Fabrication of DC-plated nanocrystalline copper electrodeposits

The microstructure was investigated for D.C.-plated copper electrodeposits, prepared from two types of electrolyte with an applied voltage of 5 V and current densities ranging from 0.01 to 0.06 A cm(-2), onto Si substrate con taining a thin stacked layer of ionized metal plasma (IMP) copper seed and a TiN diffusion barrier. Reduced grain size of copper electrodeposits was f ound with increasing deposition current density. Electroplated copper film with an average grain size of 100 nm could be produced with current densiti es of 0.05-0.06 A cm(-2). The surface morphology of the copper electrodepos its was very rough at low current densities and its roughness correlated we ll with the observed microstructures. The resistivity of the copper film wa s high (similar to 2.5 mu Omega cm) at low current densities, due to the pr esence of a high defect density, but it decreased to a value of 2.0 mu Omeg a cm with increasing current densities, which resulted in a decrease in the defect density within the films. Both electrolytes produced similar result s. (C) 1999 Elsevier Science S.A. All rights reserved.