12017-12-8Relevant articles and documents
Silicide formation of polycrystalline silicon by direct metal implantation
Kozicki,Robertson
, p. 878 - 881 (1989)
This paper discusses an alternative method of silicide formation on poly-Si which allows a higher degree of control than conventional polycide formation methods. The technique involves the direct implantation of high doses of transition metal ions into the poly-Si layer, followed by a transient annealing step.
A comparative infrared study of H2O reactivity on Si(100)-(2×1), (2×1)-H, (1×1)-H and (3×1)-H surfaces
Ranga Rao,Wang, Zhi-Hong,Watanabe, Hidekazu,Aoyagi, Mutsumi,Urisu, Tsuneo
, p. 178 - 188 (2004)
The water adsorption on the bare and H-terminated Si(1 0 0) surfaces has been studied by the BML-IRRAS technique. It is found that H-terminated surfaces are much less reactive compared to the bare silicon surfaces. The (1×1)-H and (3×1)-H surfaces show similar and less reactivity pattern compared to the (2×1)-H surface. At higher exposures, the water reaction with coupled monohydride species provides an effective channel for oxygen insertion into the back bonds of dihydride species. It is not attributed to the H-Si-Si-H + H 2O → H-S-Si-OH + H2, which could give rise to the characteristic Si-H and Si-OH modes, respectively at 2081 and 921 cm -1. A more suitable reaction mechanism involving a metastable species, H-Si-Si-H + H2O → H2Si ? HO-Si-H (metastable) explains well the bending modes of oxygen inserted silicon dihydride species which are observed relatively strongly in the reaction of water with H-terminated Si(1 0 0) surfaces.
Polycrystalline silicon/CoSi2 Schottky diode with integrated SiO2 antifuse: A nonvolatile memory cell
Herner,Mahajani,Konevecki,Kuang,Radigan,Dunton
, p. 4163 - 4165 (2003)
The development of a low-cost, field-programmable memory cell device based on CoSi2/polysilicon Schottky diodes with integrated SiO2 antifuses was discussed. An SiO2 antifuse thin film was also grown in between the polysilicon and CoSi2. The ability to grow thin, high quality SiO2 films directly on CoSi2 allowed cells to be formed using a polysilicon deposition doped with a single dopant type.
Interaction of cobalt with the Si(1 0 0)2 × 1 surface studied by photoelectron spectroscopy
Gomoyunova,Pronin,Gall,Vyalikh,Molodtsov
, p. 174 - 182 (2005)
Cobalt adsorption and condensation on the Si(1 0 0)2 × 1 surface as well as solid-phase reaction of CoSi2 formation have been studied by high-resolution photoelectron spectroscopy with synchrotron radiation. We have measured the Si 2p and valence-band spectra after the Co deposition from a submonolayer coverage to 6 ML thickness and a subsequent annealing to 600 °C. Room temperature Co adsorption results in the loss of the initial surface reconstruction, and the chemisorbed Co atoms appear to be embedded into the upper layer of Si(1 0 0); however, no stable CoSi2 was observed. With further metal deposition, a discontinuous solid solution CoSi film was formed and the dissolved Si concentration decreased with the distance from the crystal surface. The formation of cobalt disilicide was found to occur in the range of 250-400 °C.
Formation of CoSi2 on various polycrystalline silicon structures and its effects on thermal stability
Bae, Jong-Uk,Sohn, Dong Kyun,Park, Ji-Soo,Han, Chang Hee,Park, Jin Won
, p. 1551 - 1554 (2000)
We have investigated formation of CoSi2 on various grain sizes of polycrystalline Si (poly-Si) with emphasis on its thermal stability. As the grain size of poly-Si decreases, CoSi2 phase is formed at lower temperature because of the diffusion of Co atoms along grain boundaries of poly-Si during the rapid thermal annealing process. The enhanced reaction of cobalt with silicon on small-grain-sized poly-Si creates a rough CoSi2/poly-Si interface, which becomes thermally unstable. CoSi2 formed on amorphous Si showed less thermal stability than that found on medium and large grain sized poly-Si.
Synthesis of epitaxial ternary Co1-xFexSi2 silicides with CsCl- and CaF2-type cubic structures on Si(111) by codeposition techniques
Hong,Pirri,Wetzel,Gewinner
, p. 13040 - 13050 (1997)
We have grown ternary Co1-xFxSi2 suicide films, about 100 A thick, by codeposition onto Si(111) held at room temperature in the whole composition range 0≤x≤1. Low-energy electron diffraction, inelastic medium-energy electron diffraction, x-ray diffraction, x-ray photoelectron diffraction, and photoemission spectroscopy techniques are used to investigate the atomic and electronic structure of these ternary suicides. It is found that the as-deposited films are metallic and adopt an ordered cubic structure of CsCl type with essentially random vacancies, except in Co-rich films (x≤0.25) where a tendency toward an ordered vacancy arrangement of the CaF2 type is already visible. Upon annealing at 650°C, these suicides are found to be metastable, but phase separation does not take place. Fe-rich (x≥0.85) films invariably convert into a semiconducting phase with a structure similar to the orthorhombic β-FeSi2 one. Yet, most interestingly, the cubic structure is preserved for x≤0.85, i.e., stabilized when the Co content exceeds about 15%. X-ray diffraction reveals that these phases exhibit partial CaF2 long-range order. The order parameter is close to zero for x=0.85 and increases rapidly with increasing Co content. The data indicate that Fe does not merely substitute for Co atoms in a perfect CaF2-type CoSi2 structure. Several of the Fe and possibly Co atoms preferentially occupy the interstitial octahedral sites of this latter structure even for x≤0.50, while for x≥0.75 a local environment essentially similar to that in defected CsCl-type structure is observed for both Fe and Co sites.
Luo, Li,Muenchausen, R. E.,Maggiore, C. J.,Jimmenez, J. R.,Schowalter, L. J.
, p. 419 - 421 (1991)
Caer, G. Le,Bauer-Grosse, E.,Pianelli, A.,Bouzy, E.,Matteazzi, P.
, (1990)
Hirose, Kazuyuki,Ohdomari, Iwao,Uda, Masayuki
, (1988)
Franciosi, A.,Weaver, J. H.
, p. 324 - 335 (1983)
Spontaneous vacancy array formation on FeSi2 and CoSi 2 formed on Si(100)2×n surface
Wang, Jun-Zhong,Jia, Jin-Feng,Liu, Hong,Li, Jian-Long,Liu, Xi,Xue, Qi-Kun
, p. 1990 - 1992 (2002)
Atomic structure of FeSi2 or CoSi2 grown on the Si(100)2×n surface has been investigated by scanning tunneling microscopy. After annealing the Fe or Co covered Si(100)2×n substrate at ～800°C, an ordered adatom vacancy array appears on the nominal 1×1 surface of the formed FeSi2 or CoSi2 islands, which has not been observed for silicide on the Si(100)-2×1. Upon further annealing to ～1100°C, the vacancies coalesce into striped domains along one of the 〈011〉 directions. These nanostructured features are a result of the Ni impurities, and can be a promising template for fabricating nanodot arrays.
Photoemission study of cobalt interaction with the oxidized Si(1 0 0)2 × 1 surface
Gomoyunova,Pronin,Malygin,Gall,Vyalikh,Molodtsov
, p. 2449 - 2456 (2006)
The interaction of cobalt atoms with an oxidized Si(1 0 0)2 × 1 surface was studied by photoelectron spectroscopy with synchrotron radiation at room and elevated temperatures. The SiOx layer grown in situ on the crystal surface was ～0.3 nm thick, and the amount of deposited cobalt was varied within eight atomic layers. It was found that Co atoms could penetrate under the SiOx layer even at room temperature in the initial growth. As the Co amount increased, a ternary Co-O-Si phase was formed at the interface, followed by a Co-Si solid solution. Silicide synthesis associated with the decomposition of these phases started under the SiOx layer at ～250 °C, producing cobalt disilicide with a stable CaF2-type of structure.
59Co spin-lattice relaxation in superconductor CoSi2
Ohno,Kanashiro,Yamada,Yamanishi,Tanaka,Kishimoto,Nakamura,Michihiro
, p. 307 - 309 (1997)
59Co NMR has been measured in order to make clear the superconducting properties of CoSi2 from a microscopic viewpoint. The relaxation rate is proportional to temperature over the measured temperature range of 77.3-750 K. The Knight shift is independent of temperature.
Growth of carbon nanotubes on cobalt disilicide precipitates by chemical vapor deposition
Mao,Sun,Qian,Pan,Chang,Zhou,Wang,Xie
, p. 3297 - 3299 (1998)
We have successfully grown carbon nanotubes on cobalt-implanted silicon with various doses. The morphology of such tubes has been examined by scanning electron microscopy, transmission electron microscopy, and Raman scattering. On contrary to the commonly
Microwave activated combustion synthesis of bulk cobalt silicides
Jokisaari,Bhaduri,Bhaduri
, p. 160 - 167 (2005)
CoSi and CoSi2 bulk intermetallic compounds have generated some interest as potential electronic and structural materials. Combustion synthesis has been shown to be an effective method for the preparation of many intermetallic compounds, but requires a high adiabatic temperature to propagate. Thermodynamic calculations show that cobalt silicides require activation. Microwave activation is attractive for combustion synthesis reactions, allowing rapid heating and cooling rates, volumetric heating, and direct absorption of energy by the reaction zone. In this study, a microwave activated combustion synthesis process was used to produce CoSi and CoSi2 bulk cobalt silicides. Thermal activation and conventional combustion synthesis were also attempted, and the results of the three processes are compared.
Evaluation of thermal stability for CMOS gate metal materials
Cabral Jr.,Lavoie,Ozcan,Amos,Narayanan,Gusev,Jordan-Sweet,Harper
, p. F283-F287 (2004)
We present an evaluation of the thermal stability for various elemental metals and binary/ternary conducting compounds on gate dielectrics. The continued scaling of polysilicon gated complementary metal oxide semiconductor (CMOS) devices may face limitations such as polydepletion, incompatibility with some high-k dielectrics, high series resistance, and boron penetration. In this study, 24 different elemental metals and metallic compounds with work functions ranging from 4.0 to 5.2 eV covering n-type field effect transistor (nFET), midgap, and pFET gate electrodes were examined. The films were characterized during rapid thermal annealing in a forming gas ambient up to 1000°C. Three techniques, in situ X-ray diffraction, resistance, and elastic light scattering analysis were used simultaneously during annealing. It was found that many of the elemental materials, especially those with nFET work functions, undergo reactions with the SiO2 and Al2O3, gate dielectrics, while others became unstable because of melting (Al) or agglomeration (Co, Ni, Pd and CoSi2). Two binary compounds, W 2N and RuO2, underwent dissociation in the hydrogen-containing ambient Materials stable above 700°C include Mo, W, Re, Ru, Co, Rh, Ir, Pd, Pt, W2N, TaN, TaSiN, and CoSi2, making them possible choices for integration involving higher temperature processing.
Investigations on chemical vapour transport of intermetallic phases in the system Co/Fe/Si
Boldt,Reichelt,Bosholm,Oppermann
, p. 1839 - 1845 (2003)
The ternary phases existing on the quasi binary section CoSi/FeSi and CoSi2/β-FeSi2 have been investigated by solid state reactions and chemical transport. The solid solution serie CoxFe 1-xSi can be described as a regular solution. The transport behaviour calculated is in good agreement with the experiments. The phases have been characterized by X-ray powder diffraction, EDX and ICP-OES. The temperature dependence of the resistivity has been measured from 20 K up to room temperature on single crystals.
Superconductivity of intermetallic compound CoSi2
Tsutsumi, Kitomi,Takayanagi, Shigeru,Ishikawa, Masayasu,Hirano, Toshiyuki
, p. 2237 - 2238 (1995)
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Preferential Co-Si bonding at the Co/SiGe(100) interface
Boyanov,Goeller,Sayers,Newmanich
, p. 3060 - 3062 (1997)
The initial stages of the reaction of Co with Si0.79Ge0.21(100) were studied in situ with extended x-ray absorption fine structure spectroscopy and reflection high energy electron diffraction. The Si:Ge ratio in the first coordinatio
The Co/Si(1 1 1) interface formation: A temperature dependent reaction
Luches,Rota,Valeri,Pronin,Valdaitsev,Faradzhev,Gomoyunova
, p. 303 - 311 (2002)
We have investigated the reaction of Co with the Si(1 1 1) surface both at room temperature (RT) and at high temperature (500-650 °C). The temperature evolution of the RT deposited 10 ML film has also been studied. The films, prepared by the different methods, have been structurally characterized by means of primary-beam diffraction modulated electron emission. Auger electron spectroscopy has been used to follow their stoichiometric evolution. For RT deposition the films have been found to have a B-type (180° rotated with respect to the underlying Si(1 1 1) surface) cubic structure with a Co content and an interlayer spacing increasing with thickness. After 650 °C annealing, the films are completely reacted and have an unstrained B-type CoSi2 structure. High temperature (500 °C) deposition of Co leads to the formation of stoichiometric CoSi2 films. Both annealed and high temperature grown films are found to be Si terminated.
Si/Co-CoSi2/reduced graphene oxide ternary nanocomposite anodes for Li-Ion batteries with enhanced capacity and cycling stability
Park, A Reum,Nam, Myeong Gyun,Kim, A-Young,Kim, Kwang Su,Sher Shah, Md. Selim Arif,Lee, Jun Young,Kim, Woo-Jae,Lee, Joong Kee,Yoo, Pil J.
, p. 1134 - 1142 (2017)
Silicon (Si) is a promising anode material for high-performance Li-ion batteries (LIBs), but it undergoes rapid capacity fading through severe volumetric expansion during Li insertion/extraction. Although alloying Si with various metal sources has been pursued to mitigate the structural deterioration, the resulting materials have shown the intrinsic problem of low electrical conductivity. To address this conflicting issue, here we describe a novel ternary nanocomposite of Si/Co-CoSi2/reduced graphene oxide (rGO) made using a facile process of mechanical mixing of Si nanoparticles, Co3O4 microparticles, and rGO nanosheets, followed by carbothermal reduction. Specifically, rGO, which has high electrical conductivity and structural integrity, could work as both a conductive matrix and a reducing agent in forming the Co-CoSi2 phase inside the Si domains during thermal treatment. The proposed ternary nanocomposites exhibited a noteworthy specific capacity of 952 mA h g?1 with 79.3% capacity retention after 80 cycles at a current density of 100 mA g?1. We attribute the improved electrochemical performance to the increased structural stability offered by the Co-CoSi2 phase and the interconnected conductive framework of the rGO nanosheets. Therefore, we expect our design process for Si/Co-CoSi2/rGO ternary nanocomposites to be applicable to other materials that can eventually be used as high-performance anodes for the next generation LIBs.
