Synthesis of High Dielectric Constant Titanium Oxide Thin Films by Metalorganic Decomposition

概要

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Titanium-containing alkoxide (Ti[i-OCH(CH_3)_2]4) dissolved in 2-rnethoxyethanol was directly deposited onto silicon by the metalurganic decumpositiun (MOD) technique. Titanium oxide (TiO_2) thin films are formed uniformly on Si after high-temperature annealing. Raman and X-ray diffraction measurements indicate that the structure changes completely from anatase to rutile phase at an annealing temperature of 700℃. During the crystallization, however, the reaction starts at the TiO_2/Si interface, resulting in the formation of interfacial SiO_2 layer with a thickness of 2.6 nm. In contrast, the TiO_2 thickness was fairly constant. The capacitance-voltage characteristics revealed that with annealing temperature, the dielectric constant increases to a maximum (ε_<max> = 48) at 700C℃. However, the dielectric constant decreases again above 700℃ due tu the occurrence of interfacial SiO growth. For the well crystallized TiO_2 films, the leakage current decreases to 7 × 10^<-8> A/cm^2 at 2 MV/cm and the maximum breakdown field is 3.3 MV/cm. The hO_2 thin films formed by MOD are expected to act as a suitable dielectric in place of conventional thin SiO_2 for future integrated circuits.
社団法人応用物理学会の論文
2002-11-30