Three-dimensional Monte-Carlo computer simulation of grain growth in electro-plated pure Ni

A Monte-Carlo computer simulation code was developed to study grain growth characteristics during thin film deposition. The simulation algorithm was based on the minimization of the sum of the anisotropic surface energy and grain boundary energy. The average grain size and the surface roughness of the plated layer increased rapidly with the thickness of deposition, but the rate of the increase diminished with large thickness. In the simulation, it was found that the surface energy term dominated over the grain boundary energy term and consequently a strong {111} fiber texture was predicted. To verify the results of the computer simulation, an experiment was conducted to electro-deposit pure Ni on a Cu substrate. The thickness dependence of the microstructure, particularly roughness and grain size, was consistent with the prediction by the simulation. The roughness increased with thickness in the initial period but became saturated in the later period. Increasing the current density during electro-plating or increasing the deposition rate in the computer simulation randomized the texture and refined the grain size, which was attributed to insufficient diffusion at the specimen surface. In the experiment a pronounced {100} texture was found due to hydrogen adsorption. Minimization of hydrogen adsorption by strong agitation or by addition of boric acid decreased the intensity of the {100} texture substantially, confirming the rationale based on the hydrogen adsorption.