Morphology of nanometer-thick electrolytic copper layers investigated by atomic force microscopy

The effect of electrolytic deposition parameters on the morphology of very thin (5 nm) copper layers was investigated by atomic force microscopy. Such thin copper layers were electrodeposited from solutions with different concentrations of copper sulfate and sulfuric acid on silicon wafers sputter-coated with a Ti layer and a Cu top layer. The characterization of these layers by atomic force microscopy shows that 5 nm thick Cu layers deposited by galvanostatic electrodeposition are homogeneous and present granular features on the surface. An increase of the copper sulfate concentration results in an increase in the size of the granular surface features. The lowest surface roughness is observed at a concentration of 100 g/L sulfuric acid. (C) 1999 The Electrochemical Society. S0013-4651(98)03-041-9. All rights reserved.