Electrodeposition of CoWP Film: I. Electrochemical and Compositional Analyses

Abstract

Electrochemical characterization of electrodeposition of CoWP films on copper substrate from a citrate electrolyte was carried out using voltammetry and chronoamperometry techniques. The voltammetry experiments revealed that codeposition of cobalt, tungsten, and phosphorus from an electrolyte containing cobalt sulfate, sodium tungstate, sodium hypophosphite, and tri-sodium citrate occurred via a nucleation process under mass-transfer control. The chronoamperometric study showed an instantaneous nucleation mechanism during electrocrystallization of CoWP on copper. Finally, a bath was developed from which CoWP thin films were deposited at room temperature on copper-coated silicon wafers. Surface analysis using X-ray photoelectron spectroscopy revealed that the films contained elemental cobalt, tungsten, phosphorus, hydroxide of cobalt, and oxides of cobalt and tungsten. Scanning electron microscopy and atomic force microscopy images showed that the films had typical spherical nodular structures with good uniformity and dense coverage.