arranged as a structure of one or more monolayers and a method of fabricating such a dielectric layer produce a dielectric layer for use in a variety of electronic devices. In an embodiment, a hafnium tantalum oxide film may be formed by depositing hafnium and tantalum by atomic layer deposition onto a substrate surface. Embodiments include structures for capacitors, transistors, memory devices, and electronic systems with dielectric layers containing a hafnium tantalum oxide film arranged as a structure of one or more monolayers, and methods for forming such structures.

Film Uniformity in Atomic Layer Deposition

Abstract: The sources of non-uniformity in thin films produced using atomic layer deposition (ALD) have been investigated by reviewing the mechanical hardware of ALD reactors, precursors, and the by-products of surface reactions. The most common causes of non-uniformity are overlapping pulses, thermal self-decomposition of precursors, and non-uniform gas distribution. Less studied, however, are the consequences of downstream surface reactions of gaseous by-products. In particular, titanium nitride films have been found to be significantly less uniform than those of transition metal oxides deposited from metal halides. The influence of reaction by-products on the TiN film growth has been studied by comparing the deposition in the cross-flow and showerhead style reactors. Finally, the sources of non-uniformity in plasma enhanced (PE) ALD are illustrated by studying the TiN deposition process.