Porous Copper Films Research Articles

BME-Assisted Fabrication of Porous Copper Films with Adjustable Porosity and Ligament Width for Microelectronic Interconnects

Monolithic porous Cu films are synthesized through the use of bicontinuous microemulsion (BME) to serve as a flexible template. The BME system is made up of a series of interconnected linked water and hydrocarbon phases. This one-of-a-kind structure enables precision Cu electrodeposition only in the aqueous phase, avoiding undesirable electrodeposition in the oil phase. We can fine-tune the porosity and ligament width of the resultant copper film by altering the oil phase proportion in the soft template. This Sn-plated porous Cu is capable of both low-temperature reflow and high-temperature service. The flexible template approach shows great potential for creating porous Cu with changeable porosity, allowing for more control over compositions. This approach has potential applications in advanced packaging technologies.

Self-Oxidation Resistance of the Curved Surface of Achromatic Copper.

Copper surfaces that exhibit a wide range of achromatic colors while still metallic have not been studied, despite advancements in antireflection coatings. A series of achromatic copper films grown with [111] preferred orientation by depositing three-dimensional (3D) porous nanostructures is introduced via coherent/incoherent atomic sputtering epitaxy. The porous copper nanostructures self-regulate the giant oxidation resistance by constructing a curved surface that generates a series of mono-atomic steps, followed by shrinkage of the lattice spacing of one or two surface layers. First-principles calculations confirm that these structural components cooperatively increase the energy barrier against oxygen penetration. The achromaticity of the single-crystalline porous copper films is systematically tuned by geometrical parameters such as pore size distribution and three-dimensional linkage. The optimized achromatic copper films with high oxidation resistance show an unusual switching effect between superhydrophilicity and superhydrophobicity. The tailored 3D porous nanostructures can be used for numerous applications, such as antireflection coatings, microfluidic devices, droplet tweezers, and reversible wettability switches. This article is protected by copyright. All rights reserved.

Screen-Printed Carbon Electrodes with Macroporous Copper Film for Enhanced Amperometric Sensing of Saccharides.

A porous layer of copper was formed on the surface of screen-printed carbon electrodes via the colloidal crystal templating technique. An aqueous suspension of monodisperse polystyrene spheres of 500 nm particle diameter was drop-casted on the carbon tracks printed on the substrate made of alumina ceramic. After evaporation, the electrode was carefully dipped in copper plating solution for a certain time to achieve a sufficient penetration of solution within the polystyrene spheres. The metal was then electrodeposited galvanostatically over the self-assembled colloidal crystal. Finally, the polystyrene template was dissolved in toluene to expose the porous structure of copper deposit. The morphology of porous structures was investigated using scanning electron microscopy. Electroanalytical properties of porous copper film electrodes were evaluated in amperometric detection of selected saccharides, namely glucose, fructose, sucrose, and galactose. Using hydrodynamic amperometry in stirred alkaline solution, a current response at +0.6 V vs. Ag/AgCl was recorded after addition of the selected saccharide. These saccharides could be quantified in two linear ranges (0.2–1.0 μmol L−1 and 4.0–100 μmol L−1) with detection limits of 0.1 μmol L−1 glucose, 0.03 μmol L−1 fructose, and 0.05 μmol L−1 sucrose or galactose. In addition, analytical performance of porous copper electrodes was ascertained and compared to that of copper film screen-printed carbon electrodes, prepared ex-situ by the galvanostatic deposition of metal in the plating solution. After calculating the current densities with respect to the geometric area of working electrodes, the porous electrodes exhibited much higher sensitivity to changes in concentration of analytes, presumably due to the larger surface of the porous copper deposit. In the future, they could be incorporated in detectors of flow injection systems due to their long-term mechanical stability.

Tailoring the internal structure of porous copper film via size-controlled copper nanosheets for electromagnetic interference shielding

We studied the effects that internal porous structures tailored using size-controlled copper nanosheets (Cu NSs) had on the electromagnetic interference (EMI) shielding performance of the resulting Cu NS films. Cu NSs were carefully synthesized as two-dimensional (2D) conductive fillers, and their size was controlled by adjusting the concentrations of the shape modifier (iodine), stabilizer (hexadecylamine) and reductant (glucose). Three kinds of Cu NSs had the size of 3.8 μm (Max. 10.0 μm), 8.9 μm (Max. 28.0 μm), and 12.2 μm (Max. 33.7 μm) and used as a conductive filler for shielding film by spray printing. The films had different surface coverages, film thicknesses, and EMI shielding effectiveness (SE) at a fixed loading weight of 0.6 mg/cm2. The smallest to largest Cu NSs exhibited EMI shielding performances of 6.3 dB, 43.6 dB, and 69.7 dB, respectively, so performance was directly proportional to size.

Dual-functional porous copper films modulated via dynamic hydrogen bubble template for in situ SERS monitoring electrocatalytic reaction

Dual-functional porous copper films were prepared by dynamic hydrogen bubble template (DHBT) technique to achieve in situ SERS monitoring of electrocatalytic reaction. The morphology and SERS activity of porous copper films were effectively modulated by electrolyte additive, current density, and deposition time. The interfacial evolution behaviors of porous copper films were monitored by in situ synchrotron radiation X-ray imaging. The three-dimensional porous copper films in the presence of CTAB additive present a thinner leaf-like dendritic structure and excellent SERS activity. Although the diverse morphologies of porous copper films are obtained with inorganic additives including (NH4)2SO4, Na2SO4, or NaCl, they are deleterious to the SERS activity due to the microstructural changes of copper films, even significantly lower than that of the additive-free condition. The obtained porous copper films exhibit high sensitivity (10−9 mol/L) and good reproducibility for efficient SERS detection. Furthermore, the electrocatalytic reduction process of 4-nitrophenol on the porous copper films was successfully in situ monitored based on their excellent SERS activity.

A self-supported, three-dimensional porous copper film as a current collector for advanced lithium metal batteries

3D porous Cu foil fabricated by the painting–alloying–dealloying method exhibits excellent electrochemical performance as a current collector for Li metal batteries.

Facile and Green Preparation of Three-Dimensionally Nanoporous Copper Films by Low-Current Electrical Field-Induced Assembly of Copper Nanoparticles for Lithium-Ion Battery Applications

Porous copper (Cu) films were facilely and greenly fabricated by low-current electrical field-induced assembly of ~ 3 nm Cu nanoparticles (NPs) in several minutes using generated hydrogen bubbles as dynamic negative templates. The porous films had open three-dimensionally (3D) interconnected nanopores and uniform pore size distribution and exhibited a hierarchical structure composed of supraparticles that were further composed of the Cu NPs. Lattice-to-lattice connectivity in the self-assembly of the NPs in the 3D structures enables fast charge transport. The structure/morphology of the porous Cu materials can be tuned by adjusting the concentration of the additives, applied potential/current densities and assembly time. A growth mechanism of the porous films was reasonably proposed for the field-induced assembly of the Cu NPs. The porous Cu film-supported Si electrode showed high capacity of 1173 mAh g−1 and retention rate of 87% after 10 cycles at 1 C. Our research sheds a light on preparing 3D nanoporous structures especially for suitable electrodes in electrochemical energy storage devices.

A method for quantifying in plane permeability of porous thin films

The in-plane permeability of porous thin films is an important fluid mechanical property that determines wicking and pressure-driven flow behavior in such materials. This property has so far been challenging to measure directly due to the small sidewall cross-sectional area of thin films available for flow. In this work, we propose and experimentally demonstrate a novel technique for directly measuring in-plane permeability of porous thin films of arbitrary thicknesses, in situ, using a manifold pressed to the top surface of the film. We both measure and simulate the influence of the two dimensional flow field produced in a film by the manifold and extract the permeability from measurements of pressure drop at fixed flow rates. Permeability values measured using the technique for a periodic array of channels are comparable to theoretical predictions. We also determine in-plane permeability of arrays of pillars and electrodeposited porous copper films. This technique is a robust tool to characterize permeability of thin films of arbitrary thicknesses on a variety of substrates. In Supplementary material, we provide a solid model, which is useful in three-dimensional printer reproductions of our device.

Effect of Multifunctional (NH4)2SO4 and Co-deposition Factors on Porous Copper Film

Effect of Multifunctional (NH4)2SO4 and Co-deposition Factors on Porous Copper Film

Generation of a metal porous film by arc discharge

The copper wire vaporization method is applied to obtain porous copper film on a silicon surface. We determine the distribution of the surface clusters over the sizes and the density. The average size of the clusters under optimal conditions (at a distance of 2 mm from the discharge) is about 0.5 μm, and the deposition density is 3–5 clusters per squared μm.

Structure and properties of porous nickel and copper films produced by vacuum deposition from the vapour phase

The porous thick nickel and copper films were deposited by electron beam physical vapour deposition (EB-PVD) in vacuum. The microstructure and deformation behaviour of the films were investigated using scanning electron microscopy and high temperature dilatometer. It is shown that porous structure of vacuum condensates is unstable, and at heating it transforms from open-type porous structure into porous structure of closed type. It is assumed that such thermal instability of porous structure can be due to the presence of high density of vacancy-type defects in the structure of such materials. Change of structural state of vacuum condensates during heating at application of continuous load influences the conditions of their superplastic deformation. Possibility of application of such foils as interlayers in pressure welding is discussed.

Changes of Motional Resistance during the Electrochemical Deposition and the Anodic Dissolution of Copper in Diluted Sulphuric Solutions

The electrochemical deposition of copper has been extensively studied. In some experimental conditions, this electrodeposition represents the base of the calibration of the electrochemical quartz microbalances (EQCM). This technique allows the detection of intermediate species which are formed in the interfacial region, by measuring the F(dm/dq) function during electrochemical experiments. Furthermore, R-EQCM devices provides additional information on the deposited layers and the electrode/solution interfacial regions, by measuring instantaneously the motional resistance R of the equivalent Butterworth-Van-Dyke circuit. This resistance could be almost considered as the sum of three different contributions as a first approach: Ro, due to the electrode (quartz/Au/Cu) system, RCu related with the Cu phase, and the RCu/solution associated with the Cu / solution interface: R = Ro+RCu+RCu/solution This work explores the interpretation of this magnitude and its dependence on the nature of the interfacial region. For this purpose, the electrochemical deposition of copper as well as its anodic dissolution in acid sulfuric aqueous solutions were studied. . Generally, measuring the resonance frequency, it is concluded that in the deposition and the anodic dissolution of copper, the instantaneous values of F (dm /dq) and F (D m/Dq) (measured in an interval of time) approaching 32 g·.mol – 1. This means that the overall reaction involves the transfer of two electrons per atom of copper. This is useful from a practical perspective: Both deposition and anodic dissolution of copper are suitable to calibrate the microbalance and for correcting the theoretical factor between mass and frequency that provides the Sauerbrey equation. However, although both processes have an efficiency near to 100 %, there is always a little hydrogen evolution which is manifested by a small increase of pH solution during the experiments of copper electrodeposition . Since hydrogen gas at room temperature is slightly soluble in water, the production of hydrogen results in bubbles whose size depends on the medium composition and temperature which affect the surface tension. It is known that the rate of this process increases at higher cathodic overpotentials, which is able to generate superhydrophobic surfaces on metallic copper [2]. Due to the formation of hydrogen bubbles on the copper is the reason that the measure of the motional resistance shows periodic oscillations (Figure 1) and his period exceeds to the time of formation of successive copper layers during the electrochemical deposition. The relative maxima of these fluctuations should correspond to the hydrogen microbubbles leaving the electrode surface. The function dm/dt evolves parallel on time to the R value during the copper deposition. From the aforesaid results, it is inferred the great usefulness of the in situ measure of the motional resistance for obtaining information about the electrode/solution interfacial region. The F (dm/dq), dm/dt function, and the appropriate measure of the motional resistance are useful to explain the interfacial differences that occur between the deposition and anodic dissolution of copper. The results points to the fact that the calibration of the Sauerbrey equation perhaps is better during the anodic process of dissolution than by means of an electrodeposition process, since during this last process, hydrogen bubbles are produced, whose kinetics can be followed by the oscillations of the motional resistance.The aforesaid results are consistent with the spectroelectrochemical measurements. Figure 1. Oscillations of motional resistance R during a galvanostatic (I = - 2 mA) cooper deposition on Au (23,1 mm2) electrode in a 0.5 M CuSO4 diluted sulphuric aqueous solution (pH =1) at 298 K. REFERENCES [1] D. Giménez-Romero, C. Gabrielli, J.J. García-Jareño, H. Perrot, F. Vicente Electrochemical quartz crystal microbalance study of copper electrochemical reaction in acid medium containing chlorides,. J. Electrochem. Soc. 153 (2006)J32-J39. [2] Ying Li , Wen-Zhi Jia , Yan-Yan Song , and Xing-Hua Xia, Superhydrophobicity of 3D Porous Copper Films Prepared Using the Hydrogen Bubble Dynamic Template. Chem. Mater. 19 (23) (2007) 5758–5764. ACKNOWLEDGEMENTS Part of this work was supported by FEDER-CICyT CTQ2015-71794-R. Figure 1

Preparation of three-dimensional porous Cu film supported on Cu foam and its electrocatalytic performance for hydrazine electrooxidation in alkaline medium

A three-dimensional porous copper film is directly deposited on Cu foam by an electrodeposition method using hydrogen bubbles as dynamic template (denoted as Cu/Cu foam). Its electrocatalytic activity toward hydrazine electrooxidation is tested by linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Compared with Cu foam, hydrazine electrooxidation on the Cu/Cu foam electrode shows that the onset oxidation potential displays a ~100 mV negative shift, the current density at −0.6 V raises about 14 times, the apparent activation energy and the charge transfer resistance reduce significantly. The increasing electrocatalytic performance for hydrazine electrooxidation is mainly caused by the highly porous structure of the Cu/Cu foam electrode which can provide a large surface area and make electrolyte access the electrocatalyst surfaces more easily. Hydrazine electrooxidation on the Cu/Cu foam electrode proceeds through a near 4-electron process.

Morphologies and wetting properties of copper film with 3D porous micro-nano hierarchical structure prepared by electrochemical deposition

Three-dimensional porous micro-nano hierarchical structure Cu films were prepared by electrochemical deposition with the Hydrogen bubble dynamic template. The morphologies of the deposited films characterized by Scanning Electronic Microscopy (SEM) exhibit a porous micro-nano hierarchical structure, which consists of three levels in different size scales, namely the honeycomb-like microstructure, the dendritic substructure and the nano particles. Besides, the factors which influenced the microscopic morphology were studied, including the deposition time and the additive Ethylene diamine. By measuring the water contact angle, the porous copper films were found to be super-hydrophobic. The maximum of the contact angles could reach as high as 162.1°. An empirical correlation between morphologies and wetting properties was revealed for the first time. The pore diameter increased simultaneously with the deposition time while the contact angle decreased. The mechanism was illustrated by two classical models. Such super-hydrophobic three-dimensional hierarchical micro-nano structure is expected to have practical application in industry.

One-step preparation of porous copper nanowires electrode for highly sensitive and stable amperometric detection of glyphosate

AbstractA simple and sensitive amperometric method for the detection of glyphosate based on a porous copper nanowire electrode is presented. The porous nanowires were fabricated simply by a one-step electrodeposition using hydrogen bubbles generated during the deposition to produce pores. These porous nanowires provided a 1.4 times larger surface area than a porous copper film. After the fabrication process the porous copper nanowires can be applied directly as a working electrode with the same custom-built flow cell. The detection was carried out by measuring the oxidation signal of copper; this increased with the concentration of glyphosate due to dissolution of the copper from the electrode. Under optimal conditions, the responses of the sensor were linear between 0.010-5.0 μmol L

3D Porous Copper Films with Large Specific Surface Prepared by Hydrogen Bubble Template

3D Porous Copper Films with Large Specific Surface Prepared by Hydrogen Bubble Template

Preparation and Characterization of Porous Nano Copper Films

Nanocrystalline porous copper films were prepared by sol–gel method with polyethylene glycol (PEG) as organic template, copper acetate as raw material and (di) ethanolamine (DEA) as chelating agent. Copper nanowire array films were fabricated by electrodeposition within anodic aluminum oxide (AAO) membrane. The films were analyzed by infrared absorption (IR), thermogravimetry-derivative thermogravimetry (TG-DTG), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM) and atomic force microscope (AFM). The structure of the copper films which achieved by sol–gel was remarkable influenced by sol concentration, polyethylene glycol content and annealing temperature. The effects of annealing temperature and the way of gelation on grain sizes were discussed. The results showed that films could be made under the optimum condition: sol concentration was 0.6 mol/L, annealing temperature was 500 C, and polyethylene glycol content was 0.35 g. The structure of the nanoarray films which obtained by electrodeposition was influenced by current density and electrodeposition time. When the electrodeposition time was 5 min, and current density was 1.0 A/dm2, the nanoarray structure was the best.

Fabrication and Characterization of Nanoscale Porous Copper Film

Cu-38Zn thin film (wt %) was deposited on the unheated microscope glass at the nanometer scale by DC magnetron sputtering. Subsequently, the nanocrystalline films were dealloyed in H2SO4 aqueous solution etching of zinc component, resulting in the formation of nanoscale porous copper film with average porous diameter of approximately 94 nm. The films microstructure and element composition were characterized by X-ray diffraction and scanning electron microscopy. The experimental results show that Cu-38Zn films are quasi-amorphous structure, porous copper film with different porous sizes is prepared by selective dissolution of zinc atoms from a nanocrystalline dual-phase film under free corrosion conditions, the grain size of the Cu-Zn films has an important effect on the dealloying process and the microstructures of the nanoscale copper films.

Role of surfactants in construction of porous copper film by electrodeposition approach

Porous copper films have been successfully electrodeposited using a hydrogen bubble template. The cationic surfactant cetyl trimethylammonium bromide, the anionic surfactant sodium dodecyl sulphate, the non-ionic surfactant alkylphenol polyoxyethylene and combined surfactants were used as additives to the electroplating baths. The purpose was to evaluate the effects of these surfactants on the microstructure and morphology of porous electrodeposited copper films. X-ray diffraction results show an obvious difference in the crystallinities of porous copper films derived from baths containing different surfactants. Field emission scanning electron microscopy micrographs reveal that both the size and morphology of the pore walls acutely depend on the type of surfactant.

The porous CuO electrode fabricated by hydrogen bubble evolution and its application to highly sensitive non-enzymatic glucose detection

The porous Cu film was deposited on a Pt/Ti/Si substrate by electrochemical deposition accompanied by hydrogen evolution at very high current densities. CuO films with similar morphologies were obtained by subsequent annealing of the porous copper films. The morphology, composition and structure of the porous Cu and porous CuO were investigated by FE-SEM, EDS and XRD methods. The complete transformation of Cu to CuO after annealing was indicated. The sensing performances of the porous CuO film were evaluated in alkaline solution with the porous CuO film showing a wide linearity range from 1 μM to 2.5 mM with sensitivity of 2.9 mA cm −2 mM −1, and detection limit of 0.14 μM. The sensor showed good selectivity to conventional intermediates such as AA and UA and long term stability.