Increase In Deposition Rate Research Articles

Electrodeposition of Dense Lead Telluride Thick Films in Alkaline Solutions

Dense PbTe thick films were electrodeposited in alkaline solutions by an underpotential deposition mechanism of Pb on overpotential deposited Te. The composition of Pb is critical for the material properties. The composition of the electrodeposited PbTe films was Te-rich. Although the applied potential had no substantial effect on the Pb composition, it needs to be in the proper range (from −0.8 to −1.1 V vs. sat. Ag/AgCl) to avoid further reduction of Te to Te22− or keep the reduction of Te to Te22− at a low reaction rate. To deposit dense thick films the pH must be maintained in the range 10.5 to 12.3. Higher TeO32− concentrations and lower pH values decreased the Pb composition but increased deposition rates. Varying the TeO32− concentration changed the surface morphology of thick PbTe films, but all the thick films were found to be dense in the SEM cross section images. The ratio of EDTA4−/Pb2+ is also a critical effect, and the data showed that 7.5 was the optimum ratio with the given conditions, where the electrodeposited PbTe film was dense without cracks. A high deposition rate (approx. 163 μm/h) was achieved by high TeO32− concentrations (i.e., 550 mM) and at the deposition potential of 1.05 V vs sat. Ag/AgCl. The as-deposited PbTe films have relatively high Seebeck coefficient (i.e., 524 μV/K), but low electrical conductivity compared to bulk counterpart which might be attributed to lower crystallinity of PbTe with embedded Te nanocrystals.

Evaluation of High-Speed Copper Plating Products for RDL, Micropillar, and Fan-Out Applications

Increasing market demand for portable high-performance electronic devices is requiring an increase in the I/O density in the chip packaging used to make these products. Flip-chip interconnects that enable advanced packaging utilize a C4 bumping process with lead-free solder to make the chip interconnection. However, with the decreasing chip size and tighter I/O pitch requirements that are needed to realize high-performance, Cu pillar plating has emerged as an enabling technology to meet the technical demands. Cu pillars, capped with a lead-free solder, allow for increased I/O density while still maintaining the standoff needed for proper thermal and electrical performance of stacked chips. With this realized performance, there is expected to be a significant increase in capacity of Cu pillar in the industry, requiring electrolytic Cu plating products with fast deposition rates in order to decrease wafer plating time and increase throughput. In this paper, Cu electroplating products are evaluated for plating performance at increased deposition rates for Cu pillar applications ranging from micropillar (<20 μm feature size), to standard pillar (20 – 75 μm feature size), redistribution layer (RDL) wiring, and the emerging fan-out wafer level packaging (FO-WLP), which encompasses megapillars (>150 μm feature sizes) as well as stacked via RDL designs. The chief performance criteria for evaluation is the ability to increase deposition rates while maintaining feature height uniformity, smooth and uniform feature morphology, and ability to plate a wide variety of feature sizes and shapes. Additionally, performance of these products is assessed on their ability to plate highly pure Cu deposits which enable void-free integration with lead-free solder without the need of (but is compatible with) a cost-added barrier layer.

Исследование состава и структуры цинк-никелевых покрытий, осажденных из слабокислого электролита на железный подслой

Zinc-nickel alloy coatings have great advantages over many monometallic coatings. However, their use in practice is limited due to the complex mechanism of processes that is studied insufficiently. The paper is devoted to the investigation of the electrolysis parameters on zinc-nickel coating composition and structure during еlectroplating at the iron underlayer of copper substrate from weakly acidic chloride electrolyte. The chemical composition of the electrolyte was monitored by dichromatometriс and complexometric titration. Study of phase composition was performed using an X-ray diffractometer Rigaku Ultima IV. Gross composition was measured using a scanning electron microscope JEOL JSM-6460LV. It was found that аn increase of the current density increases the rate of deposition of the alloy. Increase of temperature leads to an increase of the proportion of nickel in the alloy, and an increase in the nickel deposition rate. Zinc deposition rate is not affected by temperature. Moreover, an abnormal codeposition of the alloy was observed in the entire investigated range of temperatures and current densities. As the temperature changes, The surface of the micro-relief changes with increasing temperature, the grain size becoming smaller and the surface smoother. X-ray analysis of the coatings showed that they are a homogeneous nickel-base solid solution. Сoating structure corresponds best to the face-centered cubic lattice.

Stratigraphy of alluvia and phases of the Holocene floods in the valleys of the Eastern Carpathians foreland

The studied sequences of alluvia in the catchments of the Upper Dniester, Seret and Prut Rivers record the occurrence of the Late Vistulian terrace and 3–4 levels of the Holocene terraces as well as several series of the alluvial fills and paleochannel systems dated at 11,800–10,700 BP (13,470 ± 85–12,600 ± 40 cal BP), 10,500–9800 BP (12,740 ± 60–11,220 ± 15 cal BP), 8700–7500 BP (9625 ± 65–8350 ± 20 cal BP), 5500–5100 BP (6295 ± 10–5845 ± 75 cal BP), 3100–2700 BP (3310 ± 30–2800 ± 40 cal BP), 2100–1700 BP (2060 ± 55–1590 ± 30 cal BP), Middle Ages, Little Ice Age and the last 150–200 years. The distinguished alluvial fills and flood phases in the valleys of the Eastern Carpathian foreland record, similarly to the valleys of the Upper Vistula River catchment in the Western Carpathian foreland, rhythmic changes in the precipitation (climate humidity) and hydrological regime, as well as an increasing human impact (deforestation and cultivation) during the last two thousand years. These changes are recorded in the sequences of floodplains by an increase in number and deposition rate of the overbank (sand-silt) series. Simultaneously, these changes are visible in pollen diagrams recording deforestation phases in floodplains (Neolithic Period, Roman Period and Middle Ages).

Electrophoretic Deposition of Aqueous Nano‐Cr2O3 Suspension

The coating of nano‐Cr2O3 was successfully fabricated via aqueous electrophoretic deposition (EPD). The deposition behavior aqueous nano‐Cr2O3 suspension was affected by the added amount of nitric acid. The morphology of electrophoretic Cr2O3 coating was significantly influenced by the deposition voltage. For a suitable EPD, stable aqueous nano‐Cr2O3 suspension could be obtained by the addition of 0.0025 M nitric acid, and the suitable deposition voltage was 5 V. For the purpose of increasing deposition rate which was limited by lower deposition voltage, it was suggested to employ higher suspension concentration of Cr2O3.

Sediment in Alluvial and Lacustrine Debris Fans as an Indicator for Land Degradation Around Lake Ashenge (Ethiopia)

AbstractSediments deposited by (paleo) flash floods can hold valuable information on processes of environmental change, land degradation or desertification. In order to assess the suitability of flash flood deposits as proxies for land degradation, we monitored a representative gully segment in North Ethiopia (Ashenge catchment), investigated a sequence of alluvial debris fans downstream of this segment and dated a neighbouring subaquatic debris fan using short‐lived 210Pb isotope counting. During one rainy season (July–September 2014), we measured daily rainfall, peak discharge, bedload transport, suspended sediment load and sediment deposition rates. The data show that sediment deposition in the debris fans is significantly dependent on micro‐topography (net incision in micro‐channels) (p < 0·1) and position within the sequence (net incision farther away from the lake) (p < 0·05). As sediment transfer to the lake significantly depends on the balance between available water and sediment (ratio rainfall depth/bedload transport) (p < 0·05), we could reconstruct the hydro‐sedimentary evolution of the gully over the past half century and validate it with aerial photographs and semi‐structured interviews. The findings are consistent with the short‐lived isotope count results, indicating increased sediment supply from the 1970s onwards, when little amounts of clay were deposited in the lake (<5%), and a subrecent clear water effect that resulted in increased deposition rates of clay in the lacustrine debris fan. Overall, our analysis indicates that debris fan sediments can be used to estimate past environmental degradation rates, if the contemporary water and sediment behaviour is well understood. Copyright © 2015 John Wiley & Sons, Ltd.

Characterization of nanocrystalline Ti films deposited by DC magnetron sputtering onto FTO glass substrate

Abstract

(Invited) Electroless Deposition of Ruthenium Using Sodium Borohydride Reducing Agent: A Mechanistic Study Using Electrochemical Quartz Crystal Microbalance

Further miniaturization of interconnects and devices to keep up with Moore’s law in the 21st century requires materials innovation. Copper, as the interconnect metal has been the workhorse of the semiconductor industry for the past two decades. As wire dimensions shrink below 20 nm in future technology nodes, the ability of copper to meet the conductivity and reliability benchmarks is strained1. One metal that becomes attractive at smaller dimensions (<10 nm) is ruthenium, due to its high conductivity and electromigration resistance2. Traditional routes for metallization of ruthenium includes physical vapor (PVD), chemical vapor (CVD) and atomic layer deposition (ALD). PVD suffers from its line-of-sight, non-conformal deposition process that is not suitable for narrow, high aspect ratio geometries. CVD and ALD processes are slower and more expensive than PVD. Here we present an electroless deposition process (ELD) for ruthenium that overcomes some of the obstacles associated with the aforementioned processes. ELD is inherently selective which yields conformal coating in challenging geometries. Furthermore, ELD has lower cost of ownership due to relatively inexpensive precursors and significantly higher deposition rate than ALD and CVD. Here, sodium borohydride is used as the reducing agent for electroless deposition of Ru, and the effects of temperature, precursor and ligand concentrations on ruthenium growth rate are characterized. A linear increase in deposition rate is observed with increasing temperature and ruthenium concentration. A critical borohydride concentration is observed at ~2 g/L, where the maximum deposition rate is obtained. The mechanism of the ruthenium deposition process (reduction half-reaction) is further investigated via electrochemical quartz crystal microbalance (EQCM) analysis to probe the role of pH and complexation. Ru deposition on Cu initiates at a potential of -1.05 V vs. Ag/AgCl reference electrode, and further analysis indicates that a high pH of the electrolyte is needed to suppress any side reaction(s) and to form kinetically active ruthenium-hydroxy complexed species. Finally, some challenges to integration and different applications for an electroless deposited Ru are highlighted. Figure 1: (a) Linear potential scan of the background electrolyte and the electrolyte containing Ru precursor. Increase in current density is observed at potential <-1.05 V vs. Ag/AgCl. Coupled quartz crystal microbalance analysis (b) confirms Ru deposition at potentials more cathodic than -1.05 V vs. Ag/AgCl.

Magnetic nanoparticles augmented composite membranes in removal of organic foulant through magnetic actuation

Exploring ways to remove foulants is of great importance for sustainable membrane operation in wastewater treatment. This study investigates the efficiency of humic acid removal by a magnetic responsive Fe3O4–PES nano-composite membrane. Magnetic responsive iron oxides (Fe3O4) were first end-capped onto the surface of a polyethersulfone (PES) membrane using a polyelectrolyte modification method. The amount of end-capped Fe3O4 was varied by adjusting the concentration of suspended magnetite nanoparticles from 100ppm to 2500ppm. A quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), contact angle measurement and X-ray photoelectron spectroscopy (XPS) were used to determine the adsorption kinetics and the morphology of Fe3O4 deposited on PES membranes. The combined results of frequency shifts (Δf) and changes in the dissipation factor (ΔD) from QCM-D demonstrated an increased deposition rate of Fe3O4 as the concentration of suspended magnetite nanoparticles was increased. As for filtration studies, when the Fe3O4–PES nano-composite membranes were exposed to an alternatively switching oscillating external magnetic field, torque effects on the nanoparticles were generated and twisted the deposited Fe3O4 nano-colloids. This magnetic nanoparticles augmented nano-composite membrane was able to retain a normalized flux of 0.96 (J=32.8Lm−2h−1) with rejection of 99.4±0.14%. This was due to the twisting effect of the Fe3O4 nanoparticles that reduces concentration polarization near the top surface of the membrane and consequently reduces the potential for membrane fouling.

Effects of sputtering voltage and current on the composition and microstructure of the CIGS films prepared by one-step pulsed DC magnetron sputtering

Cu(In, Ga)Se2 (CIGS) films were deposited at room temperature by one-step pulsed DC magnetron sputtering under different sputtering powers and pulse frequencies, and the effects of sputtering voltage and current on the composition and microstructure of the deposited GIGS films were systematically investigated. The results indicated the composition of the deposited films was seriously affected by the sputtering voltage and current. Moreover, a semiempirical formula was used to estimate the composition of the deposited CIGS films. On the whole, the estimated results can accord with the corresponding experimental results. In addition, the deposition rate (corresponding to sputtering current) is considered as the key factor of affecting the preferred orientation of the films in the present work, i.e., the preferred orientation changed from (112) to (220)/(204) with increasing deposition rate. Moreover, the electrical properties were measured for the CIGS films deposited at different sputtering powers, which were closely associated with the composition and microstructure of the films. The surface morphologies of the CIGS films deposited at different pulse frequencies were observed, which shown the granule size in the deposited films was mainly affected by the sputtering voltage.

Multilayer modelling of ozone fluxes on winter wheat reveals large deposition on wet senescing leaves

Understanding how ozone is deposited on vegetation canopies is needed to perform tropospheric greenhouse gas budgets and evaluate the associated damage on vegetation. In this study, we propose a new multilayer scheme of ozone deposition on vegetation canopies that predicts stomatal, cuticular and soil deposition pathways separately. This mechanistic ozone deposition scheme is based on the multi-layer, multi-leaf mass and energy transfer model MuSICA. This model was chosen because it explicitly simulates the processes of rain interception, through fall and evaporation at different depths within the vegetation canopy, so that ozone deposition on wet leaf cuticles can be explicitly modelled with ozone dissolution, diffusion and chemical reaction inside the water films. The model was evaluated against a 3-year dataset of ozone, CO2 and evapotranspiration flux measurements over a winter wheat field near Paris, France (ICOS Fr-GRI). Only periods with fully developed canopies (including senescence) were considered to minimise the contribution of soil deposition to the total ozone flux. Before senescence, the model could reproduce the measured ozone deposition rates as well as the CO2 and water vapour fluxes. During senescence, large ozone deposition rates were observed under wet canopy conditions that could only be explained by first-order reaction rates in the water film of around 105s−1. Such reaction rates are not compatible with the chemical composition of rainwater. We therefore hypothesise that, during senescence, the cell content leaks out of the leaves when they become wet, exposing anti-oxidants to ozone. These results provide for the first time a mechanistic explanation of the commonly observed increase in ozone deposition rates during rain or dew formation.

Hole mobility in thermally evaporated pentacene: Morphological and directional dependence

Pentacene has been extensively studied as an active material for organic field-effect transistors as it shows very good charge carrier mobility along its preferred transport direction. In this contribution, we investigate the hole transport in pentacene thin films by measurement in conventional lateral organic field-effect transistors (OFETs), which yields the hole mobility along the a-b plane of pentacene, and by the recently published potential mapping (POEM) approach, which allows for direct extraction of the charge carrier mobility perpendicular to the substrate, in this case perpendicular to the a-b plane, without the assumption of a specific transport model. While the mobility along the a-b plane—determined from OFET measurements—is found to be in the region of 0.45 cm2/Vs, transport perpendicular to this plane shows an average mobility at least one order of magnitude lower. Investigating also how these effective mobility values depend on the deposition rate of the pentacene films, we find that the decrease in grain size for increasing deposition rate causes the mobility to decrease both parallel and perpendicular to the substrate due to the increased number of grain boundaries to be overcome. For the out-of-plane transport, this effect is found to saturate for deposition rates higher than 2.5 Å/s.

Modeling aerosol dynamics of cigarette smoke in a denuder tube

A new aerosol dynamics model, ADiC (Aerosol Dynamics in Containments), was developed, which considers the effects of coagulation, heat and vapor transfer, phase transition and deposition of particles. The particle size distribution is represented by individual uniform distributions situated in a fixed size grid. That way numerical diffusion is avoided and quasi-simultaneous simulation of coagulation and growth processes is possible. Due to the complexity of the computer model, partial model validation was performed by testing the individual sub-models against the existing experimental evidence.The ADiC model was used to simulate the aerosol dynamics of freshly generated cigarette smoke in acid-covered denuder tubes. Modeling results were compared to data from several studies that report nicotine deposition rates. Simulations revealed that several parameters with large uncertainties can potentially have great effects on the nicotine deposition rate. A nicotine protonation interval from 75% to 90% of the nicotine mass initially on the particle fits the experimental data well in the posterior tube sections. For the anterior tube sections, however, a steady increase of nicotine protonation by roughly 15% is required. Loss of water in denuder tubes has not been documented in the experimental studies found in the literature. Increased deposition rates by a factor up to 7 have been simulated in case of the denuder tube being a perfect sink for water. A simplified sub-model describing diffusion limited phase transition showed a considerable effect on total nicotine deposition of the order of 10% and more for experimentally determined viscosity values. Temperature differences between the tube wall and the aerosol have a considerable, however timely very limited, effect on deposition rate.Several poorly quantified processes and parameters have been discussed and simulated with respect to their potential to affect nicotine deposition rate in a denuder tube. While some of them are difficult to measure (e.g. nicotine protonation, diffusion limited transport within particles), others (e.g. water deposition within the denuder tube) can easily be determined. Thus, the ADiC model can be used, apart from evaluating experimental data, as a tool to plan and design experimental setups.

Effect of the low magnetic field on the electrodeposition of CoxNi100 − x alloys

Magnetic, chemical and structural properties of electrosynthesized CoxNi100−x have been studied. The electrodeposition has been conducted both in the presence and absence of a low magnetic field. The application of a perpendicular magnetic field during the synthesis modified slightly the morphology of the alloys. These changes depend more on the film composition than on the applied field, as demonstrated by AFM images. In the absence of magnetic field, the CoxNi100−x film grows along the (200) direction. However, when the magnetic field was applied, a preferential orientation along the (111) direction was observed. No important magnetic changes are induced by the presence of the magnetic field during the growth. Based on X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) experiments, the chemical composition of the films was preserved during preparation regardless of whether or not magnetic field is applied. There has been observed an increase in deposition rate in the presence of field even at these low magnetic fields.

A Novel Method to Obtain Higher Deposition Rates of CdTe Using Low Temperature LPCVD for Surface Passivation of HgCdTe

The deposition rate of CdTe passivation films has been increased greatly by the implementation of a novel design of a graphite cracker cell. This cracker cell, consisting of an integrated diffuser, facilitates the efficient cracking of precursors. CdTe deposition rate has been increased from ~50 nm/h (without any cracker cell) to ~420 nm/h using this novel experimental set-up. H2 flow through the main gas flow line has been increased to obtain a progressive increase in deposition rates. CdTe deposited on high aspect ratio HgCdTe samples showed adequate conformal coverage on the side walls and also on the bottom of the trenches. Microwave photoconductive decay measurements were done on planar and patterned HgCdTe substrates at 77 K to extract the minority carrier lifetimes. There was a significant improvement in the lifetime of planar HgCdTe samples after CdTe passivation, though patterned HgCdTe samples showed a minor improvement. An additional annealing step was conducted at 250°C for 20 min in the presence of H2 after the deposition of CdTe passivation films. Minority carrier lifetimes improved further post-annealing, probably due to the formation of a graded interface between CdTe and HgCdTe.

High power pulsed magnetron sputtering: A method to increase deposition rate

High power pulsed magnetron sputtering (HPPMS) is a state-of-the-art physical vapor deposition technique with several industrial applications. One of the main disadvantages of this process is its low deposition rate. In this work, the authors report a new magnetic field configuration, which produces deposition rates twice that of conventional magnetron's dipole magnetic field configuration. Three different magnet pack configurations are discussed in this paper, and an optimized magnet pack configuration for HPPMS that leads to a higher deposition rate and nearly full-face target erosion is presented. The discussed magnetic field produced by a specially designed magnet assembly is of the same size as the conventional magnet assembly and requires no external fields. Comparison of deposition rates with different power supplies and the electron trapping efficiency in complex magnetic field arrangements are discussed.

Growth of TixAl1 − xOy films by atomic layer deposition using successive supply of metal precursors

Atomic layer deposition (ALD) of thin ternary films from TiCl4, trimethylaluminum (TMA), AlCl3 and H2O was investigated at different successions of precursor pulses with the aim to explore passivation effect of TiCl4 to the chemisorption of TMA and AlCl3. Concentrations of Ti and Al in the films grown on silicon substrates at 100–500°C in different ALD precursor sequences were studied. In order to obtain additional information about the deposition mechanisms, the behavior of the quartz crystal microbalance (QCM) signal during ALD cycles was characterized and analyzed at a deposition temperature of 200°C. Post-deposition analysis revealed up to 2 times lower Al2O3 deposition rate in the TiCl4-TMA-H2O and TiCl4-AlCl3-H2O processes than that in the TiCl4-H2O-TMA-H2O and TiCl4-H2O-AlCl3-H2O processes, respectively. Despite of the markedly reduced growth rate of Al2O3 in the TiCl4-TMA-H2O and TiCl4-AlCl3-H2O processes, films with Al/(Al+Ti) ratios exceeding 0.5 were obtained. Consequently, the surface intermediate species, which stopped further adsorption of TiCl4, limited the adsorption of AlCl3 and TMA only partially. Enhanced growth rate of TiO2 was observed in films grown in the TiCl4-TMA-H2O and TiCl4-H2O-TMA-H2O processes. QCM revealed more efficient chlorine release and thereby reduced effect of steric hindrance in those processes. In addition, marked increase of Al2O3 deposition rate was observed in the TiCl4-H2O-TMA-H2O and TiCl4-TMA-H2O processes with the increase of deposition temperature from 300°C to higher temperatures. As no increase of this kind was recorded in the TMA-H2O process, the effect was related to the influence of Ti-containing surface layer on the adsorption of TMA.

Low Friction-Coefficient TiBCN Nanocomposite Coatings Prepared by Cathode Arc Plasma Deposition**supported by National Natural Science Foundation of China (Nos. 11350110206, 11375133) and the Fundamental Research Funds for the Central Universities of China (No. 11275141)

TiBCN nanocomposite coatings were deposited on cemented carbide and Si (100) by a cathode arc plasma system, in which TiB2 cathodes were used in mixture gases of N2 and C2H2. X-ray diffraction shows that TiB2 and Ti2B5 peaks enhance at low flow rates of C2H2, but they shrink when the flow rate is over 200 sccm. An increase of deposition rate was obtained from different TiBCN thicknesses for the same deposition time measured by scanning electron microscopy. Atomic force microscopy shows that the surface roughnesses are ˜10 nm and ˜20 nm at C2H2 flow rates of 0-100 sccm and of 150-300 sccm, respectively. High resolution transmission electron microscopy and X-ray photoelectron spectroscopy show that the coatings consist of nanocrystal phases Ti2BB, TiB2 and TiN, and amorphous phase carbon and BN. The average crystal sizes embedded in the amorphous matrices are 200 nm and 10 nm at C2H2 flow rates of 200 sccm and 300 sccm, respectively. In Raman spectra, the D- and G-bands increase with C2H2 flows at low flow rates, but weaken at high flow rates. The microhardness of the coatings decreases from 28.6 GPa to 20 GPa as the C2H2 increases from 0 sccm to 300 sccm, and the ball-on-disk measurement shows a dramatic decrease of the friction coefficient from 0.84 to 0.13. The reason for the reduced hardness and friction coefficient with the change of C2H2 flow rates is discussed.

Influence of substrate potential on a-Si:H passivation of Si foils bonded to glass

In the future solar devices will be manufactured onto thin mono-crystalline silicon wafers (foils) potentially bonded to substrate carriers. In this study, the influence of the substrate carrier potential (grounded or floating) on the amorphous silicon a-Si:H surface passivation of the bonded foil is discussed for the cases of conductive and insulating substrate carriers. A conductive carrier leads to an increase in deposition rate and ion bombardment energy, which is detrimental for sample lifetime. An insulating carrier, e.g., a glass substrate, inverts the trend and improves the a-Si:H surface passivation.

Easily controlled dye doped phosphorescent OLEDs with evaporation rate in single furnace

Electrical and optical characteristic, surface morphology and energy transfer of Ir(ppy)3:PtTPP were studied as a function of thermal evaporation rate. We have investigated the effect of various evaporation rates for mixture of dyes using single furnace method. When the deposition rate increased from 0.5 to 5Ǻ/s, the luminescence efficiency, current density and energy transfer of OLED increased. AFM measurements showed that the surface roughness of the Ir(ppy)3:PtTPP films decreased with increasing deposition rates. These blends show excellent red emitting guest–host system with easier deposition rate control.