Journal of Vacuum Science & Technology A Vacuum Surfaces and Films (J VAC SCI TECHNOL A )

Publisher: American Vacuum Society; American Institute of Physics, American Vacuum Society


The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles. JVST A will include topics such as applied surface science, electronic materials and processing, fusion technology, plasma technology, surface science, thin films, vacuum metallurgy, and vacuum technology. It will contain the program and papers from the AVS National Symposium as well as the papers from other conferences and symposia sponsored by the AVS and its Divisions. JVST A is published six times annually.

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    Journal of Vacuum Science and Technology A website
  • Other titles
    Journal of vacuum science & technology. A. Vacuum, surfaces, and films, JVST A, Journal of vacuum science and technology., Vacuum, surfaces, and films
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    Periodical, Internet resource
  • Document type
    Journal / Magazine / Newspaper, Internet Resource

Publisher details

American Vacuum Society

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    • Author can archive a pre-print version
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    • Author can archive a post-print version
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    • On a public eprint server
    • On authors and employers website
    • Publisher's version/PDF may be used, on authors and employers website only
    • Must link to publisher abstract version
    • Published source must be acknowledged (see policy for wording)
    • If funding agency rules apply, authors may post articles in PubMed Central 12 months after publication
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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Atomic layer deposition (ALD) holds markedly high potential of becoming the enabling method for achieving the three-dimensional all-solid-state thin-film lithium ion battery (LiB). One of the most crucial components in such a battery is the electrolyte that needs to hold both low electronic conductivity and at least fair lithium ion conductivity being at the same time pinhole free. To obtain these desired properties in an electrolyte film, one necessarily has to have a good control over the elemental composition of the deposited material. The present study reports on the properties of ALD lithium aluminum oxide (LixAlyOz) thin films. In addition to LiB electrolyte applications, LixAlyOz is also a candidate low dielectric constant (low-k) etch stop and diffusion barrier material in nanoelectronics applications. The LixAlyOz films were deposited employing trimethylaluminum-O3 and lithium tert-butoxide-H2O for Al2O3 and Li2O/LiOH, respectively. The composition was aimed to be controlled by varying the pulsing ratio of those two binary oxide ALD cycles. The films were characterized by several methods for composition, crystallinity and phase, electrical properties, hardness, porosity, and chemical environment. Regardless of the applied pulsing ratio of Al2O3 and Li2O/LiOH, all the studied ALD LixAlyOz films of 200 and 400 nm in thickness were polycrystalline in the orthorhombic β-LiAlO2 phase and also very similar to each other with respect to composition and other studied properties. The results are discussed in the context of both fundamental ALD chemistry and applicability of the films as thin-film LiB electrolytes and low-k etch stop and diffusion barriers.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2015; 33(1):01A101-01A101-7.
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    ABSTRACT: The fracture strength of Al2O3 membranes deposited by atomic layer deposition at 110, 150, 200, and 300 °C was investigated. The fracture strength was found to be in the range of 2.25–3.00 GPa using Weibull statistics and nearly constant as a function of deposition temperature. This strength is superior to common microelectromechanical systems materials such as diamondlike carbon, SiO2, or SiC. As-deposited membranes sustained high cycling pressure loads >10 bar/s without fracture. Films featured, however, significant reduction in the resistance to failure after annealing (800 °C) or high humidity (95%, 60 °C) treatments.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2015; 33(1):01A106-01A106-5.
  • Sathees Kannan Selvaraj, Christos G. Takoudis
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    ABSTRACT: The authors report the development and implementation of a scalable control program to control flow type atomic layer deposition (ALD) reactor with multiple precursor delivery lines. The program logic is written and tested in labview environment to control ALD reactor with four precursor delivery lines to deposit up to four layers of different materials in cyclic manner. The programming logic is conceived such that to facilitate scale up for depositing more layers with multiple precursors and scale down for using single layer with any one precursor in the ALD reactor. The program takes precursor and oxidizer exposure and purging times as input and controls the sequential opening and closing of the valves to facilitate the complex ALD process in cyclic manner. The program could be used to deposit materials from any single line or in tandem with other lines in any combination and in any sequence.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2015; 33(1):013201-013201-8.
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    ABSTRACT: The authors report on the structural and electrical properties of TiN/Al2O3/TiN metal–insulator–metal (MIM) capacitor structures in submicron three-dimensional (3D) trench geometries with an aspect ratio of ∼30. A simplified process route was employed where the three layers for the MIM stack were deposited using atomic layer deposition (ALD) in a single run at a process temperature of 250 °C. The TiN top and bottom electrodes were deposited via plasma-enhanced ALD using a tetrakis(dimethylamino)titanium precursor. 3D trench devices yielded capacitance densities of 36 fF/μm2 and quality factors >65 at low frequency (200 Hz), with low leakage current densities (<3 nA/cm2 at 1 V). These devices also show strong optical iridescence which, when combined with the covert embedded capacitance, show potential for system in package (SiP) anticounterfeiting applications.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2015; 33(1):01A103-01A103-5.
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    ABSTRACT: Atomic layer deposition (ALD) is a technique for depositing thin films of materials with a precise thickness control and uniformity using the self-limitation of the underlying reactions. Usually, it is difficult to predict the result of the ALD process for given external parameters, e.g., the precursor exposure time or the size of the precursor molecules. Therefore, a deeper insight into ALD by modeling the process is needed to improve process control and to achieve more economical coatings. In this paper, a detailed, microscopic approach based on the model developed by Yanguas-Gil and Elam is presented and additionally compared with the experiment. Precursor diffusion and second-order reaction kinetics are combined to identify the influence of the porous substrate's microstructural parameters and the influence of precursor properties on the coating. The thickness of the deposited film is calculated for different depths inside the porous structure in relation to the precursor exposure time, the precursor vapor pressure, and other parameters. Good agreement with experimental results was obtained for ALD zirconiumdioxide (ZrO2) films using the precursors tetrakis(ethylmethylamido)zirconium and O2. The derivation can be adjusted to describe other features of ALD processes, e.g., precursor and reactive site losses, different growth modes, pore size reduction, and surface diffusion.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2015; 33(1):01A104-01A104-7.
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    ABSTRACT: At present flexible electronic devices are under extensive development and, among them, flexible organic light-emitting diode displays are the closest to a large market deployment. One of the remaining unsolved challenges is high throughput production of impermeable flexible transparent barrier layers that protect sensitive light-emitting materials against ambient moisture. The present studies deal with the adaptation of the atomic layer deposition (ALD) process to high-throughput roll-to-roll production using the spatial ALD concept. We report the development of such a process for the deposition of 20nm thickness Al2O3 diffusion barrier layers on 500mm wide polymer webs. The process uses trimethylaluminum and water as precursors at a substrate temperature of 105°C. The observation of self-limiting film growth behavior and uniformity of thickness confirms the ALD growth mechanism. Water vapor transmission rates for 20nm Al2O3 films deposited on polyethylene naphthalate (PEN) substrates were measured as a function of substrate residence time, that is, time of exposure of the substrate to one precursor zone. Moisture permeation levels measured at 38°C/90% relative humidity by coulometric isostatic–isobaric method were below the detection limit of the instrument (<5x10-4 g/ for films coated at web moving speed of 0.25m/min. Measurements using the Ca test indicated water vapor transmission rates ~5x10-6 g/ Optical measurements on the coated web showed minimum transmission of 80% in the visible range that is the same as the original PEN substrate.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 08/2014; 32(5):051603.
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    ABSTRACT: Several concepts of integration of the epitaxial rare-earth oxides into the emerging advanced semiconductor on silicon technology are presented. Germanium grows epitaxially on gadolinium oxide despite lattice mismatch of more than 4%. Additionally, polymorphism of some of the rare-earth oxides allows engineering of their crystal structure from hexagonal to cubic and formation of buffer layers that can be used for growth of germanium on a lattice matched oxide layer. Molecular beam epitaxy and metal organic chemical vapor deposition of gallium nitride on the rare-earth oxide buffer layers on silicon is discussed.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 06/2014; 32:041506.
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    ABSTRACT: A closed ion source (CIS) has been optimized by investigating the effect of electron entrance slit size and the effect of mesh in the slit. A stainless steel mesh was placed on the electron entrance slits for a uniform potential distribution inside the CIS anode. Sensitivity of the closed ion sources having four different slit sizes with and without the mesh was compared using mass spectra of SF6 gas (97% He gas base) introduced into the CIS anode through a needle valve. For each CIS, isolation of anode potential with a mesh in the slit exhibited a significant sensitivity enhancement, but ion current measured directly behind each CIS showed negligible mesh effect. In order to elucidate the mesh effect, electron trajectories were simulated inside the anode. The computer simulation shows that, with mesh in the slit, more electrons are focused to a central region of the anode. This suggests ions generated in the CIS with mesh should have higher probability of passing through the quadrupole mass filter.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 03/2014; 32(20):021603.
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    ABSTRACT: The authors report on Langmuir probe measurements that show that hydrocarbon surfaces in contact with Ar plasma cause changes of electron energy distribution functions due to the flux of hydrogen and carbon atoms released by the surfaces. The authors compare the impact on plasma properties of hydrocarbon species gasified from an etching hydrocarbon surface with injection of gaseous hydrocarbons into Ar plasma. They find that both kinds of hydrocarbon injections decrease electron density and slightly increase electron temperatures of low pressure Ar plasma. For low percentages of impurities (∼1% impurity in Ar plasma explored here), surface-derived hydrocarbon species and gas phase injected hydrocarbon molecules cause similar changes of plasma properties for the same number of hydrocarbon molecules injected into Ar with a decrease in electron density of ∼4%.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 02/2014; 32(3):030601.
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    ABSTRACT: Water cluster ion beams were irradiated on mica surfaces to investigate the interaction between molecular cluster ions and a mica surface. The contact angle of the mica surface increased with increasing dose of the water cluster ion beam, but the increase in the contact angle was smaller than that induced by an ethanol cluster ion beam. The surface roughness also increased with increasing dose of the water cluster ion beam, whereas the intensity of K 2p x-ray photoelectron spectroscopy peaks decreased with increasing dose of the water cluster ion beam. The decrease in the number of potassium atoms together with the increase in the surface roughness may be the causes of the increase in the contact angle.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2014; 32(2):02B109-02B109-4.
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    ABSTRACT: Two types of bilayer thin films with different deposition sequences, i.e., amorphous Ge under Al (a-Ge/Al) and the inverse (Al/a-Ge), were prepared by magnetron sputtering at room temperature. In-situ and ex-situ thermal annealing were compared to study the effect of the stacking sequence on crystallization of amorphous Ge. Although metal-induced crystallization occurred in both cases at low temperature, layer exchange was observed only in a-Ge/Al. In fact, compressive stress could usually be produced when Ge atoms diffused into Al grain boundaries and crystallized there. In the a-Ge/Al system, the stress could be released through diffusion of Al atoms onto the surface and formation of hillocks. Thus, grain boundary (GB) mediated crystallization was dominant in the whole process and layer exchange occurred. However, in the Al/a-Ge system, it was difficult for stress to be relaxed because the Ge sublayer and substrate restricted the diffusion of Al atoms. GB-mediated crystallization was, therefore, considerably suppressed and interface-mediated crystallization was preferred without layer exchange. This leads to distinct morphologies of dendrites in the two systems.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2014; 32(3):031501-031501-7.
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    ABSTRACT: The failure mechanisms arising from the instability in operation of indium gallium zinc oxide based thin film transistors (TFTs) upon prolonged real application stresses (bias and illumination) have been extensively studied and reported. Positive and negative gate bias conditions, along with high photonic energy wavelengths within visible light spectrum are used as stress conditions. The increased carrier concentration due to photonic excitation of defects within bandgap and ionization of deep level vacancies is compensated by the reduction in off currents under illumination due to the trapping of carriers in the intermetal dielectric. Band lowering at the source-channel junction due to accumulation of negative carriers repelled due to negative gate bias stress further causes high carrier flow into the channel and drives the devices into failure. The defect identification during failure and degradation assisted in proposing suitable low temperature post processing in specific ambients. Reliability tests after specific anneals in oxygen, vacuum, and forming gas ambients confirm the correlation of the defect type with anneal ambient. Annealed TFTs demonstrate high stabilities under illumination stresses and do not fail when subjected to combined stresses that cause failure in as-fabricated TFTs. Oxygen and forming gas anneals are impactful on the reliability and opens an area of study on donor and vacancy behavior in amorphous mixed oxide based TFTs. The subthreshold swing, field-effect mobilities, and off currents provide knowledge on best anneal practices by understanding role of hydrogen and oxygen in vacancy annihilation and transistor switching properties.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2014; 32(2):021101-021101-6.
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    ABSTRACT: In situ phosphorus-doped polycrystalline silicon (polysilicon) films grown on silicon oxide layers using trisilane (Si3H8) and phosphine (PH3) as precursors are investigated as a function of the Si3H8/PH3 gas flow ratio and the growth temperature. At a high flow rate for Si3H8 in the temperature range of 600–700 °C, the deposition process is controlled by the rate of desorption of hydrogen molecules on the surface, which has an activation energy of 1.13 eV. For a low Si3H8 flow rate at growth temperatures >650 °C, however, the deposition is limited by the diffusion of Si3H8 gas to the surface. The presence of phosphorus decreases the crystallization temperature of the polysilicon layers during growth. In addition, the ratio of phosphorus incorporated into the polysilicon decreases with increasing growth temperature because of the increase in the growth rate. The resistivity of the phosphorus-doped polysilicon films decreases with increasing deposition temperature at the same phosphorus concentration, indicating that the use of a high growth temperature results in an enhancement in the activation of phosphorus in the polysilicon films during growth.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2014; 32(3):031510-031510-7.

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