| 1. |
- Ahvenniemi, Esko, et al.
(författare)
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Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"
- 2017
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 35:1
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Forskningsöversikt (refereegranskat)abstract
- Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency.
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| 2. |
- Dezelah, Charles L., et al.
(författare)
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The Atomic Layer Deposition of HfO2 and ZrO2 using Advanced Metallocene Precursors and H2O as the Oxygen Source
- 2008
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Ingår i: Chemical Vapor Deposition. - : Wiley. - 0948-1907 .- 1521-3862. ; 14:11-12, s. 358-365
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Tidskriftsartikel (refereegranskat)abstract
- The atomic layer deposition (ALD) of HfO2 and ZrO2 thin films is investigated using (MeCp)(2)HfMe2, (MCp)(2)Hf(OMe)(Me), (MeCp)(2)ZrMe2, and (MeCp)(2)Zr(OMe)(Me) as the precursors at deposition temperatures between 300 and 500 degrees C, with water vapor as the oxygen Source. A self-limiting growth mechanism is confirmed at 350 degrees C for all the metal precursors examined. The processes provide nearly stoichiometric HfO2 and ZrO2 films with carbon and hydrogen concentrations below 0.5 and 1.0 at.-%, respectively, for representative samples. All films are polycrystalline as deposited, and possess a thin interfacial SiO2 layer. The capacitance-voltage (C-V) and Current density-voltage (I-V) behavior is reported and discussed for capacitor structures containing films from this study.
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| 3. |
- Jogi, Indrek, et al.
(författare)
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Atomic layer deposition of high capacitance density Ta2O5-ZrO2 based dielectrics for metal-insulator-metal structures
- 2010
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 87:2, s. 144-149
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated electrical properties of laminated atomic layer deposited films: ZrO2-Ta2O5, ZrO2-Nb2O5-Ta2O5, ZrO2-TaxNb1-xO5 and Ta2O5-ZrxNbyOz. Even though the capacitances of laminates were often higher compared to films of constituent materials with similar thickness, considerably higher charge storage factors, Q were achieved only when tetragonal ZrO2 was stabilized in ZrO2-Ta2O5 laminate and when the laminate thickness exceeded 50 rim. The decreased Q values in the case of most laminates were the result of increased leakage currents. In the case of thinner films only Ta2O5-ZrxNbyOz, stack possessed capacitance density and Q value higher than reference HfO2. Concerning the conduction mechanisms, in the case of thinner films, the Ta2O5 or TaxNb1-xO5 apparently controlled the leakage either by Richardson-Schottky emission or Poole-Frenkel effect. (C) 2009 Elsevier B.V. All rights reserved
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| 4. |
- Kukli, Kaupo, et al.
(författare)
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Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen
- 2012
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:7, s. 2756-2763
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Tidskriftsartikel (refereegranskat)abstract
- Ru thin films were grown on hydrogen terminated Si, SiO2, Al2O3, HfO2, and TiO2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4-20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250-255 degrees C, the growth of the Ru films was favored on silicon, compared to the growth on Al2O3, TiO2 and HfO2. At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO2, compared to the process on silicon. At 320-325 degrees C, no growth occurred on Si-H and SiO2-covered silicon. Resistivity values down to 18 mu Omega.cm were obtained for ca. 10 nm thick Ru films.
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| 5. |
- Kukli, Kaupo, et al.
(författare)
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Atomic Layer Deposition of Ruthenium Films on Strontium Titanate
- 2011
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Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880 .- 1533-4899. ; 11:9, s. 8378-8382
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Tidskriftsartikel (refereegranskat)abstract
- Atomic layer deposition of ruthenium on SrTiO(3) layers was investigated using (C(2)H(5)C(5)H(4)) center dot (NC(4)H(4))Ru and air as precursors. For comparison, the growth was studied also on ZrO(2) films and SiO(2)/Si surfaces. Deposition temperature was 325 degrees C. Using rather short but intense air pulses, smooth and uniform Ru films were deposited on SrTiO(3). The films were crystallized at early stages of the growth. The nucleation density and rate on SrTiO(3) were notably lower compared to that on ZrO(2) and SiO(2), but the physical qualities including the film conductivity were considerably enhanced after reaching Ru film thickness around 10 nm.
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| 6. |
- Kukli, Kaupo, et al.
(författare)
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Holmium and titanium oxide nanolaminates by atomic layer deposition
- 2014
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 565, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- Nanolaminate (nanomultilayer) thin films of TiO2 and Ho2O3 were grown on Si(001) substrates by atomic layer deposition at 300 degrees C from alkoxide and beta-diketonate based metal precursors and ozone. Individual layer thicknesses were 2 nm for TiO2 and 4.5 nm for Ho2O3. As-deposited films were smooth and X-ray amorphous. After annealing at 800 degrees C and higher temperatures the nanolaminate structure was destroyed by solid-state reaction to form Ho2Ti2O7. The films demonstrated diamagnetic or paramagnetic behaviour in the as-deposited state. After annealing, the films possessed net magnetic moment, allowing one to record saturation magnetization and weak coercivity.
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| 7. |
- Kukli, Kaupo, et al.
(författare)
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Structure and morphology of Ru films grown by atomic layer deposition from 1-ethyl-1 '-methyl-ruthenocene
- 2010
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 312:12-13, s. 2025-2032
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Tidskriftsartikel (refereegranskat)abstract
- Ru thin films were grown on TiO2, Al2O3, HfO2, and ZrO2 films as well as on HF-etched silicon and SiO2-covered silicon by atomic layer deposition from 1-ethyl-1'-methyl-ruthenocene, (CH3C5H4) (C2H5C5H4)Ru, and oxygen. The growth of Ru was obtained and characterized at temperatures ranging from 250 to 325 degrees C. On epitaxial rutile, highly oriented growth of Ru with hexagonal structure was achieved, while on other substrates the films possessed nonoriented hexagonal structure. Ruthenium oxide was not detected in the films. The lowest resistivity value obtained for 5.0-6.6 nm thick films was 26 mu Omega cm. The conductivity of the films depended somewhat on the deposition cycle time parameters and, expectedly, more strongly on the amount of deposition cycles. Increase in the deposition temperature of underlying metal oxide films increased the conductivity of Ru layers.
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| 8. |
- Niinisto, Jaakko, et al.
(författare)
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Advanced cyclopentadienyl precursors for atomic layer deposition of ZrO2 thin films
- 2008
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Ingår i: Journal of Materials Chemistry. - : Royal Society of Chemistry (RSC). - 0959-9428 .- 1364-5501. ; 18:28, s. 3385-3390
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Tidskriftsartikel (refereegranskat)abstract
- ZrO2 thin films were grown onto silicon (100) substrates by atomic layer deposition (ALD) using novel cyclopentadienyl-type precursors, namely (CpMe)(2)ZrMe2 and (CpMe)(2)Zr(OMe) Me (Cp = cyclopentadienyl, C5H5) together with ozone as the oxygen source. Growth characteristics were studied in the temperature range of 250 to 500 degrees C. An ALD-type self-limiting growth mode was verified for both processes at 350 degrees C where highly conformal films were deposited onto high aspect ratio trenches. Signs of thermal decomposition were not observed at or below 400 degrees C, a temperature considerably exceeding the thermal decomposition temperature of the Zr-alkylamides. Processing parameters were optimised at 350 degrees C, where deposition rates of 0.55 and 0.65 angstrom cycle(-1) were obtained for (CpMe)(2)ZrMe2/O-3 and (CpMe)(2)Zr(OMe)Me/O-3, respectively. The films grown from both precursors were stoichiometric and polycrystalline with an increasing contribution from the metastable cubic phase with decreasing film thickness. In the films grown from (CpMe)(2)ZrMe2, the breakdown field did not essentially depend on the film thickness, whereas in the films grown from (CpMe)(2)Zr(OMe)Me the structural homogeneity and breakdown field increased with decreasing film thickness. The films exhibited good capacitive properties that were characteristic of insulating oxides and did not essentially depend on the precursor chemistry.
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| 9. |
- Pore, Viljami, et al.
(författare)
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Atomic layer deposition of ferromagnetic cobalt doped titanium oxide thin films
- 2011
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Ingår i: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. - 0040-6090. ; 519:10, s. 3318-3324
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Tidskriftsartikel (refereegranskat)abstract
- TiO2 thin films doped or mixed with cobalt oxide were grown by atomic layer deposition using titanium tetramethoxide and cobalt(III)acetylacetonate as metal precursors. The films could be deposited using both 03 and H2O as oxygen precursors. The films grown using water exhibited considerably smoother surface than those grown with ozone. The TiO2:Co films with Co/(Co + Ti) cation ratio ranging from 0.01 to 0.30 were crystallized by annealing at 650 C, possessing mixed phase composition comprising rutile and anatase and, additionally, CoTiO3 or CoTi2O5. The annealed films demonstrated magnetic response expressed by magnetization curves with certain hysteresis and coercive fields.
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| 10. |
- Santala, Eero, et al.
(författare)
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Metallic Ir, IrO2 and Pt Nanotubes and Fibers by Electrospinning and Atomic Layer Deposition
- 2009
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Ingår i: Nanoscience and Nanotechnology Letters. - : American Scientific Publishers. - 1941-4900 .- 1941-4919. ; 1:3, s. 218-223
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional iridium and iridium oxide fibers were prepared by electrospinning of polyvinyl pyrrolidone ethanol solution which contained iridium(III) acetylacetonate as iridium precursor. The Ir precursors/polymer composite fibers were subsequently thermally annealed at 500 degrees C in air for 4 hours to remove the organic parts and leave IrO2 fibers. Metallic iridium fibers were obtained by reducing the IrO2 fibers with hydrogen. Also tubes by fiber templates-process is used to demonstrate how metallic Ir, IrO2 and Pt nanotubes can be produced by combining atomic layer deposition and electrospinning.
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| 11. |
- Schulz, Felix, et al.
(författare)
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Molecular Hydrogen Tweezers : Structure and Mechanisms by Neutron Diffraction, NMR, and Deuterium Labeling Studies in Solid and Solution
- 2011
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 133:50, s. 20245-20257
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of reversible hydrogen activation by ansa-aminoboranes, 1-N-TMPH-CH(2)-2-[HB(C(6)F(5))(2)]C(6)H(4) (NHHB), was studied by neutron diffraction and thermogravimetric mass-spectroscopic experiments in the solid state as well as with NMR and FT-IR spectroscopy in solution. The structure of the ansa-ammonium borate NHHB was determined by neutron scattering, revealing a short N-H center dot center dot center dot H-B dihydrogen bond of 1.67 angstrom. Moreover, this intramolecular H-H distance was determined in solution to be also 1.6-1.8 angstrom by (1)H NMR spectroscopic T(1) relaxation and ID NOE measurements. The X-ray B-H and N-H distances deviated from the neutron and the calculated values. The dynamic nature of the molecular tweezers in solution was additionally studied by multinuclear and variable-temperature NMR spectroscopy. We synthesized stable, individual isotopic isomers NDDB, NHDB, and NDHB. NMR measurements revealed a primary isotope effect in the chemical shift difference (P)Delta(1)H(D) = delta(NH) - delta(ND) (0.56 ppm), and hence supported dihydrogen bonding. The NMR studies gave strong evidence that the structure of NHHB in solution is similar to that in the solid state. This is corroborated by IR studies providing clear evidence for the dynamic nature of the intramolecular dihydrogen bonding at room temperature. Interestingly, no kinetic isotope effect was detected for the activation of deuterium hydride by the ansa-aminoborane NB. Theoretical calculations attribute this to an "early transition state". Moreover, 2D NOESY NMR measurements support fast intermolecular proton exchange in aprotic CD(2)Cl(2) and C(6)D(6).
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| 12. |
- Usman, Muhammad, et al.
(författare)
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Toward the Understanding of Stacked Al-Based High-k Dielectrics for Passivation of 4H-SiC Devices
- 2011
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 158:1, s. H75-H79
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Tidskriftsartikel (refereegranskat)abstract
- Metal insulator semiconductor structures using high-k materials have been prepared and investigated for the passivation of 4H-SiC surfaces. Alternate layers of AlN and Al2O3 were deposited on 8 nm thermally grown SiO2 on epitaxial SiC, forming multilayer stacked dielectrics. Atomic layer deposition (ALD) has been used for the deposition. Our results show that the AlN, deposited by ALD, has a columnar polycrystalline structure with boundaries related to the step bunching of SiC epitaxial layer. Capacitance-voltage measurements have been performed at room temperature, 100, 200, and 300 degrees C. Annealing of the samples was also performed at these temperatures and they were consecutively measured at room temperature. Current-voltage measurements have also been performed before and after annealing. It has been observed that the stack with a bottom layer of Al2O3, forming an interface with the thin SiO2, is more stable at high temperatures; however, its breakdown voltage is less than that of the other stack with AlN forming the bottom layer. The breakdown behavior of the stacks is also found to be different depending on the order of AlN and Al2O3 layers.
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