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Couches organiques ultra minces greffées sur Si (111) pour la microélectronique

Dorin Dusciac
Abstract : The use of high-K oxides as gate dielectrics in MOS Field Effect Transistors appears as a mandatory step to maintain the continuous increase of the electric performances of these electronic devices. Unfortunately, the deposition of these oxides generates serious problems (formation of an intermediate silicon oxide or metallic silicide layer, poor control of the electronic quality of interfaces, low carrier mobility, etc.). Direct grafting of organic monolayers on Si prior to high-K material deposition appears as an efficient method for obtaining a high-quality Si/high-K interface. The grafting of organic saturated chains by Si-O-C bonding has been explored. Thermal stability of the grafted monolayers has been studied using infrared spectroscopy. The spectra indicate that monolayer decomposition takes place via the fragmentation of the grafted chains rather than via Si-O-C bond breaking. This process has been modeled with a numerical simulation. For the optimization of the grafted organic monolayers, efforts have been oriented towards the grafting of ultra-short functional chains with hydrophilic end groups. However, the functional end groups of these chains may interfere with the grafting reaction, either by inhibiting the reactivity of the end group to be grafted, or by inducing parasitic reactions. The hydrolysis of short grafted esters has not been achieved without the parallel hydrolysis of the Si-O-C bonding. The deposition of HfO2 layers has been performed on organic monolayers that can be grafted in controlled conditions. The deposited layers are continuous, nevertheless their roughness is higher than that of layers deposited directly onto non-grafted silicon surfaces. Infrared analysis indicates partial decomposition of the organic layer but the silicon surface appears well protected from oxidation. These preliminary results suggest that the thermal stability of the organic layer does not constitute an insurmountable barrier and that the explored pathway may be considered as viable. Key-words: organic layers, high-K oxides, grafting, infrared spectroscopy, thermal stability, hydrolysis
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Dorin Dusciac. Couches organiques ultra minces greffées sur Si (111) pour la microélectronique. Engineering Sciences [physics]. Ecole Polytechnique X, 2008. English. ⟨pastel-00004637⟩

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