Showing papers on "Silicon oxide published in 2010"

Resistive switches and memories from silicon oxide.

Abstract: Because of its excellent dielectric properties, silicon oxide (SiO(x)) has long been used and considered as a passive, insulating component in the construction of electronic devices. In contrast, here we demonstrate resistive switches and memories that use SiO(x) as the sole active material and can be implemented in entirely metal-free embodiments. Through cross-sectional transmission electron microscopy, we determine that the switching takes place through the voltage-driven formation and modification of silicon (Si) nanocrystals (NCs) embedded in the SiO(x) matrix, with SiO(x) itself also serving as the source of the formation of this Si pathway. The small sizes of the Si NCs (d ∼ 5 nm) suggest that scaling to ultrasmall domains could be feasible. Meanwhile, the switch also shows robust nonvolatile properties, high ON/OFF ratios (>10(5)), fast switching (sub-100-ns), and good endurance (10(4) write-erase cycles). These properties in a SiO(x)-based material composition showcase its potentials in constructing memory or logic devices that are fully CMOS compatible.

Optical identification of atomically thin dichalcogenide crystals

Abstract: We present a systematic study of the optical contrast of niobium diselenide and molybdenum disulfide flakes deposited onto silicon wafers with a thermally grown silicon oxide layer. We measure the optical contrast of flakes whose thickness, which is obtained by atomic force microscopy, ranges from 200 layers down to a monolayer using different illumination wavelengths in the visible spectrum. The refractive index of these thin crystals has been obtained from the optical contrast using Fresnel law. In this way the optical microscopy data can be quantitatively analyzed to determine the thickness of the flakes in a fast and nondestructive way.

Formation of silicon oxide using non-carbon flowable cvd processes

Abstract: A method of forming a silicon oxide layer is described. The method may include the steps of mixing a carbon-free silicon-and-nitrogen containing precursor with a radical precursor, and depositing a silicon-and-nitrogen containing layer on a substrate. The silicon-and-nitrogen containing layer is then converted to the silicon oxide layer.

Method of growing oxide thin films

Abstract: Process for producing silicon oxide containing thin films on a growth substrate by the ALCVD method. In the process, a vaporisable silicon compound is bonded to the growth substrate, and the bonded silicon compound is converted to silicon dioxide. The invention comprises using a silicon compound which contains at least one organic ligand and the bonded silicon compound is converted to silicon dioxide by contacting it with a vaporised, reactive oxygen source, in particular with ozone. The present invention provides a controlled process for growing controlling thin films containing SiO2, with sufficiently short reaction times.

Reliability Issues of SiC MOSFETs: A Technology for High-Temperature Environments

Abstract: The wide-bandgap nature of silicon carbide (SiC) makes it an excellent candidate for applications where high temperature is required. The metal-oxide-semiconductor (MOS)-controlled power devices are the most favorable structure; however, it is widely believed that silicon oxide on SiC is physically limited, particularly at high temperatures. Therefore, experimental measurements of long-term reliability of oxide at high temperatures are necessary. In this paper, time-dependent dielectric-breakdown measurements are performed on state-of-the-art 4H-SiC MOS capacitors and double-implanted MOS field-effect transistors (DMOSFET) with stress temperatures between 225°C and 375°C and stress electric fields between 6 and 10 MV/cm. The field-acceleration factor is around 1.5 dec/(MV/cm) for all of the temperatures. The thermal activation energy is found to be ~ 0.9 eV, independent of the electric field. The area dependence of Weibull slope is discussed and shown to be a possible indication that the oxide quality has not reached the intrinsic regime and further oxide-reliability improvements are possible. Since our reliability data contradict the widely accepted belief that silicon oxide on SiC is fundamentally limited by its smaller conduction-band offset compared with Si, a detailed discussion is provided to examine the arguments of the early predictions.

Post-planarization densification

Abstract: Processes for forming high density gap-filling silicon oxide on a patterned substrate are described. The processes increase the density of gap-filling silicon oxide particularly in narrow trenches. The density may also be increased in wide trenches and recessed open areas. The densities of the gap-filling silicon oxide in the narrow and wide trenches/open areas become more similar following the treatment which allows the etch rates to match more closely. This effect may also be described as a reduction in the pattern loading effect. The process involves forming then planarizing silicon oxide. Planarization exposes a new dielectric interface disposed closer to the narrow trenches. The newly exposed interface facilitates a densification treatment by annealing and/or exposing the planarized surface to a plasma.

Dielectric Films Comprising Silicon And Methods For Making Same

Abstract: Described herein are methods of forming dielectric films comprising silicon, such as, but not limited to, silicon oxide, silicon oxycarbide, silicon carbide, and combinations thereof, that exhibit at least one of the following characteristics: low wet etch resistance, a dielectric constant of 6.0 or below, and/or can withstand a high temperature rapid thermal anneal process. Also disclosed herein are the methods to form dielectric films or coatings on an object to be processed, such as, for example, a semiconductor wafer.

Brightly luminescent organically capped silicon nanocrystals fabricated at room temperature and atmospheric pressure.

Abstract: Silicon nanocrystals are an extensively studied light-emitting material due to their inherent biocompatibility and compatibility with silicon-based technology. Although they might seem to fall behind their rival, namely, direct band gap based semiconductor nanocrystals, when it comes to the emission of light, room for improvement still lies in the exploitation of various surface passivations. In this paper, we report on an original way, taking place at room temperature and ambient pressure, to replace the silicon oxide shell of luminescent Si nanocrystals with capping involving organic residues. The modification of surface passivation is evidenced by both Fourier transform infrared spectroscopy and nuclear magnetic resonance measurements. In addition, single-nanocrystal spectroscopy reveals the occurrence of a systematic fine structure in the emission single spectra, which is connected with an intrinsic property of small nanocrystals since a very similar structure has recently been observed in specially p...

Infrared characterization of interfacial Si-O bond formation on silanized flat SiO2/Si surfaces.

Abstract: Chemical functionalization of silicon oxide (SiO2) surfaces with silane molecules is an important technique for a variety of device and sensor applications. Quality control of self-assembled monola...

Charge-optimized many-body potential for the hafnium/hafnium oxide system

Abstract: A dynamic-charge, many-body potential function is proposed for the hafnium/hafnium oxide system. It is based on an extended Tersoff potential for semiconductors and the charge-optimized many-body potential for silicon oxide. The materials fidelity of the proposed formalism is demonstrated for both hafnium metal and various hafnia polymorphs. In particular, the correct orders of the experimentally observed polymorphs of both the metal and the oxide are obtained. Satisfactory agreement is found for the structural and mechanical properties, defect energetics, and phase stability as compared to first-principles calculations and/or experimental values. The potential can be used in conjunction with the previously determined potentials for the Si and SiO2 system. This transferability is demonstrated by comparing the structure of a hafnia/silicon interface to that previously determined from electronic-structure calculations.

Methods of fabricating silicon oxide layers using inorganic silicon precursors and methods of fabricating semiconductor devices including the same

Abstract: Methods of fabricating a silicon oxide layer using an inorganic silicon precursor and methods of fabricating a semiconductor device using the same are provided. The methods of fabricating a semiconductor device include forming a tunnel insulating layer and a charge storage layer on a substrate; forming a dielectric layer structure on the charge storage layer using an atomic layer deposition (ALD) method, the dielectric layer structure including a first dielectric layer formed of silicon oxide, a second dielectric layer on the first dielectric layer formed of a material different from the material forming the first dielectric layer, and a third dielectric layer formed of the silicon oxide on the second dielectric layer; and forming a control gate on the dielectric layer structure. The first and third dielectric layers formed of the silicon oxide are formed using a first gas including an inorganic silicon precursor, a second gas including hydrogen gas or a hydrogen component, and a third gas including an oxide gas.

Resistive interlayer for improved performance of thin film silicon solar cells on highly textured substrate

Abstract: The deposition of thin-film silicon solar cells on highly textured substrates results in improved light trapping in the cell. However, the growth of silicon layers on rough substrates can often lead to undesired current drains, degrading performance and reliability of the cells. We show that the use of a silicon oxide interlayer between the active area and the back contact of the cell permits in such cases to improve the electrical properties. Relative increases of up to 7.5% of fill factor and of 6.8% of conversion efficiency are shown for amorphous silicon cells deposited on highly textured substrates, together with improved yield and low-illumination performance.

Silicon oxide based n-doped layer for improved performance of thin film silicon solar cells

Abstract: We propose the use of n-doped silicon oxide as alternative n-layer in thin film Si p-i-n solar cells. By varying input gas ratios, films with a wide range of optical and electrical properties are obtained. Applying these layers in solar cells, good electrical and optical properties are demonstrated. A relative efficiency increase up to 13.6% has been observed on the cells adopting a simple Ag back contact. A similar spectral response as with the cell with standard n-layer plus ZnO/Ag back contact is obtained. The deposition of a buffer layer at the back contact can therefore be avoided.

ZnO nanowires grown on SOI CMOS substrate for ethanol sensing

Abstract: This paper reports on the integration of zinc oxide nanowires (ZnO NWs) with a silicon on insulator (SOI) CMOS (complementary metal oxide semiconductor) micro-hotplate for use as an alcohol sensor. The micro-hotplates consist of a silicon resistive micro-heater embedded within a membrane (composed of silicon oxide and silicon nitride, supported on a silicon substrate) and gold bump bonded aluminum electrodes that are used to make an ohmic contact with the sensing material. ZnO NWs were grown by a simple, low-cost hydrothermal method and characterised using SEM, XRD and photoluminiscence methods. The chemical sensitivity of the on-chip NWs to ethanol vapour (at different humidity levels) was characterised at two different temperatures namely, 300 °C and 400 °C (power consumption was 24 mW and 33 mW, respectively), and the sensitivity was found to be 0.1%/ppm (response 4.7 at 4363 ppm). These results show that ZnO NWs are a promising material for use as a CMOS ethanol gas sensor that offers low cost, low power consumption and integrated circuitry.

Dielectric film formation using inert gas excitation

Abstract: Methods of forming a silicon-and-nitrogen-containing layers and silicon oxide layers are described. The methods include the steps of mixing a carbon-free silicon-containing precursor with plasma effluents, and depositing a silicon-and-nitrogen-containing layer on a substrate. The silicon-and-nitrogen-containing layers may be made flowable or conformal by selection of the flow rate of excited effluents from a remote plasma region into the substrate processing region. The plasma effluents are formed in a plasma by flowing inert gas(es) into the plasma. The silicon-and-nitrogen-containing layer may be converted to a silicon-and-oxygen-containing layer by curing and annealing the film.

Diamond, titanium dioxide, titanium silicon oxide, and barium strontium titanium oxide nanoparticles as matrixes for direct matrix-assisted laser desorption/ionization mass spectrometry analysis of carbohydrates in plant tissues.

Abstract: Nanoparticles (NPs) of diamond, titanium dioxide, titanium silicon oxide, barium strontium titanium oxide, and silver (Ag) were examined for their potential as MALDI matrixes for direct laser desorption/ionization of carbohydrates, especially fructans, from plant tissue. Two sample preparation methods including solvent-assisted and solvent-free (dry) NPs deposition were performed and compared. All examined NPs except for Ag could desorb/ionize standard sucrose and fructans in positive and in negative ion mode. Ag NPs yielded good signals only for nonsalt-doped samples that were measured in the negative ion mode. In the case of in vivo studies, except for Ag, all NPs studied could desorb/ionize carbohydrates from tissue in both the positive and negative ion modes. Furthermore, compared to the results obtained with soluble sugars extracted from plant tissues, fructans with higher molecular weight intact molecular ions could be detected when the plant tissues were directly profiled. The limit of detection (L...

Solar cell and manufacturing method thereof

Abstract: A method for forming a doped region in a solar cell includes preparing a first and second surface of a substrate, forming a first doped region doped with a first dopant in a part of the first surface, forming a silicon oxide layer on the first surface, the silicon oxide layer including a first silicon oxide layer on the first doped region and having a first thickness, and a second silicon oxide layer on a portion of the first surface undoped by the first dopant and having a second thickness that is less than the first thickness, implanting a second dopant from outside the first surface into the first silicon oxide layer and the second silicon oxide layer, and forming a second doped region adjacent the first doped region by performing heat treatment on the first silicon oxide layer, the second silicon oxide layer, and the substrate.

Comparative Study of Titanium Dioxide Atomic Layer Deposition on Silicon Dioxide and Hydrogen-Terminated Silicon

Abstract: Atomic layer deposition (ALD) of amorphous titanium dioxide (TiO2) at 100 °C using the precursors titanium tetrachloride (TiCl4) and water (H2O) was studied on two different surfaces by in situ X-ray photoelectron spectroscopy (XPS). The initial growth rate on hydroxyl-enriched silicon dioxide (SiO2) is found to be higher than on hydrogen-terminated silicon. Moreover, the data show that the growth rate is accelerated during the first several ALD cycles on both surfaces. The interface between the SiO2 substrate and TiO2 is abrupt and composed of Si−O−Ti bonds. On the hydrogen-terminated silicon surface, the XPS results provide evidence of direct Si−Ti bond formation without traces of interfacial oxide. However, a silicon oxide layer forms on this surface after vacuum annealing, concurrent with the reduction of TiO2, suggesting that the TiO2 film is the oxygen source for the silicon oxidation under these conditions. Chlorine incorporates into the TiO2 films on both surfaces and is found to concentrate near ...

Biofunctionalization on Alkylated Silicon Substrate Surfaces via “Click” Chemistry

Abstract: Biofunctionalization of silicon substrates is important to the development of silicon-based biosensors and devices. Compared to conventional organosiloxane films on silicon oxide intermediate layers, organic monolayers directly bound to the nonoxidized silicon substrates via Si−C bonds enhance the sensitivity of detection and the stability against hydrolytic cleavage. Such monolayers presenting a high density of terminal alkynyl groups for bioconjugation via copper-catalyzed azide−alkyne 1,3-dipolar cycloaddition (CuAAC, a “click” reaction) were reported. However, yields of the CuAAC reactions on these monolayer platforms were low. Also, the nonspecific adsorption of proteins on the resultant surfaces remained a major obstacle for many potential biological applications. Herein, we report a new type of “clickable” monolayers grown by selective, photoactivated surface hydrosilylation of α,ω-alkenynes, where the alkynyl terminal is protected with a trimethylgermanyl (TMG) group, on hydrogen-terminated silico...

The influence of SiOx and SiNx passivation on the negative bias stability of Hf-In-Zn-O thin film transistors under illumination

Abstract: The stability of hafnium indium zinc oxide thin film transistors under negative bias stress with simultaneous exposure to white light was evaluated. Two different inverted staggered bottom gate devices, each with a silicon oxide and a silicon nitride passivation, were compared. The latter exhibits higher field effect mobility but inferior subthreshold swing, and undergoes more severe shifts in threshold voltage (VT) during negative bias illumination stress. The time evolution of VT fits the stretched exponential equation, which implies that hydrogen incorporation during the nitride growth has generated bulk defects within the semiconductor and/or at the semiconductor/gate dielectric interface.

Electrons as "invisible ink": fabrication of nanostructures by local electron beam induced activation of SiOx.

Abstract: The injection or removal of electrons can be used to trigger chemical processes, such as bond formation or dissociation. In this regard, electrons are an excellent and “clean” tool to modify or engineer the properties of different materials. The availability of localized electron probes, for example, in scanning electron microscopy (SEM), has made it possible to apply electron-induced processes on the nanometer and subnanometer scale. This approach can be used to target the generation of extremely small, pure nanostructures with lithographic control, which is one of the main goals in nanotechnology. The starting point of our study was the electron beam induced deposition (EBID) technique. The principle of EBID is outlined in Scheme 1a–c. A highly focused electron beam locally decomposes adsorbed precursor molecules to leave a deposit of nonvolatile fragments. The importance of EBID recently increased since it superseded focused ion beam processing as a method to repair lithographic masks in the semiconductor industry. The underlying physical and chemical principles of electron-induced bond making and breaking are in general also of great interest for important technological applications such as electron beam lithography (EBL), which is the standard method of generating the masks for UV lithography. As there is a large variety of precursor molecules and there are nearly no restrictions in regard to the substrate, EBID allows almost every combination of deposit material and substrate to be targeted. As a prototype example for conductive structures on an insulating material, our aim here was to generate clean iron nanostructures on a SiOx layer on Si(001). Scheme 1a–c depicts a schematic representation of

Molecular layer deposition of thiol-ene multilayers on semiconductor surfaces.

Abstract: The fabrication of organic thin films with controlled chemical structure in the vertical direction (parallel to surface normal) is important for many practical and technological applications in organic electronics, chemical-resistant films, and biocompatible materials, among others. In order to achieve composition control in the z-direction, molecular layer deposition (MLD: covalent layer-by-layer assembly) of thin, organic films on silicon, silicon oxide, and germanium surfaces was carried out, using the well-established UV-induced thiol−ene reaction. Through successive contact of an interface with dithiol and diene molecules under UV irradiation for short periods (∼30 min, room temperature), well-defined thin films can be obtained. Linear increases in film thickness with respect to layer number were obtained for shorter aliphatic dienes and dithiols (C ≤ 8), but with longer molecules and with aromatic substrates a self-limiting situation sets in whereby both ends of the molecule react with the surface, ...

Negative electrode material for nonaqueous electrolyte secondary battery, making method and lithium ion secondary battery

Abstract: A negative electrode material for nonaqueous electrolyte secondary batteries comprises composite particles which are prepared by coating surfaces of particles having silicon nano-particles dispersed in silicon oxide with a carbon coating, and etching the coated particles in an acidic atmosphere. The silicon nano-particles have a size of 1-100 nm. The composite particles contain oxygen and silicon in a molar ratio: O

Graphene nanoribbon thin films using layer-by-layer assembly.

Abstract: Described here is a room temperature procedure to fabricate graphene nanoribbon (GNR) thin films. The GNRs, synthesized by unzipping carbon nanotubes, were reduced and functionalized. The functionalized GNRs are negatively or positively charged, which are suitable to assemble thin films by electrostatic layer-by-layer absorption. The homogenous full GNR films were fabricated on various substrates with controllable thicknesses. By assembling the GNRs films on silicon oxide/silicon surfaces, bottom-gated GNR thin-film transistors were fabricated in a solution processed technique.

High-Quality Low-Temperature Silicon Oxide by Plasma-Enhanced Atomic Layer Deposition Using a Metal–Organic Silicon Precursor and Oxygen Radical

Abstract: Recently, SiO2 grown at low temperatures has been highlighted for a range of applications. In this letter, SiO2 films were deposited at 280°C by plasma-enhanced atomic layer deposition (ALD) using bis-diethylamino-silane and O2 plasma. The electrical conduction mechanisms of a 38-nm-thick SiO2 film were found to be ohmic and Fowler-Nordheim tunneling in the low- and high-voltage ranges, respectively. The electrical breakdown field of the silicon oxide films was measured at ~10 MV/cm. The excellent breakdown field was well explained by the fact that ALD SiO2 has very low carbon content (<; 0.5%) and does not have any oxygen deficiency and nonbridging oxygen. Compared to wet SiO2, the increase in etch rates was attributed to the existence of strained bonds.

Organic light emitting device and manufacturing method thereof

Abstract: PURPOSE: An organic light emitting device and a method for manufacturing the same are provided to improve a moisture preventive property and surface roughness by forming a barrier layer which includes a stack comprising a silicon oxide film and a silicon oxynitride film. CONSTITUTION: A barrier layer is formed on a substrate. A silicon oxynitirde inorganic film is stacked on a silicon oxide inorganic film in order to form the barrier layer. The density of the silicon oxynitride inorganic film is higher than that of the silicon oxide inorganic film. A first electrode is formed on the barrier layer. A second electrode is formed on the first electrode. An organic film is formed between the first electrode and the second electrode.

Thermal enhancement of chemical doping in graphene: a Raman spectroscopy study

Abstract: The Raman spectrum of monolayer graphene deposited on the top of a silicon oxide/silicon substrate was investigated as a function of temperature up to 515 K. An anomalous temperature dependence of the Raman features was observed, including an important frequency upshift for the Raman G band at room temperature, after the heating process. On the other hand, the frequency of the Raman G' band is only slightly affected by the thermal treatment. We discuss our experimental results in terms of doping and strain effects associated with the interaction of graphene with the substrate and with the presence of water in the sample. We conclude that the doping effect gives the most important contribution to the spectral changes observed after the thermal cycle.