Electron Beam Charging Research Articles

Unraveling Li growth kinetics in solid electrolytes due to electron beam charging.

Revealing the local structure of solid electrolytes (SEs) with electron microscopy is critical for the fundamental understanding of the performance of solid-state batteries (SSBs). However, the intrinsic structural information in the SSB can be misleading if the sample's interactions with the electron beams are not fully understood. In this work, we systematically investigate the effect of electron beams on Al-doped lithium lanthanum zirconium oxide (LLZO) under different imaging conditions. Li metal is observed to grow directly on the clean surface of LLZO. The Li metal growth kinetics and the morphology obtained are found to be heavily influenced by the temperature, accelerating voltage, and electron beam intensity. We prove that the lithium growth is due to the LLZO delithiation activated by a positive charging effect under electron beam emission. Our results deepen the understanding of the electron beam impact on SEs and provide guidance for battery material characterization using electron microscopy.

Electric Field-Induced Water Condensation Visualized by Vapor-Phase Transmission Electron Microscopy.

Understanding the nanoscale water condensation dynamics in strong electric fields is important for improving the atmospheric modeling of cloud dynamics and emerging technologies utilizing electric fields for direct air moisture capture. Here, we use vapor-phase transmission electron microscopy (VPTEM) to directly image nanoscale condensation dynamics of sessile water droplets in electric fields. VPTEM imaging of saturated water vapor stimulated condensation of sessile water nanodroplets that grew to a size of ∼500 nm before evaporating over a time scale of a minute. Simulations showed that electron beam charging of the silicon nitride microfluidic channel windows generated electric fields of ∼108 V/m, which depressed the water vapor pressure and effected rapid nucleation of nanosized liquid water droplets. A mass balance model showed that droplet growth was consistent with electric field-induced condensation, while droplet evaporation was consistent with radiolysis-induced evaporation via conversion of water to hydrogen gas. The model quantified several electron beam-sample interactions and vapor transport properties, showed that electron beam heating was insignificant, and demonstrated that literature values significantly underestimated radiolytic hydrogen production and overestimated water vapor diffusivity. This work demonstrates a method for investigating water condensation in strong electric fields and under supersaturated conditions, which is relevant to vapor-liquid equilibrium in the troposphere. While this work identifies several electron beam-sample interactions that impact condensation dynamics, quantification of these phenomena here is expected to enable delineating these artifacts from the physics of interest and accounting for them when imaging more complex vapor-liquid equilibrium phenomena with VPTEM.

On-Wafer Electron Beam Detectors by Floating-Gate FinFET Technologies

A novel electron beam detector made on Si wafers by the advanced CMOS FinFET processes has been proposed in this study. Through electron beam (e-Beam) charging of on-wafer sensing pads, electron dosage can be registered on the detector for follow-up read-out. Without external power or battery connections, this detector has successfully delivered on-chip dosage, intensity, and energy after e-Beam exposure.

Electron-beam charging of sapphire preirradiated by Arn+ clusters

Kinetics of sapphire single crystals charging under electron beam irradiation has been studied. The electron beam energy was 5 and 15 keV. The sapphire was preliminary irradiated with ArN+ cluster ions with the energy of 7–15 keV. The charging characteristics of virgin sapphire samples and those of the samples irradiated with atomic Ar+ and cluster ArN+ ions were compared. It was found that cluster ion preirradiation reduces the charging time of sapphire by almost two orders of magnitude. Possible explanations of the phenomenon are discussed.

Electron-beam charging of dielectrics preirradiated with moderate-energy ions and electrons

The effects of charging of dielectric targets irradiated with moderate-energy electrons in a scanning electron microscope are examined. Considerable differences in the kinetics of charging of the reference samples and the samples preirradiated with ions and electrons are reported. These differences are attributed to the processes of radiation-induced defect formation in Al2O3 (sapphire) and SiO2 that are, however, dissimilar in nature. The contributions of surface structure modification and changes in the electrophysical parameters of the surface (specifically, the charge spreading effect) are revealed. Critical doses of irradiation with Ar+ ions and electrons inducing active defect formation in dielectric targets and critical values of internal charge fields producing a significant contribution to the temporal parameters of Al2O3 and SiO2 charging are determined.

Application of charging effects in evaluating storage space of tight reservoirs: A case study from Permian Lucaogou Formation in Jimusar sag, Junggar Basin, NW China

According to the study of the electron beam charging effects of oil-bearing samples from tight reservoirs, a “Two-step Cross-section Back Scattered Electron (BSE) Imaging Method” is put forward, revealing the distribution of residual oil (the oil without loss in the vacuum conditions) in the tight reservoir. With the injection of charging agent, the connectivity of the pore system can also be characterized by this method, and a novel quantitative method of evaluating the effectiveness of reservoir space is established. For the tight reservoir samples from the Permian Lucaogou Formation in the Jimusar sag in the Junggar Basin, which was taken as an example, the strong charging effects mainly result from the residual oil in pores. The oil from pyrolysis of organic matter was widely stored in the pores both inside and nearby organic matter, or existing in poor organic matter area. Due to the super-large analyzing area, the Two-step Cross-section BSE Imaging Method can solve the weak representation of analysis area caused by the heterogeneity. The method of injection of charging agent works well in revealing the connectivity of the pore system. The total plane porosity of oil-bearing samples from the tight reservoir of the Lucaogou Formation is 12.56%, and the connectivity of the whole pore system in the sample reaches as high as 90%. The effectiveness of the reservoir space is very high.

Manipulating Ferroelectric Domains in Nanostructures Under Electron Beams

Freestanding BaTiO3 nanodots exhibit domain structures characterized by distinct quadrants of ferroelastic 90° domains in transmission electron microscopy (TEM) observations. These differ significantly from flux-closure domain patterns in the same systems imaged by piezoresponse force microscopy. Based upon a series of phase field simulations of BaTiO3 nanodots, we suggest that the TEM patterns result from a radial electric field arising from electron beam charging of the nanodot. For sufficiently large charging, this converts flux-closure domain patterns to quadrant patterns with radial net polarizations. Not only does this explain the puzzling patterns that have been observed in TEM studies of ferroelectric nanodots, but also suggests how to manipulate ferroelectric domain patterns via electron beams.

Modeling of Electron Beam Charging of an Insulating Layer on a Silicon Substrate

Charging effects caused by secondary electron (SE) emission near a 100-nm-high SiO2 step on a Si substrate are investigated. The system was irradiated by a 1-keV electron beam. We modeled SE emission by performing dynamic and self-consistent calculations of electron transport inside and outside the system. The model accounts for the electric field generated by positive and negative charges in the SiO2 step. Positive charging of the SiO2 step reduces the total electron yield to unity during irradiation. When the irradiation position is moved close to the edge of the step, charging decreases strongly and the electron yield increases sharply due to additional SE emission from the side wall of the step. When the Si substrate is irradiated with the electron beam, many SEs re-enter the side wall of the SiO2 step so that the wall surface becomes negatively charged. This negative charging deters other SEs from re-entering the step. Consequently, the reduction in the total electron yield of the Si substrate near the wall is more localized than that without charging. [DOI: 10.1380/ejssnt.2011.112]

Modelling and observations of electron beam charging of an insulator/metal bilayer and its impact on secondary electron images in defect inspection equipment

A self-consistent simulation of secondary electron (SE) emission and charging of a SiO(2) layer with the thickness of several tens of nanometres on Si is incorporated into a trajectory simulation of emitted SEs above the surface, the centre area of which is charged by electron beams (EBs) at the energy range from 300 to 2000 eV. In order to study the influence of the charging of an insulating layer on defect inspection, a pseudo-image is reconstructed from net SE yields calculated at each point of the SiO(2) surface locally applied the positive voltage. The image contrast between charged and uncharged areas is compared with the observation of thermally oxidized layer with the thickness of 24-106 nm on a Si wafer. The image contrast is very sensitive to the thickness of the SiO(2) layer, which is verified by both observed and calculated images. The calculated changes of the images with the layer thickness and the primary electron energy reproduce the experimental observations fairly well. This confirms a highly sensitive detection mechanism for tiny defects in insulating patterns on a metal hard mask for an EB defect inspection equipment.

Electron-beam charging of polytetrafluoroethylene

The charging of polytetrafluoroethylene films by irradiation with fast electrons having an energy insufficient for the complete penetration through the entire thickness of the polymer was theoretically analyzed. The calculation results take into account the distribution of both the dose rate and the bulk electron thermalization rate over the film thickness in the approximation of prescribed radiation-induced conductivity of polytetrafluoroethylene. The influence of the parameters of radiation-induced conductivity on the charging behavior and on the time dependence of the transient current detected with the use of the split Faraday cup was examined. It was found that the observed transient current inversion is adequately explained with allowance for the specifics of radiation-induced conductivity in polytetrafluoroethylene.

Electron beam charging of insulators with surface layer and leakage currents

The electron beam induced self-consistent charge transport in layered insulators (here, bulk alumina covered by a thin silica layer) is described by means of an electron-hole flight-drift model and an iterative computer simulation. Ballistic secondary electrons and holes, their attenuation and drift, as well as their recombination, trapping, and detrapping are included. Thermal and field-enhanced detrapping are described by the Poole–Frenkel effect. Furthermore, an additional surface layer with a modified electric surface conductivity is included which describes the surface leakage currents and will lead to particular charge incorporation at the interface between the surface layer and the bulk substrate. As a main result, the time-dependent secondary electron emission rate σ(t) and the spatial distributions of currents j(x,t), charges ρ(x,t), field F(x,t), and potential V(x,t) are obtained. For bulk full insulating samples, the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and σ=1. In the case of a measurable surface leakage current, the steady stationary state is reached for σ<1. First measurements are extended to the sample current measurement including nonstationary components of charge incorporation and polarization as well as dc components of leakage currents.

Electron Beam Bias for Thin Capacitor Web Coating

Electron beam induced bias was applied for high speed, high quality coating of ultra thin capacitor web. Electron beam charging applies a static charge to the film and allows higher bias voltages than conventional bias systems. Using a numerical calculation of the electrical and thermal forces at work it can be shown that electron beam bias results in better cooling and lower peak temperatures of the film. The advantages for the film coating process are higher possible coating speeds and/or better film quality. Further, the effect of pinholes during coating is much reduced.

Non-Conductive Specimens and Prevention of Electron Beam Charging

Non-Conductive Specimens and Prevention of Electron Beam Charging

Electron beam excitation in thin layered samples

Energy transfer distributions d E / d x and respective excitation depth functions Φ of electron beams in heterogeneous layered samples are described by a successive Effective Layer method. This method is based on electron transmission rates through the top multilayer system replaced by an “effective layer” of the following bottom material. Thus energy depositions in heterogeneous layered metal samples (Al, Ag and Au) and dielectric insulating samples SiO 2–Al 2O 3 are given. For the latter ones special energy-range relations R ( E 0 ) have been deduced for the common energy regions (1–30) keV of scanning electron microscopy (SEM). Application are given by cathodoluminescence depth profiling and electron beam charging of non-conductive samples.

Evaluation of damage induced by electron-beam irradiation to metal-oxide semicondoctor gate pattern and method for damage-free inspection

We analyze the electron-irradiation damage induced in wafers by scanning electron microscope (SEM) inspection, which uses SEM images of voltage contrast formed by the charges on the pattern. The effects of electron-beam energy and charging on a metal-oxide semiconductor (MOS) capacitor are studied. We find that the higher energy electron beam, whose electron range is larger than the thickness of the gate electrode, creates traps at the interface between the silicon substrate and the gate dielectric. The flat-band voltage is shifted by the created traps. Although these traps are created by the transmission of the electron beam into the dielectric, they are not created only by charging on the gate electrode; neither is an oxide fixed charge created in the MOS capacitor. Accordingly, for damage-free inspection of MOS devices, the electron-beam energy should be low enough that the electron range is smaller than the thickness of the gate electrode. On the other hand, the flat-band voltage does not shift, owing to charging on the pattern surface during the electron irradiation. However, the gate dielectric is broken down by charging on the gate electrode at high voltage. Accordingly, for damage-free inspection, the charging voltage should be controlled so as not to break down the gate dielectric.

Selfconsistent Electron Beam Charging of Non-Conductive Specimen in SEM and ESEM

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

Electron beam charging of insulators: A self-consistent flight-drift model

Electron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges ρ(x,t), the field F(x,t), and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate σ(t) and the surface potential V0(t). For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and σ=1. Especially for low electron beam energies E0<4keV the incorporation of mainly positive charges can be controlled by the potential VG of a vacuum grid in front of the target surface. For high beam energies E0=10, 20, and 30keV high negative surface potentials V0=−4, −14, and −24kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected.

Electron-beam charging of poly(methyl methacrylate)

The charging of bulk poly(methyl methacrylate) by irradiation with electrons of ∼2 MeV energy at room temperature in vacuum was studied. The experimental data obtained using the split Faraday cup are compared with the results of numerical simulation assuming one-dimensional geometry with allowance for the spatial distribution of dose rate and injected-electron current, nonlinear properties of radiation-induced conductivity in the prebreakdown electric-field region, and the intrinsic conductivity of poly(methyl methacrylate). It was shown that published data on the electric field strength measured by means of the electro-optical Kerr effect in electron-beam charged poly(methyl methacrylate) agree satisfactorily with the calculation results.

Electron beam induced conductivity in poly(methylmethacrylate) and SiO2 thin films

Electron beam charging and discharging of insulating samples is greatly influenced by electron beam induced conductivity (EBIC). Most prior studies on EBIC focused on inorganic materials; measuring EBIC in organic resist was hampered by high extrinsic leakage and low induced conductivity. We describe here EBIC in thin (1 μm) films of poly(methylmethacrylate) (PMMA) and thermal SiO2. The measurements were made using the external bias method, with the insulating thin film sandwiched between a metal electrode and a highly doped silicon substrate. Under the same exposure conditions, we found the induced conductivity in PMMA to be almost two orders of magnitude less than that in SiO2. The induced current in PMMA responds linearly to the bias, regardless of the polarity, but the induced current in SiO2 is surprisingly dependent on not only electron beam energy, but also on bias polarity. When the top metal electrode is biased positively and the electron beam has high enough energy to penetrate the electrode and the oxide, the results indicate that an internal emission of electrons from the silicon substrate into the oxide contributes substantially to the total measured current.

Electromechanical modeling and properties of the electret film EMFI

An electromechanical film can be manufactured with different thickness and elasticity. The thickness for sensor and actuator applications is typically between 30 and 70 /spl mu/m. The film is modeled using a simplified structure, which shows the reciprocity of the sensor and actuator operation models. The value of the transducer constant depends on the ambient temperature and increases at higher temperatures. During aging the transducer constant begins to decrease permanently at 323 K, but some sensitivity remains even at 333 K. Corona charging that gives a sensitivity value /spl sim/200 pCN/sup -1/ for HS01 type film is preferred over electron beam charging. The development of such films is aimed at sensor and actuator applications. An interesting field is the active control of sound where flat and efficient microphones and loudspeakers are needed.