Benzotriazole Films Research Articles

Study on the corrosion resistance of new reticulated organic polymerized film on copper foil surface

In response to the policy of energy saving and emission reduction, the field of new energy vehicles is booming, and along with it, the technical requirements for lithium-ion batteries are becoming more and more stringent. Electrolytic copper foil, as the anode collector material of lithium batteries, seriously affects the progress of lithium technology, and electrolytic copper foil with high corrosion and oxidation resistance is the key to ensuring its performance. Experimentally, the BTA-Si passivation film layer was constructed on the surface of electrolytic copper foil by compounding benzotriazole (BTA) and silane coupling agent (JH-M902) with an easy-to-operate chemical impregnation method. The results of electrochemical analysis and characterization showed that JH-M902 hydrolyzed to produce Si-OH and then dehydrated and polymerized with Cu-OH to form Si-O-Cu or partially dehydrated and polymerized with each other to form Si-O-Si, which formed an intertwined organic reticulation film on the electrolytic copper foil. At the same time, BTA and copper oxides form a BTA-Cu complex, which is adsorbed and perpendicular to the copper foil. The combination of the two can not only make up for the gap in the organic mesh layer but also anchor the mesh layer, thus inhibiting its desorption in harsh external environments. Immersed in 3.5 wt% NaCl, the self-corrosion current density (icorr) of BTA-Si passivation film is only 1.115 × 10−7 A/cm2, and the corrosion inhibition rate as high as 99.56 %, which is far better than that of the single BTA and Si passivation film. In addition, the BTA-Si passivation film is smooth, dense, and thin, which significantly improves the corrosion resistance of copper foil without changing its original structure.

Flow-through electrochemical removal of benzotriazole by electroactive ceramic membrane

Benzotriazole (BTA) is a widely used anticorrosive additive that is of endurance, bioaccumulation and toxicity, and BTA industrial wastewater treatment remains a challenge. This study reports efficient electrochemical removal of BTA by titanium oxide (TiSO) electroactive ceramic membrane (ECM), indicated by 98.1% removal at current density of 20 mA∙cm−2 and permeate flux of 692 LHM under cathode-to-anode flow pattern (1 h). Electrochemical analysis demonstrated the pH-dependent formation of anti-corrosive BTA film on the TiSO anode, which was responsible for improved BTA removal for cathode-to-anode (CA) flow pattern compared with that for anode-to-cathode (AC). The modelling results showed the CA flow pattern to be more favourable for BTA oxidation mediated by electro-generated •OH by preventing the formation of deactivation film via creating an alkaline boundary layer at the anode/electrolyte interface. Intermediates and essential active sites were identified by using experimental analysis and theoretical density functional theory (DFT) calculations, thereby the most likely degradation pathways were underlined. Toxicity analysis revealed remarkable decrease in oral rat LD50 values and bioaccumulation factor during electrochemical degradation of BTA. This study provides a proof-in-concept demonstration of effective removal for anti-corrosive emerging pollutants by TiSO-ECM under flow-through pattern.

Thin Benzotriazole Films for Inhibition of Carbon Steel Corrosion in Neutral Electrolytes

This article investigates the modification of a carbon steel surface by benzotriazole (BTA), and the structure and properties of the formed layers. Adsorption was studied by surface analytical methods such as X-ray photoelectron spectroscopy (XPS) and reflecting infrared microscopy (FTIR). It has been established that a polymer-like film containing iron-azole complexes that are 2 nm thick and strongly bonded to the metal is formed on the surface as a result of the azole interacting with a steel surface. This film is capable to inhibit uniform and localized corrosion of steel in neutral aqueous electrolytes containing chloride ions. It is shown that the iron-azole layer located at the interface acts as a promotor of adhesion, increasing the interaction of polymeric coatings with the steel surface. Taking into account these properties, the steel pretreatments can be used for improving the anticorrosion properties of polymeric coatings applied for the protection of steel constructions.

(Invited) Quantification and Characterization of Adsorbed BTA on Copper Surfaces Under Conditions Relevant to Barrier CMP

In the formation of copper interconnects by CMP, barrier polishing is typically carried out using alkaline slurries containing copper corrosion inhibitors. Benzotriazole (BTA) has been the inhibitor of choice in such slurries. The effect of BTA on copper corrosion has been extensively studied in the past few decades, and there is general agreement that the adsorbed film formed in acidic solutions is a multilayer film with a chemisorbed first layer. However, simultaneous real time measurement of the amount of BTA adsorbed and characterization of nature of the adsorbed film (rigid/viscoelastic) has received very little attention. The objective of this work was to measure the extent of BTA adsorption onto PVD Cu films and characterize the nature of the adsorbed film in real time using a quartz crystal microbalance with dissipation monitoring (QCMD) capability. Quartz crystals (fundamental frequency of 5 MHz) coated with ~300 nm PVD copper layer were used in the experiments. To mimic the conditions during barrier polishing, BTA dissolved in alkaline solutions was pumped through the flow cell containing the crystal, and the change in crystal oscillation frequency and dissipation data were collected at a time resolution of fraction of a second for several minutes. This was followed by rinsing with DI or solutions containing selected surfactants to determine extent of desorption of BTA. As an example, adsorption of BTA from a solution of pH 10 is shown in figure 1. The measured frequency shift (Δf) and dissipation shift (ΔD) at different overtones (multiples) of crystal fundamental frequency are plotted as a function of time. At the time marked with t1, a sharp decrease of frequency may be seen, which indicates rapid adsorption of BTA. The data points for all frequencies fall on one curve indicating that the adsorbed BTA film on copper is quite rigid in nature. This is confirmed by very little measured change in the ΔD values. At the end of adsorption marked with t2, deionized water was introduced into the system, and the positive shift of frequency is indicative of BTA removal and/or etching of copper in DI water. In the presentation, results of adsorption and desorption experiments carried out under different experimental conditions will be presented. The disruption of adsorbed BTA layer by selected chemicals will be addressed. Figure 1

The interaction between CuO and inhibitor including Cl− by using molecular dynamics

The high concentration of Cl− in seawater causes serious corrosion of copper and enormous economic losses. In order to reveal the microscopic mechanism and kinetic process of Cl− in different corrosion inhibition films, the diffusion of Cl− in benzotriazole, mercaptobenzothiazole and methyl benzene three nitrogen thiazole and the interaction between CuO (−1 0 0) and three corrosion inhibition films were researched by using molecular dynamic simulation. The research indicated that corrosion inhibition mechanisms of the three films are not the same. The inhibition of benzotriazole and methyl benzene three nitrogen thiazole is mainly because of direct chemical adsorption. However, the inhibition of mercaptobenzothiazole is because of indirect chemical adsorption. The diffusion coefficient of Cl− in benzotriazole, mercaptobenzothiazole and methyl benzene three nitrogen thiazole is 1·634 × 10−5, 1·656 × 10−5 and 1·627 × 10−5 cm2 s−1, respectively. All of them are relatively low, so the three inhibitors can effectively prevent Cl− diffusing into themselves. Furthermore, pore connectivity is worst for benzotriazole film and the membrane structure is more stable than that of methyl benzene three nitrogen thiazole and mercaptobenzothiazole.

Passivation of Copper: Benzotriazole Films on Cu(111)

Benzotriazole (BTAH) has been used as a copper corrosion inhibitor since the 1950s. However, the molecular level detail of how adsorption and surface passivation occur remains a matter of debate. BTAH adsorption on a Cu(111) single crystal has been investigated from medium coverage to multilayer using scanning tunneling microscopy (STM), temperature-programmed desorption (TPD), high resolution electron energy loss (HREEL) spectroscopy and supporting density functional theory (DFT) calculations. Both physisorbed and chemisorbed phases are observed. One extended and highly ordered self-assembled metal−organic phase is seen at saturation coverage and above. A metastable phase is also observed. Complete desorption occurs at ca. 600 K. Those structures are critically discussed in the light of some of the various adsorption models reported in the literature and an alternative adsorption model is proposed. These results allow a further understanding of the interaction between benzotriazole and copper and, in turn, may help understanding the mechanism for protection of copper and copper alloys from corrosion, substantially contributing to a long-standing debate.

Chemical roles on Cu-slurry interface during copper chemical mechanical planarization

In order to optimize the existing slurry for low down-pressure chemical mechanical polishing/planarization (CMP), copper CMP was conducted in H2O2 based slurries with benzotriazole (BTA) and glycine at different pH values. The film composition was investigated by the Nano Hardness Tester and XPS tests. Furthermore, the film structure forming on the copper surface at different pH values was investigated by adopting electrochemical impedance spectroscopy (EIS) technology. In the acidic slurry, discontinuous and porous BTA film covering the Cu/Cu2O surface enhanced the mechanical effect during Cu CMP process, resulted in highest CMP removal rate. In neutral slurry, the lowest CMP removal rate and static corrosion rate were resulted from compacted passivation film on the copper surface. In the alkaline slurry, the mechanical effect was limited by the rapid chemical dissolution. The results will benefit optimization of the slurry and operate conditions during low down-pressure CMP process.

Shell‐isolated nanoparticle enhanced Raman spectroscopy (SHINERS) investigation of benzotriazole film formation on Cu(100), Cu(111), and Cu(poly)

AbstractBenzotriazole (BTAH) is well known as an effective corrosion inhibitor for Cu because of its ability to make a coordination polymer film on the surface that provides a barrier to Cu oxidation. BTA− film formation was investigated on single‐crystal and polycrystalline Cu surfaces with shell‐isolated nanoparticle enhanced Raman spectroscopy (SHINERS) using silica‐encapsulated Au nanoparticles. Potential‐dependent spectra display reversible film formation on polycrystalline Cu and irreversible film formation on single‐crystal Cu. Grain boundaries leading to smaller BTA−‐Cu oligomers are proposed to be the reason for cathodic degradation of the BTA− polymeric films on polycrystalline Cu. Copyright © 2011 John Wiley & Sons, Ltd.

Suppression of Cu Oxidation Using Environmentally Friendly Inhibitors under Conditions of High Temperature and High Humidity for Cu/Low-k

The Cu surface at a via bottom is exposed to conditions of high temperature and high humidity during annealing after the via hole for Cu/low-k interconnection is cleaned. The Cu surface is oxidized by the water desorbed from the low-k film. The suppression of Cu corrosion is a necessary process. Benzotriazole (BTA) has been used as a conventional Cu corrosion inhibitor, but it has a large environmental impact. An environmentally friendly inhibitor to replace BTA is required. In this study, adenine and hypoxanthine are used as environmentally friendly Cu corrosion inhibitors. We have succeeded in effectively suppressing Cu corrosion under conditions of high temperature and high humidity using adenine and hypoxanthine. We have also investigated the desorption temperature of Cu corrosion inhibitor films by thermal desorption spectroscopy (TDS). We have found that adenine and hypoxanthine are stable inhibitors during annealing. Moreover, it is clear from impedance measurements that adenine and hypoxanthine inhibitor films are thinner than BTA films. Adenine and hypoxanthine can readily be applied to next-generation LSI devices.

Impedance and XPS study of benzotriazole films formed on copper, copper–zinc alloys and zinc in chloride solution

The formation of protective layers on copper, zinc and copper–zinc (Cu–10Zn and Cu–40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole was studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper–zinc alloys and zinc metal. The surface layers formed on alloys in BTAH-inhibited solution comprised both polymer and oxide components, namely Cu(I)BTA and Zn(II)BTA polymers and Cu 2O and ZnO oxides, as proved by the in-depth profiling of the layers formed. A tentative structural model describing the improved corrosion resistance of Cu, Cu– xZn alloys and Zn in BTAH containing chloride solution is proposed.

Cu Post-CMP Displacement Cleaning: A Mechanistic Product Development Approach Based on Selected Thermodynamic and Kinetic Data

ABSTRACTA mechanistic product development approach will be presented that utilized selected thermodynamic and kinetic data for development of a Cu post-CMP cleaner for use after polishing with either high or low pH slurry. A Pourbaix diagram offers the thermodynamically stable Cu species vs. pH and open circuit potential (OCP) for an aqueous cleaner. Pourbaix diagrams do not provide any information on the kinetics for dissolution of water soluble species. Cu oxide dissolution rates were measured using an electrochemical cell. Deposition and removal rates for benzotriazole (BTA) and 1,2,4-triazole (TAZ) were measured using an electrochemical cell with a quartz crystal microbalance (QCM). Passivator film deposition was investigated to determine the film type and thickness resulting from a typical CMP process. BTA and TAZ films deposited near neutral pH were thicker than those deposited at high pH. TAZ films were significantly thinner (∼20Å) than BTA films deposited under similar conditions, approaching a self assembled monolayer (SAM). The BTA removal rate for a citrate solution with a pH of 4 was 20Å/min., an order of magnitude lower than that for TMAH-containing solutions. The TAZ removal rate for an oxalate solution with a pH of 4 was 240Å/min., which was twice the removal rate for BTA deposited under similar conditions. An appropriate TAZ solution was found to displace BTA on Cu and leave a hydrophilic, thin (∼20Å) passivating layer of TAZ. Other Cu passivators were also examined but only TAZ protected all Cu crystallographic orientations observed. BTA, 5-aminotetrazole (5-ATA) and 4-carboxybenzotriazole (CBTA) did not protect some Cu crystal orientations, leading to etching of entire grains and increased surface roughness. BTA and CBTA yielded hydrophobic Cu surfaces, leading to surface wetting issues and the potential for watermarks. A new alkaline Cu post-CMP cleaner was developed to remove residues resulting from slurries, regardless of their pH, which utilizes TAZ to displace BTA and protect Cu, significantly lower organic defects, reduce surface roughness, provide a hydrophilic Cu surface, and significantly extend the staging time allowed between the clean process and subsequent wafer processing.

Anion Effects on Cu–benzotriazole Film Formation: Implications for CMP

We examine the effect of different anions in solutions containing benzotriazole (BTA) on the Cu removal rate during chemical mechanical planarization (CMP). In solutions containing both and BTA, the Cu removal rate is nearly a factor of twenty lower than in solutions containing either or BTA alone. As-grown BTA films from solutions containing different anions are characterized using atomic force microscopy, ellipsometry, Raman spectroscopy, mass spectrometry, and open-circuit-potential measurements. Films grown from halide-containing solutions are found to be considerably thicker than those grown from other anions. The difference in Cu removal rate correlates well with the different as-grown film thicknesses.

Adsorption of Benzotriazole on the Surface of Copper Alloys Studied by SECM and XPS

The formation of inhibitive benzotriazole films on copper and copper alloyed with silver has been studied with scanning electrochemical microscopy (SECM) and X-ray photoelectron spectroscopy (XPS). The SECM measurements showed that the film grows rapidly on oxygen-free dehydrated copper (OF-HC) and that the rate depends on the substrate potential. The benzotriazole films were also observed on silver alloyed copper; however, electropolishing prevents film growth by enriching the surface with silver. XPS results show that the film consisted of on both materials. No evidence of was found.

Corrosion of Copper in BTA Solutions

The effect of benzotriazole (BTA) on the open-circuit potential of copper in buffered acid solutions was studied in the absence of the passive Cu(I)BTA film. The film was removed from the surface by in situ continuous scratching of the electrode. At a film-free surface BTA acted mainly as a cathodic inhibitor in contrast to its well-established role as an anodic inhibitor at the film-covered copper surface. The implications for chemical mechanical polishing of copper in BTA-containing slurries are discussed.

Growth of Passivating CuBTA Films on Copper in Aqueous Chloride/Benzotriazole Solutions

The growth of cuprous benzotriazole films (CuBTA), formed on Cu monocrystals and vapor deposited films under controlled potential conditions (+0.040 vSHE.) in I M NaCI + 5.6 X 10 M 1-H benzotriazole, has been studied by measurement of electrical charge. Film growth follows a direct logarithmic relationship to 25 nm thickness and effects of crystallographic orientation are insignificant. Variations in film growth under similar test conditions are attributed to variations in the randomness of CuBTA polymers in the film. A limiting film thickness is predicted, after which slow dissolution occurs without further thickening.

In-situ AFM study of pitting corrosion of Cu thin films

We applied an in situ electrochemical atomic force microscope (AFM) to investigate the pitting corrosion and the effect of benzotriazole (BTA) on corrosion inhibition of Cu films in 0.01 M NaHCO 3. The Cu films are 800 Å thick deposited on polished Si(100) wafers. Pit growth was observed in a range from hundreds of nanometers to millimeters using the combination of atomic force microscopy (AFM) and optical microscopy. The use of flat thin Cu films on inert substrates simplifies the three-dimensional problem to two dimensions allowing the observation of the detailed structure at initial stages. Our study has found that pits grow by two mechanisms depending upon the applied potential. Stepping the potential from the open-circuit potential to the region between the repassivation potential ( E r) and the pitting potential ( E p) generates pits with irregular perimeters. These pits range from hundreds of nanometers to a few microns in diameter. If the potential is stepped above E p, large pits greater than 10 μm in diameter were observed with smoother perimeters. The pitting rate at this potential is probably quite high so that corrosion products accumulate at pit edges to form ridges observed by AFM. On the other hand, if the potential is linearly ramped at 10 mV s −1 to values well above E p and then ramped back to the open-circuit potential at the same rate, large pits with diameters over 10 μm were formed. The perimeters of these pits are smooth and circular, indicating a mass-transport controlled growth mechanism. The edges of these pits are clean and flat, suggesting that materials quickly dissolve into the solution and the corrosion process is in equilibrium with the local electrolyte concentration within the pits. The addition of 0.2 mM BTA in 0.01 M NaHCO 3 solution results in the formation of a BTA film on the Cu surface, which effectively protects Cu from corrosion. Pitting potential of Cu surfaces covered with BTA films is dramatically increased by more than 700 mV, so that, practically, pitting corrosion is not a concern.

A Vibrational Structural Analysis of Benzotriazole Adsorption and Phase Film Formation on Copper Using Surface-Enhanced Raman Spectroscopy

The adsorption of benzotriazole (BTAH) on copper in aqueous electrolytes is examined by means of a vibrational analysis utilizing surface-enhanced Raman spectroscopy (SERS) as a function of solvent deuteration, pH, and electrode potential in order to examine adsorbate speciation, surface bonding, and the potential-dependent onset of CuIBTA phase film formation. In acidic media at pH > 1, the monoprotonated acid BTAH constitutes the predominant adsorbate, being replaced by the diprotonated BTAH2+ species by pH 0, and the basic BTA- form in alkaline electrolytes. The analysis of adsorbate speciation is facilitated by the presence of several coupled ring modes yielding vibrational bands in the 1050−1350 cm-1 region that are sensitive to deuteration of the triazole ring nitrogen(s). Insight into the adsorbate molecular geometry and mode of surface attachment is obtained by examining the adsorption-induced alterations in frequency, bandwidth, and relative intensity of the various benzotriazole ring modes. These changes are especially prevalent for triazole ring vibrations and some deuteration-sensitive modes, the latter apparently associated with Fermi resonance effects. The former torsional/bending ring vibrations also exhibit potential-dependent frequencies (i.e., an electrochemical Stark effect), reflecting copper−triazole electronic interactions. Taken together, the SER spectral features for BTAH and BTA- suggest surface attachment via a pair of triazole nitrogens with a tilted (or vertical) orientation; the single nitrogen binding site anticipated for BTAH2+ is consistent with the milder vibrational perturbations observed for this adsorbate. The transformation from adsorbed benzotriazole to a CuIBTA film at higher potentials is readily diagnosed from the SER spectra, including the observed lack of a D/H vibrational effect on the latter species. The structure of benzotriazole films in air is also examined; emersion of adsorbed BTAH from solution spontaneously yields a CuIBTA layer via a coupled O2-induced electrochemical pathway. The thermal stability of copper-benzotriazole films in ambient-pressure O2 and N2 from 25 to 300 °C was also probed with SERS.

Corrosion of copper metal in distillation process

Corrosion in atmospheric distillation is caused by hydrochloric acid produced by the hydrolysis of water soluble magnesium and calcium chlorides found in the crude oil. Corrosion of copper metal during distillation of Geisum crude oil (vapour phase ) at 100, 150, 200, 250, and 300°C in absence and presence of 5 per cent H2O was studied. The corrosion of copper metal in the vapour phase is higher than in the liquid phase. Hydrogen sulphide is not the only corrodant present; hydrogen chloride and volatile acids are other important corrodants. The effect of adding different inhibitors with various concentrations on the corrosion of copper metal was also studied. The rate of inhibition increases with addition of chlorinated hexadecylamine as compared with that obtained by addition of ammonia alone. The inhibitive efficiency of copper increased rapidly as the copper benzotriazole film grows rapidly.

In Situ STM Study of (100) Cu Electrodes in Sulfuric Acid Solution in the Presence of Benzotriazole: Adsorption, Cu Corrosion, and Cu Deposition

Atomic‐resolution in situ scanning tunneling microscopy (STM) observations of (100) Cu electrodes in solution containing to M benzotriazole (BTA) are presented. At potentials ⩽ −0.6 V vs. a ( sat.) reference electrode ordered superstructures of a chemisorbed BTA adlayer as well as a disordered, chainlike structure, suggesting a polymerized BTA film, were observed. Cu corrosion commences at potentials ⩽ −0.4 V by the formation of monoatomic etch pits and slow step flow etching, resulting in roughening of the Cu surface. On changing the potential back to ⩽ −0.6 V the surface becomes level again due to redeposition of dissolved Cu at the Cu steps.

Using Polarised, Ultra-Soft X-Ray Absorption Spectroscopy to Probe Molecular Orientation in Benzotriazole Films Adsorbed on Partly Oxidised Copper

Abstract Data are presented of polarisation studies carried out to elucidate the orientation of the benzotriazole molecule adsorbed onto copper thin films. Spectra were obtained at the carbon K-edge. Comparisons are made between this and the orientations of structurally similar molecules; indazole, methyl benzotriazole and benzimidazole. Different copper film thicknesses and degrees of oxidation were investigated, and a film of benzotriazole on silver was also examined. All of the molecules were found to be oriented normal to the substrate, except benzimidazole on copper, which showed no orientation dependence.