[en] Zirconium doped indium oxide thin films were deposited by the atomic layer deposition technique at 500 deg. C using InCl₃, ZrCl₄ and water as precursors. The films were characterised by X-ray diffraction, energy dispersive X-ray analysis and by optical and electrical measurements. The films had polycrystalline In₂O₃ structure. High transparency and resistivity of 3.7x10^-4 Ω cm were obtained

[en] In this paper, the possibilities of rare-earth oxides as gate dielectrics are discussed. The thin films have mostly been fabricated by physical vapor deposition methods. The rare earths most often studied are yttrium, lanthanum and gadolinium. The deposition of the gate oxide should be carried out under mild conditions, and therefore chemical deposition techniques are preferred. Atomic layer deposition of rare-earth oxides is introduced and special attention is given to the volatile precursors and deposition processes. The electrical properties of rare-earth oxide gate oxides will be highlighted. The results obtained are encouraging and the use of rare-earth oxides in gate stacks is possible. Especially, they may be important in connection to III-V compounds

[en] Stoichiometric HfO₂ films were atomic layer deposited from HfI₄ and HfCl₄ at 300 deg. C on p-Si(1 0 0) substrates. Water was in both cases used as an oxygen precursor. The films consisted dominantly of monoclinic HfO₂ phase. Additional tetragonal HfO₂ could be detected only in the films grown from HfCl₄. Effective permittivities were frequency-independent and varied in the range of 12-14, without clear dependence on the precursor used. Oxide rechargeable trap densities were relatively high for the films grown from HfCl₄. The films grown from HfI₄ were more resistant against breakdown. The films grown from either precursor contained 0.4 at.% of halide residues and 1.0-1.5 at.% hydrogen. Annealing in forming gas at 400 deg. C did not affect the film composition. The growth rate was somewhat more stable in the HfI₄ based process

[en] Hf-Si-O mixture films were fabricated by atomic layer deposition at 400 deg. C on Si(1 0 0) substrates. The deposition sequence for one hafnium silicon oxide submonolayer comprises surface reactions between Si(OC₂H₅)₄ and HfCl₄, followed by the hydrolysis step in order to effectively remove the residual ligands. The effective permittivity, leakage current, and capacitance-voltage behavior depended on the hafnium/silicon ratio and on the oxide/silicon interface quality. The dielectric quality can be modulated for various configurations of stacked layers with different hafnium to silicon ratios

[en] Reaction mechanisms in the Ti(NMe₂)₂(OⁱPr)₂-D₂O and Ti(OⁱPr)₃[MeC(NⁱPr)₂] [also written Ti(OⁱPr)₃(NⁱPr-Me-amd)]-D₂O atomic layer deposition processes were studied in situ with quartz crystal microbalance (QCM) and quadrupole mass spectrometry (QMS) at 275 °C. For the Ti(NMe₂)₂(OⁱPr)₂-D₂O process, both QCM and QMS results indicated adsorption of the Ti(NMe₂)₂(OⁱPr)₂ molecule through an exchange of at least one of its –NMe₂ ligands with surface hydroxyl groups. Regarding the Ti(OⁱPr)₃(NⁱPr-Me-amd)-D₂O process, a mismatch between the QCM and QMS results revealed more complex reactions: the decomposition of the [MeC(NⁱPr)₂] [also written (NⁱPr-Me-amd)] ligand is suggested by the shape of the QCM data and the intensity of the QMS signals belonging to fragments of the [MeC(NⁱPr)₂] [also written (NⁱPr-Me-amd)] ligand. A simple calculation model associating the growth rate per cycle of a crystalline film and the surface area taken by the ligands remaining after saturation was also used to support the decomposition of the [MeC(NⁱPr)₂] [also written (NⁱPr-Me-amd)] ligand. The observed high growth rate is incompatible with the whole [MeC(NⁱPr)₂] (also written [NⁱPr-Me-amd)] ligand remaining on the surface

[en] Nanotubular titanium dioxide thin films were prepared by anodization of titanium metal films evaporated on indium tin oxide (ITO) coated glass. A facile method to enhance the adhesion of the titanium film to the ITO glass was developed. An optimum thickness of 550 nm for the evaporated titanium was found to keep the film adhered to ITO during the anodization. The films were further modified by growing amorphous titania, alumina and tantala thin films conformally in the nanotubes by atomic layer deposition (ALD). The optical, electrical and physical properties of the different structures were compared. It was shown that even 5 nm thin layers can modify the properties of the nanotubular titanium dioxide films. (paper)

[en] A versatile synthesis procedure for composite nanofibers, combining electrospinning and atomic layer deposition (ALD), is presented. Both solid core/sheath nanofibers and nanoparticle loaded nanotubes can be made, depending on the order of calcination of the electrospun fiber and the ALD process. Magnetic and photocatalytic nanofibers prepared this way can be recycled readily by collecting with a magnet.

[en] Nanotubular Ta₂O₅- and TiO₂-based structures were prepared by atomic layer deposition of Ta₂O₅ and TiO₂ thin films, conformally on pore walls of porous alumina membranes. Both self-supporting alumina membranes and Si-supported thin-film membranes were studied as templates. Long Ta₂O₅ and TiO₂ nanotubes were prepared successfully with the self-supporting membranes. The TiO₂ nanotubes showed photocatalytic activity in methylene blue degradation under UV illumination. The Ta₂O₅ and TiO₂ nanotubes were further modified by depositing Pt nanoparticles inside them. The Si-supported thin-film membranes were used as templates for the preparation of robust Ta₂O₅-coated Ni nanorod arrays on a Si substrate using electrodeposition, chemical etching and atomic layer deposition. In addition to photocatalysis, the nanostructures prepared in this work may find applications as other catalysts and as solid-state or electrochemical capacitors.

[en] Self-assembled monolayers (SAMs) of 1-dodecanethiol (CH₃(CH₂)₁₁SH) were prepared from the vapor phase and used as a passivation layer for selective-area ALD. Thiol SAMs have commonly been prepared by immersing the substrates into a solution containing alkyl thiols. Formation of SAMs from the vapor phase, however, has advantages compared to liquid phase preparation. Passivation of surface can be done as a part of the ALD process forming a SAM first and then continuing with the common ALD process. SAMs can also be applied to three-dimensional structures relying on chemical selectivity of the thiol SAM formation. For example in the copper damascene process the thiol SAMs should form only on the copper surface but not on the insulators. In this study, the SAMs were prepared by placing the substrate and the alkylthiol to the reaction chamber and heating the system to the temperature of 73 °C. Preparation time varied from 0.5 to 24 h. Passivation properties of SAMs were tested with ALD iridium and polyimide processes. Iridium was deposited at 250  ° C for 500 cycles and polyimide at 160  ° C for 20 cycles. (paper)

[en] Thin films from transition metal oxides have become of increasing interest for various applications, especially in high-k and resistive switching devices. In this work, we studied the influence of processing on the structural, morphological and electrical properties of ZrO₂ and combination of ZrO₂/TiO₂ in the form of laminates and bilayers. The films were deposited from Zr(NEtMe)₄ (TEMAZ) and Ti(OiPr)₄ (TTIP) by atomic layer deposition using ozone or water as the oxygen sources. Deposition temperatures were 200 C, 240 C, and 280 C. The films were characterized with X-ray diffraction, X-ray reflectometry, atomic force microscopy, scanning electron microscopy, and electrical measurements. Differences in structure and electrical properties were found depending on type of oxygen source. Ozone grown ZrO2 films showed an (111) oriented cubic structure, whereas the ones deposited with water were polycrystalline with a cubic/tetragonal mixed phase in thicker films. Resistive switching of metal-insulator-metal structures was scrutinized. Structures like Pt/ZrO₂/Ti/Pt, Pt/ZrO/TiO₂/Ti/Pt, and Pt/TiO₂/ZrO₂/Ti/Pt showed different kinds of resistive switching behavior.