ZrO2 thin films were grown by atomic layer deposition from new cyclopentadienyl precursors on planar TiN and SiO2/Si substrates, as well as on silicon having deep trenches with aspect ratio of 1:60. The films demonstrated conformal growth in trenches achieving step coverage of 80%-90%. ZrO2 films crystallized either after exceeding threshold thickness or upon annealing dominantly in the cubic or tetragonal polymorph. Leakage current densities of (7-9) x 10(-8) A/cm(2) at capacitance equivalent oxide thicknesses of 0.76-0.82 nm were reached. (C) 2009 American Vacuum Society. [DOI:10.1116/1.3071844]