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Polyvinylpyrrolidone (PVP) is studied in this paper as an inhibitor of cobalt electrodeposition. The suppression effect of PVP was analyzed through electrochemical methods, including cyclic voltammetry (CV) and galvanostatic measurements (GM) tests. It is indicated that PVP effectively suppresses the electrodeposition of cobalt and chloride ion accelerates this suppression. Further experiments verify that PVP inhibits the deposition of cobalt through the adsorption on the electrode surface. Quantum chemical calculations were employed to calculate the molecular orbitals of PVP and the electrostatic potential (ESP) energy of the involved molecules. The simulation results imply that the amide group acts as the main electrophilic attack region and facilitates nucleophilic reactions to bond with cobalt. High aspect ratio trench filling on silicon wafer was achieved with the addition of PVP, which confirms that PVP is an applicable inhibitor for the practical electrodeposition of cobalt filling. The mechanism of cobalt trench filling was proposed to explain the role of PVP in the electroplating filling. Besides, crystalline and morphological characterizations reveal that PVP is able to inhibit the specific crystal growth of cobalt, especially the growth of 220 crystal plane, affect the crystal morphology of cobalt and improve surface compactness.

A novel additive system comprising bis-(sodium sulfopropyl)-disulfide, polyethylene glycol and hydroquinone (HQ) was developed and investigated to achieve high rate copper electrodeposition at high temperature. HQ, as the key additive compound in this system, refines the Cu grain, makes the coating surface bright and smooth at high current density. The underlying mechanism of the additive-assisted electroplating was investigated through electrochemical, morphological characterizations and molecular dynamics simulation. Nanocubical copper particles were found through chronoamperometry tests, which explains the fine crystalline Cu grains and the bright coating surface. Additionally, the formation of the nanocubical copper particles is caused by the different adsorption energies of HQ on (311), (111) and (220) crystal faces and further leads to a strong suppression on the (220) orient crystal faces. Moreover, the electroplating results of through-holes illustrate the feasibility of this additive system in practical applications.

Copper oxide (CuO) particles with loose agglomeration of porous flakes were treated by ultrasound in different solvents. CuO particles with completely discrete flakes were obtained with ultrasonic surface treatment in ethyl alcohol as a polar solvent while CuO particles with compacted flake agglomeration were found after ultrasonic treatment in diethyl ether as a non-polar solvent. CuO particles after ultrasonic treatment were characterized to investigate the effects of morphological appearance on size distribution, sedimentation velocity, specific surface area, ultraviolet-visible (UV–vis) absorption spectra, diffraction angle of X-ray diffraction (XRD) pattern, binding energy of X-ray photoelectron spectroscopy (XPS), Raman intensity and dissolution rate. CuO particles with completely discrete flakes exhibited a fastest dissolution rate of 7 s in 12.5 vol% H2SO4 for rapid complement of cupric ions so that the electrolyte for copper electrodepositon could meet the requirement of stable concentration of cupric ions to generate fine copper deposits in a plating system with insoluble anode.

Optoplasmonic materials comprising both photonic and plasmonic elements are of particular interest for the development of substrates for surface-enhanced Raman spectroscopy (SERS). In this work, a layer of analyte-carrying dielectric nano/microspheres is placed on top of a monolayer of gold nanoparticles to enhance the intensity of the electric (E-) field localization and to enrich the analyte close to the electromagnetic hot spots. Numerical simulations of the hybrid structure confirm an increased and spatially expanded E-field enhancement at the interface. Due to a decreasing filling fraction with increasing size of the dielectric spheres, simulations predict a saturated SERS enhancement for dielectric microspheres with a diameter larger than 4 μm, which is confirmed by experimental SERS measurements. The dielectric microsphere can be functionalized with surface ligands that facilitate the binding of target molecules in solution. The deposition of the analyte-loaded microspheres on the self-assembled gold nanoparticle ensures a high local concentration of analytes in the electromagnetic "hot" surface. The performance of the optoplasmonic SERS approach for detecting methamphetamine in saliva and urine is tested, and the detection of analytes at nanomolar (nM) concentrations is demonstrated.

The surface roughening process of substrates plays a critical role in the pre-treatment of industrial metal deposition. In this work, five different coarsening treatments were applied to coarsen the surface of carbon fiber/cyanate ester composite for improving the quality of subsequent electroless copper plating. The particular effects of coarsening treatments on carbon fiber/cyanate ester are characterized with morphological, chemical and surface tension-based measurements. The results show that coarsening treatments lead to different surface hydrophilicity and morphology for the composites, thus affecting the adhesion, surface roughness and surface morphology of the deposited copper layer. Compared with the other tested coarsening treatments (including sand-grinding, oxidation, air plasma, the combined action involving sand-grinding and air plasma), the combined action involving sand-grinding and oxidation yields the promoted coarsening of the composite and then results in optimized adhesion for the following electroless copper plating as conductive patterns.

Polyethylene glycol (PEG) is widely used in copper plating as an inhibitor. The PEG-Cu+-Cl structure is recognized as the dominant factor in the inhibition mechanism of PEG. In this work, we investigated the influence of temperature on the PEG-Cl inhibition system. Molecular dynamic (MD) simulations based on Density Functional Theory (DFT) were employed to examine the influence of temperature on the adsorption of Cl− on copper surface and the structure of PEG-Cu+-Cl. According to the MD results, it is assumed that there is a negative correlation between the inhibition effect of PEG and the working temperature. The results of corresponding electrochemical measurements are in good agreement with this assumption and the surface morphology analysis of plated copper films confirms this correlation.

The micron-size anisotropic growth of electroless nickel‑phosphorus plating was realized on the fine sliver lines with the width of ≤15 μm. Growth of nickel‑phosphorus alloy occurred preferentially in the width direction at a growth rate approximately twice than that in the thickness direction during electroless plating in a bath with periodical positive and negative rotation. The growth rate in the width direction reaches 15–18 μm in 30 min. The dominant nickel‑phosphorus growth in the width direction is attributed to the enhancement of mass transfer rate for solution at the edge of silver lines or nickel‑phosphorus layer, as a result of the better wettability of ceramic than Pd-activated silver and nickel‑phosphorus layer. The suppression of lead acetate at the layer edge is enhanced by nonlinear diffusion instead of wettability difference. A possible mechanism for the formation of nickel‑phosphorus layer morphology as functions of mass transfer and lead distribution was proposed to explain the growth behavior of anisotropic electroless nickel‑phosphorus plating. Furthermore, this anisotropic electroless nickel‑phosphorus plating process was employed to form a novel L-shape terminal electrode structure of chip inductor.