Driving Efficiency and Reliability in AI Hardware: Leading Edge Pulse Plating Solutions for Uniform Copper Deposition

Titanium-based composites with bioactive phases were produced with TiH2and 10% in volume of calcium phosphate. The mixtures were prepared either by conventional powder metallurgy processing or by ultrasound, dried in a rotary evaporator, pressed at 600 MPa and vacuum-sintered at 1200 °C for 2 hours. Crystal phases of the as-fabricated composites are found to be α-Ti, CaTiO3and TixPyphase (s). The TixPyand CaTiO3phases resulted from the reaction between titanium and tricalcium phosphate at about 1130 °C. Calcium phosphate was better dispersed by ultrasound leading to a higher compressive strength of the composite and a more uniform Ca-P deposition in simulated body fluid solution.

Uniform TNT growth on complex geometries, such as screw-threaded surfaces, is challenging due to non-uniform electric fields in anodization. This study examines TNT growth on screw threads and dental implants, intending to determine the impact of geometry on the electric field distribution using Finite Element Analysis (FEA). Simulation results showed that the electric field intensity was highly variable, with increased values on teeth and decreased values on the root and flank, causing nonuniform growth of TNTs. Experimental anodization coupled with Field-Emission Scanning Electron Microscopy (FESEM) affirmed the findings with shorter TNTs on the root and more stable growth on the teeth and flanks. TNT diameter correlated with applied DC voltage, while TNT length, with variations of 6 μm, was highly sensitive to the cathode design. To solve the problem, a new multicathode anodization cell was developed to produce a uniform field distribution. By adjustment of the cathode-to-anode (CA) area ratio, it was discovered that a CA of 1 yielded the optimal results, and this resulted in uniform TNT growth in all regions. Lower CAs (e.g., 0.5:1) resulted in low field strength and incomplete TNT growth, and high CAs (2:1) led to over-dissolution and structural damage. Optimization on actual dental implants using the CA 1 setup and two-stage anodization process yielded a more controlled TNT length and diameter. The final TNT morphology on the dental implant had TNT length variations of 0.4 μm with a 100 nm diameter. These results reveal the importance of the electric field uniformity in anodizing implants with complex geometries. The proposed multicathode design presents an efficient and scalable solution for uniform TNT layer deposition on dental implants and similar freeform curved surfaces.

The industrial electroless copper plating solutions containing formaldehyde as reducing agent are known from the middle of this century and are widespread in the practice up to now. However, the investigation of this system remains actual because of its complexity, e. g.alkaline medium, hydrated form of formaldehyde (methanediol), Cu(II) complex compounds with different ligands, additives which improve the properties of the coatings obtained and/or protect from the reduction of copper(II) in the solution bulk. Moreover, various equilibria are possible including deprotonation of methanediol, Cu(II) complex formation, additional interactions between components of the solution.The aims and tasksof this work were to investigate or define more precisely equilibria in conventional alkaline solutions of electroless copper deposition as well as influence of the nature of Cu(II) ligands on the copper deposition process.This research report deals with the results obtained by means of dc-polarography, vis-spectrophotometry, voltammetry, potentiometry, pH-metry, 1H and 13C NMR spectroscopy, scanning electron microscopy, X-ray diffractometry and gravimetry.The composition, stability and the values of the diffusion coefficient of Cu(II) complex compounds with ligands (EDTA, DTPA, pyridine-2,6-dicarboxylic acid and 4-hydroxypyridine-2,6-dicarboxylic acid, Quadrol, L(+)-, D(–)- and DL()-tartrate, glycerol, saccharose and OH- ions) which are used or usable in alkaline electroless copper deposition solutions were established. The formation of mixed complex compounds between Cu(II) complexonates and K4Fe(CN)6, as well as between Cu(II) tartrate complexes and methanediol was investigated. The interaction of methanediol with L(+)-tartrate alongside with the influence of the ionic strength and cation nature on the deprotonation of methanediol in alkaline solutions were studied.The kinetic data on electroless copper deposition from solutions containing above-mentioned ligands is presented and the influence of the ligand nature on the process of electroless copper deposition is discussed.

Various metals have been plated on germanium and silicon. These semiconductors usually have oxide layers on them which could interfere with the intimate contact required between metal and semiconductor for good adhesion and the desired electrical properties. Oxide films and residues from chemical etching on germanium can be removed by cathodic reduction prior to metal deposition in many plating solutions. Sixteen different metals were plated on n‐ and p‐type germanium. Since oxide films on silicon are difficult to reduce cathodically, other methods of removing the oxide film are employed to produce adherent electrodeposits on silicon.

Electroless Metallic Coating on Plastic Parts Produced by Rapid Prototyping Technique

Electroless copper deposition for ULSI

Electroless copper deposition on TaN, (x = 0-1) barrier films was investigated in terms of nitrogen flow rates. Field-emission scanning electron microscopy micrographs of the electroless copper deposition on TaN x barrierand palladium-activated TaN x barrier films showed that the density of the copper aggregates and of palladium nuclei increased with increasing nitrogen flow rate. As a result, the more uniform and excellent electroless copper deposition was acquired as the nitrogen flow rate increases. Plan-view transmission electron microscopy micrographs of palladium activated TaN x for 5 s showed that palladium nuclei formed on grain boundaries, especially on grain edges of TaN x barrier films in the initial stage of palladium activation.

Silver nanowire (AgNW) emerges as a next‐generation transparent electrode material, offering enhanced flexibility and ease of fabrication compared to traditional transparent electrode materials, such as metallic oxides. In the previous research, the uniform deposition of AgNWs on flat surfaces is demonstrated, exhibiting high conductivity, flexibility, and excellent transmittance. However, the evolution of nano‐electronics technology necessitates the fabrication of transparent electrodes on non‐flat surfaces, such as those found in zenithal bistable devices and reconfigurable Fresnel lenses. In this study, a method is proposed to deposit AgNW material on uneven surfaces using the Mylar‐bar‐coating method, with a polyvinyl chloride (PVC)‐based Fresnel lens serving as the target surface. Additionally, the impact of varying AgNW suspension concentrations on transmittance and sheet resistance is investigated. To further reduce sheet resistance, a layer of conductive polymer, poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), is deposited on the AgNWs. The measurements reveal that a 2 mg mL−1 sample exhibits a sheet resistance of 187.83 W W−1 with 87.4% transmittance at 550 nm. After the PEDOT:PSS process, the sheet resistance decreases to 122.84 W W−1 with 84.4% transmittance. In this research, a solution is offered for the uniform deposition of AgNWs on patterned surfaces, paving the way for the next generation of optical devices.

Electrodeposition of metals in microgravity conditions

This study investigates the non-uniformity (NU%) of copper deposition in a three-dimensional panel electroplating cell using COMSOL Multiphysics® 6.1 (COMSOL Inc., Burlington, MA, USA). To ensure the accuracy of the simulated current efficiency, the modeling was initially conducted on the electrodeposition of nanoscale metal wires (Nanowires, NWs) using the Finite Element Method (FEM) in COMSOL. After verifying that the simulation accurately reflected the current efficiency at the nanoscale, the model was scaled up to simulate full-sized panel-level electroplating. Various simulation conditions were explored, including two dimensional and three dimensional, electrode kinetics equations, electrolyte compositions, and current densities. The effects of these parameters on current efficiency and deposition uniformity were analyzed to develop a highly accurate COMSOL model. In terms of electrode kinetics, the study compares the advantages and limitations of secondary current distribution and tertiary current distribution models found in the previous literature, and evaluates their simulation results. Furthermore, to reflect the experimental condition where a pre-deposited copper seed layer was applied to reduce internal cathode resistance, the electrode shell physics module in COMSOL was implemented to simulate the potential distribution across the cathode surface. The results confirm that the numerical model using the tertiary current distribution provides more accurate predictions compared to the conventional secondary current distribution approach.

It is well known that a solute usually carries out a non-uniform deposition when deposited from an evaporating droplet. The evaporation behavior of volatile micro droplets with nanoliter volume has been modeled and experimented in detail for insight into this phenomenon. The results show that there are two phases existing during the whole evaporation of water droplets: (I) constant baseline region in first 50% of total time; (II) constant contact-angle region in the last 50% of total time. The average volume rate of evaporation is 1.66 nl/s for the initial baseline of 2.27 mm during 2160 sec. Furthermore, the evaporation experiment performed in circular nanoliter wells, of height 65 /spl mu/m and diameters ranging from 240 /spl mu/m to 1270 /spl mu/m, demonstrated that the moving speeds of thin water films during rupture ranged from 20 /spl mu/m/s to 25 /spl mu/m/s; for larger circular wells, there was a higher initial broken percentage. This study may be beneficial to the design of microstructures for uniform solute deposition from the evaporation of liquid droplets.

Electrodeposition of copper into sub‐0.25 μm features has been studied theoretically and experimentally. A physically based two‐dimensional (2D) pseudo‐steady state and a one‐dimensional (1D) unsteady‐state mass‐transfer model have been developed to study the effect of important parameters on the step coverage, evolution of copper deposits in damascene features, and deposition rate inside high aspect ratio single and dual damascene features. An analytical model that assumes linear deposition kinetics and a fixed boundary also has been developed and found to be in good agreement with the numerical results of the free boundary models to about 50% filling of the feature. A new criterion, based on the pulse plating parameters, for optimizing the opposing trends in step coverage and the deposition rate is also given. Copper has been deposited into submicron features, by dc and pulse plating, using an alkaline bath. Deposit evolution inside trenches has been studied by performing sequential plating experiments. Copper deposits with good morphology and resistivity were obtained using the alkaline bath. Experimental observations have been compared to the model trends and found to be in good agreement. Pulse plating experiments show that the deposit quality and the step coverage are improved over dc plating. Slanting the sidewalls also improves step coverage as shown by 2D model calculations. © 2000 The Electrochemical Society. All rights reserved.

Endpoint detectable plating through femtosecond laser drilled glass wafers for electrical interconnections

Electroless Nickel Immersion Gold (ENIG) is one of the important final finish techniques that is used in the printed circuit board industry. Despite its relatively expensive cost compared to other final finishing processes such as OSP and immersion Tin etc., ENIG has many advantages. The low reactivity of Au can protect the underlying Ni and Cu surfaces from oxidation and keeps the board suitable for long storage time. It provides excellent surface planarity suitable for soldering, especially for tiny parts such as BGA and FlipChip, and the surface remains solderable even after multiple reflow cycles. It is useful for contact surfaces such as membrane switches and contact points and may also be used for wire bonding. The Immersion Gold (IG) bath provides the protective Au layer after the Electroless Ni (EN) process following the below equation: 2Au+ + Ni _ 2Au + Ni <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> . As an electrochemical process, the deposition rate (or Au thickness per unit of time) is highly dependent on the redox potential of Au <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> and electropotential of the Ni surface. The former can be considered as a fixed value in a Au plating solution while the latter will vary depending on the design of boards (pad size, connection of pad to the inner-layer Cu, etc.). The differences of surface potential, or so-called galvanic effect, makes the deposition of Au non-uniform, which may influence the properties of the board in many aspects. For example, chromatic aberration of the Au surface appears and some of the extremely thick Au pads may appear as red color; solderability may become uneven across all pads; and Au may be wasted due to the poor gold thickness distribution. More seriously, the galvanic effect may cause Au skip-plating, or black Ni because of Ni over-dissolution on specific pads, resulting in the solderability problem. Our new immersion gold technology can effectively reduce the galvanic effect by introducing a new chemical system. The electropotential differences were minimized among pads with various surface areas or connected to different inner-layer copper areas thus providing a uniform gold deposition. Meanwhile, the plated Au thickness can be steadily increased from less than 1 microinch to 3 microinches and metallic lustre of the Au surface remained normal, from the pale yellow of thinner Au to the lemon yellow of thicker Au. Ni corrosion resistance remained good for a range of Au thickness from 1 microinch to 3 microinches. Modified HNO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> porosity test yielded good results. Solderability test using SAC305 solder showed good reliability after 0×, 3× reflow and baking (150 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> C, 4 hours) conditions in ball shear and ball pull test.

Copper-based electrocatalytic materials play a critical role in various electrocatalytic processes, including the electroreduction of carbon dioxide and nitrate. Three-dimensional nanostructured electrodes are particularly advantageous for electrocatalytic applications due to their large surface area, which facilitates charge transfer and mass transport. However, the real surface area (RSA) of electrocatalysts is a crucial parameter that is often overlooked in experimental studies of high-surface-area copper electrodes. In this study, we investigate the roughness factors of electrodeposited copper foams with varying thicknesses and morphologies, obtained using the hydrogen bubble dynamic template technique. Underpotential deposition (UPD) of metal adatoms is one of the most reliable methods for estimating the RSA of highly dispersed catalysts. We aim to illustrate the applicability of UPD of lead for the determination of the RSA of copper deposits with hierarchical porosity. To find the appropriate experimental conditions that allow for efficient minimization of the limitations related to the slow diffusion of lead ions in the pores of the material and background currents of the reduction of traces of oxygen, we explore the effect of lead ion concentration, stirring rate, scan rate, monolayer deposition time and solution pH on the accuracy of RSA estimates. Under the optimized measurement conditions, Pb UPD allowed to estimate roughness factors as high as 400 for 100 µm thick foams, which translates into a specific surface area of ~6 m2·g−1. The proposed measurement protocol may be further applied to estimate the RSA of copper deposits with similar or higher roughness.