Modeling of Transient Electrochemical Systems Involving Moving Boundaries

Abstract

Pulse and pulse-reverse plating of copper in high-aspect-ratio trenches was numerically investigated by a 2D model that solves unsteady-state mass transport and incorporates adaptive meshing capabilities for moving boundaries. A numerical method, FIDIPIDDIS, based on general finite difference that includes transient systems, diffusion, migration and convection, fluid flow, multiple species, reactions in complex geometries, and shape change was developed. The shape evolution during copper elec- trodeposition and electrodissolution was simulated with time. The void size behavior of this system resulting from variation of the process parameters of pulse and pulse-reverse plating and feature’s aspect ratio was investigated. Pulse and pulse-reverse plating parameters can be adjusted to minimize the void. It was concluded that at constant average plating a high duty factor provides better filling for pulse plating and an off time should follow the deposition time in pulse-galvanostatic reverse plating. However, pulse plating can obtain the same void at higher deposition rates than pulse-galvanostatic reverse plating. Void-free filling of trenches with copper at high deposition rates was related to pulse-potentiostatic reverse plating.