Oxidation Of Silicon Research Articles

Surface oxidation of amorphous Si and Ge slanted columnar and mesoporous thin films: Evidence, scrutiny and limitations for infrared optics

Issues on the superficial oxidation of mesoporous amorphous silicon and germanium photonic layers generated at oblique angles are reported. Such films were designed to improve the transmittance of optical elements over the mid-IR window (3.6–4.9 μm) by removing the light reflection. These nanostructures were deposited on silicon substrates by e-beam evaporation at room temperature. IR ellipsometry and spectrophotometry studies combined with models based on effective medium approximations predicted the presence of silicon or germanium oxides. Such oxidation was evidenced by combining X-ray photoelectron spectroscopy and advanced (scanning-)transmission electron microscopy studies based on energy-dispersive X-rays and electron energy-loss spectroscopies. Both techniques also allowed to prove the formation of core-shell-type architectures consisting of pure Si or Ge surrounded by oxidized species, even for a Ge layer subsequently capped with a dense MgF2 coating. The different approaches used for preparing electron transparent specimens (tripod polishing and focused ion-beams) confirmed a fast oxidation of the Ge nanocolumns even for short air exposure periods, and allowed comparing it with the level of oxidation promoted from other pollutant sources. This work sheds light on the spontaneous undesired oxidation in Si or Ge slanted nanorods which can diminish the performances and limit further development of optical devices.

Silicon and germanium nanostructures formed by spark discharge plasma

Formation of semiconductor nanostructures on the surface of single crystalline silicon and germanium wafers by spark discharge plasma in air was investigated. The prepared nanostructures were analyzed by means of the scanning and transmission electron microscopy and optical spectroscopy of the photoluminescence and Raman scattering. The formed nanostructures exhibit a fractal-like morphology with interconnected nanocrystals of 2-200 nm sizes that is explained by repeated processes of spark ablation and subsequent condensation. While the size and morphology of the nanostructure depend on power sources of the spark discharge, short interaction times of spark discharge plasma and target determine a relatively low efficiency of the chemical oxidation of germanium and silicon, as well as low ionic temperatures of the plasma.

An Injection Enhanced LIGBT on Thin SOI Layer Compatible With CMOS Process

In this paper, we present a lateral injection enhanced insulated gate bipolar transistor (LIEGT) and investigate its mechanism. The LIEGT features a recessed trench at the cathode side of the drift region formed by LOCal oxidation of silicon (LOCOS) process. The recessed trench suppresses holes being extracted and enhances the electron injection, thus contributing to a very low loss in the ON-state. The ON-state voltage ( ${V}_{ \mathrm{\scriptscriptstyle ON}}$ ) of the LIEGT is reduced by 24% at the current density of 200 A/cm2 and the saturation current is 40% higher than that of the conventional lateral insulated gate bipolar transistor (LIGBT). The LIEGT exhibits an improved tradeoff between ${V}_{ \mathrm{\scriptscriptstyle ON}}$ and turnoff loss ( ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ ). For the same ${V}_{ \mathrm{\scriptscriptstyle ON}}$ , the ${E}_{ \mathrm{\scriptscriptstyle OFF}}$ is decreased by 38% compared with that of the conventional LIGBT.

Improving steel melting intensity in the process of electrosmelting from waste and pellets (HBI)

The paper addresses the issue on improving the intensity of melting in the production of steels using hot briquetted iron (HBI) in the charge that mostly consists of metal waste. An analysis has been performed into the features of melting that uses charge of complex composition. To ensure the boiling of metal bath, it is recommended to introduce to the bath carbon-containing raw materials in the form of steel waste in the amount exceeding 80 %. It was established that applying HBI almost does not reduce the yield of usable metal due to a high content of metal waste that makes up the charge.At the same time, the paper analyses the role of silicon and manganese oxidation process in the refining of liquid steel at melting the alloy wastes used as charge materials in an electric arc furnace. The dependences of equilibrium concentrations of oxygen and silicon at different temperatures in the system Fe‒Si‒O have been given. In addition, the dependence diagram of manganese oxidation products in a liquid iron on the temperature and concentration of manganese in the alloy MnO‒FeO has been constructed. The equilibrium concentrations of oxygen and silicon with carbon deoxidizing capability have been defined, in the field of liquid silicates and in the field of solid SiO2.The high-quality silicon and manganese oxidation when smelting steel made from metal waste and hot briquetted iron (HBI) contributes to the fullest refining of liquid steel through the phases metal-slag or metal-gas.It has been shown that the content of silicon during electrical steel refining drops to traces. Thus, when using metal waste and pellets as charge in the steel-making process, a silicon oxidation reaction does not reach equilibrium. If a sour process is performed, then the oxidation of silicon reaches equilibrium and, under certain conditions for melting the charge under the influence of heat from an electric arc, there may occur a significant reduction of silicon that takes place at a higher temperature (a silicon-reducing process). The basic process of melting the charge from metal waste and hot briquetted iron in an electric arc furnace has been recommended. In this case, the reducing period of melting is aimed at metal deoxidation, sulphur removal, at bringing the chemical composition of steel to the preset composition, at controlling the process temperature. All these tasks are solved in parallel throughout the entire reduction period. The complete removal of oxidative slag was followed by adding to the furnace of slag-forming mixes together with deoxidizing agents, that is the new slag (carbide or white) was introduced.A rise in the furnace bath temperature decreases the equilibrium constant of manganese. Therefore, in the absence of ferromanganese additives in the bath in the process of melting refinement, the behavior of manganese in the bath can be an indicator for the metal temperature.

A hybrid silicon-sapphire cryogenic Fabry–Perot cavity using hydroxide catalysis bonding

The third-generation gravitational wave detectors under development will be operating at cryogenic temperature to reduce the thermal noise. Silicon and sapphire are promising candidate materials for the test masses and suspension elements due to their remarkable mechanical and thermal properties at cryogenic temperature. Here we present the performances of the cryogenic thermal cycling and strength testing on hydroxide catalysis bonding between sapphire and silicon. Our results suggest that although these two materials have very different coefficients of thermal expansion, if the flatness and the thermally grown SiO2 oxidation layer on the silicon surface are controlled well, the bonded samples can still survive thermal cycling from room temperature to 5.5 K. A breaking strength of MPa is measured for the bonds between sapphire and silicon with a 190 nm silicon oxidation thickness after cooling cycle. We construct a hybrid sapphire-silicon Fabry–Perot cavity with our bonding technique. The measurement results reveal that the cavity can survive repeated thermal cycling while maintaining a finesse of .

Commonality of Kinetics and Mechanisms of Galvanostatic Anodic Oxidation of Silicon, Carbide, and Silicon Nitride

Commonality of Kinetics and Mechanisms of Galvanostatic Anodic Oxidation of Silicon, Carbide, and Silicon Nitride

Novel Star Polymeric Nonionic Surfactants as Crude Oil Emulsion Breakers

AbstractThe principle focus of this work is to address the issues associated with the existence of water in crude oil, especially corrosion, scaling, viscosity, and catalyst suppression problems. This work aims to prepare star polymer nonionic surfactants based on (2Z,2′Z,2″Z)‐4,4′,4″‐((nitrilotris(ethane‐2,1‐diyl))tris(oxy))tris(4‐oxobut‐2‐enoic acid) to be used as demulsifiers. To achieve this aim, maleic anhydride was reacted with triethanolamine followed by esterification with the polyethylene oxide polypropylene oxide copolymer (PPO‐PEO 5000) and silicone polyether (ABIL B 8843). The chemical structure of the prepared compounds was assessed using gel permeation chromatography (GPC), Fourier transform infrared (FT‐IR), and 1H NMR. Demulsifier performance was determined by quantifying surface tension (ST), dynamic interfacial tension and interfacial rheology, partition coefficient (PC), and relative solubility number (RSN). The efficacy of the prepared emulsion breakers on asphaltenic crude oil emulsion was examined using the bottle test. The research results demonstrated that the prepared breaker based on the silicone polymer was more efficient in breaking the asphaltenic crude oil emulsion than a block copolymer and EO/PO‐based copolymers at 1500 ppm and after 120 min.

Model for Thermal Oxidation of Silicon

Nanometer-thick silicon oxide films are needed for miniaturization and increase in the working rate of electronic devices. Interpretation of the initial stages of silicon oxidation is necessary for fabrication of such structures. A theoretical model of the thermal oxidation of thin silicon monolayers that takes into account an increase in the stress in the transition (oxide–substrate) layer due to oxygen accumulation therein is proposed.

Oxidation of Liquid Silicon in Air Atmospheres Containing Water Vapor

The oxidation of silicon (Si) has been extensively investigated over the past 50 years. Yet, an understanding of the mechanism and rate of liquid Si oxidation in atmospheres containing water vapor, is lacking. The effect of water vapor on the oxidation process is of particular importance in the industrial, metallurgical production and processing of liquid silicon, as a significant amount of silica fume is generated under such conditions. The generation of fume is due to the active oxidation of liquid metal in the tapping, refining, and casting steps—a major occupational health and safety challenge for the Si producers. In this work, the effect of water vapor in the atmosphere on the Si oxidation rate and fume characteristics was investigated experimentally at 1823 K in air–H₂O atmospheres. Compared with oxidation in dry air, the rate of oxidation in wet air is higher, and increases to 3-fold compared to that of dry air with increasing water vapor content at 7 kPa, above which the alloy surface was passivated and the oxidation rate stable. To explain the experimental observations, Si oxidation reactions in wet atmosphere were modeled by FactSage 7.1 thermochemical software, by density functional theory (DFT) calculations, and by estimates of detailed reaction thermochemistry and kinetics using statistical thermodynamics and statistical mechanics methods. The increased rate of fuming was explained by the formation of Si–O–H species in the system and the more “sticky” nature of the H₂O molecule on the Si surface as compared to the O₂ molecule, yielding a higher degree of oxygen utilization toward active Si oxidation, that is, SiO formation.

Yttrium ultra-thin films on the Si(100)2 × 1 surface and their in situ oxidation process

Yyttrium ultra-thin films (coverage <4 ML) and their interaction with oxygen on the Si(100)2 × 1 surface have been investigated in situ by Auger electron spectroscopy, low energy electron diffraction, thermal desorption spectroscopy, and relative work function measurements. The results show that yttrium develops in amorphous successive layers, interacting strongly with silicon at the interface, causing an early surface YSi intermixing and disruption of the silicon 2 × 1 symmetry. Yttrium increases drastically the oxygen sticking coefficient on silicon surface. It is surprising that even residual oxygen on the yttrium covered surface, induces a partial oxidation of silicon even at room temperature. By providing more oxygen, an Y-silicate compound (Y-O-Si) develops simultaneously with silica (SiO2) in a competitive way to each other. The silicate is thermally promoted by post-annealing process, probably due to the enhanced yttrium-silicon intermixing and/or inter-diffusion. Both of the silica and silicate are thermally stable compounds, which dissociate and desorb from the surface only at high temperatures (>1100 K). Desorbing species such as Y2Si and SiO were recorded and attributed to the cracking of silicate and silica respectively. A significant amount of yttrium always remains and/or diffuses into the silicon substrate, even after strong annealing. Such a procedure caused the appearance of a newly observed 3 × 1 phase corresponding to submonolayer yttrium coverage.

Edge effect in the oxidation of three-dimensional nano-structured silicon

Understanding and controlling the oxidation of 3D nano-structured Si is important for the three-dimensional (3D) nano-structured vertical metal–oxide–semiconductor (MOS) field-effect transistor. The retarded oxidation of Si in a corner (edge) has been widely considered since the 1980s to be due to the compressive stress from oxide and/or the slow diffusion of the oxidant in the oxide caused by compressive stress, although some problems remain unresolved. In the current work, a sharp angle in a simultaneously oxidized concave-structured adjacent two-dimensional planar surface was observed for the first time by using transmission electron microscope, for which the traditional consideration is difficult to interpret. We also found that the oxidation of Si near the edge is delayed (edge effect) irrespective of whether the edge is non-oxidized Si3N4 or a simultaneously oxidized convex- or concave-structured adjacent two-dimensional planar surface, widely exists in different Si planar surface of the observed 3D nano-structures (pillar, fin, and terrace) independent of grain orientation. We further developed a model for the formation of the edge effect and discussed its mechanism. The edge effect completely explains the residual Si and formed SiO2 in all Si nano-structures and also contributes in intrinsically understanding and precisely controlling the oxidation of 3D nano-structured Si for future device fabrications.

Characteristics and reliability of VDMOS under capacitive loads

The failure mechanism of vertical double-diffusion metal-oxide-semiconductor (VDMOS) turning on under capacitive loads is analyzed. Due to the structural features of the device, it is easy to burnout at the source pad (SPAD) area when turning on under capacitive loads. On the basis of simulation, thermal characteristics of VDMOS devices under capacitive loads are analyzed. The results show that junction temperatures (Tj) are obviously affected by capacitive load values (CL) and thermal resistances (Rth) of VDMOS devices. When Rth = 0.1 °C/W or Rth = 0.15 °C/W, curves between Tj and CL present an approximately linear relationship, while when Rth = 0.2 °C/W, the rate of Tj rising with CL shows an increasing trend. At last, the influences of device structure and process on capacitive load limits are verified by experiments. The results show that the design of local oxidation of silicon (LOCOS) structure has little effect on capacitive load limits of devices, while the capacitive load limit of the fourth generation (R4) process devices is obviously higher than that of the fifth generation (R5) process devices.

Size‐Controlled Si Nanocrystals Fabricated by Electron Beam Evaporation

Multilayers consisting of silicon nanocrystals (Si NCs) and SiO2 are successfully fabricated by electron beam evaporation, using pure Si and SiO2 targets in an oxygen‐rich atmosphere for alternately depositing silicon‐rich oxide (SRO) layers and SiO2 barriers, respectively. A post‐deposition annealing process is carried out at different temperatures in order to achieve the Si precipitation in the form of nanocrystals. The stoichiometry of the layers is determined by X‐ray photoelectron spectroscopy, which confirms the controlled silicon oxidation in order to attain SRO layers. Transmission electron microscopy and Raman‐scattering measurements confirm the presence of crystalline Si‐nanoprecipitates. Photoluminescence spectra from the Si NC samples can be deconvolved into two contributions, whose dynamics suggest that two different luminescent centers are responsible for the optical emission of the samples.

Mechanistic study of the atomic layer deposition of scandium oxide films using Sc(MeCp)2(Me2pz) and ozone

The atomic layer deposition (ALD) of scandium oxide (Sc2O3) thin films is investigated using Sc(MeCp)2(Me2pz) (1, MeCp = methylcyclopentadienyl, Me2pz = 3,5-dimethylpyrazolate) and ozone on hydroxyl-terminated oxidized Si(111) substrates at 225 and 275 °C. In situ Fourier transform infrared spectroscopy reveals that 1 not only reacts with surface hydroxyl groups at 275 °C, as expected but also with the SiO2 layer, as evidenced by losses in the SiO2 longitudinal optical and transverse optical phonon modes, resulting in the partial transformation of near-surface SiO2 to an ScSixOy interface layer. Ozone then combusts the MeCp groups of the O–Sc(MeCp)2 chemisorbed species, yielding surface carbonates, and oxidizes some of the underlying silicon, evidenced by gains in the SiO2 phonon modes. The Me2pz group from the next pulse of 1 reacts with these surface carbonates, leading to Sc–O–Sc bond formation (Sc2O3 deposition) and the restoration of an O–Sc(MeCp)2 surface. The reaction of the SiO2 substrate with 1 and the oxidation of silicon by ozone are temperature-dependent processes that occur during the initial cycles of film growth and directly impact the changes in the intensities of the SiO2 phonon modes. For instance, the intensity of the net gains in the phonon modes following ozone exposure is greater at 275 °C than at 225 °C. As the ALD cycle is repeated, the formation of an ScSixOy interface layer and deposition of an Sc2O3 film result in the gradual attenuation of the reaction of the SiO2 substrate with 1 and the oxidation of the underlying silicon by ozone. In addition to the ALD process, characterized by ligand exchange and self-limiting reactions, there are gas-phase reactions between 1 and residual water vapor near the substrate surface that lead to deposition of additional Sc2O3 and surface carbonates, the extent of which are also dependent on the temperature of the substrate. After 20 cycles of 1/ozone, the film thicknesses derived from ex situ X-ray photoelectron spectroscopy measurements are 2.18 nm (225 °C) and 3.88 nm (275 °C). This work constitutes the first mechanistic study of an Sc2O3 ALD process using ozone as the oxidant and emphasizes the significance of atypical reactions between the substrate and the reactants that influence the growth rate and near-surface stoichiometry during the initial cycles of film deposition.

Модель термического окисления кремния

AbstractNanometer-thick silicon oxide films are needed for miniaturization and increase in the working rate of electronic devices. Interpretation of the initial stages of silicon oxidation is necessary for fabrication of such structures. A theoretical model of the thermal oxidation of thin silicon monolayers that takes into account an increase in the stress in the transition (oxide–substrate) layer due to oxygen accumulation therein is proposed.

Effect of Nucleic Acids on Oxidation and Photoluminescence of Porous Silicon

Effect of Nucleic Acids on Oxidation and Photoluminescence of Porous Silicon

A revised model of silicon oxidation during the dissolution of silicon in HF/HNO3 mixtures.

The stoichiometry of wet chemical etching of silicon in concentrated HF/HNO3 mixtures was investigated. The formation of nitrogen species enriched in the etching mixture and their reactivity during the etching process was studied. The main focus of the investigations was the comprehensive quantification of the gaseous reaction products using mass spectrometry. Whereas previously it could only be speculated that nitrogen was a product, its formation was detected for the first time. The formation of hydrogen, N2, N2O and NH4+ showed a dependence on the etching bath volume used, which indicates the formation of nitrogen compounds by side reactions. Simultaneously, the ratio of the nitrogen oxides, NO and NO2, formed decreases with increasing etching bath volume, while nitric acid consumption increases, so that the formation of NO2 could also be identified as a side reaction. Based on the stoichiometries obtained, a new reaction scheme for the reduction of nitric acid during etching in HF/HNO3 mixtures and an electron balance for the oxidation of silicon is presented.

Thermal Field Stabilization of the Threshold Voltage of the Field Transistors of the Submicron Technology of the LSI

On the basis of the analysis of the volume correspondence of the phases in the active gate system Si-SiO2, the possibility of obtaining a negative charge in the shutter system of submicron LSI is shown. Such a technological method has been experimentally verified at low temperature oxidation of silicon, which is patented. Studies have established that the magnitude of charge at the interphase boundary can be significantly influenced by introducing into the oxidizing atmosphere of halogen-containing compounds.

Engulfment control of platinum nanoparticles into oxidized silicon substrates for fabrication of dense solid-state nanopore arrays

We found that platinum (Pt) nanoparticles, upon annealing at high temperature of 1000 °C, are engulfed into amorphous fused-silica or thermal oxide silicon substrates. The same phenomenon was previously published for gold (Au) nanoparticles. Similar to the Au nanoparticles, the engulfed Pt nanoparticles connect to the surface of the substrates through conical nanopores, and the size of the Pt nanoparticles decreases with increasing depth of the nanopores. We explain the phenomena as driven by the formation of platinum oxide by reaction of the platinum with atmospheric oxygen, with platinum oxide evaporating to the environment. We found that the use of Pt provides much better controllability than the use of Au. Due to the high vapor pressure of platinum oxide, the engulfment of the Pt nanoparticles into oxidized silicon (SiO2) substrates is faster than of Au nanoparticles. At high temperature annealing we also find that the aggregation of Pt nanoparticles on the substrate surface is insignificant. As a result, the Pt nanoparticles are uniformly engulfed into the substrates, leading to an opportunity for patterning dense nanopore arrays. Moreover, the use of oxidized Si substrates enables us to precisely control the depth of the nanopores since the engulfment of Pt nanoparticles stops at a short distance above the SiOx/Si interface. After subsequent etching steps, a membrane with dense nanopore through-holes with diameters down to sub-30 nm is obtained. With its simple operation and high controllability, this fabrication method provides an alternative for rapid patterning of dense arrays of solid-state nanopores at low-cost.

Nanometer-scale oxidation of Silicon surface by ICP plasma

An experimental study of growth kinetic of silicon oxide during the initial stage of plasma enhanced oxidation is performed. Measurements were done in situ by means of spectroscopic ellipsometry with time resolution of 1 s. It was shown that oxidation of silicon in plasma does not comply with Deal-Grove model of oxidation. Measurements of concentration of oxygen in plasma and ion flux were performed to define mechanisms of oxidation. Obtained results could be applied for the development of multistage plasma processes involved in formation of nanostructures in advanced processes like atomic layer etching (ALE) and area selective atomic layer deposition.