Atomic layer deposition of highly conformal films of tantalum oxide were studied using tantalum alkylamide precursors and water as the oxygen source. These films also exhibited a very high degree of conformality: 100% step coverage on vias with aspect ratios greater than 35. As deposited, the films were free of detectable impurities with the expected (2.5-1) oxygen to metal ratio and were smooth and amorphous. The films were completely uniform in thickness and composition over the length of the reactor used for depositions. Films were deposited at substrate temperatures from 50 to 350 degreesC from precursors that were vaporized at temperatures from 50 to 120 degreesC. As deposited, the films showed a dielectric constant of 28 and breakdown field consistently greater than 4.5 MV/cm. (C) 2003 Elsevier B.V. All rights reserved.