<p>Due to the constantly decreasing dimensions of electronic devices, the conventional dielectric material in transistors and capacitors, SiO<sub>2</sub>, has to be replaced by a material with higher dielectric constant. Some of the most promising candidates are tantalum oxide,Ta<sub>2</sub>O<sub>5</sub>, zirconium oxide, ZrO<sub>2</sub> and hafnium oxide, HfO<sub>2</sub>.</p><p>This thesis describes new chemical vapour deposition (CVD) and atomic layer deposition (ALD) processes for deposition of Ta<sub>2</sub>O<sub>5</sub>, ZrO<sub>2</sub> and HfO<sub>2</sub> using the metal iodides as starting materials. The layer-by-layer growth in ALD was also studied in real time with a quartz crystal microbalance (QCM) to examine the process characteristics and to find suitable parameters for film deposition.</p><p>All the processes presented here produced high-purity films at low deposition temperatures. It was also found that films deposited on Pt substrates generally crystallise at lower temperature, or with lower thickness, than on silicon and single-crystalline oxide substrates. Films grown on MgO(001) and α-Al<sub>2</sub>O<sub>3</sub>(001) substrates were strongly textured or epitaxial. For example, monoclinic HfO<sub>2</sub> deposited on MgO(001) were epitaxial for deposition temperatures of 400-500 C in ALD and 500-600 C in CVD. Electrical characterisation showed that the crystallinity of the films had a strong effect on the dielectric constant, except in cases of very thin films, where the dielectric constant was more dependent on layer thickness.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-1415 |
| Date | January 2001 |
| Creators | Forsgren, Katarina |
| Publisher | Uppsala University, Department of Materials Chemistry, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 665 |
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