Plating Bath Temperature Research Articles

Roughness development in electrodeposited soft magnetic CoNiFe films in the presence of organic additives

The effects of three additives, sodium lauryl sulfate (NaLS), saccharin (Sacc), and NaLS + Sacc, on roughness development during the electrodeposition of CoNiFe films were investigated. The characterization of these films by atomic force microscopy shows that the electrodeposits produced from NaLS containing solution result in a rough surface. The role of NaLS surfactant is to change the interfacial tension and clean non-polar species like hydrogen bubbles from the surface. In Sacc containing solution the evolution of a smooth surface is controlled by adsorbed Sacc molecule at the interface. The kinetic roughening of these deposits was investigated by dynamic scaling analysis. It was demonstrated that the roughness of CoNiFe films, obtained in the presence of NaLS + Sacc additives, was also dependent on current density, roughness of substrate, and the temperature of plating bath.

Electroless Cu deposition process on TiN for ULSI interconnect fabrication via Pd/Sn colloid activation

In this study, (100)-orientation silicon wafer coated with TiN barrier is catalyzed by a Pd/Sn colloid, which serves as an activator for electroless copper deposition. After activation, electroless deposition of Cu occurs on the catalytic surface. The coverage of the Cu deposit reaches 100% and the adsorptive amount of Pd is greatly increased by the conditioning process. The correlation between deposition rate, resistivity, morphology, crystal structure, and composition of the deposit when varying the temperature of the plating bath is discussed. The deposition rate of Cu is monitored by both the electrochemical method and the profilometer (α-step), while the other properties of the deposit are measured by four-point probe, scanning electron microscopy (SEM), x-ray diffraction (XRD), and Auger electron microscopy (AES). Deposition at 70°C is favorable due to the higher deposition rate, lower resistivity, less impurities, and more preferred orientation in the crystal structure than that at lower temperature. Problems regarding adhesion and high resistivity can be greatly mitigated via 400°C thermal annealing. The resistivity of Cu can be reduced to 2.2 μΩcm. Moreover, trenches of 1 µm and 0.25 µm on patterned wafer have been successfully filled by electroless deposition of Cu with the aid of surfactant C12.

Adhesion of electroless nickel plating on polished silicon

This work reports a study of the adhesion of electroless nickel plating on polished silicon as a function of several plating variables, namely substrate resistivity, activator composition, plating duration, and plating bath temperature. It is shown that an adhesion strength of ∼100 kg/cm2 or more can be obtained, irrespective of the silicon doping, for plating used in semiconductor devices. However, for this purpose, an appropriate silicon activation step is essential, except when the silicon is heavily N-type doped.

Submicrometer Platinum Electrodes by Through-Mask Plating

A through-mask electroplating process is described for forming Pt electrode structures with the vertical sidewalls and submicrometer dimensions desired for dynamic random access memory applications. The plating process used an aqueous KOH-based solution of “Pt A Salt” (Engelhard) and a sputter-deposited Pt plating base. Plating conditions were first optimized for blanket films on 200 mm diam wafers by examining the characteristics of the Pt deposits as a function of plating bath temperature and current density. Electrode features were then formed on similar wafers by plating through a patterned mask. Integration issues discussed include potential reactions of the dielectric mask with the underlying Pt plating base, surface modification of the exposed Pt plating base prior to plating, and erosion of the dielectric mask by the plating solution. © 2001 The Electrochemical Society. All rights reserved.

Critical influence of plating bath temperature on Cu damascene electrodeposits

The plating bath temperature has a critical influence on the damascene gap fill quality. Scanning electron microscopy studies indicated that over a small temperature range from 20 to 30 °C defect-free electroplated Cu fill was obtained. The effect was attributable to the initial nucleation and the chemistry of the plating bath, particularly the functionality of the additives. Secondary ion mass spectroscopy analysis showed different impurity levels of H, C, O, S, and Cl incorporated within the films. X-ray diffraction analysis on blanket Cu films indicated that, although all the Cu films had roughly the same (111) texture strength after plating, after a high temperature anneal at 450 °C for 30 min, the films deposited at higher temperatures exhibited much stronger (111) texture than the others. However, x-ray pole figure analysis of Cu lines with 0.35 μm linewidth and 0.40 μm spacing indicated roughly the same (111) texture intensity after the anneal. The shortened transformation time and more tensile stress observed on blanket Cu films plated at low temperatures were due to smaller grains and less dense packing of deposits which were formed at low temperature plating. Severe anisotropy of the stress was measured in 0.35 μm Cu lines where the stress perpendicular to the trench and along the surface normal were only about half of the stress parallel to the trench. This indicates the existence of strong side wall interaction between Cu and the dielectrics.

A low cost metallization scheme for double sided buried contact silicon solar cells

Abstract The buried contact solar cells (BCSC) technology has recently penetrated commercial manufacturing and markets giving performance increases in the vicinity of 30% over previous commercial technologies. However, the development of the new generation of higher efficiency BCSCs with grooves on both surfaces has been greatly retarded by the inability of standard electroless plating solution to simultaneously plate both n-type and p-type silicon. A simple, low cost and effective method of applying an ohmic contact simultaneously to both n-type and p-type silicon surfaces has been developed. The preliminary results for double sided buried contact silicon solar cells utilizing this low cost scheme are also presented. The fill factors of these cells are found to be comparable to cells making use of other metallization schemes using commercially available solutions. This is an indication that a good ohmic contact is formed between the nickel and silicon despite the exclusion of the sensitiser which is commonly believed to initiate the metal plating process. It could therefore be inferred that the activation and sensitising steps are not necessary in solar cell fabrication provided the plating bath temperature is high enough to release the nickel ions for effective metallisation.

ガラスと無電解ニッケルめっきの密着性

Various factors influencing the adhesion between glass and electroless nickel plated films were investigated. In terms of the film, it was found that the use of glycine as a complexing agent resulted in films that exhibited good adhesion. Adhesive strength also increased at lower pH and lower plating bath temperature. In terms of pretreatment, etching was important to improving adhesion. Adhesive strength was greatest when the glass was first etched with sodium hydroxide, next etched with hydrofluoric acid and then treated with methylate. Adhesion was also increased by decreasing the level of dissolved oxygen in the catalyzing treatment solution and plating bath.

Investigation of solar selective and microstructural properties of molybdenum black immersion coatings on cobalt substrates

Molybdenum black solar selective coatings have been produced on cobalt by immersion in a solution of ammonium paramolybdate and nickel sulphate. The cobalt was electroplated on nickel-plated copper prior to immersion in the paramolybdate solution. The maximum solar absorptance of the resulting molybdenum black coating was about 0.91. The minimum emittance was about 0.1 for coatings on cobalt deposited with an addition agent and about 0.23 for coatings on cobalt deposited without addition agent in the 60 °C plating solution. These differences have been related to the coating morphology determined by scanning electron microscopy. The emittance of coatings on cobalt deposited without addition agent decreases (or remains unchanged) during short-term heat treatment while that of coatings deposited on cobalt plated with addition agent increases somewhat. Reduction of the cobalt plating bath temperature to 45 °C can also lead to good initial coating properties but without the requirement for an addition agent in the cobalt plating bath. XPS studies show that the oxidation state of molybdenum in the coatings is approximately + 5 corresponding to Mo4O11. This reduces to + 4 after argon ion bombardment. Some cobalt may be present in the coatings in the form of CoO.

Mössbauer and x-ray fluorescence studies of Tin—Nickel electrodeposited alloys

Tin—nickel electrodeposited alloys were studied by the help of Mössbauer spectroscopy and energy dispersive X-ray fluorescence. The tin phase composition consisted of Ni 3Sn 4 intermetallic compound, elemental tin and η-Cu 6Sn 5 formed at the interface of the copper substrate. Increments of the quantity of nickel in the electrodeposited alloys are observed when the plating bath temperature is increased.

Development of a coating technique for inertial confinement fusion plastic targets

Deuterated polystyrene as a target material offers several advantages over other polymers because of the following: (1) it is chemically and physically stable at ordinary conditions, (2) it can be easily formed into spherical shells, and (3) it has a very high fraction of D2/H2 (above ∼99%). As in our previous studies, the fabrication method was basically a utilization of the emulsion technique. This method is well suited to mass-producing the polymer targets without microprocessing techniques. We have developed a fabrication method for single shell targets and an extension of this technique also enables us to fabricate double shell targets. This new method is faster and less labor intensive than previous techniques. The development of ICF experiments requires multilayer structure targets; we have developed, moreover, a new fabrication technique called the multicoating method. The polymer coating can be fabricated by the application of an emulsion technique. On the other hand, with metal coating, a nonelectroplating method was used, and nickel was employed as the coating metal. The thickness of the polymer coating layer can be controlled with the rotational speed of a stirrer in the emulsion. In the case of nickel coating, it is achieved by controlling the plating bath temperature and immersion time during the plating process. The experiment resulted in the development of a new technique for the fabrication of multilayer targets and low density, thick polymer-layer-coated targets.

Microstructural and mechanical property evaluation of black-chrome coated solar collectors

Concentrating solar collector assemblies of the substrate steel surface electroplated with a nickel coating followed by a thin black chrome solar absorber overlayer have been studied for the role and optimization of plating parameters such as; plating time, current density, plating bath temperature, chromic acid concentration, role of chromonyx addition agent, anode-to-cathode ratio of the plating arrangement, current efficiency of electroplating, and role of substrate finish; and over-growths were evaluated in each case for solar absorptance values. Within the range studied (3–36 min), 18 min of plating time is seen to give the highest absorptance value (96%). Current density variation, within the limits of this study (21.6–54 A/dm 2) shows that an optimum absorptance (93.2%) is attained with a current density of 43.2 A/dm 2. Variations in bath temperature of plating (0–30°C) yields a maximum in absorptance (93.2%) in coatings done at 10°C. The optimum value in solar absorptance (97.9%) is obtained at 375.95 g chromic acid/ l (50 oz/gal) addition to the plating bath, within the range, 225.57–413.54 g/ l (30–55 oz/gal), studied. Chromonyx addition agent, suggested for the plating bath, is seen to optimize at 30% of the bath volume in the range (21–33% of the volume) studied. Anode-to-cathode proportions of the plating arrangement are seen to yield a maximum absorptance (98.4%) at a ratio of 2 within the ratios evaluated (1–6 anode/cathode ratios). Current efficiencies of plating show a much higher value (92%) for nickel electroplating than for black-chrome coating (0.20%) for platings done at 10°C, 43.2 A/dm 2, and an electrode spacing of 1.27 cm. Finally, the role of substrate-surface finish, evaluated through coating black-chrome onto steel and nickel or nickel sheets show absorptance values to be quite similar in both cases, (93.0%) for black-chrome on steel plus nickel arrangement and (93.1%) for black chrome plated onto nickel sheets, at 10°C for a period of 3 min, and were extremely close in value for all bath temperatures (0–30°C) evaluated. Scanning electron microscopy and replication electron transmission microscopy done on plated and plated and ion-milled surfaces of solar collector growths did not yield conclusive data, but high magnification studies of the surfaces with the scanning electron microscope indicate an alteration of growth characteristics with variations in deposition temperatures. Finally, the strength of adhesion of the plated layers onto substrate surfaces was measured through tensile testing at ambient temperature. Values attained for adhesion strength (in excess of 100 kg/cm 2 in each case) indicate that the electroplated nickel and black-chrome layers are well attached to their respective substrates and possible failure of these coatings is unlikely to be due to insufficient adhesion.

クロムメッキにおける酸化皮膜の影響について

The effects of dipping time in chromium plating bath before the electroplating and of anodic oxidation by bipolarization during the plating were investigated. The following results were obtained: (1) When the dipping time was long or the sample was subjected to anodic oxidation in the chromium plating bath, an oxide film was formed on the nickel plating surface; then, the deposition range of chromium plating became narrower, which made it difficult to get an excellent bright chromium plating. (2) The effects of anodic oxidation were greater when the temperature of plating bath was higher and they were nearly proportional to the oxidation time; then, the deposition range of chromium plating became narrower, which finally led to very little deposits. (3) The effects of anodic oxidation were greater in Sargent bath than in hydrofluosilicic acid bath.

The preparation and structure of electrodeposited sponge cadmium electrodes

AbstractA method is described for preparing coherent sponge cadmium electrodes on cadmium‐plated substrates by electrodeposition from cadmium chloride solutions in the absence and presence of potassium chloride. The deposit morphology was shown to be a function of current density, pH, plating bath composition and temperature. Of the five main deposit types observed, only one, a sponge with very small crystallites, displayed high electrochemical activity when cycled in KOH solution and had sufficient coherence and adherence to its substrate to be considered suitable as a battery electrode. This material had a useful capacity approximately twice that of conventional electrodes, implying a net increase in battery capacity of at least 30% if conventional sintered plate positives were used. In addition, the elimination of the sintered nickel substrate and the possibility of continuous production methods promised a lower cost.In a separate series of experiments, ultramicrotome sections of the sponge deposits were examined by transmission electron microscopy. For specimens having a high electrochemical activity (more than 70% of the deposit being capable of reversible cycling in KOH solution) crystallite dimensions up to several microns in length and 0.5 to 1 micron in diameter appeared to predominate. This was consistent with measurements of the depth of oxidation observed on block cadmium electrodes and with the structure inferred from powder X‐ray diffraction examination.

Internal Stress in Electrodeposited Tin-Nickel Alloy

SYNOPSISMeasurements have been made of the internal stress in deposits of tin-nickel alloy. The method of Brenner and Senderoff was used. The alloy can be deposited over a range of 36,000 lb/in2 tensile to 40,000 lb/in2 compressive stress. The factors affecting stress are plating bath temperature, current density and chloride content. The change from tensile to compressive stress, brought about by either raising the bath temperature or adding choride, is in both cases accompanied by a small increase in the nickel content of the deposit. When plated on flat panels of steel, the deposit tends to crack when the stress exceeds 7,000 lb/in2 tensile. Examination of the effect of chloride suggests that deposition occurs from a complex ion of the type (NiSnF4Cl2)--, in chloride-fluoride solutions and from (NiSnF6)-- in all-fluoride solutions. A simple equation relates stress, bath temperature and current density in an all-fluoride electrolyte. For certain applications, it is recommended that, in making up a bath ...