Copper Electrodeposition Process Research Articles

Electrodeposited copper nanocubes on multi-layer graphene: A novel nanozyme for ultrasensitive dopamine detection from biological samples

In this paper, copper nanocubes (CuNCs) were grown on top of few-layer and multi-layer graphene (FLG and MLG) nanomaterial by electrodeposition, to develop a sensitive and selective nanozyme based electrochemical sensor for the determination of dopamine from plasma samples. The copper electrodeposition process was intensively studied and optimized to obtain cubic shape CuNPs on top of graphene that increased the active area of the sensor. The surface of the nanomaterial was investigated with several microphysical characterization techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), and Fourier-transform infrared (FTIR), Raman, and X-ray photoemission spectroscopies (XPS). Further, the nanozyme sensor based on CuNCs-Gr/SPCE was electrochemically characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the response towards the oxidation of DA was investigated using the differential pulse voltammetry (DPV) technique. The signal recorded with CuNCs-Gr/SPCE was linear in a wide range (0.001 – 100 µM), with a low limit of detection of 0.33 nM and a very high sensitivity of 196 mA/moL-1. The developed sensor showed high selectivity towards DA in presence of other neurotransmitters. The detection of DA in human plasma samples was obtained with 95.8–100.2 % recovery percentage, proving the reliability of the method.

High Sensitivity Bimetallic Electrode Generation through the Study of Copper Electrocrystallisation on Metallic Substrates (Md/Ms) in Acidic Media

The electrochemical nucleation of copper on metallic substrates in acidic media was investigated using cyclic voltammetry and chronoamperometry. The purpose is to optimize the operating conditions for preparing a high sensitivity bimetallic electrode. Indeed, optimizing the electrodeposition parameters whereby two different metals are present: deposited metal Md and substrate metal Ms, allows the generation of a large number of microelectrodes, correspondingly, yield the largest active surface, and so, increasing the electrode sensitivity.The aim of this study is to highlight the positive impact of controlling the electrodeposition process of a metal on a substrate and determining the operation conditions towards the augmentation of the active surface area of an electrode.This work is focused on studying the first instance of copper nuclei formation on the electrode surface and the growth of these nuclei over time. Factors influencing deposit quality and allow to yield the highest specific surface area were considered, principally the overvoltage and the deposit cutoff charge. The nucleation phenomena and the initial growth of the copper nuclei on three different metallic substrates was studied. The plot of the experimental results were compared to theoretical models for the two possible nucleation modes: instantaneous and progressive. The nucleation phenomena was overseen on cyclic voltammetry recorded and the electrodeposition overvoltage were determined for each couple (Md/Ms). Chronoamperometric measurements evidenced that copper electrodeposition process involves progressive nucleation on the substrates, which was confirmed by scanning electron microscopy (SEM). Afterward, the germination rates were determined.The optimum theoretical cutoff charges were calculated from chronoamperograms using Faraday’s law and were experimentally verified.Optimal operating conditions were determined for the preparation of bimetallic electrodes with the largest active surface area. Subsequently, copper deposition runs were carried out on the three electrode substrates. The formed bimetallic electrodes were tested using square wave voltammetry for their ability to detect species requiring high sensitivity identification tools such as nitrates in seawater. In open ocean, the concentration of nitrates can drop from few dozens of micromolars to as littles as few nanomolars.The copper nuclei fount out to be unstable on the substrate in maritime area due to corrosion and attack by dissolved oxygen. A cathodic polarization by applying a direct current was applied to protect the deposited copper.

The Pivotal Role of Uniformity of Electrolytic Deposition Processes to Improve the Reliability of Advanced Packaging

Abstract Heterogeneous integration is considered as the key technology to create large, complex System in Package (SiP) assemblies of separately manufactured, smaller components. Proper control of the uniformity of each process step constitutes one of the main challenges during integration of the different components into a higher-level assembly. In this context, processes that create thick layers by electrochemical deposition are especially susceptible to variations across the substrate. Such processes include copper pillar and bump as well as tin-silver applications. Insufficient coplanarity of electrolytic copper would result in significant reliability issues or evolution of stress in the package. Upcoming hybrid bump designs with features of different dimensions pose additional challenges to the electrolytic copper and tin-silver processes. Purposeful adjustment of differences between the heights of pillars of different diameters may be required after the copper process step in order to obtain the best uniformity for the complete stack with tin-silver on top. In addition to coplanarity, the electrolytic process should allow modification shape of the individual pillar or bump. In this context, a versatile copper electrodeposition process will be discussed that allows adjustment to a broad variety of uniformity parameters and combinations thereof. In combination with suitable tin-silver deposition processes, this process is expected to significantly improve the reliability of copper pillars and bumps for advanced packaging applications.

The Adsorption Structure of Polyethylene Imine on Copper Surfaces for Electrodeposition

Challenging copper electrodeposition processes for semiconductor applications require in depth understanding of the mode of operation of the organic plating additives. For this purpose, polyethylene imine (PEI) as a prototypical leveler additive is investigated by simulations, including adsorption at the interface between copper as well as chloride‐covered copper and water. Conformational analysis of the dihedral angles along the polymer chain allows insights into structural changes upon adsorption of the molecules in comparison with the bulk electrolyte. Distribution of the respective atoms of the polymeric molecules sorted by elements along the surface normal further provides information about the orientation. Both conformational changes and orientation depend on the degree of protonation, i.e., the pH value or acid concentration of the electrolyte. The results are compared with electrochemical and spectroelectrochemical data to confirm the accuracy of the simulations and to allow correlation to the performance in the actual deposition process.

Interface adhesion enhancement by condensed aromatic ring expansion of naphthalene imide derivatives for microvia metallization by copper electroplating

Copper electrodeposition is the preferred approach to fabricate the metallic part of printed circuit board (PCB). However, super-filling of the highly variable topography requires chemical additives, particularly leveler. Herein, three water-soluble naphthalene imide derivatives (NPI) were rationally synthesized and applied as levelers for microvias electrodeposition. Due to the expansion of aromatic ring of naphthalene, the adhesion of NPI to copper surface is improved. Comprehensive electrochemical measurements and microvia deposition experiments demonstrate that the adhesion enhancement of the leveler brings about better filling performance. Theoretical calculations unveiled that the variations of the condensed aromatic ring is the main reason for the change of the bandgap and of the adsorption energy of NPI toward the copper surface. Upon using the heptacyclic NPI (1c) as leveler, a thin copper film with thickness of the order of nanometer was achieved, which is of considerable importance for the building-up high-density-interconnected PCB. Finally, potentiodynamic polarization and secondary ion mass spectrometry measurements were used to investigate the consumption and incorporation of NPI 1c into the copper film upon the deposition process, in order to optimally parametrize the usage of NPI 1c during the copper electrodeposition process.

CFD Approach to Investigating Electrochemical Hydrodynamics and Mass Transport in a Copper Electrodeposition Process Using a Rotating Disk Electrode

CFD Approach to Investigating Electrochemical Hydrodynamics and Mass Transport in a Copper Electrodeposition Process Using a Rotating Disk Electrode

ELECTRODEPOSITION OF COPPER IN ULTRASONIC FIELD FROM SPENT ETCHING SOLUTIONS

It is studied the regeneration and utilization possibility of spent nitric acid solutions for copper and its alloys etching for the creating an environmentally clean closed-cycle production of regenerated electrolytes. It is established that some difficulties arise when using the electrochemical method in the regeneration process of these solutions: during copper electrodeposition from spent copper-containing nitric acid solutions, nitric acid decomposes with vigorous evolution of nitrogen dioxide, which prevents copper ions reduction. In order to suppress the side process, it was proposed to partially neutralize the solution, not reaching the pH of copper hydration (pH 4-5). It is revealed that a decrease in the concentration of metal cations occurs due to partial neutralization of the nitric acid contained in the solution by concentrated alkali solution. The pulsed electrolysis mode was used to increase the efficiency of the metal ions electrodeposition process from dilute solutions. It is established that the using of pulsed electrolysis can reduce diffusion difficulties that arise in a dilute spent nitric acid copper-containing solution, thereby intensify the process of copper electrodeposition. It is showed that the prospects of using ultrasound to increase the rate of the copper electrodeposition process and improve the quality of the resulting coating. It is studied the ultrasound field effect on nucleation during copper electrodeposition in a pulsed mode from a partially neutralized electrolyte simulating the spent nitrate solution of etching copper alloys on various materials by the potentiostatic. It is established an increase in the number of copper nucleus that form on the studied substrates (graphite, copper, steel) at the initial time under the action of an ultrasonic field. It is concluded that the use of ultrasound allows to intensify the process of metal electrodeposition. An increase in current efficiency during copper electrodeposition and an increase in the copper extraction degree using ultrasonic field are achieved at lower cathodic current densities in a pulse. It is substantiated using of graphite foil and steel as cathode materials in the copper extraction from the spent nitric acid etching solution.

In-situ electrochemical SPR study of gold surface smoothing by repetitive cathodic deposition and anodic dissolution of copper in an ionic liquid

Abstract We performed in-situ analysis of the initial process of copper electrodeposition in an ionic liquid (IL), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (C4mimTFSA), using electrochemical surface plasmon resonance (ESPR), where the SPR resonance angle (Δθ) was recorded simultaneously with cyclic voltammograms (CVs) at the gold interface of C4mimTFSA. Δθ shifted at the potentials where faradaic current appears in the CVs, indicating that SPR probes the redox processes of copper between Cu2+, Cu+, and Cu metal. In stark contrast to the fact that the CVs are not cycle dependent, the amount of the Δθ shift due to the copper electrodeposition decreased with increasing the CV cycle. A model reflectivity analysis using the Bruggeman effective medium approximation predicted that this decrease in Δθ is due to the decrease in the roughness of the gold surface, and it was actually confirmed by ex-situ atomic force microscopy observation. Since the dissolution of gold was found to be negligible from the atomic absorption measurement of IL after the ESPR measurements, the roughness decrease of the gold surface is likely due to the surface diffusion of gold atoms promoted during copper electrodeposition and dissolution processes. It was found that ESPR can track the surface roughness change of the gold electrode in an in-situ manner in the order of A.

An integrated capture of copper scrap and electrodeposition process to enrich and prepare pure palladium for recycling of spent catalyst from automobile

The coordinated treatment for two kinds of waste is an effective way to save energy and improve the recovery efficiency of resource. In worldwide, more than half of palladium is used to produce catalysts in automobile. However, with the increasing consumption of palladium, the scarcity of palladium resource is becoming prominent. This paper proposed an integrated process based on capture of copper scrap and electrodeposition process to recycle palladium in spent catalysis from automobile. The technological process mainly consisted of two procedures: capture of copper scrap with the purposes of enriching palladium and electrodeposition process with the purposes of separating and purifying palladium. Several highlights were summarized as follows: (i) a capture mechanism of palladium by copper scrap was studied by the calculation of surface thermodynamics and first principles. (ii) Optimum designs, parameter and product analysis were developed to guide industrial recycling. The appropriate parameters for capture of copper scrap are the melting temperature reached 1400 °C, adding 20% dosage of copper scrap and 2 of mass ratio of SiO2/Al2O3 and for the electrodeposition process, nearly 100% of palladium was deposited on the cathode under 0.1 M concentration of HNO3, −0.042 V of electrodeposition potential and 25 °C reaction temperature with 9 h. (iii) This process overcame the shortages of traditional process and showed its efficiency and environmental performance. This study is significant for high-efficient, low-cost and environment-friendly recycling of valuable resource in spent catalysis from automobile.

Study of the Nucleation and Growth Mechanisms of Copper Electrodeposition on Bare and Nitrogen-Doped Reduced Graphene Oxide Modified SnO2:F/glass Substrates

In this article, the influence of a nitrogen-doped electrochemically reduced graphene oxide layer on the nucleation and growth mechanisms of copper electrodeposition was studied. Thus, copper electrodeposition from an acidic solution was evaluated using two different substrates: fluorine-doped tin oxide (FTO), and fluorine-doped tin oxide covered with a nitrogen-doped reduced graphene oxide layer (FTO/N-ERGO). In both cases, chronoamperometric curves were obtained, which were analyzed and deconvoluted using pre-established models and equations, where the different contribution and nucleation parameters were determined. Field emission scanning electron microscopy (FESEM) images were acquired in order to observe the morphology and verify the nuclei density for each case considered in this study. In the case of copper electrodeposition onto FTO, an instantaneous three-dimensional nucleation was observed, together with a proton reduction reaction. When FTO/N-ERGO was used as a substrate, a new instantaneous two-dimensional nucleation process was observed in addition to the processes previously described. Furthermore, the increased density of active sites and the changes in copper morphology are directly related with the N-ERGO layer, which also increased the kinetic constant for the proton reduction reaction and the nucleation rate per active site during the copper electrodeposition process.

Optimized ECD Cu RDL Process with Via Filling Capability for Next Generation Packaging

Abstract Next generation mobile devices, especially those with 5G capability, will require higher functionality and speed in combination with shrinking component as well as package dimensions. These requirements pose challenges to upcoming heterogeneous integration. In order to account for the increasingly complex technologies, filling of vias with copper will be required for packaging of the various components. Examples for such via filling applications include next generation radio frequency (RF) filters and multilayer redistribution layers (RDLs). However, the size scales of these applications vary from 100 μm to sub 5 μm. In addition to via filling of different dimensions and aspect ratios, the copper electrodeposition process is also supposed to be able to plate lines and pads within the RDLs. A combination of electrochemical and spectroscopic experiments was applied to optimize organic plating additives with respect to their suitability to deposit copper into this broad variety of structures.

Editors' Choice—Simulation of Copper Electrodeposition in Through-Hole Vias

Copper electrodeposition processes for filling metallized through-hole (TH) and through-silicon vias (TSV) depend on spatially selective breakdown of a co-adsorbed polyether-chloride adlayer within the recessed surface features. In this work, a co-adsorption-dependent suppression model that has previously captured experimental observations of localized Cu deposition in TSV is used to explore filling of TH features. Simulations of potentiodynamic and galvanostatic TH filling are presented. An appropriate applied potential or current localizes deposition to the middle of the TH. Subsequent deposition proceeds most rapidly in the radial direction leading to sidewall impingement at the via center creating two blind vias. The growth front then evolves primarily toward the two via openings to completely fill the TH in a manner analogous to TSV filling. Applied potentials, or currents, that are overly reducing result in metal ion depletion within the via and void formation. Simulations in larger TH features (i.e., diameter = 85 μm instead of 10 μm) indicate that lateral diffusional gradients within the via can lead to fluctuations between active and passive deposition along the metal/electrolyte interface.

(Invited) Enabling Fan-out Wafer-Level Package (FOWLP) through Innovative Copper Electrodeposition Processes

IC packaging technology has evolved in a quite diverse manner over the past decade, addressing both high-end and low-end applications, resulting in approaches such as package-on-package (PoP), fan-out wafer-level package (FOWLP), 3D IC integration with through-silicon via (TSV), and 2.5D with TSV-Si interposer. FOWLP technology offers significant cost and performance advantages relative to other packaging approaches and is therefore receiving widespread adoption throughout the industry for applications such baseband processor and applications processor (AP). It is anticipated that this technology may be extended for high-end devices such as field-programmable gate array (FPGA) and graphics processing unit (GPU). As a result, FOWLP technology is expected to ramp at a strong growth rate over the immediate future. FOWLP technology comprises conventional under-bump metallization (UBM) and pillar/micro-pillar, as well as new routing/connection applications such as fine-line redistribution layer (RDL) (sub 5x5 mm), integrated via-RDL structures, and mega pillars (>150 mm). These new applications drive fundamental challenges in electrodeposition. Fine-line RDL applications present challenges for both lithography and electrochemical deposition (ECD) processes. For wafer handling, the reconstituted wafers used in FOWLP can exhibit significant warpage and maintaining feature dimensions across wafer topography becomes challenging. New electroplating technology is required to prevent physical degradation of the fine-line RDL. Etchants used for copper (Cu) wet etch will preferentially attack the interface between the Cu ECD line and the Cu physical vapor deposition (PVD) seed layer, resulting in an undercut that degrades the mechanical reliability. This undercut can be minimized by using innovative electroplating technology to reduce the thickness of the Cu PVD seed layer. Thermal cracking of the Cu line has also been posed as a key integration challenge. Grain engineering is discussed as one potential solution to overcome this issue. Many of the current FOWLP approaches include the adoption of multi-layer RDL which are fabricated from low dielectric polymer passivation layers and Cu ECD lines. Multi-layer RDL patterns can result in significant topography variation, which can impact other process integration challenges such as control of critical dimensions (CDs). To minimize topography variation, a new ECD reactor design is used to provide ultra-uniform Cu ECD. Mega pillars consist of 180-220 mm (200 mm average) Cu thickness while standard Cu pillar applications typically vary between 20 and 40 μm (30 mm average) thickness. This large disparity in thickness can translate to approximately 6x longer plating times if a similar deposition rate is used. The process of plating large features employed as interconnects often encounters mass transport limitations that can curtail the deposition rate. This effect is explored in detail via computational modeling. The aspect ratio of through-resist features is shown to have a severe impact on minimum fill time, where a high (4:1) aspect ratio feature takes more than 7.5 times as long to fill as a low (1.2:1) aspect ratio feature. Convection of the electrolyte above the surface of the photoresist, which is largely influenced by the ECD reactor design, is shown to have a pronounced impact on fill times over the range of feature dimensions. Furthermore, some integration requirements for mega pillars warrant extremely high within-die uniformities and flat bump shape. Attaining such high-quality plating performance can greatly minimize the downstream planarization requirements. This paper will focus on new innovations in Cu ECD processes for fine line RDL, multi-layer RDL, and mega pillar to enable FOWLP technology.

Monitoring of SPS Concentration by the Ring Current Using a Rotating Ring-Disk Electrode with Dissolving Disk Copper to Refresh a Void Free Solution

We have devised a new method of monitoring using a rotating ring-disk electrode (RRDE) with dissolving disk copper during copper electrodeposition process. The ring current shows linear relationship with SPS concentration from 0 to 3.5 ppm. To minimize the effects of other additives on ring current monitoring, we have conducted cyclic voltammetry stripping (CVS) to estimate the amount of polyethylene glycol (PEG) and sulfonated diallyl dimethyl ammonium chloride copolymer (SDDACC), the leveler. Through silicon via (TSV) fillings have been carried out to check the void free filling of solutions. The electrolyzed solution has been prepared, after 96 hours of electrolysis, voids are formed in electrodeposition of TSV with current density 3 mA/cm2. After monitoring and adding SPS, PEG and SDDACC, we have achieved a void free filling. Therefore, electrodeposition solution is refreshed even with three organic additives.

Parameters determination for modelling of copper electrodeposition in through-silicon-via with additives

Copper electrodeposition in through silicon via (TSV) with additives is a complicated process. Experimental methods are proposed to determine parameters (exchange current density on the cathode covered by additives, cathodic transfer coefficient and effective diffusion coefficient of additives) which are used in the mathematical model describing the copper electrodeposition process controlled by the additives. Linear scan voltammetry and Bulter-Volmer equation are used to determine the exchange current densities and cathodic transfer coefficients for different cathodic surfaces (free-occupied cathode, accelerator-covered cathode and suppressor-covered cathode). Effective diffusion coefficients of additives in plating bath used in TSV-filling model are calculated according to injection experiments and Wilke-Chang equation. The curvature effect, surface diffusion and surface convection are considered in the copper electrodeposition model. Both numerical simulation and experiment are performed on the copper electrodeposition of TSV with ∅20 μm × 65 μm, and comparisons are made to validate the model. The dynamic profile of TSV and the corresponding surface coverage of additives are analyzed to explain the mechanisms of additives in the process of TSV filling.

Influences of magnetic field on the fractal morphology in copper electrodeposition

Copper magneto-electrodeposition (MED) is used decrease roughening in the copper electrodeposition process. This technology plays a vital role in electrodeposition process to synthesize metal alloy, thin film, multilayer, nanowires, multilayer nanowires, dot array and nano contacts. The effects of magnetic fields on copper electrodeposition are investigated in terms of variations in the magnetic field strength and the electrolyte concentration. Based on the experimental results, the mere presence of magnetic field would result in a compact deposit. As the magnetic field strength is increased, the deposit grows denser. The increment in concentration also leads to the increase the deposited size. The SEM image analysis showed that the magnetic field has a significant effect on the surface morphology of electrodeposits.

Influence of Glycerol on Copper Electrodeposition from Pyrophosphate Bath: Nucleation Mechanism and Performance Characterization

In order to elevate the allowable current density of pyrophosphate bath, glycerol was employed as additive for copper electrodeposition, and its influences on cathodic current efficiency, coordination environment, electrodeposition behavior and coating properties of conventional pyrophosphate bath were systematically investigated. It was demonstrated that glycerol did not change the coating's nucleation mechanism and purity, and had almost no effect on the bath's current efficiency, but effectively improved the allowable current density, increased the cathodic over-potential, and suppressed the hydrogen evolution in copper electrodeposition processes by absorption onto electrode surface. Specially, the coating electrodeposited from this optimized bath also had lower porosity and smaller micro-strain than that of produced from conventional pyrophosphate bath. Detailed analyses were conducted to clarify the mechanism responsible for the improvements.

Carbon Nanotube Fiber Pretreatments for Electrodeposition of Copper

There is increasing interest towards developing carbon nanotube‐copper (CNT‐Cu) composites due to potentially improved properties. Carbon nanotube macroscopic materials typically exhibit high resistivity, low electrochemical reactivity, and the presence of impurities, which impede its use as a substrate for electrochemical deposition of metals. In this research, different CNT fiber pretreatment methods, such as heat treatment, immersion in Watts bath, anodization, and exposure to boric acid (H3BO3), were investigated to improve the electrochemical response for copper deposition. It was shown that these treatments affect the surface activity of CNTs, including electrical resistivity, polarization resistance, and active surface area, which influence the electrodeposition process of copper. Properties of CNT structures and CNT‐Cu composites were researched by electrochemical impedance spectroscopy (EIS), galvanostatic copper deposition, scanning electron microscope (SEM), and four‐point electrical resistance measurements. Heat treatment, Watts bath, anodization, and boric acid treatments were shown to be effective for modifying the CNT surface reactivity for subsequent electrochemical deposition of copper.

Electrodeposition of Copper for Three-Dimensional Metamaterial Fabrication.

Metamaterials typically consist of metallic and dielectric repeating structures. Electrodeposition of copper is the preferred approach to fabricating the metallic part of the metamaterials of interest in this study. The highly variant topography requires chemical additives, like chloride ions, 3-mercapto-1-propanesulfonic acid (MPSA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP) to enhance bottom-up superfilling while maintaining terrace flatness. This study focuses on both experimental and computational investigations of the degradation potential of the additives and their adsorption mechanism in a highly acidic copper electrolyte in order to optimally parametrize the copper electrodeposition process. Results show Cl-MPSA-PEG-PVP additives perform well, but substitution of PVP with Janus Green B provides better terrace leveling. Additionally, NMR data show a quick and complete conversion of MPSA to bis(3-sulfopropyl) disulfide (SPS) in the acidic copper bath. Finally, FEM simulations further show that the accelerator species may initially accumulate and be transported vertically until overplating, whereby they are transported laterally.

Effects of Laser Irradiation on a Copper Electrodeposition Process and Coating Quality

Effects of Laser Irradiation on a Copper Electrodeposition Process and Coating Quality