The influence of the thin RuO2 surface layer, formed by oxidation of a Ru electrode using O-3 (250 degrees C for 15 s), on the phase formation and dielectric properties of TiO2 thin films grown by atomic layer deposition (ALD) is investigated. TiO2 films grown on the as-received Ru electrode (no O-3 pretreatment) have an anatase structure and the dielectric constant is similar to 30. However, the crystalline structure of the TiO2 film grown on an O-3 pretreated Ru electrode is rutile, and the dielectric constant is > 60. This is attributed to a structural compatibility between rutile TiO2 and RuO2. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.2131241] All rights reserved.