Preparation of Oxygen-Containing Pt and Pt Oxide Thin Films   by Reactive Sputtering and Their Characterization

Abe, Yoshio; Yanagisawa, Hideto; Sasaki, Katsutaka

doi:10.1143/jjap.37.4482

Cited by 53 publications

(22 citation statements)

References 12 publications

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“…Then the silicon substrates covered with an annealed SiO 2 buffer layer were placed standing against the walls of the closed Pyrex bottle. 18 The observed oxygen content is higher than the stoichiometric concentration, which may be attributed to absorption and surface contamination of the sample. The as-synthesized products were subsequently dried in air and analyzed by field-emissionscanning electron microscope ͑FE-SEM; JEOL, JSM-6700F͒ operated at 3.0-5.0 keV, X-ray diffractometer ͑XRD; MAC Science, MXP 18X͒ using Cu K␣ radiation ͑ = 1.540 52 Å͒, transmission electron microscope ͑TEM; JEOL, JEM-2010͒ operated at 200 keV, energy dispersive X-ray spectroscopy ͑EDS͒ attached to the JEM-2010, and X-ray photoelectron spectroscopy ͑XPS; Physical Electronics, PHI 1600͒ using Mg K␣ radiation.…”

Section: Methodsmentioning

confidence: 90%

Low-Temperature Hydrothermal Synthesis of Amorphous SiO[sub 2] Nanoblades Without Using Template and Their Intense Blue Photoluminescence

Her

Lai

2010

J. Electrochem. Soc.

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One-dimensional (1D) amorphous SinormalO2 nanoblades were synthesized by a low-temperature hydrothermal process in an aqueous solution without using template. The presence of NaOH and urea is crucial for the formation of anisotropic SinormalO2 nanostructures, but their concentrations should be carefully controlled to obtain large-scale SinormalO2 nanoblades. Increasing the synthesis temperature will increase the aspect ratios of the resultant SinormalO2 nanoblades. Intense blue luminescence centered at 3.0 and 2.8eV was observed in the as-synthesized SinormalO2 nanoblades, and the photoluminescence (PL) peak intensities were reduced by ∼21% and 44% after oxygen annealing at 300 and 600°C , respectively. The zero-crossing g value in the electron paramagnetic resonance spectra was calculated to be 2.0000, implying that there exists many E′ defect centers in the as-synthesized SinormalO2 nanoblades. The 2.8-eV band can be attributed to the neutral oxygen-vacancy defects, while the 3.0-eV band may be due to the H-complexed oxygen vacancies. (c) The Electrochemical Society.

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Section: Methodsmentioning

confidence: 90%

Low-Temperature Hydrothermal Synthesis of Amorphous SiO[sub 2] Nanoblades Without Using Template and Their Intense Blue Photoluminescence

Her

Lai

2010

J. Electrochem. Soc.

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“…Figure 4 shows the temperature dependence of oxygen impurities analyzed by a depth profile of secondary ionmass spectrography ͑SIMS͒. The oxygen impurities are thought to adsorb on the grain boundaries similar to a sputter-deposited platinum film in an oxygen-containing atmosphere, 9 because the platinum metal is not oxidized to PtO at temperatures below 400°C in the ambient pressure. [9][10][11][12] The oxygen impurities decrease with an increase in the deposition temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The oxygen impurities are thought to adsorb on the grain boundaries similar to a sputter-deposited platinum film in an oxygen-containing atmosphere, 9 because the platinum metal is not oxidized to PtO at temperatures below 400°C in the ambient pressure. [9][10][11][12] The oxygen impurities decrease with an increase in the deposition temperature. It was reported that the surface morphology of Pt CVD films was smoother due to the reduction of their surface and grain boundary energies as the amount of oxygen gas was increased during the deposition.…”

Section: Resultsmentioning

confidence: 99%

Conformal Platinum Thin Films Prepared by Chemical Vapor Deposition under High Oxygen Partial Pressure

Hiratani

Nabatame

Matsui

et al. 2002

Electrochem. Solid-State Lett.

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Conformal deposition of platinum thin films by chemical vapor deposition using ͑methylcyclopentadienyl͒trimethylplatinum as a liquid precursor, whose vapor was transferred by an argon carrier gas, is presented. Conformal coverages at thicknesses of less than 30 nm were obtained under the condition of high oxygen partial pressures and low temperatures. The surface morphology roughened and changed to a discontinuous grain growth when the film thickness and growth temperature were increased. The dense and smooth films with conformal coverage can be used in the storage nodes of capacitors in gigabit dynamic random access memories.Metal-insulator-metal ͑MIM͒ capacitors that consist of high dielectrics and noble metal electrodes are required in gigabit scale dynamic random access memories ͑DRAMs͒. However, MIM capacitors with high dielectrics do not allow for a simplified capacitor structure. Indeed, device shrinkage beyond the advantage of high permittivity requires a three-dimensional structure of capacitors to ensure a storage capacitance of over 20 fF/bit. A platinum electrode is widely used in a simple-stack capacitor of ferroelectric random access memories ͑FeRAM͒ having a 256 kbit density or less. 1 However, a platinum electrode complicates the patterning and fabrication of three-dimensional pillar-type storage nodes because of the difficulty in etching the thick film. Moreover, an additional protective layer is needed to suppress hydrogen diffusion in the back-end process, because platinum has a catalytic effect on reducing dielectric materials. A ruthenium electrode is another candidate for the noble metal electrode in DRAMs, because it enables fine patterning and suppresses such a hydrogen reduction effect. A chemical vapor deposition ͑CVD͒ process of the ruthenium electrode has recently been reported. 2 The oxidative condition is preferred to keep the dielectric layer insulating when the upper ruthenium electrode is deposited. However, the high oxygen partial pressure during the Ru-CVD changes the ruthenium metal to the oxide, RuO 2 . 2,3 Ruthenium dioxide is easily reduced under a reductive condition such as forming gas annealing, so the electrode may be deformed. 4 Therefore platinum, which is the most chemically stable metal in an oxidizing atmosphere, is still a promising candidate for the electrode of MIM capacitors. Moreover, CVD of platinum thin films enables a conformal electrode to be formed on various device structures, which solves the problem of the difficulty in etching a thick film. Among many precursors for the Pt CVD, an organometallic complex ͑methylcyclopentadienyl͒trimethylplatinum ͑MeCpPtMe 3 , Me ϭ methyl group, -CH 3 , Cp ϭ cyclopentadienyl ring, -C 5 H 4 ͒ is the most promising because it is a viscous liquid at room temperature, the vapor pressure is 0.2 Torr at 35°C, and it does not contain halogenide ions. [5][6][7] We reported in a previous paper that a CVD process using the MeCpPtMe 3 precursor is characterized by slow thermal decomposition in low oxygen partial pressure, and by ra...

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“…This matches well with the resistivity values reported in the literature. 44,45 For the Pt_20R and Pt_30R samples, we estimate the resistivity of PtO/PtO 2 to be 7 Â 10 À4 X m. This increase in conductivity is attributed to the built-in electric field generated by Pt-PtO/PtO 2 junction as illustrated in Fig. 8(c).…”

Section: Electrical Characterizationmentioning

confidence: 95%

“…Abe et al 44,45 have also evaluated Platinum oxide films and demonstrated that the PtO is metallic but PtO 2 is semiconducting in nature with a bandgap of 1.2 eV-1.5 eV. PtO 2 can be prepared using a variety of techniques such as chemical process, 41-43 reactive sputtering of Pt, [44][45][46] or oxygen plasma treatment of Pt [47][48][49] thin films. In this work, we create PtO 2 nanostructures with an embedded Pt core, in-situ, during the reactive ion etching (RIE) of Si/SiO 2 to achieve suspended core-shell structure.…”

Section: Introductionmentioning

confidence: 99%

Suspended core-shell Pt-PtOx nanostructure for ultrasensitive hydrogen gas sensor

Basu

Kallatt

Anumol

et al. 2015

Journal of Applied Physics

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High sensitivity gas sensors are typically realized using metal catalysts and nanostructured materials, utilizing non-conventional synthesis and processing techniques, incompatible with on-chip integration of sensor arrays. In this work, we report a new device architecture, suspended core-shell Pt-PtOx nanostructure that is fully CMOS-compatible. The device consists of a metal gate core, embedded within a partially suspended semiconductor shell with source and drain contacts in the anchored region. The reduced work function in suspended region, coupled with builtin electric field of metal-semiconductor junction, enables the modulation of drain current, due to room temperature Redox reactions on exposure to gas. The device architecture is validated using Pt-PtO 2 suspended nanostructure for sensing H 2 down to 200 ppb under room temperature. By exploiting catalytic activity of PtO 2 , in conjunction with its p-type semiconducting behavior, we demonstrate about two orders of magnitude improvement in sensitivity and limit of detection, compared to the sensors reported in recent literature. Pt thin film, deposited on SiO 2 , is lithographically patterned and converted into suspended Pt-PtO 2 sensor, in a single step isotropic SiO 2 etching. An optimum design space for the sensor is elucidated with the initial Pt film thickness ranging between 10 nm and 30 nm, for low power (<5 lW), room temperature operation. V C 2015 AIP Publishing LLC. [http://dx.

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Preparation of Oxygen-Containing Pt and Pt Oxide Thin Films by Reactive Sputtering and Their Characterization

Cited by 53 publications

References 12 publications

Low-Temperature Hydrothermal Synthesis of Amorphous SiO[sub 2] Nanoblades Without Using Template and Their Intense Blue Photoluminescence

Low-Temperature Hydrothermal Synthesis of Amorphous SiO[sub 2] Nanoblades Without Using Template and Their Intense Blue Photoluminescence

Conformal Platinum Thin Films Prepared by Chemical Vapor Deposition under High Oxygen Partial Pressure

Suspended core-shell Pt-PtOx nanostructure for ultrasensitive hydrogen gas sensor

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