Electroless Ni-B Research Articles

Barrier Integrity of Electroless Diffusion Barriers and Organosilane Monolayer against Copper Diffusion under Bias Temperature Stress

Barrier integrity of electroless NiB and CoWP/NiB thin layers against copper (Cu) diffusion was evaluated by time-dependent dielectric breakdown (TDDB) under bias temperature stress (BTS) using metal oxide semiconductor (MOS) test structures. The BTS tests were carried out also for an approximately 2.2-nm-thick organosilane monolayer (OSML), which has been used as the underlayer of the electroless barrier layers (EBLs). It was found that the barrier integrity of the EBLs was NiB 40 nm > NiB 10 nm > CoWP/NiB 40 nm = CoWP/NiB 10 nm in this order. The field acceleration parameter of the TDDB lifetime was almost the same for all EBLs. Initial failures and wide lifetime distributions were observed for CoWP/NiB when the NiB catalyst layer for CoWP was not thick enough, which is considered to be due to the large surface roughness. In addition, the OSML was found to have some barrier properties. Although the reliability of OSML was inferior to electroless NiB and CoWP/NiB barrier layers, it is considered that the barrier integrity of the EBLs was partially supported by the OSML.

Barrier Integrity of Electroless Diffusion Barriers and Organosilane Monolayer against Copper Diffusion under Bias Temperature Stress

Barrier integrity of electroless NiB and CoWP/NiB thin layers against copper (Cu) diffusion was evaluated by time-dependent dielectric breakdown (TDDB) under bias temperature stress (BTS) using metal oxide semiconductor (MOS) test structures. The BTS tests were carried out also for an approximately 2.2-nm-thick organosilane monolayer (OSML), which has been used as the underlayer of the electroless barrier layers (EBLs). It was found that the barrier integrity of the EBLs was NiB 40 nm > NiB 10 nm > CoWP/NiB 40 nm = CoWP/NiB 10 nm in this order. The field acceleration parameter of the TDDB lifetime was almost the same for all EBLs. Initial failures and wide lifetime distributions were observed for CoWP/NiB when the NiB catalyst layer for CoWP was not thick enough, which is considered to be due to the large surface roughness. In addition, the OSML was found to have some barrier properties. Although the reliability of OSML was inferior to electroless NiB and CoWP/NiB barrier layers, it is considered that the barrier integrity of the EBLs was partially supported by the OSML.

Deposition Mechanism of Electroless Ni-B Plating on Magnesium Alloy with Zinc Immersion Pretreatment

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The Study of Electroless Ni-B Coating on 45 Steel

In order to improve the corrosion resistance and the hardness of the 45 steel, under comparison tests, the electroless Ni-B was prepared on the 45 steel. We made a contrast test to get the optimal formula. The coating under the optimal formula was characterized by Scanning Electron Microscopy(SEM), Energy Dispersive Spectrometer(EDS), metallurgical microscope and salt spray cabinet. The experimental results showed that the electroless Ni-B coating on 45 steel was low boron coating, with high hardness, and the hardness of the coating could catch HV524; the thickness of the coating was 16μm.

Formation of Electroless Ni-B Coating on Boron Carbide Particles for Composite Processing

The present investigation is on formation of a uniform coating of Ni-B coating on the surface of B4C particle by electroless technique by varying process parameters and pH of the coating bath. The coating characteristics observed on majority of pH conditions on activated particles were mesh-like and at higher pH 12 the coated surface characteristics changes to patch like morphology. At lower alkaline condition there was not enough time for co-deposition to occur and the co-deposits appeared along with the coated particles. The studies with varying pH showed that pH 8 gives uniform coating of the entire particles surface with Ni-B and above which higher amount of co-deposited particles of Ni-B is also observed.

Supported Ni catalyst made by electroless Ni-B plating for diesel autothermal reforming

ABSTRACTCexGd1-xO2-δ (CGO)-supported Ni nano grains were prepared initially by electrolessly depositing Ni-B alloy nano particles onto an activated carbon (AC). The as-deposited Ni-B particles were then transferred from AC to CGO through the metallo-organic precursor approach. The resultant Ni/CGO catalysts displayed excellent catalytic activity and chemical stability against coking and sulfur poisoning in catalyzing autothermal reforming (ATR) of a surrogate diesel fuel, comprising dodecane, tetralin and a substituted thiophene. For comparison purpose, a Ni/CGO catalyst prepared by the conventional impregnation method was employed in the same ATR system. These two catalytic systems exhibited rather discrepant outcomes. It was found that the Ni(B)/CGO catalyst was capable of repressing selectivity of ethylene during the reforming process. In addition to this, CGO played a critical role in thermal cracking hydrocarbon chains and inhibiting sulfur poisoning.

Effect of Additives and Heat Treatment on the Formation and Performance of Electroless Nickel-Boron Plating on AZ91D Mg Alloy

The effect of thiourea (TU) and saccharin (SAC) on the deposition rate, surface morphology, boron (B) content, micro-hardness, and corrosion resistance of an electroless Ni-B plating layer on AZ91D magnesium alloy was investigated. The electroless Ni-B plating layer was characterized by scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Vickers hardness and electrochemical techniques in 3.5 wt% NaCl aqueous solution. The results showed that TU and SAC had different effects on the morphology and a similar influence on the particle size of the plating. TU slightly decreased the B content in the coating, while SAC had no effect. The two additives reduced the Ni-B plating rate and enhanced the corrosion resistance of the coating. Appropriate amounts of the additives improved higher micro-hardness of the plating. Elements diffusion occurred between substrate and coating during heat-treatment. After heat-treatment the deposited coating layer transformed from an amorphous structure to crystalline.

Influence of Process Parameters on Microhardness of Electroless Ni-B Coatings

Electroless Ni-B coatings have found large applications due to their high hardness and wear resistance. The present paper tries to investigate the influence of coating process parameters on the microhardness of electroless Ni-B coating with the help of Taguchi analysis. Four parameters, namely, bath temperature, concentration of reducing agent, concentration of nickel source, and annealing temperature, are considered and fitted into an [Formula: see text] orthogonal array to find out the optimized condition for improved hardness of the coating. The optimized condition is found to yield about 19% improvement in hardness of the coating compared to the initial condition. The significance of the process parameters and their interactions on the hardness of Ni-B coating is studied with the help of analysis of variance, which revealed that annealing temperature and concentration of reducing agent have significant influence over the hardness characteristics of electroless Ni-B coating. The compositional, microstructural, and phase structure analyses are conducted with the help of energy-dispersive X-ray analysis, scanning electron microscope, and X-ray diffraction analyzer, respectively.

Characterization of phase transformation behaviour and microstructural development of electroless Ni–B coating

Phase transformation behaviour of amorphous electroless Ni-B coating with a targeted composition of Ni-6wt% B is characterized in conjunction with microstructural development and hardness. Microscopic observations of the as-deposited coating display a novel microstructure which is already phase separated at multiple length scales. Spherical colonies of similar to 5 mu m consist of 2-3 mu m nodular regions which are surrounded by similar to 2-3 mu m region that contains fine bands ranging from 10 to 70 nm in width. The appearance of three crystalline phases in this binary system at different stages of heat treatment and the concomitant variation in hardness are shown to arise from nanoscale fluctuations in the as-deposited boron content from 4 to 8 wt%. High temperature annealing reveals continuous crystallization up to 430 degrees C, overlapping with the domain of B loss due to diffusion into the substrate. The implications of such a microstructure for optimal heat treatment procedures are discussed. (C) 2011 Elsevier B.V. All rights reserved.

Roughness Optimization of Electroless Ni-B Coatings Using Taguchi Method

In this paper, the authors present an experimental study of roughness characteristics of electroless Ni-B coatings and optimization of the coating process parameters based on L27 Taguchi orthogonal design. Three coating process parameters are considered viz. bath temperature, reducing agent concentration, and nickel source concentration. It is observed that concentration of reducing agent together with bath temperature play a vital role in controlling the roughness characteristics of the coatings. The analysis yields the optimum coating parameter combination for minimum roughness. A reduction of about 15% is observed in roughness at the optimal condition compared to the initial condition. The microstructure, composition, and the phase content of the coating are also studied with the help of scanning electron microscopes energy dispersive X-ray analysis, and X-ray diffraction analysis, respectively.

Chemical Vapor Deposition of Nanocarbon on Electroless NiB Catalyst Using Ethanol Precursor

Nanocarbon materials have been expected as post-Cu interconnect materials for large-scale integrated circuits (LSIs). In this paper, we present a nanocarbon deposition process using electroless plated NiB as the catalyst, which features conformal deposition on patterned dielectric surfaces. It was found that carbon nanotubes (CNTs) and graphitic films were deposited on the electroless NiB by atmospheric pressure chemical vapor deposition (CVD) using ethanol as the precursor. The graphitic quality estimated from the Raman spectra of the nanocarbon on the NiB catalyst was equivalent to that on a sputter-deposited pure Ni catalyst. The nanocarbon shape was dependent on NiB thickness, and CNTs were grown on 10-nm-thick NiB and graphitic films were grown on 30 nm or thicker NiB. The deposition temperature can be lowered to 505 °C, although the graphitic quality was degraded. It is considered that the electroless catalysts can be effective for nanocarbon deposition on patterned dielectric surfaces.

The effects of deposition parameters on surface morphology and crystallographic orientation of electroless Ni-B coatings

Electroless Ni-B coatings were deposited on AISI 304 stainless steels by electroless deposition method, which was performed for nine different test conditions at various levels of temperature, concentration of NaBH4, concentration of NiCl2, and time, using the Taguchi L9(34) experimental method. The effects of deposition parameters on the crystallographic orientation of electroless Ni-B coatings were investigated using SEM and XRD equipment. SEM analysis revealed that the Ni-B coatings developed six types (pea-like, maize-like, primary nodular, blackberry-like or grapes-like, broccoli-like, and cauliflower-like) of morphological structures depending on the deposition parameters. XRD results also showed that these structures exhibited different levels of amorphous character. The concentration of NaBH4 had the most dominant effect on the morphological and crystallographic development of electroless Ni-B coatings.

Fractal characterisation of electroless Ni-B coating and optimisation of coating parameters

This paper presents an experimental study of fractal characteristics of the surface profile of electroless Ni-B coating and optimisation of coating parameters based on L27 Taguchi orthogonal design. Optimum coating parameter combinations are identified to yield the optimum (maximum) fractal dimension by Taguchi analysis so that a smoother coating surface is obtained. Bath temperature is found to be the most important coating parameter in controlling the fractal characteristics of Ni-B coatings. The interaction between reducing agent concentration and the nickel source concentration also has high contribution in controlling the fractal characteristics of Ni-B coating. The coating is characterised for its microstructure and composition by scanning electron microscopy, X-ray diffraction analysis and energy dispersive X-ray analysis.

Electrochemical Study on Electroless Nickel Plating Using Sodium Borohydride as the Reductant

We studied electroless Ni-B plating with sodium borohydride as the reductant by linear sweep voltammetry. The effects of bath solution composition and operating conditions on the cathodic reduction and anodic oxidation were studied. Increases in the concentrations of nickel acetate and sodium borohydride accelerated the reduction of Ni 2 + and the oxidation of BH -, respectively. Ethylenediamine, sodium hydroxide, thiourea and saccharin sodium inhibited both the cathodic and anodic reactions to varying degrees. Additionally, sulfur in the additives promoted the dissolution of nickel. High temperature was beneficial to both the cathodic reduction and anodic oxidation.

Study of Potentiodynamic Polarization Behaviour of Electroless Ni-B Coatings and Optimization using Taguchi Method and Grey Relational Analysis

Electroless nickel coatings are very popular for their corrosion resistant actions. The present article attempts to study the corrosion behaviour of electroless Ni-B coatings by varying the coating parameters viz. bath temperature, reducing agent concentration and nickel source concentration together with the annealing temperature. The electrochemical parameters viz., corrosion potential and corrosion current density are evaluated with the help of potentiodynamic polarization experimentation. Taguchi based Grey analysis is employed in order to optimize this multiple response problem and the optimal combination of parameters for maximum corrosion resistance for Ni-B coatings is presented. Moreover, analysis of variance reveals that bath temperature and concentration of nickel source have significant influence on the corrosion performance of the coating. The microstructure characterization of the coating is also conducted with the help of scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The Ni-B coating in general exhibits a nodular structure and turns crystalline with heat treatment. The corroded surface exhibits cracks and black spots which imply the occurrence of localized corrosion.

A parametric investigation of the friction performance of electroless Ni‐B coatings

AbstractFriction performance of electroless Ni‐B coatings sliding against steel is experimentally investigated in this paper. Friction performance is measured in terms of coefficient of friction (COF) for varying tribological testing parameters such as load, speed and time. Taguchi‐based optimisation of the testing parameters is attempted to find the optimal combination of testing parameters for minimum COF. An analysis of variance reveals that all the testing parameters have significant influence on the friction performance of the coating. Also, the interaction between load and speed is found to affect the friction more compared with the rest of the interactions. The coating characterisation is done with the help of scanning electron microscopy (SEM), energy dispersive X‐ray and X‐ray diffraction analysis. It is found that the Ni‐B coating is amorphous in the as‐deposited condition but gradually turns crystalline with heat treatment. The sliding tracks observed with SEM showed that abrasive failure is the predominant wear mechanism. Copyright © 2010 John Wiley & Sons, Ltd.

Mechanical Reliability of Sn-Ag BGA Solder Joints With Various Electroless Ni-P and Ni-B Plating Layers

The mechanical reliability of Sn-3.5 wt.%Ag solder joints with four different electroless Ni plating layers [Ni-1B, Ni-3B, Ni-7P, and Ni-10P (in wt.%)] was investigated as a function of aging time up to 60 days at 150 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C. The ultimate shear stresses for fracture were higher in the ball shear tests when using Ni-B samples than those with Ni-P metallization if the aging treatment at 150 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C was shorter than 15 days, and vice versa when the aging time was higher than 45 days. In all the joints, Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> intermetallic compounds (IMCs) were formed at the interfaces. The thickness of the IMC layer increased with decreasing B or P content, i.e., increasing Ni content. The reaction rate between the Sn-Ag solder and Ni-P was slower than that between the Sn-Ag solder and Ni-B. In the shear test, the failure mode switched from a bulk-related failure (ductile fracture) to an interface-related failure (brittle fracture), depending on the aging time. After prolonged aging treatment, weak solder/Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> interfaces led to a failure mode of brittle fracture for all the solder joints, due to the formation of thick Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> IMCs. The failure for the Sn-Ag/Ni-B joints was more abrupt and brittle due to the formation of the thick, interfacial Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> IMC. The results demonstrated that the Sn-Ag/Ni-P joint was more reliable than the Sn-Ag/Ni-B joint from the viewpoints of interfacial IMC thickness and long-term mechanical reliability.

Anisotropic Deposition of Localized Electroless Nickel for Preferential Bridge Connection

Preferential bridge connection by localized electroless NiB deposition was investigated. The phenomenon of “bridge” formation by so-called extraneous deposition was utilized as a technique to perform the selective deposition of NiB on organic surfaces. The films used for bridging were preferentially deposited in the area between facing pads. The deposition proceeded in the direction perpendicular to the surfaces of the facing pads. The occurrence of this anisotropic deposition strongly depends on solution diffusion, and the fabrication of a connection could be controlled by changing the pattern and pad dimensions. This method does not use a resist pattern for selective deposition; thus, it is a high throughput maskless fabrication process for the connection between separated pads. Using this technology, a preferential bridge connection for a pad array with a pad width, a pad height, a distance of between the facing pads, and a pitch was fabricated. Moreover, the combined use of localized electroless deposition and conventional electroless deposition on the bridging film is expected to realize for pad-to-pad connections with low electric resistance.

Future Technology Proposal for Damascene Process Using All Wet Electrochemical Technique

All-wet process was developed for fabricating diffusion barrier layer and Copper wiring for ultra large scale integration (ULSI) by means of a combination technique of electroless deposition and surface modification of Pd-activated ligand-bearing organic layer. In this paper, we performed detailed analysis of the Pd-activated ligand-bearing organic layer. Moreover, we successfully deposited thin electroless NiB layer on the Pd-activated molecular layer of 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS) in a small reactor at a low temperature in a few minutes.

Fabrication of Electroless CoWP/NiB Diffusion Barrier Layer on SiO2 for ULSI Devices

We investigated the electroless CoWP/NiB diffusion barrier layer for ultralarge-scale integration (ULSI) interconnection by forming the immobilizing Pd catalyst on an organosilane layer. When the electroless CoWP film was formed directly on a Pd-activated organosilane layer, it became islandlike and did not form a continuous layer. When it was formed on an electroless NiB deposited on a Pd-activated organosilane layer, the electroless CoWP film was uniform and formed a continuous layer 10 nm thick. The transmission electron microscopy images of the interfaces of showed that, at an annealing temperature up to for 30 min, the interfaces remained unchanged and clear, showing no trace of Cu diffusion into the substrate. In-plane X-ray diffraction patterns indicated that the CoWP/NiB film had an amorphous structure and was stable against heat-treatment up to for 30 min. An evaluation of sheet resistance measurements suggested that the CoWP/NiB film shows appropriate barrier properties for Cu diffusion up to . The CoWP/NiB film was used as a seed for electroless Cu plating. Trenches 100 nm wide were coated with a 10 nm CoWP/NiB barrier followed by successful trench filling by electroless Cu plating.