Nucleation and growth of Cu thin films on silicon wafers deposited by radio frequency sputtering

The early stage of Cu nucleation and the subsequent film growth on silicon wafers prepared by radio frequency (rf) sputtering is investigated in this study by atomic force microscopy. Experimental results indicate that isolated island nuclei are initially formed and a transition layer is later formed due to the increasing number of nuclei and a poorly crystallized deposit layer in between. The transition layer transforms into a single layer of grains afterward. Cu grains are observed to agglomerate and coalesce, thereby causing increasing surface roughness with increasing deposition time. (C) 1997 Elsevier Science S.A.