| 1. |
- Forsgren, Katarina, et al.
(författare)
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Deposition of HfO2 thin films in HfI4-based processes
- 2002
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 149:10, s. F139-F144
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Tidskriftsartikel (refereegranskat)abstract
- This study describes deposition of HfO2 thin films by chemical vapor deposition (CVD) and atomic layer deposition (ALD) using HfI4 as the metal precursor. The layer-by-layer growth was also studied in real time with a quartz crystal microbalance. In ALD, the deposition rate was independent of the growth temperature, whereas in CVD, an exponential rate increase was observed. Monoclinic HfO2 was deposited on MgO and poly-Si substrates in a wide temperature range, and the choice of substrate had a strong influence on the orientation of the films. Epitaxial growth of HfO2 was observed on MgO(001) substrates at 400-500°C in the ALD process and at 500-600°C in the CVD process. The electrical characterization showed that the crystallinity of the films had a stronger influence on the dielectric constant than did the film thickness.
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| 2. |
- 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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| 3. |
- Jogi, Indrek, et al.
(författare)
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Precursor-dependent structural and electrical characteristics of atomic layer deposited films : Case study on titanium oxide
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:6, s. 1084-1089
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Tidskriftsartikel (refereegranskat)abstract
- Thin (10-20 nm) TiO2 films were atomic layer deposited from TiCl4, Ti(OC2H5)(4), H2O and H2O2 in the substrate temperature range 125-350 degrees C. The structure, chemical composition and electrical properties were correlated to the process temperature and nature of precursors, whereas the effect of precursors on conduction mechanisms was considerable only in the films grown at 125 degrees C, otherwise controlled by oxide-electrode interfaces. The use of chloride resulted in films with highest permittivity while the use of hydrogen peroxide resulted in lowest permittivity but also in lowest leakage. The post-deposition (pre-metallization) annealing resulted in densification and (re)crystallization of TiO2 layer but also in thickening of low-permittivity interface layers.
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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. |
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| 6. |
- Kukli, Kaupo, et al.
(författare)
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Effect of selected atomic layer deposition parameters on the structure and dielectric properties of hafnium oxide films
- 2004
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Ingår i: Journal of Applied Physics. ; 96:9, s. 5298-5307
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Tidskriftsartikel (refereegranskat)abstract
- Hf02 films were atomic layer deposited from HfCl4 and H20 onSi(lOO) in the temperature range of 226-750 °C. The films consisted of dominantly the monoclinic polymorph. Elastic recoildetection analysis revealed high residual chlorine and hydrogen contents (2-5 at. %) in the films grown below 300-350 °C. The content of residual hydrogen and chlorine monotonouslydecreased with increasing growth temperature. The effctive permittivity insignificantly depended on thegrowth temperature and water partial pressure. Capacitance-voltage curves exhibited market hysteresis especially in the films grown at 400-450 ° C, and demonstrated enhanced distortions likely due to the increased trap densities in the films grown at 700-750 °C. Changes in water pressure led to some changes in the extent of crystallization, but did not induce any clear change; in the capacitance of the dielectric layer.
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| 7. |
- Kukli, Kaupo, et al.
(författare)
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Engineering structure and properties of hafnium oxide films by atomic layer deposition temperature
- 2005
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 479:1-2, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- HfO2 films were atomic layer deposited from HfCl4 and H2O on Si(100) in the temperature range of 300–600 °C. At low temperatures, films grow faster and are structurally more disordered, compared to films grown at high temperatures. At high temperatures, the films are better crystallized, but grow slower and contain grain boundaries extending from substrate to gate electrode. Film growth rate and capacitance of HfO2 dielectric layers was improved by depositing stacked structures with polycrystalline films of higher purity at 600 °C on thin HfO2 sublayer grown on Si at 300 °C.
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| 8. |
- 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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| 9. |
- Tamm, Aile, et al.
(författare)
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Atomic layer deposition of high-k dielectrics on carbon nanoparticles
- 2013
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 538, s. 16-20
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanoparticles were synthesized from 5-methylresorcinol and formaldehyde via base catalysed polycondensation reaction and distributed over silicon oxide wafers and aluminium oxide thin films. These particles essentially possessed monocrystalline graphite structure. The particles were covered by hafnium oxide thin films in metal chloride based atomic layer deposition process carried out at 300 degrees C. Upon deposition of HfO2, thin crystalline metal oxide layer containing mostly cubic phase was formed. At the same time, deposition of the metal oxide caused reduction of the sizes of graphite particles and essential increase in the disorder in carbon.
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| 10. |
- Tamm, Aile, et al.
(författare)
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Atomic layer deposition of ZrO2 for graphene-based multilayer structures: In situ and ex situ characterization of growth process
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlag. - 1862-6300 .- 1862-6319. ; 211:2, s. 397-402
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Tidskriftsartikel (refereegranskat)abstract
- Real time monitoring of atomic layer deposition by quartz crystal microbalance (QCM) was used to follow the growth of ZrO2 thin films on graphene. The films were grown from ZrCl4 and H2O on graphene prepared by chemical vapor deposition method on 100-nm thick nickel film or on Cu-foil and transferred onto QCM sensor. The deposition was performed at a substrate temperature of 190 degrees C. The growth of the dielectric film on graphene was significantly retarded compared to the process carried out on QCM without graphene. After the deposition of dielectric films, the basic structure of graphene was retained.
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