Development and Characterization of Co-Ni Alloys for Microsystems Applications

Abstract

A chloride plating bath, containing boric acid and saccharin has been optimized to obtain homogeneous Co-Ni deposits over normalSi/SiO2/normalTi/normalNi substrate. The goal is to explore the synergy of these layers in microsystems applications. Anomalous codeposition occurs and both electrochemical and structural results indicate that obtained Co-Ni layers correspond to solid solutions of face-centered cubic (fcc) structure, whose composition may be varied as a function of the electrodeposition parameters. Results of the electrochemical and magnetic characterization carried out are presented, showing the trends of a soft magnetic material, i.e., high saturation magnetization (1.2 T) and low coercivity. Smooth surfaces and a steady deposition rate were observed in the Co-Ni deposits on silicon-based unpatterned substrates. In order to check the versatility and the compatibility of this Co-Ni electrodeposition with the standard microsystems fabrication technology, two processes, surface- and bulk-technology based, have been carried out. Due to the high selectivity and homogeneity of the Co-Ni layer, it has been possible to pattern the deposits with a definition down to 10 μm, as well as to fabricate 3D structures. Methods to liberate the Co-Ni films from the silicon-based substrate have been developed; as a result, low-stressed freestanding structures are presented. © 2002 The Electrochemical Society. All rights reserved.

Influence of a cationic surfactant in the properties of cobalt–nickel electrodeposits

“…Changes observed both in morphology and structure of CoNi deposits prepared in presence of DTAC respect to those obtained in absence of additive were not consequence of the composition variation. In DTAC absence, independently of the alloy composition, the obtained CoNi deposits corresponded to a similar structure and morphology [12,13].…”

“…In our laboratory, a chloride electrodeposition bath useful to prepare magnetic CoNi deposits was developed [12][13][14]. Good adherence, brilliant aspect, smooth surface and a constant deposition rate were obtained in all tested substrata.…”

Electrolytical deposition of NiCo films on Fe micro‐particles

“…[1,2] Investigations on electrodeposited Ni-Co alloys have indicated that their properties strongly depend on the cobalt content. [3,4] Nickel-cobalt deposition belongs to the anomalous type, which means that deposition of the less noble metal (Co) in a twocomponent alloy is greatly favoured.…”

“…[3,4] Nickel-cobalt deposition belongs to the anomalous type, which means that deposition of the less noble metal (Co) in a twocomponent alloy is greatly favoured. [2,5,6] There are several researchers explaining the above anomalous phenomena, with the competition adsorption of metal hydroxides, monohydroxides, or metal ions since the hydrogen evolution reaction resulted in local increase in pH near deposit-electrolyte interface. [1,7 -9] The electrolytic coating of powder particles could achieve great importance in powder metallurgy as it is one of the processes that give the best homogeneity of the final product.…”

Kinetics and electrocatalytic behavior of nanocrystalline CoNiFe alloy in hydrogen evolution reaction

“…electrocatalytic activities, etc. [20,21]. For instance, Au nanoparticles were found to possess extraordinary electrocatalytic activity towards many reactions, while the bulk Au electrodes showed much less or even fairly poor electrocatalytic activity towards the same reactions [22].…”