Ru is the most promising material for the capacitor electrode in the next generation dynamic random access memories. Ru thin films, however, which are deposited by chemical vapor deposition (CVD) have high tensile stresses. Therefore, many problems with respect to device reliability such as peeling or thermal deformation have been reported. In this study, we investigated the effects of the various deposition parameters on the stress behaviors. Ru thin films were prepared by metal-organic CVD on (100) Si substrate using RuCp(i-PrCp) precursor and O-2 reaction gas. Internal stress of Ru thin film was measured using the laser scanning method. As the Ru film grew, tensile stress increased. And the tensile stress also increased with reduction of substrate temperature. These tendencies are attributed to low atomic mobility of the Ru material (T-m = 2523 K). In addition, tensile stress increased more than 300 MPa after the annealing process. It can be explained by densification through rearrangement of Ru atoms during annealing. Based on these results, we examined the origins of this stress generation with quantitative analysis. Then the experiments to reduce these stresses were performed by control of the deposition rate. Under the lower deposition rate, the film became a denser structure and this led the tensile stress, reducing successfully down to about 180 MPa from 560 MPa. (C) 2003 American Vacuum Society.