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An investigation of the etching characteristics and mechanism for both Si and SiO2 in CF4/C4F8/Ar inductively coupled plasmas under a constant gas pressure (4 mTorr), total gas flow rate (40 sccm), input power (800 W), and bias power (150 W) was performed. It was found that the variations in the CF4/C4F8 mixing ratio in the range of 0-50% at a constant Ar fraction of 50% resulted in slightly non-monotonic Si and SiO2 etching rates in CF4-rich plasmas and greatly decreasing etching rates in C4F8-rich plasmas. The zero-dimensional plasma model, Langmuir probe diagnostics, and optical emission spectroscopy provided information regarding the formation-decay kinetics for the plasma active species, along with their densities and fluxes. The model-based analysis of the etching kinetics indicated that the non-monotonic etching rates were caused not by the similar behavior of the fluorine atom density but rather by the opposite changes of the fluorine atom flux and ion energy flux. It was also determined that the great decrease in both the Si and SiO2 etching rates during the transition from the CF4/Ar to C4F8/Ar gas system was due to the deposition of the fluorocarbon polymer film.

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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 Ion/Ioff 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 normalCl2∕Ar , normalCl2∕He , and normalCl2∕normalN2 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 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 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.