Stoichiometric crystalline binary metal oxide thin films can be used as channel materials for transparent thin film transistors. However, the nature of the process used to fabricate these films causes most binary metal oxide thin films to be highly conductive, making them unsuitable for channel materials. We overcame this hurdle by forming stoichiometric ultra-thin (5 nm) crystalline In₂O₃ films by using a thermal atomic layer deposition method. Specifically, (3-(dimethylamino)propyl)dimethylindium was used as a liquid precursor and ozone as an oxygen source to grow In₂O₃ thin films at a high growth rate of 0.06 nm/cycle. Adjustment of the deposition processing temperature followed by annealing in an oxygen atmosphere enabled us to fully crystallize the film into a cubic bixbyite structure with the retained stoichiometry. The transparent crystalline ultra-thin In₂O₃-based bottom-gate thin film transistors showed excellent and statistically uniform switching characteristics such as a high I_on/I_off ratio exceeding 10⁷, a high linear mobility of 41.8 cm²/V s, a small subthreshold swing of 100 mV/dec, and a low hysteresis of 0.05 V. Our approach offers a straightforward scheme, which is compatible with oxide electronics, for fabricating a transparent metal oxide device without resorting to complicated oxide compositional strategies.

This work reports the influence of gas mixing ratio on the <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Ar</mml:mi></mml:mrow></mml:math>Cl2∕Ar , <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">He</mml:mi></mml:mrow></mml:math>Cl2∕He , and <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Cl2∕N2 plasma parameters, steady-state densities, and fluxes of active species in the planar inductively coupled plasma reactor. The investigation combined plasma diagnostics by Langmuir probes and quadrupole mass spectroscopy with a global (zero-dimensional) plasma model. It was shown that the dilution of <mml:math display="inline"><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>Cl2 by any additive gas results in a noticeable change in both the electron temperature and density, as well as provides the acceleration in the electron impact dissociation kinetics of <mml:math display="inline"><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>Cl2 molecules. No qualitative differences for the given three systems in regard to relative changes in active species densities and model-predicted etch rate behaviors were obtained.

This work summarizes the results of our previous studies related to investigations of reactive ion etching kinetics and mechanisms for widely used silicon-based materials (SiC, SiO₂, and Si_xN_y) as well as for the silicon itself in multi-component fluorocarbon gas mixtures. The main subjects were the three-component systems composed either by one fluorocarbon component (CF₄, C₄F₈, CHF₃) with Ar and O₂ or by two fluorocarbon components with one additive gas. The investigation scheme included plasma diagnostics by Langmuir probes and model-based analysis of plasma chemistry and heterogeneous reaction kinetics. The combination of these methods allowed one (a) to figure out key processes which determine the steady-state plasma parameters and densities of active species; (b) to understand relationships between processing conditions and basic heterogeneous process kinetics; (c) to analyze etching mechanisms in terms of process-condition-dependent effective reaction probability and etching yield; and (d) to suggest the set gas-phase-related parameters (fluxes and flux-to-flux ratios) to control the thickness of the fluorocarbon polymer film and the change in the etching/polymerization balance. It was shown that non-monotonic etching rates as functions of gas mixing ratios may result from monotonic but opposite changes in F atoms flux and effective reaction probability. The latter depends either on the fluorocarbon film thickness (in high-polymerizing and oxygen-less gas systems) or on heterogeneous processes with a participation of O atoms (in oxygen-containing plasmas). It was suggested that an increase in O₂ fraction in a feed gas may suppress the effective reaction probability through decreasing amounts of free adsorption sites and oxidation of surface atoms.