Use Of Linear Sweep Voltammetry Research Articles

A high-uniformity, high-purity copper pillar ECP process with limited acid concentration

The requirements for wafer-level packaging (WLP) are becoming more and more stringent both from a sustainability perspective and process performance. For instance, there is a demand for continuous process improvement for within die uniformity (WID) and operating in a low acid environment for copper pillar plating. Antagonistic these requests are; however, we must devise novel ECP techniques and additive designs to meet such ambitious targets. The additives consist of an accelerator, suppressor, and leveler. The systematic use of Linear Sweep Voltammetry (LSV) aided the study of the electrochemical response to screen the additives and determine the Wagner number (Wa) in the current density region of interest. In addition, the rigorous use of the Design of Experiment (DOE) enabled us to determine the concentrations for combining this new leveler and suppressor with the accelerator. Owing to designing the right leveler and suppressor, we controlled the free acid concentration at 10% (100 g/L) while maintaining the WID below 2.5% and controlling the within-feature (WIF) less than 1µm (~2.0%), using a deposition rate of approximately 2.0 µm/min, to various wafer patterns with various aspect ratios and layouts. Lastly, the resulting film properties are as crucial as ECP performance. SIMS studies support a deficient level of inclusion in the copper film with a total impurity of 3.1 ppm, including C, O, N, S, and Cl. Therefore, when studied with a solder cap, the Kirkendall void performance was outstanding based on minimal voids post 10X reflow cycles and high-temperature storage. The shear stress test measuring the bonding between the copper and its pad on the wafer is 18.4 gf/mil2.

Low-cost voltammetric sensor based on an anionic surfactant modified carbon nanocomposite material for the rapid determination of curcumin in natural food supplement

A highly sensitive and selective voltammetric method was developed for the determination of curcumin using sodium dodecyl sulfate modified carbon nanocomposite paste electrode. The electrochemical performance for curcumin was characterized by the use of linear sweep voltammetry, cyclic voltammetry, and differential pulse voltammetry. These measurements showed that the sodium dodecyl sulfate modified carbon nanocomposite paste electrode provided excellent electrocatalytic enhancement for the oxidation of curcumin compared to an unmodified carbon nanocomposite paste electrode. Using the optimized conditions, the oxidation peak current showed a linear response from 2 × 10−7 to 1 × 10−6 M and 1.5 × 10−6 to 4.5 × 10−6 M with a detection limit equal to 2.7 × 10−8 M and limit of quantification equal to 9.2 × 10−8 M. The simultaneous determination of curcumin and vitamin B2 included a well resolved peaks, that provides rapid and selective analysis in the presence of vitamin B2. Moreover, the practical application of the developed electrode was performed for the analysis of a natural food supplement for curcumin.

Protonic EDLC cell based on chitosan (CS): methylcellulose (MC) solid polymer blend electrolytes

In this work, preparation and application of solid polymer blend electrolytes (SPBEs) based on chitosan: methylcellulose (CS:MC) incorporated with various amounts of ammonium iodide (NH4I) salt are described. Solution cast technique was adapted for the preparation of the SPBE films. Structural investigation and extent of interaction of the NH4I salt with the CS:MC film surface were conducted through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements. Electrical DC conductivity of the prepared samples was studied by electrochemical impedance spectroscopy. It is confirmed through transference number (TNM) analysis that ions are the dominant charge carrier in the polymer electrolyte system, in which the ionic (tion) and electron (tel) transference numbers were found to be 0.934 and 0.036, respectively. Through the use of linear sweep voltammetry (LSV), the CS:MC:NH4I system is found to experience electrolyte degradation at 2.1 V. The polymer blend electrolyte sample with highest DC conductivity property was also used as separator in electrical double-layer capacitor (EDLC) cell. Two identical activated carbon electrodes were used to sandwich the electrolyte film. Cyclic voltammetry (CV) was used to show the capacitive behavior of the fabricated EDLC cell, in which no redox peaks were observed. The EDLC was examined for 100 cycles at current density of 0.2 mA/cm2. The values of specific capacitance and equivalent series resistance were determined to be 1.76 F/g, and 650 to 1050 Ω, respectively.

Unveiling the Hard Anodization Regime of Aluminum: Insight into Nanopores Self-Organization and Growth Mechanism

Pores growth mechanism and their self-ordering conditions are investigated for nanoporous alumina membranes synthesized by hard anodization (HA) of Al in a broad range of anodic conditions, covering oxalic acid electrolytes with concentrations from 0.300 M down to 0.075 M and potentiostatic anodization voltages between 120 and 225 V. The use of linear sweep voltammetry (LSV) and scanning and transmission electron microscopy, together with image analysis techniques allow one to characterize the intrinsic nature of the HA regime. HA of aluminum is explained on the basis of a phenomenological model taking into account the role of oxalate ions and their limited diffusion through alumina nanochannels from a bulk electrolyte. The depletion of oxalate ions at the bottom of the pores causes an increased growth of the alumina barrier layer at the oxide/electrolyte interface. Furthermore, an innovative method has been developed for the determination of the HA conditions leading to self-ordered pore growth in any given electrolyte, thus allowing one to extend the available range of interpore distances of the highly ordered hexagonal pore arrangement in a wide range of 240-507 nm, while keeping small pore diameters of 50-60 nm.

Synthesis and Comparative Study of Nanoporous Palladium-Based Bimetallic Catalysts for Formic Acid Oxidation

In view of the inherent limitations of current portable technology energy sources, the implementation of micro fuel cells is becoming increasingly appealing. This has generated great interest in the development of direct formic acid micro fuel cells. In this study, nanoporous Pd and four nanoporous bimetallic Pd-M catalysts with an atomic ratio of 90:10, where M = Cd, Pb, Ir, and Pt, were synthesized via a facile hydrothermal method and examined for the electrochemical oxidation of formic acid. The electrocatalytic activity of these nanoporous electrode materials was studied with the use of linear sweep voltammetry and chronoamperometry. Our chronoamperometric measurements have shown that the initial electrochemical performance of the nanoporous Pd-M electrodes toward formic acid oxidation was almost independent of the alloying materials; however, the second incorporated metal strongly affected the stability of the Pd-based electrocatalysts. The mechanisms of the oxidation of formic acid were further examined with the aid of in situ electrochemical ATR-FTIR spectroscopy. For the nanoporous Pd, PdCd, and PdPb catalysts, oxidation proceeds through the direct mechanism, whereas the indirect mechanism, along with major CO poisoning, was observed in the case of the PdIr and PdPt catalysts. The incorporation of even small amounts of Pt and Ir to Pd was found to inhibit the oxidation of formic acid. On the other hand, the addition of Pb to Pd served to promote the direct mechanism, which in turn makes these Pd-based catalysts both cost and electrocatalytically more effective.

Voltammetric Sensor for Total Cholesterol Determination

We report on a voltammetric sensor for the detection of total cholesterol. The sensor was fabricated by co-immobilization of two enzymes: cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) on porous graphite. The electrochemical behavior of the sensor was studied with the use of linear sweep voltammetry. It has been shown that the sensor has high stability and high sensitivity (16μA mM−1 cm−2). The biosensor exhibited a wide linear range up to 300mol/dm3 in a condition close to physiological (pH=6.86). Besides, the interferences of some key analytes containing in the blood were studied. As a matter of fact, making a fabricated sensor is rather promising for using in clinical practice.

The Use of Linear Sweep Voltammetry in Condition Monitoring of Diesel Engine Oil

Abstract One of the main ways to decrease engine oil changes is to increase drain intervals. Although it has been a controversial subject for years, increased drain intervals can be accomplished safely using lubricant analysis. Over the years, many diesel engine operators have effectively employed used oil analysis to extend engine oil drain intervals safely by monitoring the condition of the oil and the engine. Various tests have been used for the monitoring of engine oil. However, although it has been used for years to evaluate the remaining useful life of industrial lubricants, linear sweep voltammetry has not been used for routine monitoring of engine oil. This paper will show how linear sweep voltammetry can be an effective method for maximizing extended drain intervals in an over-the-road heavy-duty trucking fleet.

Differentiation between phenol- and amino-substances in voltammetry determination of synthetic antioxidants in oils

Abstract The paper describes a method of voltammetric determination of antioxidants in lubricating oils developed with the use of Linear Sweep Voltammetry (LSV) and Fast Scan Differential Pulse Voltammetry (FSDPV). Experimental conditions have been found for simultaneous determination of phenol-based antioxidants and amino-antioxidants: the phenols can be electrochemically oxidized using the polarisation of gold disc electrode (AuDE) in the potential range of 0–1400 mV in 0.2 M H2SO4 in the presence of ethanol and acetonitrile at the ratio of 3:1. Secondary aromatic amines can be determined directly in this supporting electrolyte; the presence of phenolic antioxidants does not interfere with this analysis. On the other hand, secondary aromatic amines interfere with the determination of phenolic substances; therefore, the amines present have to be eliminated in a suitable way. A procedure for masking the aromatic amines using their reaction with nitrous acid has been suggested and optimised. The nitrosamines thus formed can be used for sensitive and selective determination of amino-antioxidants by means of cathodic reduction on the hanging mercury drop electrode (HMDE) using Fast Scan Differential Pulse Voltammetry. The method was applied in analysis of real samples of lubricating oils.

Investigation of the Metal–Oxide Buried Interfacial Zone with Linear Sweep Voltammetry

Interest in copper as a technologically important material needs to be met with greater understanding of the fundamental chemical reactions of copper. In particular, there is still a lack of universal agreement on the oxidation process of bulk copper and thin copper films. In this study, the authors demonstrate the use of linear sweep voltammetry (LSV) to study buried structures in the oxide layers on copper. In particular, LSV can be used to detect reactions at buried interfaces. It is also emphasized that surface scientists should recognize Cu3O2 and the decomposition of copper oxides at the metal–oxide interface in new studies on copper oxidation and in interpreting already existing copper oxidation data. The two key parameters that drive oxide growth and decomposition are demonstrated to be oxygen activity and the free energies of formation of the oxides (per mole of oxide ion). The complex nature of the oxidation of copper, as well as other metals and alloys, can be described qualitatively using the Modified Cabrera–Mott (C–M) Model. Surface studies of oxidation of metals and alloys need to be supported and complemented by other techniques such as chemical or electrochemical methods.

Electrochemical Properties Of Copper Oxide Surfaces, Buried Interfaces, And Subsurface Zones And Their Use To Characterize These Entities

ABSTRACTElectrochemistry of oxides is an expanding area of oxide characterization. Although, interfacial characterization techniques including surface science methods have contributes substantially to our current understanding of the processes involved in the oxidation of metals and alloys. The characterization of subsurface zones and buried interfaces still remain a major challenge. Copper reactions with oxygen have been studied by high vacuum based techniques of AES, ELS, ISS, XPS. SIMS, LEED. STM, SEXAFS, HEIS and PFDMS and with optical methods, like UV-Vis-NIR, diffuse reflectance spectroscopy, FTIR and photoluminescence spectroscopes. However it has become evident that the processes that produce thermally and plasma grown oxide films on metals and alloys are electrochemical in nature and can be modeled by electrochemical concepts. Therefore, it is important that the oxide over layers, thin films and thick films be characterized by electrochemical means -with electrochemical methods, such as linear potential sweep voltammetry, cyclis voltammetry, galvanostatic reduction and coulometry which allow the identification of copper (I), copper (II) and copper (III) oxides. Interest in copper as a technologically important material needs to be met with greater understanding of the fundamental nature of copper oxide structures. In this study, the authors demonstrate the use of Linear Sweep Voltammetry (LSV) to study buried structures in the thermally grown oxide layers on copper. In particular, LSV can be used to detact reactions at buried interfaces. It also recognizes Cu3O2 and the decomposition of copper oxides at the metal-oxide layers on copper. In particular, LSV can be used to detect reactions at buried interface. The two key parameters that drive oxide growth and decomposition are demonstrated to be oxygen activity and the free energies of formation of the oxides. The complex nature of the oxidation of copper, as well as other metals and alloys, will be described qualitatively using the Modified Cabrera-Mott (C-M) Model. Surface studies of oxidation of metals and alloys need to be supported and complemented by other techniques such as electrochemical methods.

Investigation of LiMn 2O 4 cathodes for use in rechargeable lithium batteries by linear sweep voltammetry : Part I. Theoretical study

Linear sweep voltammetry (LSV) is a well-known tool for electrochemical investigations. Different aspects on the use of LSV in the study of an intercalation electrode in the rechargeable lithium battery system have been studied. Mathematical models were used to simulate voltammetry responses for an intercalation material influenced by solid phase diffusion, charge transfer and IR-drop. It was shown how the peak potential and the peak current density vary with sweep rate for different rate determining processes. The simulations show that finite and semi-infinite diffusion is relatively easy to distinguish and also, these two processes behave differently from processes influenced by charge transfer and an external IR-drop. However, the separation of charge transfer and IR-drop is difficult. The use of the convolution sweep voltammetry method was also investigated. It was found that finite diffusion and a non-zero initial concentration limit the applicability in these systems.

Electrochemical kinetic parameters for the cathodic deposition of copper from dilute aqueous acid sulfate solutions

AbstractThe use of linear‐sweep voltammetry and chronopotentiometry for the determination of kinetic parameters for the electrolytic recovery of copper from a simulated acid‐copper electroplating waste solution was demonstrated. For the electrodeposition of copper from solutions of 0.007˜0.008 mol/L CuSO4 + 0.5 mol/L H2SO4 at 25°, the recommended values of the transfer coefficient (α) and exchange current density (i0) are α = 0.46±0.06 (95% confidence interval) and i0 = 11±4 A/m2. The close agreement between these values and the available literature values indicates the reliabilaity of the voltammetric and chronopotentiometric methods.

A voltammetric study of galena immersed in acetate solution at pH 4.6

The electrochemistry of galena in an acetate solution at pH 4.6 has been studied through the use of linear sweep voltammetry. Analysis of the voltammograms for anodic limits as high as 845 mV indicates that S0 is the sulphur-bearing species generated during the oxidative dissolution of galena. Furthermore, interpretation of the electrochemical data on the basis of thermodynamic considerations indicates that galena interacts with the acetate electrolyte and that Pb(CH3COO)2(aq) is also produced during anodic oxidation. When the scan direction is reversed in the cathodic direction, the oxidation products are removed by two reduction reactions when the solution is quiescent: the recombination of Pb(CH3COO)2 and S0 to form PbS and the reduction of S0 to H2S. In a stirred solution, only the second reaction is possible. Experiments conducted in the presence of 10−3 or 10−2 M lead acetate indicate that the presence of dissolved lead tends to inhibit the dissolution process. Furthermore, metallic lead can begin to deposit on the galena surface when the potential drops below about −330 mV SHE. The data also agree most closely with thermodynamics when Pb(CH3COO)2 is considered to be the aqueous species involved in the deposition and dissolution of metallic lead.

The use of linear sweep voltammetry to study the addition of electrogenerated–CH2CN to aromatic carbonyl compounds

A general electronalytical method for studying the rate of reaction between an electrogenerated species, e.g. nucleophile, base, electrophile, acid, or radical and an electroactive substrate is described. The method has been used to study the addition of electrogenerated –CH2CN to aromatic carbonyl compounds. The cyanomethyl anion has been generated in two ways, (i) by reduction of azobenzene in acetonitrile, which involves protonation of the dianion by the solvent, and (ii) by reduction of cyanomethyltriphenyl-phosphonium and -arsonium cations in dimethylformamide, which involves reductive cleavage. A computer simulation of the electroanalytical experiments is described and representative results are given, including estimates of the rate constants for the addition of –CH2CN to a series of alkyl phenyl ketones.