TheThermodynamics and Kinetics Study of Growth Behavior of Sono-Electrodeposited Cu Thin Films

Abstract

The extensive use of copper thin films are in decorative, protective, electronic and magnetic devices and systems. In all of these applications, the performance and reliability of the copper films are critically determined by their microstructure, including grain shape, grain size, grain distribution, defect density and texture. These in turn are all strongly affected by the conditions under which the films are formed and can be modified through grain growth during post processing such as annealing. Thus the post synthesis thermodynamics and kinetics study of growth of films is undeniably a field of great technological importance. The application of ultrasound to crystallizing systems appears to offer significant potential for modifying and improving both the process and products. We have compared the crystallinity, composition and ex-situ growth behavior of the as-deposited copper thin films to similar films prepared under ultrasonic irradiation. Copper films have been electrodeposited on graphite substrate from aqueous acidic sulphate bath at different depositional potentials. The deposition mechanism has been studied by using cyclic voltametry and chronoamperometry. The structures, morphology, composition, phases, roughness, thickness, grain distribution of the film have been investigated using scanning probe microscope (SPM), scanning electron microscope (SEM) and x-ray diffraction (XRD) techniques. From the results of SPM and SEM, the copper morphologies are found to be significantly distinct with and without irradiation. The growth of the films has been quantified under a dynamic thermal atmosphere of different heating rates by a differential scanning calorimeter (DSC). For the understanding of atomic processes, the activation energy for growth is determined. The surface morphology of the sonicated deposits are found to be uniform after growth. The results of the present investigation may open up new possibilities for the use of sonoelectrochemically synthesized films for various application areas.