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Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films

Issue 1 • Date Jan 2014

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Displaying Results 1 - 25 of 35
  • Selective atomic layer deposition of zirconia on copper patterned silicon substrates using ethanol as oxygen source as well as copper reductant

    Page(s): 010601 - 010601-4
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    The authors report a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces. Instead of using common atomic layer deposition (ALD) oxygen sources such as water, oxygen, or ozone, the authors use ethanol, which serves as oxygen source for the ALD on the silicon side and as effective reducing agent on the copper side, thereby selectively depositing ZrO2 film on the silicon surface of the substrate without any deposition on copper up to at least 70 ALD cycles. The resulting ZrO2 nanofilm is found to be an effective copper diffusion barrier at temperatures at least up to 700 °C. View full abstract»

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  • In situ synchrotron based x-ray techniques as monitoring tools for atomic layer deposition

    Page(s): 010801 - 010801-14
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    Atomic layer deposition (ALD) is a thin film deposition technique that has been studied with a variety of in situ techniques. By exploiting the high photon flux and energy tunability of synchrotron based x-rays, a variety of new in situ techniques become available. X-ray reflectivity, grazing incidence small angle x-ray scattering, x-ray diffraction, x-ray fluorescence, x-ray absorption spectroscopy, and x-ray photoelectron spectroscopy are reviewed as possible in situ techniques during ALD. All these techniques are especially sensitive to changes on the (sub-)nanometer scale, allowing a unique insight into different aspects of the ALD growth mechanisms. View full abstract»

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  • Reactor concepts for atomic layer deposition on agitated particles: A review

    Page(s): 010802 - 010802-13
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    The number of possible applications for nanoparticles has strongly increased in the last decade. For many applications, nanoparticles with different surface and bulk properties are necessary. A popular surface modification technique is coating the particle surface with a nanometer thick layer. Atomic layer deposition (ALD) is known as a reliable method for depositing ultrathin and conformal coatings. In this article, agitation or fluidization of the particles is necessary for performing ALD on (nano)particles. The principles of gas fluidization of particles will be outlined, and a classification of the gas fluidization behavior of particles based on their size and density will be given. Following different reactor concepts that have been designed to conformally coat (nano)particles with ALD will be described, and a concise overview will be presented of the work that has been performed with each of them ending with a concept reactor for performing spatial ALD on fluidized particles. View full abstract»

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  • Vacuum sealing using atomic layer deposition of Al2O3 at 250 °C

    Page(s): 01A101 - 01A101-5
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    This paper describes the use of low-temperature atomic layer deposition (ALD) of Al2O3, for vacuum seals in wafer-level vacuum packaging and other applications. The conformal coverage provided by ALD Al2O3 is shown to seal circular micromachined cavities. The cavities are 0.8 μm in height, 400 μm in diameter, and are capped by porous plasma-enhanced chemical vapor deposited dielectrics that form a membrane. The ALD Al2O3 film, of thickness ≈0.2 μm, is deposited at a temperature of 250 °C on this membrane. The retention of vacuum is indicated by the deflection of the membrane. Lifetime tests extending out to 19 months are reported. View full abstract»

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  • Adhesion testing of atomic layer deposited TiO2 on glass substrate by the use of embedded SiO2 microspheres

    Page(s): 01A102 - 01A102-5
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    In this paper, the authors present a new adhesion test method, which is under development, to study the interfacial mechanical parameters of atomic layer deposited (ALD) thin films. A highly sensitive lateral force adhesion testing tool was used to measure the lateral detaching force of 8 μm diameter SiO2 microspheres embedded in 100 nm ALD TiO2 thin film grown in 200 °C. The resulting holes in the coating were characterized with scanning electron microscope plus energy dispersive x-ray spectroscopy and the delaminated areas were measured with image analysis software. The corresponding detaching force (F) was compared to the delaminated area (A) to calculate the critical stress value (σ), which relates to the mechanical adhesion of the coating and also includes the effect of other influencing factors such as the film cohesion. The measured critical stress (σ) of the ALD TiO2 coating on a glass substrate was 36 ± 12 MPa based on the measurement of 43 microspheres. View full abstract»

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  • HfO2 dielectric film growth directly on graphene by H2O-based atomic layer deposition

    Page(s): 01A103 - 01A103-5
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    Due to its exceptionally high carrier mobility, International Technology Roadmap for Semiconductors considers graphene to be among the candidate materials for postsilicon electronics. In order to realize graphene-based devices, thin and uniform-coverage high-κ dielectrics without any pinholes on top of graphene is required. There are no dangling bonds on defect-free graphene surface; it is difficult to grow uniform-coverage high-κ dielectrics on graphene directly by atom layer deposition. Meanwhile, degradation of defects in graphene/high-κ structure is necessary for the optimization of high-κ dielectrics fabrication technology. Here the authors report on a H2O-based atom layer deposition method used for HfO2 growth, where physically adsorbed H2O molecules on graphene surface act as oxidant, and self-limit react with metal precursors to form HfO2 film onto graphene directly. Raman spectra reveal H2O-based atom layer deposition method will not introduce defects into graphene. The surface root mean square of HfO2 films is down to 0.9 nm and the capacitance of HfO2 films on graphene is up to 2.7 μF/cm2, which indicate high quality and compactness of HfO2 films. View full abstract»

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  • Kinetic study on hot-wire-assisted atomic layer deposition of nickel thin films

    Page(s): 01A104 - 01A104-7
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    High-purity Ni films were deposited using hot-wire-assisted atomic layer deposition (HW-ALD) at deposition temperatures of 175, 250, and 350 °C. Negligible amount of nitrogen or carbon contamination was detected, even though the authors used NH2 radical as the reducing agent and nickelocene as the precursor. NH2 radicals were generated by the thermal decomposition of NH3 with the assist of HW and used to reduce the adsorbed metal growth precursors. To understand and improve the deposition process, the kinetics of HW-ALD were analyzed using a Langmuir-type model. Unlike remote-plasma-enhanced atomic layer deposition, HW-ALD does not lead to plasma-induced damage. This is a significant advantage, because the authors can supply sufficient NH2 radicals to deposit high-purity metallic films by adjusting the distance between the hot wire and the substrate. NH2 radicals have a short lifetime, and it was important to use a short distance between the radical generation site and substrate. Furthermore, the impurity content of the nickel films was independent of the deposition temperature, which is evidence of the temperature-independent nature of the NH2 radical flux and the reactivity of the NH2 radicals. View full abstract»

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  • Hybrid inorganic–organic superlattice structures with atomic layer deposition/molecular layer deposition

    Page(s): 01A105 - 01A105-5
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    A combination of the atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques is successfully employed to fabricate thin films incorporating superlattice structures that consist of single layers of organic molecules between thicker layers of ZnO. Diethyl zinc and water are used as precursors for the deposition of ZnO by ALD, while three different organic precursors are investigated for the MLD part: hydroquinone, 4-aminophenol and 4,4′-oxydianiline. The successful superlattice formation with all the organic precursors is verified through x-ray reflectivity studies. The effects of the interspersed organic layers/superlattice structure on the electrical and thermoelectric properties of ZnO are investigated through resistivity and Seebeck coefficient measurements at room temperature. The results suggest an increase in carrier concentration for small concentrations of organic layers, while higher concentrations seem to lead to rather large reductions in carrier concentration. View full abstract»

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  • Role of plasma enhanced atomic layer deposition reactor wall conditions on radical and ion substrate fluxes

    Page(s): 01A106 - 01A106-6
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    Chamber wall conditions, such as wall temperature and film deposits, have long been known to influence plasma source performance on thin film processing equipment. Plasma physical characteristics depend on conductive/insulating properties of chamber walls. Radical fluxes depend on plasma characteristics as well as wall recombination rates, which can be wall material and temperature dependent. Variations in substrate delivery of plasma generated species (radicals, ions, etc.) impact the resulting etch or deposition process resulting in process drift. Plasma enhanced atomic layer deposition is known to depend strongly on substrate radical flux, but film properties can be influenced by other plasma generated phenomena, such as ion bombardment. In this paper, the chamber wall conditions on a plasma enhanced atomic layer deposition process are investigated. The downstream oxygen radical and ion fluxes from an inductively coupled plasma source are indirectly monitored in temperature controlled (25–190 °C) stainless steel and quartz reactors over a range of oxygen flow rates. Etch rates of a photoresist coated quartz crystal microbalance are used to study the oxygen radical flux dependence on reactor characteristics. Plasma density estimates from Langmuir probe ion saturation current measurements are used to study the ion flux dependence on reactor characteristics. Reactor temperature was not found to impact radical and ion fluxes substantially. Radical and ion fluxes were higher for quartz walls compared to stainless steel walls over all oxygen flow rates considered. The radical flux to ion flux ratio is likely to be a critical parameter for the deposition of consistent film properties. Reactor wall material, gas flow rate/pressure, and distance from the plasma source all impact the radical to ion flux ratio. These results indicate maintaining chamber wall conditions will be important for delivering consistent results from plasma enhanced atomic layer- deposition systems. View full abstract»

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  • Capacitance and conductance versus voltage characterization of Al2O3 layers prepared by plasma enhanced atomic layer deposition at 25 °C≤ T ≤ 200 °C

    Page(s): 01A107 - 01A107-10
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    In this work, plasma enhanced atomic layer deposited (PE-ALD) samples were prepared at substrate temperatures in the range between room temperature (RT) and 200 °C and investigated by capacitance–voltage and conductance–voltage recordings. The measurements are compared to standard thermal atomic layer deposition (T-ALD) at 200 °C. Very low interface state density (Dit) ∼1011 eV−1 cm−2 could be achieved for the PE-ALD process at 200 °C substrate temperature after postdeposition anneal (PDA) in forming gas at 450 °C. The PDA works very effectively for both the PE-ALD and T-ALD at 200 °C substrate temperature delivering also similar values of negative fixed charge density (Nfix) around −2.5 × 1012 cm−2. At the substrate temperature of 150 °C, highest Nfix (−2.9 × 1012 cm−2) and moderate Dit (2.7 × 1011 eV−1 cm−2) values were observed. The as deposited PE-ALD layer at RT shows both low Dit in the range of (1 to 3) × 1011 eV−1 cm−2 and low Nfix (−4.4 × 1011 cm−2) at the same time. The dependencies of Nfix, Dit, and relative permittivity on the substrate temperatures and its adjustability are discussed. View full abstract»

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  • Low temperature hydrogen plasma-assisted atomic layer deposition of copper studied using in situ infrared reflection absorption spectroscopy

    Page(s): 01A108 - 01A108-8
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    Atomic layer deposition (ALD) is an ideal technique to deposit ultrathin, conformal, and continuous metal thin films. However, compared to the ALD of binary materials such as metal oxides and metal nitrides, the surface reaction mechanisms during metal ALD are not well understood. In this study, the authors have designed and implemented an in situ reflection-absorption infrared spectroscopy (IRAS) setup to study the surface reactions during the ALD of Cu on Al2O3 using Cu hexafluoroacetylacetonate [Cu(hfac)2] and a remote H2 plasma. Our infrared data show that complete ligand-exchange reactions occur at a substrate temperature of 80 °C in the absence of surface hydroxyl groups. Based on infrared data and previous studies, the authors propose that Cu(hfac)2 dissociatively chemisorbs on the Al2O3 surface, where the Al-O-Al bridge acts as the surface reactive site, leading to surface O-Cu-hfac and O-Al-hfac species. Surface saturation during the Cu(hfac)2 half-cycle occurs through blocking of the available chemisorption sites. In the next half-reaction cycle, H radicals from an H2 plasma completely remove these surface hfac ligands. Through this study, the authors have demonstrated the capability of in situ IRAS as a tool to study surface reactions during ALD of metals. While transmission and internal reflection infrared spectroscopy are limited to the first few ALD cycles, IRAS can be used to probe all stages of metal ALD starting from initial nucleation to the formation of a continuous film. View full abstract»

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  • Growth mode evolution of hafnium oxide by atomic layer deposition

    Page(s): 01A109 - 01A109-5
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    HfO2 thin films were deposited using tetrakis-ethylmethylamido hafnium and H2O as precursors on silicon by atomic layer deposition (ALD). The morphology and microstructures at different ALD cycles were characterized by atomic force microscopy and high-resolution transmission electron microscopy. Based on the height–height correlation function and power spectral density function, quantitative analysis of surface morphologies was performed. Three characteristic dimensions (ξ1, ξ2, and ξ3) corresponding to three surface structures, islands, local and global fluctuations, were identified. The evolution of ALD growth mode at range of the three critical scales was investigated, respectively. It suggests the transformation of growth mode from quasi two-dimensional layer-by-layer to three-dimensional island for global fluctuations. View full abstract»

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  • Numerical modeling of carrier gas flow in atomic layer deposition vacuum reactor: A comparative study of lattice Boltzmann models

    Page(s): 01A110 - 01A110-10
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    This paper characterizes the carrier gas flow in the atomic layer deposition (ALD) vacuum reactor by introducing Lattice Boltzmann Method (LBM) to the ALD simulation through a comparative study of two LBM models. Numerical models of gas flow are constructed and implemented in two-dimensional geometry based on lattice Bhatnagar–Gross–Krook (LBGK)-D2Q9 model and two-relaxation-time (TRT) model. Both incompressible and compressible scenarios are simulated and the two models are compared in the aspects of flow features, stability, and efficiency. Our simulation outcome reveals that, for our specific ALD vacuum reactor, TRT model generates better steady laminar flow features all over the domain with better stability and reliability than LBGK-D2Q9 model especially when considering the compressible effects of the gas flow. The LBM-TRT is verified indirectly by comparing the numerical result with conventional continuum-based computational fluid dynamics solvers, and it shows very good agreement with these conventional methods. The velocity field of carrier gas flow through ALD vacuum reactor was characterized by LBM-TRT model finally. The flow in ALD is in a laminar steady state with velocity concentrated at the corners and around the wafer. The effects of flow fields on precursor distributions, surface absorptions, and surface reactions are discussed in detail. Steady and evenly distributed velocity field contribute to higher precursor concentration near the wafer and relatively lower particle velocities help to achieve better surface adsorption and deposition. The ALD reactor geometry needs to be considered carefully if a steady and laminar flow field around the wafer and better surface deposition are desired. View full abstract»

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  • X-ray reflectivity characterization of atomic layer deposition Al2O3/TiO2 nanolaminates with ultrathin bilayers

    Page(s): 01A111 - 01A111-4
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    Nanolaminate structures have many prospective uses in mechanical, electrical, and optical applications due to the wide selection of materials and precise control over layer thicknesses. In this work, ultrathin Al2O3/TiO2 nanolaminate structures deposited by atomic layer deposition from Me3Al, TiCl4, and H2O precursors with intended bilayer thicknesses ranging from 0.1 to 50 nm were characterized by x-ray reflectivity (XRR) measurements. The measurements were simulated to obtain values for thickness, density, and roughness of constituting layers. XRR analysis shows that the individual layers within the nanolaminate remain discrete for bilayers as thin as 0.8 nm. Further reduction in bilayer thickness produces a composite of the two materials. View full abstract»

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  • Growth behavior and properties of atomic layer deposited tin oxide on silicon from novel tin(II)acetylacetonate precursor and ozone

    Page(s): 01A112 - 01A112-6
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    In this work, a novel liquid tin(II) precursor, tin(II)acetylacetonate [Sn(acac)2], was used to deposit tin oxide films on Si(100) substrate, using a custom-built hot wall atomic layer deposition (ALD) reactor. Three different oxidizers, water, oxygen, and ozone, were tried. Resulting growth rates were studied as a function of precursor dosage, oxidizer dosage, reactor temperature, and number of ALD cycles. The film growth rate was found to be 0.1 ± 0.01 nm/cycle within the wide ALD temperature window of 175–300 °C using ozone; no film growth was observed with water or oxygen. Characterization methods were used to study the composition, interface quality, crystallinity, microstructure, refractive index, surface morphology, and resistivity of the resulting films. X-ray photoelectron spectra showed the formation of a clean SnOx–Si interface. The resistivity of the SnOx films was calculated to be 0.3 Ω cm. Results of this work demonstrate the possibility of introducing Sn(acac)2 as tin precursor to deposit conducting ALD SnOx thin films on a silicon surface, with clean interface and no formation of undesired SiO2 or other interfacial reaction products, for transparent conducting oxide applications. View full abstract»

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  • Atomic layer deposition of bismuth oxide using Bi(OCMe2iPr)3 and H2O

    Page(s): 01A113 - 01A113-6
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    Bismuth oxide thin films were deposited by atomic layer deposition using Bi(OCMe2iPr)3 and H2O at deposition temperatures between 90 and 270 °C on Si3N4, TaN, and TiN substrates. Films were analyzed using spectroscopic ellipsometry, x-ray diffraction, x-ray reflectivity, high-resolution transmission electron microscopy, and Rutherford backscattering spectrometry. Bi2O3 films deposited at 150 °C have a linear growth per cycle of 0.039 nm/cycle, density of 8.3 g/cm3, band gap of approximately 2.9 eV, low carbon content, and show the β phase structure with a (201) preferred crystal orientation. Deposition temperatures above 210 °C and postdeposition anneals caused uneven volumetric expansion, resulting in a decrease in film density, increased interfacial roughness, and degraded optical properties. View full abstract»

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  • Waterless TiO2 atomic layer deposition using titanium tetrachloride and titanium tetraisopropoxide

    Page(s): 01A114 - 01A114-9
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    The surface chemistry for TiO2 atomic layer deposition (ALD) typically utilizes water or other oxidants that can oxidize underlying substrates such as magnetic disks or semiconductors. To avoid this oxidation, waterless or oxidant-free surface chemistry can be used that involves titanium halides and titanium alkoxides. In this study, waterless TiO2 ALD was accomplished using titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). In situ transmission Fourier transform infrared (FTIR) studies were employed to study the surface species and the reactions during waterless TiO2 ALD. At low temperatures between 125 and 225  °C, the FTIR absorbance spectra revealed that the isopropoxide species remained on the surface after TTIP exposures. The TiCl4 exposures then removed the isopropoxide species and deposited additional titanium species. At high temperatures between 250 and 300  °C, the isopropoxide species were converted to hydroxyl species by β-hydride elimination. The observation of propene gaseous reaction product by quadrupole mass spectrometry (QMS) confirmed the β-hydride elimination reaction pathway. The TiCl4 exposures then easily reacted with the hydroxyl species. QMS studies also observed the 2-chloropropane and HCl gaseous reaction products and monitored the self-limiting nature of the TTIP reaction. Additional studies examined the waterless TiO2 ALD growth at low and high temperature. Quartz crystal microbalance measurements observed growth rates of ∼3 ng/cm2 at a low temperature of 150  °C. Much higher growth rates of ∼15 ng/cm2 were measured at a higher temperature of 250  °C under similar reaction conditions. X-ray reflectivity analysis measured a growth rate of 0.55 ± 0.05 Å/cycle at 250  - 6;C. X-ray photoelectron depth-profile studies showed that the TiO2 films contained low Cl concentrations <1 at. %. This waterless TiO2 ALD process using TiCl4 and TTIP should be valuable to prevent substrate oxidation during TiO2 ALD on oxygen-sensitive substrates. View full abstract»

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  • Vibration atomic layer deposition for conformal nanoparticle coating

    Page(s): 01A115 - 01A115-5
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    A vibration atomic layer deposition reactor was developed for fabricating a conformal thin-film coating on nanosize particles. In this study, atomic layer deposition of 10–15-nm-thick Al2O3 films was conducted on a high-surface-area acetylene black powder with particle diameters of 200–250 nm. Intense vibration during the deposition resulted in the effective separation of particles, overcoming the interparticle agglomeration force and enabling effective diffusion of the precursor into the powder chunk; this phenomenon led to the formation of a conformal film coating on the nanopowder particles. It was also confirmed that the atomic layer deposition Al2O3 films initially grew on the high-surface-area acetylene black powder particles as discrete islands, presumably because chemisorption of the precursor and water occurred only on a few sites on the high-surface-area acetylene black powder surface. Relatively sluggish growth of the films during the initial atomic layer deposition cycles was identified from composition analysis. View full abstract»

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  • On the reliability of nanoindentation hardness of Al2O3 films grown on Si-wafer by atomic layer deposition

    Page(s): 01A116 - 01A116-6
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    The interest in applying thin films on Si-wafer substrate for microelectromechanical systems devices by using atomic layer deposition (ALD) has raised the demand on reliable mechanical property data of the films. This study aims to find a quick method for obtaining nanoindentation hardness of thin films on silicon with improved reliability. This is achieved by ensuring that the film hardness is determined under the condition that no plastic deformation occurs in the substrate. In the study, ALD Al2O3 films having thickness varying from 10 to 600 nm were deposited on a single-side polished silicon wafer at 300 °C. A sharp cube-corner indenter was used for the nanoindentation measurements. A thorough study on the Si-wafer reference revealed that at a specific contact depth of about 8 nm the wafer deformation in loading transferred from elastic to elastic–plastic state. Furthermore, the occurrence of this transition was associated with a sharp increase of the power-law exponent, m, when the unloading data were fitted to a power-law relation. Since m is only slightly material dependent and should fall between 1.2 and 1.6 for different indenter geometry having elastic contact to common materials, it is proposed that the high m values are the results from the inelastic events during unloading. This inelasticity is linked to phase transformations during pressure releasing, a unique phenomenon widely observed in single crystal silicon. Therefore, it is concluded that m could be used to monitor the mechanical state of the Si substrate when the whole coating system is loaded. A suggested indentation depth range can then be assigned to each film thickness to provide guidelines for obtaining reliable property data. The results show good consistence for films thicker than 20 nm and the nanoindentation hardness is about 11 GPa independent of film thickness. View full abstract»

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  • Film properties of low temperature HfO2 grown with H2O, O3, or remote O2-plasma

    Page(s): 01A117 - 01A117-6
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    A reduction of the deposition temperature is necessary for atomic layer deposition (ALD) on organic devices. HfO2 films were deposited by ALD on silicon substrates in a wide temperature range from 80 to 300 °C with tetrakis[ethylmethylamino]hafnium as metal precursor and H2O, O3, or an remote O2-plasma as oxygen source. Growth rate and density were correlated to electrical properties like dielectric constant and leakage current of simple capacitor structures to evaluate the impact of different process conditions. Process optimizations were performed to reduce film imperfections visible at lower deposition temperatures. Additionally, the influence of postdeposition annealing on the structural and electrical properties was studied. View full abstract»

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  • Atomic layer deposition of HfxAlyCz as a work function material in metal gate MOS devices

    Page(s): 01A118 - 01A118-7
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    As advanced silicon semiconductor devices are transitioning from planar to 3D structures, new materials and processes are needed to control the device characteristics. Atomic layer deposition (ALD) of HfxAlyCz films using hafnium chloride and trimethylaluminum precursors was combined with postdeposition anneals and ALD liners to control the device characteristics in high-k metal-gate devices. Combinatorial process methods and technologies were employed for rapid electrical and materials characterization of various materials stacks. The effective work function in metal–oxide–semiconductor capacitor devices with the HfxAlyCz layer coupled with an ALD HfO2 dielectric was quantified to be mid-gap at ∼4.6 eV. Thus, HfxAlyCz is a promising metal gate work function material that allows for the tuning of device threshold voltages (Vth) for anticipated multi-Vth integrated circuit devices. View full abstract»

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  • Atomic layer deposition of molybdenum oxide using bis(tert-butylimido)bis(dimethylamido) molybdenum

    Page(s): 01A119 - 01A119-6
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    Molybdenum trioxide films have been deposited using thermal atomic layer deposition techniques with bis(tert-butylimido)bis(dimethylamido)molybdenum. Films were deposited at temperatures from 100 to 300 °C using ozone as the oxidant for the process. The Mo precursor was evaluated for thermal stability and volatility using thermogravimetric analysis and static vapor pressure measurements. Film properties were evaluated with ellipsometry, x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and secondary electron microscopy. The growth rate per cycle was determined to extend from 0.3 to 2.4 Å/cycle with <4% nonuniformity (1-sigma) with-in-wafer across a 150 mm wafer for the investigated temperature range. View full abstract»

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  • Rutile-structured TiO2 deposited by plasma enhanced atomic layer deposition using tetrakis(dimethylamino)titanium precursor on in-situ oxidized Ru electrode

    Page(s): 01A120 - 01A120-5
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    In this work, tetrakis(dimethylamino)titanium precursor as well as in-situ oxidized ruthenium bottom electrode were used to grow rutile-structured titanium dioxide thin layers by plasma enhanced atomic layer deposition. Metal–insulator–metal capacitors have been elaborated in order to study the electrical properties of the device. It is shown that this process leads to devices exhibiting excellent results in terms of dielectric constant and leakage current. View full abstract»

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  • In situ reaction mechanism studies on the Ti(NMe2)2(OiPr)2-D2O and Ti(OiPr)3[MeC(NiPr)2]-D2O atomic layer deposition processes

    Page(s): 01A121 - 01A121-7
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    Reaction mechanisms in the Ti(NMe2)2(OiPr)2-D2O and Ti(OiPr)3[MeC(NiPr)2] [also written Ti(OiPr)3(NiPr-Me-amd)]-D2O atomic layer deposition processes were studied in situ with quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) at 275 °C. For the Ti(NMe2)2(OiPr)2-D2O process, both QCM and QMS results indicated adsorption of the Ti(NMe2)2(OiPr)2 molecule through an exchange of at least one of its –NMe2 ligands with surface hydroxyl groups. Regarding the Ti(OiPr)3(NiPr-Me-amd)-D2O process, a mismatch between the QCM and QMS results revealed more complex reactions: the decomposition of the [MeC(NiPr)2] [also written (NiPr-Me-amd)] ligand is suggested by the shape of the QCM data and the intensity of the QMS signals belonging to fragments of the [MeC(NiPr)2] [also written (NiPr-Me-amd)] ligand. A simple calculation model associating the growth rate per cycle of a crystalline film and the surface area taken by the ligands remaining after saturation was also used to support the decomposition of the [MeC(NiPr)2] [also written (NiPr-Me-amd)] ligand. The observed high growth rate is incompatible with the whole [MeC(NiPr)2] (also written [NiPr-Me-amd)] ligand remaining on the surface. View full abstract»

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  • Conduction processes in metal–insulator–metal diodes with Ta2O5 and Nb2O5 insulators deposited by atomic layer deposition

    Page(s): 01A122 - 01A122-6
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    Metal–insulator–metal diodes with Nb2O5 and Ta2O5 insulators deposited via atomic layer deposition are investigated. For both Nb2O5 and Ta2O5, the dominant conduction process is established as Schottky emission at small biases and Frenkel–Poole emission at large biases. Fowler–Nordheim tunneling is not found to play a role in determining current versus voltage asymmetry. The dynamic dielectric constants are extracted from conduction plots and found to be in agreement with measured optical dielectric constants. Trap energy levels at ϕT ≈ 0.62 and 0.53 eV below the conduction band minimum are estimated for Nb2O5 and Ta2O5, respectively. View full abstract»

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Aims & Scope

The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles.

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G. Lucovsky
North Carolina State University