Ru films were successfully prepared by plasma-enhanced atomic layer deposition (PEALD) using and plasma. To optimize Ru PEALD process, the effect of growth temperature, plasma power and plasma time on the growth rate and preferred orientation of the deposited film was systemically investigated. At a growth temperature of and plasma power of 100W, the saturated growth rate of 0.038 nm/cycle was obtained on the flat /Si substrate when the and plasma time was 7 and 10 sec, respectively. When the growth temperature was decreased, however, an increased plasma time was required to obtain a saturated growth rate of 0.038 nm/cycle. Also, plasma power higher than 40 W was required to obtain a saturated growth rate of 0.038 nm/cycle even at a growth temperature of . However, (002) preferred orientation of Ru film was only observed at higher plasma power than 100W. Moreover, the saturation condition obtained on the flat /Si substrate resulted in poor step coverage of Ru on the trench pattern with an aspect ratio of 8:1, and longer plasma time improved the step coverage.