Optimizing the geometry of aerodynamic lens injectors for single-particle coherent diffractive imaging of gold nanoparticles

Single-particle X-ray diffractive imaging (SPI) of small (bio-)nanoparticles (NPs) requires optimized injectors to collect sufficient diffraction patterns to allow for the reconstruction of the NP structure with high resolution. Typically, aerodynamic lens-stack injectors are used for NP injection. However, current injectors were developed for larger NPs (>100 nm), and their ability to generate high-density NP beams suffers with decreasing NP size. Here, an aerodynamic lens-stack injector with variable geometry and a geometry-optimization procedure are presented. The optimization for 50 nm gold-NP (AuNP) injection using a numerical-simulation infrastructure capable of calculating the carrier-gas flow and the particle trajectories through the injector is also introduced. The simulations were experimentally validated using spherical AuNPs and sucrose NPs. In addition, the optimized injector was compared with the standard-installation `Uppsala injector' for AuNPs. Results for these heavy particles showed a shift in the particle-beam focus position rather than a change in beam size, which results in a lower gas background for the optimized injector. Optimized aerodynamic lens-stack injectors will allow one to increase NP beam density, reduce the gas background, discover the limits of current injectors and contribute to structure determination of small NPs using SPI.

Carrier-Gas Induced Changes in the Structural, Stoichiometric and Photocatalytic Characteristics of Gallium Oxide Nanostructures

Ga2O3/ITO/glass photoelectrodes prepared by the CVD method has rarely been tested in the electrochemical cell for water splitting. In this study, we investigate the photoelectrolytic performance of Ga2O3/ITO-glass photocatalysts produced by the high-temperature CVD route. The changing of N2 carrier gas flow rate from 0 to 1800 seem induces change in the materials properties. XRD signal strength of the produced bi-phase Ga2O3 is observed to deteriorate, while diffraction line width broadens with increasing N2 supply. Films show a combination of nanoclumps and nanostrips morphology. Ga/O ratio decreases, while the optical bandgap gradually increases from 4.37 to 4.42 eV with increasing O content and crystallite size. Photoluminescence measurements show UV, blue, green and red emissions, respectively. Linear sweep voltammetry of the electrodes in 0.1 M KOH electrolyte shows improvement in photocurrent density from 160 to 257 μA/cm2 versus Ag/AgCl at 1 V bias, and a maximum photon-to-current conversion efficiency 0.06%.

IOT-based in situ condition monitoring of semiconductor fabrication equipment for e-maintenance

PurposeThe purpose of this paper is to demonstrate industrial Internet of Things (IIoT) solution to improve the equipment condition monitoring with equipment status data and process condition monitoring with plasma optical emission spectroscopy data, simultaneously. The suggested research contributes e-maintenance capability by remote monitoring in real time.Design/methodology/approachSemiconductor processing equipment consists of more than a thousand of components, and unreliable condition of equipment parts leads to the failure of wafer production. This study presents a web-based remote monitoring system for physical vapor deposition (PVD) systems using programmable logic controller (PLC) and Modbus protocol. A method of obtaining electron temperature and electron density in plasma through optical emission spectroscopy (OES) is proposed to monitor the plasma process. Through this system, parts that affect equipment and processes can be controlled and properly managed. It is certainly beneficial to improve the manufacturing yield by reducing errors from equipment parts.FindingsA web-based remote monitoring system provides much of benefits to equipment engineers to provide equipment data for the equipment maintenance even though they are physically away from the equipment side. The usefulness of IIoT for the e-maintenance in semiconductor manufacturing domain with the in situ monitoring of plasma parameters is convinced. The authors found the average electron temperature gradually with the increase of Ar carrier gas flow due to the increased atomic collisions in PVD process. The large amount of carrier gas flow, in this experimental case, was 90 sccm, dramatically decreasing the electron temperature, which represents kinetic energy of electrons.Research limitations/implicationsSemiconductor industries require high level of data security for the protection of their intellectual properties, and it also falls into equipment operational condition; however, data security through the Internet communication is not considered in this research, but it is already existing technology to be easily adopted by add-on feature.Practical implicationsThe findings indicate that crucial equipment parameters are the amount of carrier gas flow rate and chamber pressure among the many equipment parameters, and they also affect plasma parameters of electron temperature and electron density, which directly affect the quality of metal deposition process result on wafer. Increasing the gas flow rate beyond a certain limit can yield the electron temperature loss to have undesired process result.Originality/valueSeveral research studies on data mining with semiconductor equipment data have been suggested in semiconductor data mining domain, but the actual demonstration of the data acquisition system with real-time plasma monitoring data has not been reported. The suggested research is also valuable in terms of high cost and complicated equipment manufacturing.

Study on Effects of Carrier Gas Flow Rate on Properties of Low Dielectric Constant Film Deposited by Plasma Enhanced Chemical Vapor Deposition Using the Octamethylcyclotetrasiloxane Precursor

In semiconductor industry, low-dielectric-constant SiCOH films are widely used as inter-metal dielectric (IMD) material to reduce a resistance-capacitance delay, which could degrade performances of semiconductor chips. Plasma enhanced chemical vapor deposition (PECVD) system has been employed to fabricate the low-dielectric-constant SiCOH films. In this work, among various parameters (plasma power, deposition pressure, substrate temperature, precursor injection flow rate, etc.), helium carrier gas flow rate was used to modulate the properties of the low-dielectric-constant SiCOH films. Octamethylcyclotetrasiloxane (OMCTS) precursor and helium were injected into the process chamber of PECVD. And then SiCOH films were deposited varying helium carrier gas flow rate. As helium carrier gas flow rate increased from 1500 to 5000 sccm, refractive indices were increased from 1.389 to 1.428 with enhancement of mechanical strength, i.e., increased hardness and elastic modulus from 1.7 and 9.1 GPa to 3.3 and 19.8 GPa, respectively. However, the relative dielectric constant (k) value was slightly increased from 2.72 to 2.97. Through analysis of Fourier transform infrared (FTIR) spectroscopy, the effects of the helium carrier gas flow rate on chemical structure, were investigated. It was thought that the increase in helium carrier gas flow rate could affect the density with changes of chemical structure and composition. In conclusion, regulation of helium carrier gas flow rate can effectively modulate k values and mechanical strength, which is needed for IMD material in semiconductor fabrication possess.

Optymalizacja warunków oznaczania wody metodą miareczkowania kulometrycznego z odparowaniem dla olejów smarowych

The knowledge of the water content of various petroleum products, including lubricating oils, additives and various innovative products, is important from the point of view of manufacturing, purchasing or selling them, due to the impact on their quality and performance characteristics. In the case of lubricating oils, the presence of water can lead to premature corrosion and wear, the formation of deposits, which leads to reduced lubrication and premature clogging of filters, reduced action of additives or undesirable bacterial growth. The article presents the study on the selection of optimal conditions for the determination of water content by coulometric Karl-Fischer titration with evaporation in lubricating oils. The tests were carried out using a coulometer with a titration cell without a diaphragm by Metrohm, 917 Coulometer model with an automatic sample feeder equipped with a heating chamber 885 Compact Oven Sample Changer. Various types of lubricating oils were selected for testing, namely engine oils of different viscosity classes (5W/40, 10W/40, 15W/40, 5W/30), gear oil, hydraulic oil, turbine oil, base oil and hydraulic fluid. All selected samples of lubricating oils were tested in four different measuring conditions: 110°C and 20 ml/min; 150°C and 50 ml/min, 180°C and 50 ml/min and 150°C and 70 ml/min. It was found that for all the lubricating oils, the best results were obtained with a furnace temperature setting of 150°C and a carrier gas flow of 50 ml/min or 70 ml/min. The influence of various factors, such as the sample weight, the furnace temperature, the carrier gas flow velocity on the test course and the analysis speed, was determined. Increased carrier gas flow of up to 70 ml/min does not shorten the analysis time. In some cases, an increase in the oven temperature may speed up the analysis, but this is quite risky for some samples that decompose at given temperature. It is therefore safer to conduct the test at an oven temperature of 150°C. The speed of analysis is most influenced by an appropriate selection of the sample quantity under analysis. Depending on the water content in the tested sample, the appropriate sample weight should be selected. It should be small enough not to excessively extend the analysis, but also large enough that the amount of titrated water is at least twice as large as in the blank.

Parametric Redesign of a Convergent-Divergent Cold Spray Nozzle

The generation of a high velocity carrier gas flow for cold metal particle applications is addressed; with specific focus on titanium cold spraying. The high hardness of this material makes cold spraying titanium difficult to achieve by industry standard nozzles. The redesign of a commercial conical convergent-divergent cold spray nozzle is achieved by the application of aerospace design codes; based on the Method of Characteristics; towards producing a more isentropic expansion by contouring the nozzle walls. Steady threedimensional RANS SST k-ω simulations of nitrogen are coupled two-way to particle parcel tracking in the Lagrangian frame of reference. The new contoured nozzle is found to produce higher particle velocities with greater radial spread; when operated at the same conditions/cost of operation as the commercial nozzle. These numerical results have shown the potential for extending cold spray to high density and low ductility particles by relatively minor rig modifications; through an effective synergy between gas dynamics and material science.

Experimental investigation of AC two-channel gliding arcs discharge plasma driven kerosene cracking

To improve the ignition and combustion performance of aviation kerosene, two-channel gliding arcs plasma was adopted to crack kerosene into active components, such as gaseous light hydrocarbons and H2. The influence of carrier gas flow rate on discharge characteristics and cracking effects were investigated. Experimental results indicate that, compared to single channel discharge, the power of two-channel gliding arcs discharge is greater while the arcs cover twice as much area as that of single channel discharge. The cracking rate of two-channel discharge plasma is greater than that of single channel discharge while it shows an upward trend with greater carrier gas flow rate. Among the main components of cracking gas, the molar percentage of hydrogen is the highest and exceeds 50%. Greater carrier gas flow rate would result in lower molar percentage of hydrogen. Interestingly, the ethyl group prefers to form C2H2 as the carrier gas flow rate increases in the two-channel gliding arcs discharge while the molar percentage of C2H2 and C2H4 changes inconspicuously in the single channel discharge.

Comparison of turbulence models for two-phase flow in a centrifugal separator

The numerical results of mathematical modeling of a two-phase, axisymmetric swirling turbulent flow in the separation zone of a centrifugal separator are presented. The movement of the carrier gas flow was modeled using RANS, which were closed using the SARC turbulence models, the SST-RC model, and the SSG/LRR-RSM-w2012 model. For the numerical solution of the problem, the SIMPLE algorithm was used. The article compares the results of numerical calculation of turbulence models. The results of a comparison of numerical calculations with allowance for the effect of the solid phase on the dynamics of the air medium and without taking it into account with experimental data are presented.

MATHEMATICAL MODELING OF A TURBULENT FLOW IN A CENTRIFUGAL SEPARATOR

The numerical results of mathematical modeling of a two-phase axisymmetric swirling turbulent flow in a separation zone of a centrifugal separator are presented. The motion of the carrier gas flow is described by the Reynolds-averaged Navier-Stokes equations. A system of equations is enclosed by the Spalart-Allmaras turbulence model. The study is based on the obtained fields of averaged velocities of the carrier medium, with account for turbulent diffusion. Numerical solution to the problem is implemented using the semi-implicit method for pressure linked equations (SIMPLE). The results obtained when the solid phase effect on the air flow dynamics is taken into account are compared with those obtained when the effect is left out of account. The numerical calculations are validated using the experimental data.