Deposition Of Metal Layers Research Articles

Research regarding electromagnetic shielding achieved by the fabrics support

Electromagnetic shielding achieved by flexible materials has gained an increased significance in today’s radiation polluted environment. One of the modern approaches for obtaining electromagnetic textile shields with good surface electrical conductivity is the deposition of metallic thin films onto the fabrics. The use of the magnetron sputtering technique ensures some advantages, e.g. improved reflections of the fabric once metallic coatings are deposited on both sides of the fabric, as well as lightweight and excellent flexibility due to nanoscale thickness of layers. In the present work, cotton and polyester fabrics with various structural parameters, such as yarns count, fabric density, and specific mass were used as samples to be coated. PVD magnetron sputtering technique was utilized for the deposition of metallic layers with various thicknesses, either on one side or on both sides of the fabrics, in order to ensure good conductivity of the fabric. Besides, fabric samples with inserted conductive yarns of silver and stainless steel were considered as substrates, as well. The electromagnetic shielding tests using TEM cell evidenced good shielding effectiveness of 10-34 dB within 0.1-1000 MHz.

Well-organized organosilane composites for adhesion enhancement of heterojunctions

Flexible copper clad laminate (FCCL) is the key base material for versatile applications such as mobile devices, wearable electronics, and point-of-care biosensors. Development of adhesiveless FCCL is urgent to achieve a thinner, lighter, and thermally stable substrate for advanced high-frequency (5G) applications. In this study, a co-silanization method is proposed to functionalize the polyimide (PI) surface for efficient metal immobilization and adhesion enhancement. The co-silanization treatment features the establishment of a barricade-like network structure by the assistant organosilane, trimethoxyphenylsilane (TMPS), to generate spatial confinement effect (SCE) to effectively control the positioning and grafting orientation of the functional organosilane, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (ETAS), on the PI film. Benefitting from the effective positioning and grafting, the two types of organosilanes form a composite well-organized molecular nanolayer which is in possession of strong tethering ability for metal attachment and immobilization. Compared to the mono-silanization system with ETAS only (0.652 kgf/cm), the co-silanization treatment (ETAS + TMPS) remarkably enhances the peel strength of the deposited metal layer on PI by 53% (~1 kgf/cm).

Pre-treatment of dielectrics and technological process for deposition of chemical copper layers from copper solution with improved ecological impact

ABSTRACTIn the metallisation of dielectrics, this process and the deposited metal layer quality is influenced by the dielectric pre-treatment, and the solution compositions for both pre-treatment and metallisation are vital for establishing the optimum operating conditions for metal layer deposition. The investigations in this study were carried out on samples of acrylonitrile–butadiene-styrene (ABS – Novodur PM/2C Type, Bayer) with a working surface of 0.1 dm2. The investigated operations of the technological scheme for pre-treatment are as follows: degreasing, etching, reduction, pre-activation, activation. After passing through these operations, the ABS samples were subjected to chemical deposition of copper layers from a recently-developed solution. The copper layers were characterised by AFM, SEM, EDX, XRD and XPS analyses.

Selective Atomic Layer Deposition of Metals on Graphene for Transparent Conducting Electrode Application.

Although graphene has considerable potential as a next-generation transparent conducting electrode (TCE) material owing to its excellent optical transparency and flexibility, its electrical properties require further improvement for industrial application. This study reports a pathway of doping graphene by selective atomic layer deposition (ALD) of metals to elevate the electrical conductivity of graphene. Introduction of a novel Pt precursor [dimethyl(N,N-dimethyl-3-butene-1-amine-N)platinum(II); C8H19NPt; DDAP] facilitates a low-temperature (165 °C) process. The sheet resistance (Rs) of graphene is reduced significantly from 471 to 86.8 Ω sq-1 after 200 cycles of Pt ALD, while the optical transmittance at 550 nm (T) is maintained above 90% up to 200 cycles due to the selective growth of Pt on the defects of graphene. Furthermore, comprehensive analysis, including metal (Ru, Pt, and Ni) ALD on graphene, metal (Ru, Pt, Ni, Au, and Co) evaporation on graphene, and change in the ALD chemicals, demonstrates that ALD allows efficient graphene doping and the oxygen affinity of the metal is one of the key properties for efficient graphene doping. Finally, Pt ALD is applied to a multilayer graphene to further reduce Rs down to 75.8 Ω sq-1 yet to be highly transparent (T: 87.3%) after 200 cycles. In summary, the selective ALD of metals opens a way of improving the electrical properties of graphene to a level required for the industrial TCE application and has the potential to promote development of other types of functional metal-graphene composites.

Compressible Metalized Soft Magnetic Sponges with Tailorable Electrical and Magnetic Properties

AbstractPorous metallic sponge has shown enormous application potential in many fields including electrochemical electrode, catalysis, sensors, separation and purification, microwave and sound inhibition, etc. In this paper, we described the preparation of a class of highly compressible Ni−Co alloy‐based sponges with tailorable conductivity and soft magnetic properties as well as EMI shielding ability by employing elastic porous melamine sponge as the support. The melamine sponge was first modified by one‐step dopamine‐triggered radical polymerization reaction, in which polymer brushes with quaternary ammonium cations were grafted onto the sponge fibers for the capture of negative catalyst moieties. The immobilized catalyst moieties could subsequently induce in‐situ chemical deposition of a uniform and well‐adhesive Ni−Co alloy layer with controllable compositions and thickness on the fiber surface owing to the interpenetrating network between hydrophilic polymer brushes and the in‐situ deposited metal layer. The obtained alloy sponges show good compression‐resilience property, excellent conductivity and favorable soft magnetic performance as well as good compressive fatigue resistance during repeated compression‐release cycles, and thus can find promising applications in many fields, including pressure resistance sensors, magnetic controlled pollutant absorbents, tunable EMI shielding materials, etc.

Structure and properties of gas-dynamic coatings and evaluation of their use in sliding friction pairs

The problems of changes in the coating structure depending on the composition of the sprayed mechanical mixture using copper particles and mixture of copper and zinc particles (" brass") and the effect of structural factors on the tribological properties of the deposited metal layer are considered. The results of X-ray structural, phase, chemical and durometric analyzes, as well as tribological testing of coatings are presented. It is found that structure with hardness of ≈102.7 HV is formed in the coating from mechanical mixture of particles of copper and aluminum oxide (corundum). Numerous pores are observed in the structure of the deposited metal layer, the main size of which does not exceed 2 μm. In the coating from mechanical mixture of particles copper, zinc and aluminum oxide (corundum), structure is formed based on copper with hardness of ≈106.5 HV, zinc — ≈49.7 HV, intermetallic compounds (γ- and ε-phases) — ≈168.7 HV, the mass fraction of which is 62.0, 7.9 and 24.2 %, respectively. Both coatings can be used in sliding friction pairs.

Synthesis of Intermetallic Phases in the Nb–Cd and Mo–Cd Systems by Ion-Plasma Sputtering and Atomic Layer Deposition of Metals in Vacuum

Niobium and molybdenum dicadmides (NbCd2 and MoCd2) have been synthesized using ion-plasma sputtering and codeposition of ultrafine niobium and cadmium or molybdenum and cadmium particles on unheated substrates at a Cd concentration near 66 at % in the film, without initiating reactions leading to the formation of these compounds. Their composition, structure, and unit-cell parameters have been determined by X-ray diffraction and transmission electron microscopy. The synthesized niobium and molybdenum dicadmides can be described by tetragonal unit cells with parameters a = 0.84357 nm and c = 0.54514 nm for the former and a = 0.78231 nm and c = 0.77039 nm for the latter, in which pairs of cadmium atoms reside on lateral faces.

Improve Surfaces properties of ABS Products fabricated by fused deposition modeling (FDM) 3D Printing

FDM (fused deposition modeling) 3D printing products often suffer from high surface roughness and low durability compared to conventional methods. In this paper, the effect of surface treatment after printing and coating with a layer of metal on its properties has been studied, The mechanical surface treatment methods (sandpaper) and chemical (solvent treatment) were compared and their effect on the adhesion strength of the deposited metal layer on the surface. The surface of the ABS product was coated with a layer of metal, the effect of both treatment and coating on the mechanical properties of printing products was studied. The results showed a clear decrease in surface roughness after surface treatment, where surface roughness decreased by 92%, and the best result was when grinding with sandpaper (2000 Grit) was Ra 0.35 μm. The tensile strength after acetone surface treatment was improved by 50% and after coating the product with a layer of metal by 56.25%. The adhesion test of the surface-deposited metal (CROSS-CUT) was conducted, and the result showed that the best adhesion durability was when the surface was treated with acetone vapor before coating.

A Novel Optical Method for Nondestructive Determination of Binary Diffusion Coefficients in Metal Nanoalloy Films

A new optical method for the indirect determination of binary diffusion coefficients of metals in binary nanoalloys is presented. Beginning with an initial nano‐bilayer of two pure metals, the method is based on the measurement of the visible‐light surface plasmon resonance (SPR) characteristic of the final alloy nanolayer as a function of the diffusion process that occurred due to heat treatment at a constant temperature for a definite time. The theory behind is described and an algorithm is developed that takes the initial thickness of the deposited metal layers and the measured SPR angle of the final sample as input and accordingly calculates the binary diffusion coefficient. The proposed algorithm has been coded in the MATLAB simulator and applied to a fabricated initial Au–Ag bi‐nanolayer (Au thickness 23 nm and Ag thickness 15 nm) which is subjected to a specific heat‐treatment process (1 h at 100 °C). The binary diffusion coefficient is estimated as 6.94 × 10−17 cm2 s−1, in agreement with reported values for thin films. The novel method is nondestructive, simple, fast, and highly sensitive to changes of concentration profiles throughout multilayers, a few tens of nanometer that exhibit the SPR phenomenon.

High-performance, semiconducting membrane composed of ultrathin, single-crystal organic semiconductors

Thin film transistors (TFTs) are indispensable building blocks in any electronic device and play vital roles in switching, processing, and transmitting electronic information. TFT fabrication processes inherently require the sequential deposition of metal, semiconductor, and dielectric layers and so on, which makes it difficult to achieve reliable production of highly integrated devices. The integration issues are more apparent in organic TFTs (OTFTs), particularly for solution-processed organic semiconductors due to limits on which underlayers are compatible with the printing technologies. We demonstrate a ground-breaking methodology to integrate an active, semiconducting layer of OTFTs. In this method, a solution-processed, semiconducting membrane composed of few-molecular-layer-thick single-crystal organic semiconductors is exfoliated by water as a self-standing ultrathin membrane on the water surface and then transferred directly to any given underlayer. The ultrathin, semiconducting membrane preserves its original single crystallinity, resulting in excellent electronic properties with a high mobility up to 12 [Formula: see text] The ability to achieve transfer of wafer-scale single crystals with almost no deterioration of electrical properties means the present method is scalable. The demonstrations in this study show that the present transfer method can revolutionize printed electronics and constitute a key step forward in TFT fabrication processes.

Dual Refractive Index and Viscosity Sensing Using Polymeric Nanofibers Optical Structures

Porous materials have demonstrated to be ideal candidates for the creation of optical sensors with very high sensitivities. This is due both to the possibility of infiltrating the target substances into them and to their notable surface-to-volume ratio that provides a larger biosensing area. Among porous structures, polymeric nanofibers (NFs) layers fabricated by electrospinning have emerged as a very promising alternative for the creation of low-cost and easy-to-produce high performance optical sensors, for example, based on Fabry-Perot (FP) interferometers. However, the sensing performance of these polymeric NFs sensors is limited by the low refractive index contrast between the NFs porous structure and the target medium when performing in-liquid sensing experiments, which determines a very low amplitude of the FP interference fringes appearing in the spectrum. This problem has been solved with the deposition of a thin metal layer (~ 3 nm) over the NFs sensing layer. We have successfully used these metal-coated FP NFs sensors to perform several real-time and in-flow refractive index sensing experiments. From these sensing experiments, we have also determined that the sponge-like structure of the NFs layer suffers an expansion/compression process that is dependent of the viscosity of the analyzed sample, what thus gives the possibility to perform a simultaneous dual sensing of refractive index and viscosity of a fluid.

Mechanistic Study of Nucleation Enhancement in Atomic Layer Deposition by Pretreatment with Small Organometallic Molecules

Thermal atomic layer deposition (ALD) of metals on metal oxide surfaces typically suffers from nucleation delays that result in poor-quality films. The poor nucleation may be caused by a lack of su...

Electrochemical memristive devices based on submonolayer metal deposition

This paper explores the concept of an analog memristive device based on reversible electrochemical deposition and deplating of a submonolayer metal layer on a 108 Ω resistive bar. Initial feasibility experiments demonstrate a continuous resistance change by seven orders of magnitude during physical vapor deposition of Cu on TaNx/SOI, with the most promising range from 5.6 × 107 to 1.1 × 107 Ω/□ during a 0.64 monolayer Cu deposition. Cyclic electrochemical deposition and deplating of Cu on a metal seed on SiO2 in a 0.01M CuSO4/H2SO4 pH 1.4 solution demonstrates a reversible resistance variation with a minimum of 10 ± 1 discrete resistance states. These initial results are promising but also reveal a key materials challenge: the need for controlled and reversible electrochemical deposition/deplating of a submonolayer metal on the surface of a relatively high resistivity (≥10−2 Ω m) material.

Electrodeposition Cu and roll transfer of graphene for large scale fabrication of Cu-graphene nanolayered composite

Nanolayered composites are reported to exhibit high strength due to the high density of interfaces. Previously, metal-graphene nanolayered composite had been fabricated by vacuum based deposition of metal layers and wet transfer of graphene layers, both of which are time consuming processes that limit the scalability of the nanolayered composite. In this study, the vacuum based deposition of metal and wet transfer of graphene have been replaced with electrodeposition of metal and roll-based dry transfer of graphene to greatly enhance the scalability of the nanolayered composite fabrication. Fabricated Cu-graphene nanolayered composites with layer spacing of 200 nm, 300 nm, and 400 nm were tested under compression, and the strengths are calculated to be 1.38 GPa, 1.15 GPa, and 1.06 GPa, respectively. The strengths are within the range reported previously for the case of wet transfer and sputter deposited metal, but the new fabrication method has greatly enhanced scalability.

Selective Cu Electrodeposition for Sub-Micrometer Redistribution Layers

The density of integrated circuit (IC) was doubled by shrinking the feature size in semiconductor industry. An improvement in density of standard interconnection and the packaging technology is much slower than the IC trends. To overcome the increasing I/O interconnect gap, the semiconductor packaging technology has been driven by many researchers and companies over the many years. The redistribution layers (RDL), one of the important parts for the package process, play a role to rearrange I/O connections from the die to substrate. For fine line pitch below 10μm, the damascene RDL process was proposed. The flow of damascene RDL process was composed of photoresist patterning, a metal layer deposition, Cu electrodeposition and chemical-mechanical planarization (CMP). During the Cu electrodeposition for the damascene RDL process, Cu overburdens were formed on top surfaces of sub-micrometer trenches. Typically the CMP process has been used to remove these overburdens in semiconductor industry, however, this surface planarization process caused an increase in process cost. For prevent the Cu overburden at low cost, the selective Cu electrodeposition which is process filling only trench is required. The selective Cu electrodeposition can be achieved by μCP with various additives. The microcontact printing (μCP) process which transfers the self-assembled monolayers (SAMs) on the top surface of trenches can be one of the solutions preventing the Cu deposition on these top surfaces.[1-2] SAMs are organic molecules that formed spontaneously on the solid surface by chemisorption and organization of alkanethiol, silane, and so forth.[3] In this research, flat polydimethylsiloxane (PDMS) stamp is used for providing on the top surface of patterned substrate. Selective Cu electrodeposition was proceeded on trench in CuSO4 1 M/H2SO4 0.58M electrolyte with various additives. In this study, electrochemical behavior of additives was studied by cyclic voltammetry and selective electrodeposition process was investigated with various additives, applied potential, charge density. The µCP process show the effective suppression of Cu growth on the top surface of trenches so that Cu overburden thickness was significantly reduced. This result reveals the feasibility of Cu trench-selective deposition below 10 μm. The μCP method with various additives shows the possibility of replacing surface planarization process which removes overburden of Cu for the RDL process.. [1]Y.Xia and G. Whitesides, "Soft lithography", Annu. Rev. Mater. Sci., vol. 28, no. 1, pp. 153-184, 1998. [2]S.Alom Ruiz and C. Chen, "Microcontact printing: A tool to pattern", Soft Matter, vol. 3, no. 2, pp. 168-177, 2007. [3]P.Laibinis, G. Whitesides, D. Allara, Y. Tao, A. Parikh and R. Nuzzo, "Comparison of the structures and wetting properties of self-assembled monolayers of n-alkanethiols on the coinage metal surfaces, copper, silver, and gold", J. Am. Chem. Soc., vol. 113, no. 19, pp. 7152-7167, 1991.

Directly Writing Patterning of Conductive Material by High Voltage Induced Weak Electric Arc Machining (HV-μEAM)

An additive manufacturing (AM) method for the deposition of metallic layer in micron scale on monocrystalline silicon wafer surface by high voltage induced weak electric arc machining (HV-μEAM) has been proposed. The process characteristics of HV-μEAM are analyzed to fulfil the metal material deposition. The influence of the processing parameters on the deposition effect were studied with copper as additive electrode material. Using the optimal parameters, a number of complex trajectory deposition experiments have been carried out and a QD character-type deposition layer with a height of 139.09 μm has been obtained. The deposition has good continuity and high forming precision. It is proven that the new method is achievable and efficient for patterning metallic materials in the micro- and nano-scale on the silicon substrates surface.

İKİ AŞAMALI YÖNTEM İLE HAZIRLANAN Cu2ZnSnS4 (CZTS) İNCE FİLMLERİN ÖZELLİKLERİNDE SÜLFÜRLEMENİN ETKİSİ

In this study, CZTS thin films were grown by a two-stage method involved sputter deposition of metallic Cu, Zn, and Sn layers to form Cu/Sn/Zn/Cu metallic stacks on glass and sulfurization of the metallic stacks at 540 and 580 °C for 1 and 5 min in sulfur vapor atmosphere. The reacted samples at two different sulfurization temperatures and sulfurization times were characterized employing XRD, SEM, EDX, Raman spectroscopy, optical spectroscopy, and Van der Pauw methods. The metallic stacks and CZTS thin films showed Cu-rich and Zn-poor composition. XRD patterns of the reacted films showed almost pure kesterite CZTS phase except for presence of very small amount of Cu 2-x S phase. Raman spectra of the films verified formation of kesterite phase in the films. SEM images showed that the CZTS540-1 sample had more compact, denser and uniform structure. Optical band gap values were found to be in good agreement with the literature. The CZTS540-1 thin film showed the highest carrier concentration and lowest resistivity values amongst the other samples.

Metallic Electroconductive Transmission Lines Obtained on Textile Substrates by Magnetron Sputtering

The paper discusses the results of research concerning the formation of electroconductive transmission lines on textile substrates using the magnetron sputtering technique. The transmission lines developed can potentially be applied in clothing for emergency and security services to affect electrical connections between electronic elements incorporated in the garments. The time of metallic layer deposition and the type of substrate used was optimised in the study. The surface resistivity, resistance to bending and abrasion of the transmission lines obtained were tested. The tests demonstrated that it is possible to obtain electroconductive copper layers with a surface resistivity approximating 0.2 Ω by direct deposition on spun-bonded type polypropylene nonwoven.

A Polarization Insensitive Wide‐Band Perfect Absorber

In this article, a wide‐band and polarization‐insensitive perfect absorber composed of 4 sandwiched layers of dielectric and metal disks is introduced. Compared to classical perfect absorbers, the system supports near‐unity absorption within a wider spectral window through multiple perfect absorption mechanisms that exist due to a constituting inter‐metal disk, functioning either as a dipolar antenna or a conducting ground for different perfect absorption mechanisms. Circular shape of the antenna makes the working mechanism of the system polarization insensitive. The working principle of the system is investigated through near‐ and far‐field calculations by finite difference time domain (FDTD) simulations. A fine‐tuning mechanism of the wide‐range perfect absorption window is introduced through geometrical device parameters. The multilayer perfect absorber system is fabricated through a high‐quality fabrication method based on electron beam lithography, lift‐off method, and multi‐step deposition of metal and dielectric layers. The spectral behavior of the perfect absorber system is finally experimentally investigated through Fourier transform infrared (FTIR) spectroscopy.

Structural, optical and Schottky diode properties of Cu2ZnSnS4 thin films grown by two-stage method

CZTS thin film was prepared by a two-stage process comprising sputter deposition of metallic Cu, Zn, and Sn layers followed annealing treatment of the metallic precursors in a sulfur atmosphere at 560 °C for 3 min. The CZTS thin film was investigated in the way of structural, optical and electrical properties. The XRD pattern of Cu-poor and Zn-rich CZTS thin film was dominated by characteristic peaks of kesterite CZTS planes. Raman spectra of the film ensured formation of kesterite CZTS phase and displayed formation of CTS and ZnS phases. Dense and polycrystalline surface features were observed in SEM images of CZTS thin film. Band–band transitions was not observed due to the probable concentration of deep acceptor levels in this material. The diode parameters of Mo/CZTS/Al structure such as ideality factor, barrier height and serial resistance were calculated employing temperature dependent I–V characteristics of Mo/CZTS/Al diode structure.