| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Film Poster Session |
| Presenter: | Jaemin Kim, Sejong University, Korea |
| Authors: | J. Kim, Sejong University, Korea H.-L. Kim, Sejong University, Korea J. Gu, Sejong University, Korea S. Kim, Sejong University, Korea H. Jung, Sejong University, Korea R. Hidayat, Sejong University, Korea Y. Myung, Sejong University, Korea W.-J. Lee, Sejong University, Korea |
| Correspondent: | Click to Email |
Titanium oxide has been extensively studied for various applications including the high-permittivity dielectric of DRAM capacitors, photocatalysts, and optical coatings. Atomic layer deposition (ALD) technology is replacing physical vapor deposition or chemical vapor deposition to provide excellent step coverage, accurate film thickness control, and high stoichiometry film quality. The most common titanium precursors are homoleptic precursors, such as titanium tetraisopropoxide (TTIP) and tetrakis(dimethylamino)titanium (TDMAT). In general, higher deposition temperature improves the physical and electrical characteristics of the dielectric film, such as film density, stoichiometry, and purity. However, the TTIP and TDMAT decompose at over 200°C, resulting in poor step coverage and high impurity concentration. Therefore, we need titanium precursors with excellent thermal stability together with high reactivity and sufficient volatility. It was reported that mixed alkoxide-cyclopentadienyl titanium compounds show better thermal stability than titanium alkoxides, and the thermal stability is further improved by replacing C5H4(CH3) (MeCp) with C5(CH3)5 (Cp*) [1]. In the present study, we investigated the reaction mechanism of ALD of titanium oxide using heteroleptic titanium precursors with different cyclopentadienyl-type ligands. CpTi(OMe)3 and Cp*Ti(OMe)3 were selected to investigate the effect of cyclopentadienyl ligand. Ozone (O3) and water (H2O) were compared as the oxidizing agent. Saturation dose and the ALD temperature window were determined by measuring growth rates with different precursor feeding times, oxidizing agent feeding times, and the process temperatures. The surface reaction was investigated at different temperatures by using in-situ quartz crystal microbalance, in-situ Fourier transform infrared spectroscopy, and was simulated by density functional theory calculation.
[1] R. Katamreddy et al, ECS Transactions, 25 (4) 217-230 (2009) (doi : 10.1149/1.3205057)