Numerical simulation of superconformal electrodeposition using the level set method

Damascene copper is rapidly replacing aluminum as the interconnect material of choice in silicon technology. The change is driven by the lower electrical resistivity of copper, which decreases power consumption and permits increased central processor unit (CPU) clocking speeds. Electroplating is the preferred deposition method because it permits filling of high-aspect ratio features without seams or voids through the process of superconformal deposition, also called "superfill." This process only occurs when particular combinations of chemical additives are included in the electrolyte [1]. Two crucial mechanisms by which the additives enable superfill to occur are (a) accelerator behavior increasing the copper deposition rate as a function of coverage and (b) conservation of accelerator coverage with increasing/decreasing arc length [2]. The model presented here utilizes the level set method (LSM) to track the position of the copper/electrolyte interface as the features are filling.