Growth Characteristics of Atomic Layer Deposited TiO[sub 2] Thin Films on Ru and Si Electrodes for Memory Capacitor Applications

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Abstract
TiO2TiO2 thin films were grown by an atomic-layer-deposition process at growth temperatures ranging from 200to300°C200to300°C on Ru and Si substrates using Ti[OCH(CH3)2]4Ti[OCH(CH3)2]4 and H2OH2O 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 0.046nm∕cycle0.046nm∕cycle , respectively. The TiO2TiO2 film growth on a Ru substrate showed a rather long incubation period and the incubation period decreased with increasing Ti[OCH(CH3)2]4Ti[OCH(CH3)2]4 pulse time, whereas the H2OH2O pulse time had almost no influence on the incubation period. A growth rate transition, from low to high values, (thickness 7-8nm7-8nm ) was observed when the films were grown at temperatures 250°C250°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 TiO2TiO2 films grown at temperatures 250°C250°C showed a dielectric constant of ∼35∼35 . A 14-nm14-nm -thick TiO2TiO2 film showed an equivalent oxide thickness of 1.7nm1.7nm and a leakage current density of 5×10−6A∕cm25×10−6A∕cm2 at 1V1V .
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