Articoli di riviste sul tema "Solid nickel's etching"

Electroless plating on Acrylonitrile Butadiene Styrene (ABS) is a metallization process that involves a reduction and oxidation reaction between the nickel source and the substrate material. The purpose of this research is to determine the ability of nickel deposition in the nickel electroless plating process with a specific etching time variation. This nickel electroless procedure begins with a chromic acid etching process that can last anywhere from 15 to 55 minutes and is useful for increasing roughness and creating submicroscopic cavities. After the etching process is finished, the surface roughness test is performed with a Mitutoyo SJ-210. Additionally, the activation step is carried out for 5 minutes in order for the polymer to become a conductor, allowing the plating process to proceed. The electroless plating process was then carried out for 55 and 75 minutes, with the goal of depositing nickel metal on the ABS surface. The coating results were analyzed using Fourier Transform Infrared (FTIR) spectroscopy IRSpirit/ATR-S serial No. A224158/Shimadzu to determine the functional groups formed both before and after the coating process, X-Ray Diffraction (XRD) to determine the character of the crystal structure, and phase analysis of a solid material using PANalytical type E'xpert Pro, To determine the surface morphology, the Zeiss EVO MA 10 was used to perform scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) at 1000x magnification. The test findings demonstrate that, based on a range of investigations, etching variations of 15,25,35,45, and 55 minutes etching time 55 minutes are the best nickel deposited substrates, as evidenced by EDS data, where this treatment has the largest weight fraction of nickel. As a result, the longer the etching period, the rougher the surface becomes, affecting the capacity of nickel deposition to increase. Furthermore, it can be demonstrated in this investigation that the nickel deposited is in an amorphous form.

In this work, the infiltration technique was used to produce hydrogen electrodes for solid oxide cells. Different infiltration methodologies were tested in order to try to shorten the infiltration cycle time. The porous scaffolds used for infiltration were based on highly porous yttria-stabilized zirconia (YSZ) obtained by etching the reduced nickel from the Ni-YSZ cermet in HNO3 acid. The support had a complex structure which included a ~130 µm porous functional layer with small pores and a ~320 µm thick supporting layer with large pores. Infiltrations have been carried out using aqueous nickel nitrate solutions. Various infiltration procedures were used, differing in temperature/time profiles. The results show that slow evaporation is crucial for obtaining a homogeneous material distribution leading to high-quality samples. A longer evaporation time promotes the proper distribution of nickel throughout the porous scaffold. The shortening of the heat treatment procedure leads to blockage of the pores and not-uniform nickel distribution.

A novel chemical process has been developed to formulate injectable nickel ink for conductive film. This chemical method has the ability to remove the oxidation on nickel nano-particle surfaces during ink fabrication; the nickel ions, which are produced during chemical etching, will be reduced and bridged among original nano-nickel particles in the following thermal sintering process at 350 °C. X-ray diffraction results exhibit that the final nickel film has no significant composition change by this chemical method and that oxidation has been effectively removed. Scanning electron microscopy images show that this chemical process reduces nickel oxides into nickel and that the reduced nickel sticks on the original nickel particle surface acting as a “bridge” connecting each particle. So solid diffusion can be triggered easily among bridged nickel particles and sintered at relatively low temperatures. The resistivity of printed film is to 5 × 10 − 6 Ω ∙m which is 71-times that of bulk nickel. The fabricated conductive nickel thin film has been applied on lithium ion batteries as a current collector for cathode and anode and shows good corrosion resistance and stability.

The formation of a silicon alloy has been achieved by electron beam irradiation of a nickel-silicon bilayer. This process, called SiDWEL1 , has been developed by Quantiscript. The nickel-silicon bilayer is very thin and the electron beam operates at low energy and current. Silicide formation occurred around the interaction volume of the electrons within the material. This paper describes the nature of the structures produced and the origin of the difficulties encountered with the characterization. The necessity of further analysis with TEM based techniques is highlighted.Figure 1 presents a cross-section of a typical sample. The growth of silicide grains is induced by the e-beam irradiation of the stack for few microseconds. Nucieation is initiated by the diffusion of silicon atoms in nickel grains, induced by the heating arising from the electron beam interaction with the solid. A new phase is revealed by FE-SEM observation, after wet etching of the nickel film, as shown in figures 2 and 3.

Downsized and complex micro-machining structures have to meet quality requirements concerning geometry and convince through increasing functionality. The development and use of cutting tools in the sub-millimeter range can meet these demands and contribute to the production of intelligent components in biomedical technology, optics or electronics. This article addresses the development of double-edged micro-cutters, which consist of a two-part system of cutter head and shaft. The cutting diameters are between 50 and 200 μm. The silicon carbide cutting heads are manufactured from the solid material using microsystem technology. The substrate used can be structured uniformly via photolithography, which means that 5200 homogeneous micro-milling heads can be produced simultaneously. This novel batch approach represents a contrast to conventionally manufactured micro-milling cutters. The imprint is taken by means of reactive ion etching using a mask made of electroplated nickel. Within this dry etching process, characteristic values such as the etch rate and flank angle of the structures are critical and will be compared in a parameter analysis. At optimal parameters, an anisotropy factor of 0.8 and an etching rate of 0.34 µm/min of the silicon carbide are generated. Finally, the milling heads are diced and joined. In the final machining tests, the functionality is investigated and any signs of wear are evaluated. A tool life of 1500 mm in various materials could be achieved. This and the milling quality achieved are in the range of conventional micro-milling cutters, which gives a positive outlook for further development.

This study aims to optimize the production conditions for forming graphene directly on a quartz substrate, using a carbon 60 (C60) thin film as a solid carbon source. In this experiment, we focused on the relationships between the thickness of the C60 film and the nickel (Ni) catalyst film and the heat treatment conditions. As the thicknesses of the C60 and Ni catalyst films increased, high-crystallinity multi-layered graphene was formed, however the optical transparency of the graphene film decreased. Scanning Electron Microscopy (SEM) observations and Raman scattering spectroscopy showed that after changing the atmosphere of the heat-treatment from an argon (Ar) gas to an Ar+ hydrogen (H2) gas, the optical transparency of the graphene film was remarkably improved, due to the migration and vaporization of the Ni film, and due to etching of the multi-layered graphene.

Silicon diodes, FETs, IGBTs still keep the majority of power device market, being much cheaper compared to SiC and GaN wide band gap-based devices. To keep the Si devices competitive, their manufacturing processes must be significantly improved. This includes forming Ohmic contacts. Currently the common process is PVD – physical vapor deposition of metal stacks. This process is not efficient: not selective and wasteful - metal sputtered or evaporated from target coats entire vacuum chamber, not just wafer being processed. Electroless deposition can be potentially used for metallization of Si power devices. The electroless process can be designed selective, so the metal deposits only on silicon surface, not on areas protected by dielectric films. The deposited layer must have good adhesion to silicon surface, make Ohmic contact, and preferably converts into silicide upon anneal. Nickel satisfies all these requirements, thus is a good candidate. A major issue in Nickel plating on Si is that it does not deposits well onto very smooth polished surface of Si. Several approaches are known how to overcome this issue. Dubin [1] suggested adding pretreatment with Palladium. The Pd reacts autocatalytically on silicon surface forming Pd islands. Upon switching to Ni bath, Ni deposits on Pd first, then forms a continuous film when the islands merge. One issue in the Pd/Ni process are that the native oxide on silicon must be removed so Pd can reach Si. In Dubin’ process this is resolved by adding HF to Pd bath. Another issue is bad process repeatability – a consequence of autocatalytic nature of the Pd plating reaction. The autocatalytic processes have uncontrollable “incubation” time, therefore repeating Pd plating with same recipe (same time) does not produce the same results. We describe a new approach as to plate Nickel directly on polished Silicon surface. In our process the Pd activation of Si surface is replaced by a stain etch process. The stain etch is a process where crystalline Silicon is converted into porous Si layer [2]. Technically the stain etch is simply processing in a wet bath – mixture of concentrated nitric and hydrofluoric acids in a ratio around 1:1000. Same as in the Pd/Ni case, the process must be designed to exclude native Si oxide. We achieve this by direct switching from the stain bath to Ni bath, no water rinsing in between. The surface of wafer retrieved from the stain bath is highly hydrophobic (hydrogen terminated) thus there is no liquid drops on surface. A brief nitrogen gun drying is still performed, thus preventing contamination of Ni bath with HF. The hydrogen termination protects the surface. We tried both traditional Ni plating recipes – alkaline, and acidic [3], and found that Ni plating is good in both cases. However, the resulting Ni layer is heavily non-uniform in thickness. We observe that the Ni pattern repeats the visual pattern after the stain etch. A byproduct of the stain etch reaction is hydrogen. The hydrogen forms bubbles that stick to Si surface and cause local masking, eventually non-uniformity. Thus, the key to Ni plating uniformity is the uniform stain etch. Known approaches [2] - adding surfactants to the bath, etc. happen to be only partially efficient. Therefore, we tried new stain etch recipe: add glacial acetic acid thus getting HNA mixture 1000:1:1000. The hydrogen bubbles in the old recipe were about 2 mm in diameter and kept on Si surface for many seconds. In our recipe, the bubbles get released from Si surface as soon as they reach about 0.1 mm size. The eventual Si porous layer shows uniform color appearance across entire wafers. Notice, etching in the nitric/hydrofluoric mixture is also autocatalytic process, thus the topic of repeatability arises too. However, we use Si surface color change as the signal to finish the stain etch. Thus, we can get the same thickness porous film every time despite the incubation time varies uncontrollably. Direct Ni plating onto blanket polished Silicon wafers with the HNA 1000:1:1000 pretreatment shows uniform mirror like appearance. Very high surface area of the porous Si enables the Ni plating. Nano scale sizes of porous Si with plated Ni result in uniform silicide upon anneal. References Dubin, V.M., "Selective electroless Ni deposition onto Pd-activated Si for integrated circuit fabrication" Thin Solid Films 226,no.1(1993):94-98. Kolasinski, K.W. "Porous Si formation by galvanic etching." Handbook of Porous Silicon2 (2014). Delaunois, F. Electroless nickel plating: fundamentals to applications. CRC Press, 2019.

This paper presents a model for producing nano-microparticles by ultrasound-aided electric discharge. After machining, scanning electron microscopy (SEM) was used to check the shape and size of the nickel particles; they were found to be distributed in a few micrometers to 80 [Formula: see text]m range. The nickel particles were regular spherical shaped, and the grain sizes of the particles were different. In addition, many small particles were attached to the surface. Various methods such as inlay polishing, nitric acid etching, and direct SEM imaging were employed to determine the hollow nickel particles such as very thin particles, large thickness grains, hollow sponge-like structures, and solid particles.

AbstractMiniature solid oxide fuel cells (μSOFC) are very promising energy sources for portable devices. In this work we report on fabrication and on first experimental results of μSOFCs processed by means of silicon and thin film technology. All the layers involved in the PEN (Positive electrode-Electrolyte-Negative electrode) structure were sputter deposited on silicon wafer. The PEN membrane was liberated using deep silicon dry etching. The cathode is a combination of a very fine platinum grid covered by a thin LSC layer. The electrolyte is a bilayer of YSZ and CGO ionic conductors. Scanning electrons microscope and X-ray analysis show that the deposited films are polycrystalline with a columnar microstructure. The conductivities of these films are sufficiently high for cell operation at 550°C. The anode is composed of a NiO-Ni-CGO composite. A supporting structure consisting of an electroplated nickel grid is deposited on top of the anode and is part of it. The final PEN is a free standing 1 micron thick membrane, with a diameter of 5 mm. First measurements showed that this structure is mechanically stable up to 550°C and that the cell works with an OCV of 200 mV.

ABSTRACTLevel set methods have been used for Solid phase epitaxial regrowth, etching and deposition.This study is to model the growth of nickel silicide accurately using the level set method. NiSi growth has been observed to follow a linear-parabolic law which takes into account both diffusion and interfacial reaction. This linear-parabolic system is very similar to the Deal and Grove model of SiO2 growth. This model uses similar diffusion transport and reaction rate equations. This simulation models the growth of silicide coupling diffusion solutions to level-set techniques. Dual level sets have been used for top and bottom interface propagation of silicide; velocities were estimated based on nickel concentrations at both interfaces as well as diffusivity and reaction rate of nickel. This is important to predict precise shape of silicide that will allow current crowding and field focusing effects to be modeled in transport out of the intrinsic device into the contacting layers. These simulation models can be used for latest technology nodes at 45, 32, 22nm and special devices such as FinFET’s etc. The level set method is successfully implemented and verified in Florida Object Oriented Process Simulator and growth shapes matches well with the literature Transmission Electron Microscopy data.

AbstractSelf‐assembly of colloidal nanoparticles enables the easy building of assembly units into higher‐order structures and the bottom‐up preparation of functional materials. Nickel phosphides represent an important group of catalysts for hydrogen evolution reaction (HER) from water splitting. In this paper, the preparation of porous nickel phosphide superparticles and their HER efficiencies are reported. Ni and Ni2P nanoparticles are self‐assembled into binary superparticles via an oil‐in‐water emulsion method. After annealing and acid etching, the as‐prepared Ni‐Ni2P binary superparticles change into porous nickel phosphide superparticles. The porosity and crystalline phase of the superparticles can be tuned by adjusting the ratio of Ni and Ni2P nanoparticles. The resulting porous superparticles are effective in driving HER under acidic conditions, and the modulation of porosity and phase further optimize the electrochemical performance. The prepared Ni3P porous superparticles not only possess a significantly enhanced specific surface area compared to solid Ni‐Ni2P superparticles but also exhibit an excellent HER efficiency. The calculations based on the density functional theories show that the (110) crystal facet exhibits a relatively lower Gibbs free energy of hydrogen adsorption. This work provides a self‐assembly approach for the construction of porous metal phosphide nanomaterials with tunable crystalline phase and porosity.

AbstractPrinting functional devices on flexible substrates requires printing of high conductivity metallic patterns. To prevent deformation and damage of the polymeric substrate, the processing (printing) and post-processing (annealing) temperature of the metal patterns must be lower than the glass transition temperature of the substrate. Here, a hybrid process including deposition of a sacrificial blanket thin film, followed by room environment nozzle-based electrodeposition, and subsequent etching of the blanket film is demonstrated to print pure and nanocrystalline metallic (Ni and Cu) patterns on flexible substrates (PI and PET). Microscopy and spectroscopy showed that the printed metal is nanocrystalline, solid with no porosity and with low impurities. Electrical resistivity close to the bulk (~2-time) was obtained without any thermal annealing. Mechanical characterization confirmed excellent cyclic strength of the deposited metal, with limited degradation under high cyclic flexure. Several devices including radio frequency identification (RFID) tag, heater, strain gauge, and temperature sensor are demonstrated.

AbstractIn this study, the high-density SiC/SiO2 core–shell nanowires were synthesized on the nickel coated SiO2 (100 nm)/Si substrate by chemical vapor deposition (CVD) method with ferrocene precursor at temperature 1000 °C compared to previous studies (1300–1600 °C). The present work provides an efficient strategy for the production of SiC/SiO2 nanowires with uniform morphology and good optical properties, where the Ni layer plays important roles for this fabrication at low temperature which reduces the decomposition temperature of hydrocarbon gases and improves the growth quality of SiC nanowires. The as-synthesized SiC/SiO2 nanowires consist of single crystal 3C structures as well as 3C structures with defects along [111] direction. In the photoluminescence (PL) spectrum, the SiC/SiO2 core–shell nanowires revealed an obvious blueshift. The blueshift is due to the formation of nanoscale silicon carbide polytypism caused by the stacking faults in 3C–SiC and the nanoscale polytypism also caused the transition from indirect to direct bandgap which explains why the stacking faults percentage in SiC confirmed from X-ray diffraction (XRD) is 19%, but ultimately makes the strongest emission intensity. Finally, the PL characteristics are further improved by changing the diameter of the SiC nanowire and etching and an approximate model followed by the vapor–liquid–solid (VLS) mechanism was proposed to explain the possible growth mechanism of the SiC/SiO2 nanowires.

AbstractIn this study, the high-density SiC/SiO2 core–shell nanowires were synthesized on the nickel coated SiO2 (100 nm)/Si substrate by chemical vapor deposition (CVD) method with ferrocene precursor at temperature 1000 °C compared to previous studies (1300–1600 °C). The present work provides an efficient strategy for the production of SiC/SiO2 nanowires with uniform morphology and good optical properties, where the Ni layer plays important roles for this fabrication at low temperature which reduces the decomposition temperature of hydrocarbon gases and improves the growth quality of SiC nanowires. The as-synthesized SiC/SiO2 nanowires consist of single crystal 3C structures as well as 3C structures with defects along [111] direction. In the photoluminescence (PL) spectrum, the SiC/SiO2 core–shell nanowires revealed an obvious blueshift. The blueshift is due to the formation of nanoscale silicon carbide polytypism caused by the stacking faults in 3C–SiC and the nanoscale polytypism also caused the transition from indirect to direct bandgap which explains why the stacking faults percentage in SiC confirmed from X-ray diffraction (XRD) is 19%, but ultimately makes the strongest emission intensity. Finally, the PL characteristics are further improved by changing the diameter of the SiC nanowire and etching and an approximate model followed by the vapor–liquid–solid (VLS) mechanism was proposed to explain the possible growth mechanism of the SiC/SiO2 nanowires.