Short-chain aminosilanes, namely, bis(N,Ndimethylamino)dimethylsilane (DMADMS) and (N,Ndimethylamino)trimethylsilane (DMATMS), have been used as Si precursors for atomic layer deposition (ALD) of SiO 2 . In this work, the DMADMS and DMATMS Si precursors are utilized as inhibitors for area-selective ALD (AS-ALD). The inhibitors selectively adsorb on a SiO 2 surface but not on H− Si, so that SiO 2 becomes selectively deactivated toward subsequent ALD. The deactivation of the SiO 2 surface by the inhibitors was investigated using various experimental and theoretical methods, including surface potential measurements, spectroscopic ellipsometry, and X-ray photoelectron spectroscopy. Better inhibition was observed for ALD of Ru and Pt than for ALD of Al 2 O 3 and HfO 2 . Through quantum mechanical and stochastic simulations, the difference in the blocking ability for noble metal and metal oxide ALD by the aminosilane inhibitors could be attributed to the inherently partial surface coverage by the inhibitors at their saturation and the reactivity of the subsequent ALD precursors. As silane inhibitors can be easily integrated with vacuum-based processes to facilitate high volume manufacturing of upcoming electronic devices, the current study provides a potential approach for the utilization of AS-ALD in pattern fabrication inside 3D nanostructures.
Atomic layer deposition (ALD), based on selflimiting surface reactions, has been proven as a superior deposition method for synthesis of nanoscale thin films. In the field of oxide ALD, alumina (Al 2 O 3 ) is the most widely and thoroughly studied, prominently through using trimethylaluminum (TMA) with water (H 2 O). However, there is less information about other group 13 element (B, Ga, and In) oxides using analogous trimethyl precursors. In this study, we investigate these precursors' detailed adsorption and oxidation mechanisms during thermal ALD using density functional theory (DFT). The hydroxyl-terminated surface is transformed to a methyl-terminated surface after reacting with the trimethyl precursors. For such reaction, the reactivity of trimethylboron is significantly lower than other precursors. Meanwhile, using H 2 O, oxidation of the surface methyl is facile only for −Al−CH 3 , and stronger oxidants such as H 2 O 2 or O 3 are required for the oxidation reactions during ALD of B, Ga, and In oxides.
Due to their atomic thicknesses and semiconducting properties, two-dimensional transition metal dichalcogenides (TMDCs) are gaining increasing research interest. Among them, Hf- and Zr-based TMDCs demonstrate the unique advantage that their oxides (HfO2 and ZrO2) are excellent dielectric materials. One possible method to precisely tune the material properties of two-dimensional atomically thin nanomaterials is to adsorb molecules on their surfaces as non-bonded dopants. In the present work, the molecular adsorption of NO2 and NH3 on the two-dimensional trigonal prismatic (1H) and octahedral (1T) phases of Hf and Zr dichalcogenides (S, Se, Te) is studied using dispersion-corrected periodic density functional theory (DFT) calculations. The adsorption configuration, energy, and charge-transfer properties during molecular adsorption are investigated. In addition, the effects of the molecular dopants (NH3 and NO2) on the electronic structure of the materials are studied. It was observed that the adsorbed NH3 donates electrons to the conduction band of the Hf (Zr) dichalcogenides, while NO2 receives electrons from the valance band. Furthermore, the NO2 dopant affects than NH3 significantly. The resulting band structure of the molecularly doped Zr and Hf dichalcogenides are modulated by the molecular adsorbates. This study explores, not only the properties of the two-dimensional 1H and 1T phases of Hf and Zr dichalcogenides (S, Se, Te), but also tunes their electronic properties by adsorbing non-bonded dopants.
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