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| Hauptseite > Publikationsdatenbank > Metallorganisch chemische Gasphasenabscheidung (MOCVD) von oxidischen hoch- $\epsilon$ Schichten |
| Hauptseite > Publikationsdatenbank > Metallorganisch chemische Gasphasenabscheidung (MOCVD) von oxidischen hoch- $\epsilon$ Schichten |
| Dissertation / PhD Thesis/Book | PreJuSER-44579 |
2005
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/184
Report No.: Juel-4159
Abstract: The ongoing miniaturisation in CMOS technology requires the integration of high-k materials. The application for these high-k materials includes capacitors in DRAMs, integrated capacitors, gate oxides in MOSFETs and tunable devices. The considered materials in this work are (Ba,Sr)TiO$_{3}$, SrTiO$_{3}$ and SrTa$_{2}$O$_{6}$ and the oxides from the group IVb metals: Ti, Zr and Hf. The films were deposited on Platinum and Silicon substrates in order to evaluate the dielectric properties for applications in metal-insulator-metal (MIM) structures as well as in metal-insulator-semiconductor (MIS) structures. The high-k films were grown by metal organic chemical vapour deposition (MOCVD) and the evaluation and optimisation of the production processes is a major part of this work. The used reactor is an AIX-2600G3, which was originally constructed for the production of III-V semiconductors and which was further developed for our purposes with special emphasis to operation at low pressure and in an oxygen atmosphere. Additionally, two liquid delivery systems were tested, which are the LDS-300B from ATMI and the TRIJET from JIPELEC. Different approaches were investigated: Mixing of conventional precursors for the example of (Ba,Sr)TiO$_{3}$, test of a single source precursor for SrTa$_{2}$O$_{6}$ and tests of newly designed precursors for the group IVb-metal oxides, M-(O-I-Pr)$_{2}$(tbaoac)$_{2}$. In addition, compatibility tests of the new Titanium precursors with the conventional Strontium precursor are presented for the example of SrTiO$_{3}$. Most detailed investigations were performed on the nucleation and growth processes of (Ba,Sr)TiO$_{3}$ on Platinum <111>. Details of the nucleation were obtained from the new method of conductivity scans with the AFM. These investigations were combined with XRD, SEM, HRTEM, SPM and XPS and give a consistent picture of development of the structural properties and their dependencies on growth temperature and chemical composition. The electrical properties, especially capacity and leakage current indicate a strong dependency from film thickness, which can be explained by separating the bulk- from the interface capacity. Based on these results the interface layer was optimised by changing the interfacial stoichiometry. Additionally, SrTa$_{2}$O$_{6}$ was tested as an alternative material with low tunability and shows promising electrical results. The MOCVD growth of oxide layers on Silicon is characterized by the growth of an amorphous interfacial SiO$_{x}$ layer, which corroborates the electrical properties. For the example of SrTiO$_{3}$ on Silicon <001> details of the growth kinetics of the interfacial layer were investigated by HRTEM. The first results from group IVb oxides, which are the most promising candidates for gate oxides, are presented. Film properties, which are not influenced by the amorphous SiO$_{x}$ layer, like structure, roughness, dialectical constant of the bulk material are very promising. Hence, there remains an optimisation of the amorphous layer before integration.
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