Growth characteristics of atomic layer deposited TiO2 thin films on Ru and Si electrodes for memory capacitor applications

TiO2 thin films were grown by an atomic-layer-deposition process at growth temperatures ranging from 200 to 300 degrees C on Ru and Si substrates using Ti[OCH(CH3)(2)](4) and H2O as metal precursor and oxygen source, respectively, for metal- insulator- metal capacitor application in dynamic random access memories. The saturated film growth rate on Ru and Si substrates was 0.034 and 0.046 nm/cycle, respectively. The TiO2 film growth on a Ru substrate showed a rather long incubation period and the incubation period decreased with increasing Ti[OCH(CH3)(2)](4) pulse time, whereas the H2O pulse time had almost no influence on the incubation period. A growth rate transition, from low to high values, (thickness 7- 8 nm) was observed when the films were grown at temperatures > 250 degrees C, whereas the films grown at lower temperatures did not show the transition. The transition was due to the structural change of the film from an amorphous/ nanocrystalline to the well-crystallized polycrystalline anatase phase. The TiO2 films grown at temperatures > 250 degrees C showed a dielectric constant of similar to 35. A 14-nm-thick TiO2 film showed an equivalent oxide thickness of 1.7 nm and a leakage current density of 5 x 10(-6) A/cm(2) at 1 V. (c) 2005 The Electrochemical Society. [DOI: 10.1149/ 1.1943589] All rights reserved.