Copper Surface Research Articles

Modification of the temporal laser source term in two-temperature model

Simulations on the interaction between laser pulses with materials during pulsed laser ablation require information on the characteristics of both laser and material. While details on material properties are extensively studied, the temporal profile of the laser source term is rarely studied and is generally assumed to be Gaussian. This article explores the effects of non-Gaussian temporal laser source terms (TLSTs) in simulating the heat diffusion within a metal upon irradiation of femtosecond pulsed lasers. We employed the Two-Temperature Model (TTM) to simulate the temperature evolution on the surface of copper upon irradiation of a 100-fs laser pulse with different TLSTs at different laser repetition modes (single-shot, burst, and biburst). We used a constant total fluence of 3J/cm 2 in all cases and subsequently calculated the ablation depths based on the resulting temperature values. Our results show that non-Gaussian TLSTs generate lower electron and lattice temperatures, resulting in shallower crater depths compared to a Gaussian TLST. However, under burst and biburst modes, particularly with higher subpulse number repetition time, the results of non-Gaussian TLSTs approximate those of Gaussian TLSTs. To initiate laser ablation in such cases, higher laser fluence might be required. Our work on non-Gaussian temporal profiles in TTM simulations can be applied to other computational methods in describing laser-matter interaction.

Effect of Cu Film Thickness on Cu Bonding Quality and Bonding Mechanism.

In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids between the bonded copper interfaces. To examine the effects of copper film thickness on bonding quality and bonding mechanisms in this study, artificial voids were intentionally introduced at the bonded interfaces at temperatures of 250 °C and 300 °C. The results revealed that as the thickness of the copper film increases, there is an increase in the bonding fraction and a decrease in the void fraction. The variations in void height with different copper film thicknesses were influenced by the bonding mechanism and bonding fraction.

Effect of Temperature and NaClO on the Corrosion Behavior of Copper in Synthetic Tap Water

The corrosion behavior of copper was investigated in synthetic tap water with and without sodium hypochlorite (NaClO) at different temperatures during immersion for 70 d by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical measurement techniques. The weight loss corrosion rate and pit depth of copper first increase and then decrease with the change in solution temperature from 25 to 80 °C. This is mainly related to the corrosion products formed on the copper surface. The main corrosion products change from Cu2O and Cu2(OH)2CO3 to CuO with the increase in solution temperature. The presence of 3 ppm NaClO slightly increases the weight loss corrosion rate and pit depth of copper under all temperatures except for 50 °C and reduces the temperature of the maximum corrosion rate from 50 to 40 °C. Free chlorine reduction accelerates the cathodic reaction of the corrosion process.

Influence of chemistry and topography on the wettability of copper

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality.We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D).Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces’ wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on pattern peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing depth of the primary topography can also induce air-inclusions despite increasing peak roughness while time dependent wetting transitions were observed.

Microelectrode investigation of iron and copper surfaces aged in presence of monochloramine.

Ductile iron and copper coupons were aged 137-189 days and 2 days, respectively, with 2 mg Cl2 L-1 monochloramine under four water chemistries (pH 7 or 9 and 0 or 3 mg L-1 orthophosphate). Subsequently, microelectrode profiles of monochloramine concentration, oxygen concentration, and pH were measured from the bulk water to near the coupon reactive surface, allowing estimation of flux and apparent surface reaction rate constants for monochloramine and oxygen. Both metals showed similar trends with orthophosphate where orthophosphate decreased metal reactivity with monochloramine (pH 9) and oxygen (pH 7). Comparing iron and copper coupons, apparent surface reaction rate constants for monochloramine and oxygen were one and two orders of magnitude greater, respectively, for iron coupons under all conditions. Overall, this research provides the first insights into monochloramine concentration, oxygen concentration, and pH by direct measurement near ductile iron and copper reactive surfaces aged in the presence of monochloramine.

Grooved hybrid copper surfaces for condensation heat transfer.

Condensation is commonly utilized in numerous thermal management applications and has two modes termed filmwise and dropwise, the latter providing superior heat transfer performance. However dropwise condensation is usually limited by its dependence on gravitational shedding of condensate. To combat this, hybrid surfaces consisting of regions of different wettability have emerged as a promising solution. Of such designs, hybrid grooved surfaces consisting of grooves with varying wettability in the groove valleys and ridge tops are of current interest. To date, most such surfaces have been silicon-based and over flat substrates. In this work, condensation experiments are performed on a copper tube with fabricated grooved hybrid surfaces. The aim is to take advantage of anisotropic wetting due to the presence of grooves and condensate drainage from higher wettability regions. The experimental results quantify the heat transfer with the degree of subcooling. At the same time, droplet dynamics were studied on the hydrophobic-hydrophilic surfaces, showing several droplet growth and departure mechanisms leading to effective heat transfer.

Impact of Cu complex anions on CuZnAl intercalated hydrotalcite-like catalysts for low-carbon alcohols synthesis from syngas

Elucidating the structure-performance relationship of catalysts for low-carbon alcohols synthesis from syngas is crucial for designing efficient catalysts. In this study, CuO particle size, reducibility, and the number of oxygen vacancies could be adjusted by changing intercalated Cu complex anions, thereby affecting the catalyst's performance. The characterization results indicated that the insertion of [Cu(C2O4)2]2- between ZnAl layered double hydroxide resulted in the largest CuO particles (26.5 nm), leading to an increase in the metallic copper surface area. Consequently, the highest CO conversion (13.0 %) was achieved without altering alcohol distribution. On the other hand, when [Cu(EDTA)]2- was inserted, the catalyst possessed the smallest CuO particle size (8.9 nm), more abundant oxygen vacancies, and enhanced interaction between Cu species and ZnO, which promoted carbon chain growth and resulted in a high C2+OH proportion of 75.8 %. Our study thus provides a new perspective on catalyst structures for the syngas production of low-carbon alcohols.

Condensation of water on PDMS-coated copper surfaces for fresh water harvesting

With an increased need to solve fresh water scarcity for humanity in many places around the world, dew water harvesting is one promising approach to improve the situation. While condensation from humid air has been a research topic for many years, it is still unclear how surface wettability influences the condensation efficiency and the fresh water harvest. In this work, we contribute to bridging this knowledge gap by comparing the condensation efficiency of PDMS-coated hydrophobic and uncoated hydrophilic surfaces. We characterize the humid air velocity field to enable comparability of the present results on condensation efficiency with the results gained at other conditions. In addition, the surface wetting behavior prior to and after the condensation experiment is investigated to analyze the PDMS-coating longevity and allow to draw conclusions on their suitability for long term use in condensation applications.

Effect of micro-/nano-porous thin film surfaces prepared by a hybrid method of etching and electrochemical deposition on pool boiling heat transfer performance

Surfaces created using efficient and inexpensive methods are highly demanded in industrial applications of extremely high temperatures. In this study, Composite Nano-particle Coated Over CuO Filmed (CNCCF) surface is prepared through two processes, first through chemical etching to produce a thin film of CuO over bare Cu surface, and secondly deposition of Ni-Al2O3 composite nano-particle over CuO thin filmed copper surface by electrochemical deposition process. The completed CNCCF surface exhibits favorable characteristics for improved boiling heat transmission, such as wettability, roughness, porosity, etc. An experiment on pool boiling is conducted on the CNCCF and bare Cu surface. DI water at atmospheric pressure is used as the boiling fluid. Findings show that the CNCCF surface exhibits enhanced Critical Heat Flux (CHF) and Boiling heat Transfer Coefficient (BHTC) than bare Cu surface. The increased porosity, roughness, and other properties of the CNCCF surface are the cause of this improvement in CHF and BHTC. A high-speed camera is also used to monitor and analyze bubble behavior during boiling on all surfaces, including the Bare Cu. Further evidence for the enhancement of boiling heat transfer on the CNCCF surface comes from the nucleation site density, departure diameter, and frequency characteristics of bubbles.

Synergistic shielding of copper from nitric acid corrosion: Unveiling the mechanisms through electrochemical, characterization, and computational insights with 2-Hydroxybenzaldehyde oxime

Schiff-base metallic complexes have garnered considerable attention due to their unique attributes and broad applications across various sectors. Among these, organic Schiff-type bases have emerged as effective agents for mitigating corrosion in challenging environments. This study employs a comprehensive approach to assess the efficiency of 2-Hydroxybenzaldehyde oxime (HOBAO) in preventing copper corrosion. Synthesis and characterization of the HOBAO compound were conducted using FTIR and NMR (1H and 13C) analyses, confirming successful production. The inhibition performance on copper was investigated in a 1 M HNO3 medium utilizing gravimetric, electrochemical impedance spectroscopy, and potentiodynamic polarization techniques. Our findings reveal that HOBAO, at a concentration of 300 ppm, significantly inhibits corrosion, achieving rates of 82.00 %, 93.30 %, and 91.80 % for weight loss, polarization, and EIS analyses, respectively. SEM, EDS, and UV investigations provide evidence of the inhibitor's adsorption onto the copper surface, resulting in a smoother and more uniform appearance with minimal damage. Theoretical and practical results were meticulously compared, demonstrating that HOBAO acts as a mixed-type inhibitor with heightened effectiveness at higher concentrations of 300 ppm. SEM observations offer compelling evidence of inhibitor molecules exhibiting robust resistance against HNO3 attacks at the metal boundaries. Molecular modeling, including DFT and MD simulation studies, further support these findings, suggesting that the oxygen heteroatoms of HOBAO serve as favorable sites for molecular adsorption onto the copper surface. In conclusion, our comprehensive findings highlight HOBAO's potential as a promising copper corrosion inhibitor, particularly in environments containing nitric acid.

A novel plating bath device for reducing surface copper thickness and improving wafer-scale uniformity

Through silicon via (TSV) technology plays a pivotal role in three-dimensional integrated circuits. However, excessive surface thickness and uneven wafer plating during TSV copper electroplating pose significant challenges to TSV reliability. This paper proposes a novel rotating cathode electroplating technique that utilizes flow field induction by a rotating cathode to significantly reduce the surface copper thickness by approximately 8 μm, leading to improved uniformity of wafer-scale electroplating and facilitating rapid TSV filling. This study focuses on the impact of cathode rotation speed and chip position on TSV filling quality. The experimental findings demonstrate that increasing the cathode rotation speed reduces the diffusion layer thickness, thereby enhancing filling quality. Additionally, variations in chip position influence surface copper thickness. The introduction of bis(3-sulfopropyl) disulfide accelerant expedites the filling process, boosts the filling ratio, and enables defect-free TSV filling. This study offers valuable insights into the wafer-scale TSV electroplating process and facilitates the optimization of parameter settings during electroplating.

Adsorption Structures, Vibrational Raman Spectra and Chemical Binding Properties of Thioglycolic Acid on Cu(111) Surfaces: A DFT Study.

Copper is widely used in everyday life and industrial production because of its good electrical and thermal conductivity. To overcome copper oxidation and maintain its good physical properties, small organic molecules adsorbed on the surface of copper make a passivated layer to further avoid copper corrosion. In this work, we have investigated thioglycolic acid (TGA, another name is mercaptoacetic acid) adsorbed on copper surfaces by using density functional theory (DFT) calculations and a periodical slab model. We first get five stable adsorption structures, and the binding interaction between TGA and Cu(111) surfaces by using density of states (DOS), indicating that the most stable configuration adopts a triple-end binding model. Then, we analyze the vibrational Raman spectra of TGA adsorbed on the Cu(111) surface and make vibrational assignments according to the vibrational vectors. Finally, we explore the temperature effect of the thermodynamically Gibbs free energy of TGA on the Cu(111) surface and the antioxidant ability of the small organic molecular layer of copper oxidation on the copper surface. Our calculated results further provide evidences to interpret the stability of adsorption structures and antioxidant properties of copper.

Enhanced Nanotwinned Copper Bonding through Epoxy-Induced Copper Surface Modification.

For decades, Moore's Law has neared its limits, posing significant challenges to further scaling it down. A promising avenue for extending Moore's Law lies in three-dimensional integrated circuits (3D ICs), wherein multiple interconnected device layers are vertically bonded using Cu-Cu bonding. The primary bonding mechanism involves Cu solid diffusion bonding. However, the atomic diffusion rate is notably low at temperatures below 300 °C, maintaining a clear and distinct weak bonding interface, which, in turn, gives rise to reliability issues. In this study, a new method of surface modification using epoxy resin to form fine grains on a nanotwinned Cu film was proposed. When bonded at 250 °C, the interfacial grains grew significantly into both sides of the Cu film. When bonded at 300 °C, the interfacial grains extended extensively, eventually eliminating the original bonding interface.

Green chemical mechanical polishing of copper with 2,5-dihydroxy-1,4-dithianeas as the inhibitor: Experimental and theoretical studies

It is a great challenge to develop green chemical mechanical polishing (CMP) technique owing to the limited inhibitory performance of green inhibitors. In this study, 2,5-dihydroxy-1,4-dithiane (DHD) was found and utilized as a superior inhibitor in CMP slurry, which realized nanometer-scale smoothness for copper surface. The strong inhibition effect of DHD, in both static and dynamic situations, was demonstrated by microscopic observations and electrochemical characterizations. The effectiveness of DHD was achieved mainly through its chemisorption onto copper surface, determined by Langmuir adsorption isotherm. X-ray photoelectron spectroscopy and density-functional-theory calculations proved that the chemisorption occurred between the S atom of DHD and Cu. Overall, DHD as an efficient and eco-friendly inhibitor with low-cost exhibits immense potential for applications in chip fabrication, particularly at a low technology node.

Copper corrosion inhibition in acidic aqueous media through tolyltriazole application: performance analysis

Tolyltriazole (TTA) is recognized as an effective copper corrosion inhibitor in cooling systems due to its low toxicity and versatile properties. With the increasing focus on sustainable development, the employment of compounds of this nature has become increasingly widespread, driving the search for environmentally responsible alternatives. In this context, the aim of this work was to evaluate the efficiency of a corrosion inhibitor formulated with TTA on copper specimens in HCl 0.1 mol L−1 medium. The samples were exposed to the corrosive electrolyte with inhibitor concentrations ranging from 0 to 20 ppm. Electrochemical methods, including open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy were employed for corrosion monitoring. Overall, the results revealed that TTA behaves as a predominantly anodic inhibitor. Additionally, polarization curves demonstrated that within the Tafel region, the inhibitor adsorbs to the copper surface, following the Langmuir isotherm model. Regarding inhibitory effectiveness, the observed values ranged between 81.3 and 96.1%, while morphological analyses indicated the presence of nitrogen on the surface of the copper specimens after electrochemical tests, confirming the formation of a protective TTA film. In conclusion, this study highlights TTA's efficacy as a corrosion inhibitor, demonstrating its significant potential in safeguarding copper against acidic environments.

Experimental study of pool boiling performance of Fe3O4 ferromagnetic nanofluid on a copper surface

Nanofluids significantly enhance the critical heat flux of boiling heat transfer. This paper experimentally investigates the pool boiling performance and the influence mechanism of Fe3O4 nanofluids. Compared with deionized water, the 0.001 vol% nanofluid increases a maximum enhancement in critical heat flux by 47.90%. During nanofluid boiling, Fe3O4 nanoparticles are deposited on the surfaces. The nanoparticle deposition surfaces are physically characterized to explain the influence mechanism of Fe3O4 nanoparticles on boiling heat transfer. Nanoparticle deposition modifies the surface micro-morphology, which increases roughness and improves wettability. The changes are essential factors for the enhancement of the critical heat flux. This paper further analyses the boiling results of deionized water on the nanoparticle deposition surfaces. Compared with a polished surface, the critical heat flux and heat transfer coefficient of the nanoparticle deposition surface show maximum increases of 52.39% and 56.19%. Due to the similar enhancement of critical heat flux using the Fe3O4 nanofluid and the nanoparticle deposition surface, it is found that the increased critical heat flux of the nanofluids is attributed to the improvement of surface wettability and roughness by nanoparticle deposition. This study analyzes the mechanism of Fe3O4 nanofluid for enhancing pool boiling heat transfer from the perspective of modifying boiling surface characteristics by nanoparticle deposition, especially in wettability and roughness, which advances the understanding of enhanced boiling heat transfer by nanofluids.

Experimental comparison of pool boiling characteristics between CNT, GO, and CNT + GO‐coated copper substrate

AbstractThe present investigation aims to study the comparative analysis of CNT, GO, and CNT + GO nanoparticle coatings on copper surfaces under a pool boiling situation. Coating on copper surfaces is performed using the dip coating method. Pool boiling experiments are conducted for all the coated surfaces at atmospheric pressure. Water is used as a working fluid. A comparison was made based on the coated surface characteristics and pool boiling behavior of the samples. The results show that CNT + GO coating on copper surfaces is better in terms of critical heat flux (CHF) and boiling heat transfer coefficient (BHTC). It is also observed that CHF and BHTC of the CNT + GO‐coated surface are 129.19% and 194.75% higher, respectively, compared to the bare copper surface. Bubble dynamics studies were also performed for all the samples.

Melon seed shell synthesis N, S-carbon quantum dots as ultra-high performance corrosion inhibitors for copper in 0.5 M H2SO4

This work reports on the preparation of N, S-CQDs from melon seed shell, a common household waste that can inhibit the corrosion of copper in a 0.5 M H2SO4 solution. Additionally, by varying the preparation time and preparation temperature, the effects of N, S-CQDs on the capacity of copper to resist corrosion in 0.5 M H2SO4 solution were compared. It was also used to prove its inhibitory effect on copper in 0.5 M H2SO4 solution by a series of test methods. The corrosion inhibition rate of N, S-CQDs was 99.66 % and 99.87 % when the N, S-CQDs prepared at 160 ℃ for 6 h and 200 ℃ for 10 h were added. The results indicate that the corrosion inhibition rate of N, S-CQDs increases with increasing preparation time and temperature. XPS (X-ray photoelectron spectroscopy) and ATR-FTIR (Fourier transform infrared) were used to describe the composition and functional groups adsorbed on the surface of copper. N, S-CQDs' corrosion inhibition property was demonstrated by using an AFM (Atomic force microscope) and SEM (Scanning electron microscopy) to examine the corrosion surface morphology. Using the Langmuir adsorption model, it was found that the corrosion of copper was inhibited by both physical and chemical adsorption. A number of experimental findings demonstrate that preparation temperature and time impact the degree of carbonization, size, and functional group content of the N, S-CQDs, which in turn influences the corrosion inhibition of the N, S-CQDs. By means of heteroatom adsorption and surface structure, N, S-CQDs generate new chemical coordination bonds on the copper surface, thereby forming a protective layer, reducing the interaction between copper and 0.5 M H2SO4 solution, and generating a corrosion inhibition effect.

3-((2-ethoxyethanethioyl)thio)propane-1-sodium sulfonate as a new accelerator for copper electroplating: Electrochemical and theoretical calculation studies

Superfilling of blind holes is essential for a high density interconnect printed circuit board (PCB), for which accelerators are essential for its high quality. However, the mechanical properties of copper obtained by electroplating with accelerators commonly used in industry still need to be further improved. It has been reported that 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) can improve the copper crystal orientation and optimize the microstructure of copper plating by utilizing its CS bond. Based on this behavior, in this paper, 3-((2-ethoxyethanethioyl)thio)propane-1-sodium sulfonate (ETPS), an organic compound containing dithioester (─C(═S)─S─) special functional groups is proposed as a new accelerator for brightening coating. According to the experimental results, it is found that with ETPS as the accelerator, the superfilling of blind holes can be achieved with the reduced grain size and enhanced Cu (1 1 1) crystal surface for the copper electroplating layers; the copper microstructure with fine grains could contribute to improve the mechanical properties of copper plating. Molecular dynamics calculations have demonstrated that the inclusion of CS double bond can enhance the adsorption of ETPS on the surface of copper, leading to the accelerated deposition process of copper. This work will promote the research and development of new accelerators in the future.

Effect of Sn on the micro-structure, composition and anti-corrosion performance of reduced glutathione film on copper

An organic-inorganic hybrid film was successfully constructed via reduced glutathione (GSH) and SnSO4 on copper surface. The adsorption of sulfhydryl groups (-SH) on copper was the prerequisite for the synergistic effect of GSH and SnSO4. The addition of Sn (II) into the film formation system could improve the corrosion protection efficiency of GSH film from 90.52% to 99.89%. SEM results demonstrated that the synergistic effect between GSH and Sn (II) can improve the connection of the film and substrate. The XPS results indicated that Sn elements participated in the formation of the film with Sn (II), Sn (IV) and Sn (0). The excellent corrosion resistance of the film was attributed to the close connection between the film and the substrate and the doping of Sn with three valence states.