Effect of H2 addition during Cu thin-film sputtering

We have investigated the effect of H-2, addition during Cu sputtering. It was found that the Cu surface becomes smooth with increasing amount of H2 added to Ar plasma during Cu sputtering. The arithmetical mean roughness decreases by 40% with H-2 (60%) addition. The X-ray diffraction peak intensity ratio [Cu(111)/Cu(200)] increases with H-2 content, which indicates that the crystallinity of the Cu film has been improved. The property of Cu filling in the contact hole is much improved by H addition sputtering after low-temperature annealing (350 degrees C). Cu film was electroplated on the sputtered Cu. The roughness of the electroplated Cu surface does not depend on the roughness of the initial sputtered Cu surface even though H-2 is added during Cu sputtering. However, the crystal orientation of the electroplated Cu film [(111)/(200) ratio] can be controlled by the crystal orientation of the seed sputtered Cu film; that is, H-2 addition during Cu sputtering results in a good crystal orientation of the electroplated Cu film.