Changing Superfilling Mode for Copper Electrodeposition in Blind Holes from Differential Inhibition to Differential Acceleration

摘要

Blind holes 5μm diam and 25μm in depth were filled with electrodeposited copper. Before electrodeposition, the blind holes were fully metallized with a copper seed layer or with a thin sputtered Ta layer deposited on top of the copper seed layer. Filling of partially Ta-capped features was three times faster than filling fully metallized features. For fully metallized features, the growth mode for copper electrodeposition is dominated by diffusion adsorption of a leveling agent. For partially Ta-capped surfaces, the growth mode was modified to differential acceleration through accumulation of an accelerating species at the bottom of features.