Effect of H2 Addition during Cu Thin-Film Sputtering

Abstract

We have investigated the effect of H2 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 H2 (60%) addition. The X-ray diffraction peak intensity ratio [Cu(111)/Cu(200)] increases with H2 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 H2 addition sputtering after low-temperature annealing (350 °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 H2 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, H2 addition during Cu sputtering results in a good crystal orientation of the electroplated Cu film.